Science.gov

Sample records for heat flux performance

  1. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8%Y2O3 specimens survived 3000 of the 0.5 sec cycles with failing. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12%Y2O3 or ZrO2-20%Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  2. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8 percent Y203 specimens survived 3000 of the 0.5 sec cycles with failing. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12 percent Y2O3 or ZrO2-20 percent Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  3. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8 percent Y2O3 specimens survived 3000 of the 0.5 sec cycles with falling. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 1 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12 percent Y2O3 or ZrO2-2O percent Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  4. Experimental Performance of a Micromachined Heat Flux Sensor

    NASA Technical Reports Server (NTRS)

    Stefanescu, S.; DeAnna, R. G.; Mehregany, M.

    1998-01-01

    Steady-state and frequency response calibration of a microfabricated heat-flux sensor have been completed. This sensor is batch fabricated using standard, micromachining techniques, allowing both miniaturization and the ability to create arrays of sensors and their corresponding interconnects. Both high-frequency and spatial response is desired, so the sensors are both thin and of small cross-sectional area. Thin-film, temperature-sensitive resistors are used as the active gauge elements. Two sensor configurations are investigated: (1) a Wheatstone-bridge using four resistors; and (2) a simple, two-resistor design. In each design, one resistor (or pair) is covered by a thin layer (5000 A) thermal barrier; the other resistor (or pair) is covered by a thick (5 microns) thermal barrier. The active area of a single resistor is 360 microns by 360 microns; the total gauge area is 1.5 mm square. The resistors are made of 2000 A-thick metal; and the entire gauge is fabricated on a 25 microns-thick flexible, polyimide substrate. Heat flux through the surface changes the temperature of the resistors and produces a corresponding change in resistance. Sensors were calibrated using two radiation heat sources: (1) a furnace for steady-state, and (2) a light and chopper for frequency response.

  5. Critical heat flux performance of hypervapotrons proposed for use in the ITER divertor vertical target

    SciTech Connect

    Youchison, D.L.; Marshall, T.D.; McDonald, J.M.; Lutz, T.J.; Watson, R.D.; Driemeyer, D.E. Kubik, D.L.; Slattery, K.T.; Hellwig, T.H.

    1997-09-01

    Task T-222 of the International Thermonuclear Experimental Reactor (ITER) program addresses the manufacturing and testing of permanent components for use in the ITER divertor. Thermalhydraulic and critical heat flux performance of the heat sinks proposed for use in the divertor vertical target are part of subtask T-222.4. As part of this effort, two single channel, medium scale, bare copper alloy, hypervapotron mockups were designed, fabricated, and tested using the EB-1200 electron beam system. The objectives of the effort were to develop the design and manufacturing procedures required for construction of robust high heat flux (HHF) components, verify thermalhydraulic, thermomechanical and critical heat flux (CHF) performance under ITER relevant conditions, and perform analyses of HHF data to identify design guidelines and failure criteria and possibly modify any applicable CHF correlations. The design, fabrication, and finite element modeling of two types of hypervapotrons are described; a common version already in use at the Joint European Torus (JET) and a new attached fin design. HHF test data on the attached fin hypervapotron will be used to compare the CHF performance under uniform heating profiles on long heated lengths with that of localized, highly peaked, off nominal profiles.

  6. High flux heat exchanger

    NASA Astrophysics Data System (ADS)

    Flynn, Edward M.; Mackowski, Michael J.

    1993-01-01

    This interim report documents the results of the first two phases of a four-phase program to develop a high flux heat exchanger for cooling future high performance aircraft electronics. Phase 1 defines future needs for high flux heat removal in advanced military electronics systems. The results are sorted by broad application categories: (1) commercial digital systems, (2) military data processors, (3) power processors, and (4) radar and optical systems. For applications expected to be fielded in five to ten years, the outlook is for steady state flux levels of 30-50 W/sq cm for digital processors and several hundred W/sq cm for power control applications. In Phase 1, a trade study was conducted on emerging cooling technologies which could remove a steady state chip heat flux of 100 W/sq cm while holding chip junction temperature to 90 C. Constraints imposed on heat exchanger design, in order to reflect operation in a fighter aircraft environment, included a practical lower limit on coolant supply temperature, the preference for a nontoxic, nonflammable, and nonfreezing coolant, the need to minimize weight and volume, and operation in an accelerating environment. The trade study recommended the Compact High Intensity Cooler (CHIC) for design, fabrication, and test in the final two phases of this program.

  7. An experimental investigation of critical heat flux performance of hypervapotron in subcooled boiling

    NASA Astrophysics Data System (ADS)

    Chen, Peipei

    The successful use of subcooled flow boiling for high heat flux components requires that the critical heat flux (CHF), i.e., a fast reduction in the boiling heat transfer, must be avoided. Among the many techniques available to enhance CHF, particular attention has been focused on the hypervapotron concept. In this study, the CHF characteristics of the hypervapotron were experimentally investigated using a simulant fluid, R134a, which has been found to be an effective modeling fluid to simulate CHF in water-cooled environments. An experimental and modeling study of the subcooled boiling heat transfer on plain surface and hypervapotron has been conduced. A test facility was designed and constructed to perform required boiling heat transfer experiments. A high speed visualization system was utilized to give details of bubble formation and departure and of nucleation site density. Surface measurements of various specimens were performed to investigate the relationship between nucleation sites and surface microstructure. Full characterization of the hypervapotron effect as a function of fluid thermal hydraulic conditions was accomplished. A non-dimensional CHF correlation for smooth rectangular channels and the hypervapotron channel was developed and compared with experimental data in this work. In addition, a hot-spot model was developed to give predictions of critical heat flux on both plain and hypervapotron surfaces. It was developed on observations of bubble formation, departure and coalescence, and on the confirmation of nucleation structure on the heating surface. Finally, a numerical code was successfully developed to give CHF predictions for hypervapotron configurations. The simulation indicates that the better performance of CHF in hypervapotron configurations is a result of high conductivity material with augmented heating surfaces in subcooled boiling environment. Different fin dimensions were also tested numerically to compare the experimental results, and

  8. Arterial heat pipe performance in a transient heat flux and body force environment

    NASA Astrophysics Data System (ADS)

    Yerkes, Kirk L.; Beam, Jerry E.

    1992-10-01

    This paper reports on the effects of transient transverse and axial acceleration forces with step changes in input power on the performance of a flexible copper/water arterial heat pipe. Transient transverse accelerations were generated using a centrifuge table to simulate acceleration forces typifying high performance aircraft maneuvering. These transients consisted of step changes, steady periodic, and burst cycles in the transverse acceleration forces. Steady periodic and burst cycle transverse accelerations had frequencies of 0.01 and 0.03 Hz with peak-to-peak values of 1.1 to 9.8 g. Partial depriming of the artery, pooling of the unconstrained working fluid, and fluid sloshing were found to have a significant impact on the heat transport potential and transient behavior of the heat pipe. Repriming of the heat pipe under thermal load while being subjected to transient transverse accelerations was also demonstrated.

  9. Arterial heat pipe performance in a transient heat flux and body force environment

    SciTech Connect

    Yerkes, K.L.; Beam, J.E.

    1992-01-01

    This paper reports on the effects of transient transverse and axial acceleration forces with step changes in input power on the performance of a flexible copper/water arterial heat pipe. Transient transverse accelerations were generated using a centrifuge table to simulate acceleration forces typifying high performance aircraft maneuvering. These transients consisted of step changes, steady periodic, and burst cycles in the transverse acceleration forces. Steady periodic and burst cycle transverse accelerations had frequencies of 0.01 and 0.03 Hz with peak-to-peak values of 1.1 to 9.8 g. Partial depriming of the artery, pooling of the unconstrained working fluid, and fluid sloshing were found to have a significant impact on the heat transport potential and transient behavior of the heat pipe. Repriming of the heat pipe under thermal load while being subjected to transient transverse accelerations was also demonstrated. 22 refs.

  10. High heat flux performance of brazed tungsten macro-brush test mock-up for divertors

    NASA Astrophysics Data System (ADS)

    Patil, Yashashri; Khirwadkar, S. S.; Krishnan, D.; Patel, A.; Tripathi, S.; Singh, K. P.; Belsare, S. M.

    2013-06-01

    Plasma facing components (PFCs) of divertor will be exposed to steady state and transient heat loads up to 20 MW/m2, during operation of ITER-like plasma fusion device. The critical task in fusion research is to design, fabricate and test of PFCs. To withstand high heat loads, PFCs are designed and fabricated in flat tile, mono-block type geometries using tungsten as plasma facing material and CuCrZr alloy is used as a heat sink. These fabricated mock-ups are tested under thermal cyclic heat loads using intense electron beam in pulsed mode. Tungsten macro-brush type of mock-up has been developed by vacuum furnace brazing route. Mock-up was tested to the absorbed heat flux in the range of 0.5-9 MW/m2. Simulation of high heat flux (HHF) test under steady state and cyclic heat loads has been done using ANSYS12 finite element analysis (FEA) software. HHF tests have been successfully performed on the tungsten mock-up.

  11. Electron heat flux instability

    NASA Astrophysics Data System (ADS)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Lazar, M.; Qureshi, M. N. S.

    2017-02-01

    The heat flux instability is an electromagnetic mode excited by a relative drift between the protons and two-component core-halo electrons. The most prominent application may be in association with the solar wind where drifting electron velocity distributions are observed. The heat flux instability is somewhat analogous to the electrostatic Buneman or ion-acoustic instability driven by the net drift between the protons and bulk electrons, except that the heat flux instability operates in magnetized plasmas and possesses transverse electromagnetic polarization. The heat flux instability is also distinct from the electrostatic counterpart in that it requires two electron species with relative drifts with each other. In the literature, the heat flux instability is often called the 'whistler' heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. This paper elucidates all of these fundamental plasma physical properties associated with the heat flux instability starting from a simple model, and gradually building up more complexity towards a solar wind-like distribution functions. It is found that the essential properties of the instability are already present in the cold counter-streaming electron model, and that the instability is absent if the protons are ignored. These instability characteristics are highly reminiscent of the electron firehose instability driven by excessive parallel temperature anisotropy, propagating in parallel direction with respect to the ambient magnetic field, except that the free energy source for the heat flux instability resides in the effective parallel pressure provided by the counter-streaming electrons.

  12. High heat flux single phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  13. High heat flux single phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  14. Progress on performance assessment of ITER enhanced heat flux first wall technology after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hirai, T.; Bao, L.; Barabash, V.; Chappuis, Ph; Eaton, R.; Escourbiac, F.; Giqcuel, S.; Merola, M.; Mitteau, R.; Raffray, R.; Linke, J.; Loewenhoff, Th; Pintsuk, G.; Wirtz, M.; Boomstra, D.; Magielsen, A.; Chen, J.; Wang, P.; Gervash, A.; Safronov, V.

    2016-02-01

    ITER first wall (FW) panels are irradiated by energetic neutrons during the nuclear phase. Thus, an irradiation and high heat flux testing programme is undertaken by the ITER organization in order to evaluate the effects of neutron irradiation on the performance of enhanced heat flux (EHF) FW components. The test campaign includes neutron irradiation (up to 0.6-0.8 dpa at 200 °C-250 °C) of mock-ups that are representative of the final EHF FW panel design, followed by thermal fatigue tests (up to 4.7 MW m-2). Mock-ups were manufactured by the same manufacturing process as proposed for the series production. After a pre-irradiation thermal screening, eight mock-ups will be selected for the irradiation campaigns. This paper reports the preparatory work of HHF tests and neutron irradiation, assessment results as well as a brief description of mock-up manufacturing and inspection routes.

  15. Critical heat flux performance of hypervapotrons proposed for use in the ITER divertor vertical target

    NASA Astrophysics Data System (ADS)

    Youchison, Dennis L.; Marshall, Theron D.; McDonald, Jimmie M.; Lutz, Thomas J.; Watson, Robert D.; Driemeyer, Daniel E.; Kubik, David L.; Slattery, Kevin T.; Hellwig, Theodore H.

    1997-12-01

    Task T-222 of the International Thermonuclear Experimental Reactor (ITER) program addresses the manufacturing and testing of permanent components for use in the ITER divertor. Thermal-hydraulic and critical heat flux performance of the heat sinks proposed for use in the divertor vertical target are part of subtask T-222.4. As part of this effort, two single channel, medium-scale, bare copper alloy, hypervapotron mock-ups were designed by Sandia National Laboratories and McDonnell Douglas Aerospace (MDA), fabricated at MDA and tested at Sandia' Plasma Materials Test Facility using the EB-1200 electron beam system. The objectives of our effort were to develop the design and manufacturing procedures required for construction of robust HHF components, verify thermal-hydraulic, thermomechanical and CHF performance under ITER relevant conditions, and perform analyses of HHF data to identify design guidelines, failure criteria and possibly modify any applicable CHF correlations. This paper describes the design, fabrication and finite elements modeling of two types of hypervapotrons, a common version already in use at JET and a new attached- fin design. HHF test data on the attached-fin hypervapotron will be used to compare the CHF performance under uniform heating profiles on long heated lengths to that of localized, highly peaked, off-nominal profiles.

  16. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MaCarthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  17. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  18. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises a plurality of respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  19. Optical heat flux gauge

    SciTech Connect

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.

    1991-06-25

    A heat flux gauge is described comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  20. Optical heat flux gauge

    SciTech Connect

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.

    1989-06-07

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figs.

  1. Optical heat flux gauge

    SciTech Connect

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MaCarthur, C.D.; Cala, G.C.

    1991-09-03

    A heat flux gauge is described comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figures.

  2. Latent Heat in Soil Heat Flux Measurements

    USDA-ARS?s Scientific Manuscript database

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  3. Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

    NASA Astrophysics Data System (ADS)

    Afshari, Ebrahim; Ziaei-Rad, Masoud; Jahantigh, Nabi

    2016-06-01

    In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

  4. Optical heat flux gauge

    DOEpatents

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.

    1991-04-09

    A heat flux gauge is disclosed comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figures.

  5. Heat Flux Sensor Testing

    NASA Astrophysics Data System (ADS)

    Clark, D. W.

    2002-07-01

    This viewgraph presentation provides information on the following objectives: Developing secondary calibration capabilities for MSFC's (Marshall Space Flight Center) Hot Gas Facility (HGF), a Mach 4 Aerothermal Wind Tunnel; Evaluating ASTM (American Society for Testing and Materials) slug/ thinskin calorimeters against current HGF heat flux sensors; Providing verification of baselined AEDC (Arnold Engineering Development Center) / Medtherm gage calibrations; Addressing future calibration issues involving NIST (National Institute of Standards and Technology) certified radiant gages.

  6. Heat Flux Sensor Testing

    NASA Technical Reports Server (NTRS)

    Clark, D. W.

    2002-01-01

    This viewgraph presentation provides information on the following objectives: Developing secondary calibration capabilities for MSFC's (Marshall Space Flight Center) Hot Gas Facility (HGF), a Mach 4 Aerothermal Wind Tunnel; Evaluating ASTM (American Society for Testing and Materials) slug/ thinskin calorimeters against current HGF heat flux sensors; Providing verification of baselined AEDC (Arnold Engineering Development Center) / Medtherm gage calibrations; Addressing future calibration issues involving NIST (National Institute of Standards and Technology) certified radiant gages.

  7. Design and performance of vacuum system for high heat flux test facility

    NASA Astrophysics Data System (ADS)

    Swamy Kidambi, Rajamannar; Mokaria, Prakash; Khirwadkar, Samir; Belsare, Sunil; Khan, M. S.; Patel, Tushar; Krishnan, Deepu S.

    2017-04-01

    High heat flux test facility (HHFTF) at IPR is used for testing thermal performance of plasma facing materials or components. It consists of various subsystems like vacuum system, high power electron beam system, diagnostic and calibration system, data acquisition and control system and high pressure high temperature water circulation system. Vacuum system consists of large D-shaped chamber, target handling system, pumping systems and support structure. The net volume of vacuum chamber is 5 m3 was maintained at the base pressure of the order of 10-6 mbar for operation of electron gun with minimum beam diameter which is achieved with turbo-molecular pump (TMP) and cryo pump. A variable conductance gate valve is used for maintaining required vacuum in the chamber. Initial pumping of the chamber was carried out by using suitable rotary and root pumps. PXI and PLC based faster real time data acquisition and control system is implemented for performing the various operations like remote operation, online vacuum data measurements, display and status indication of all vacuum equipments. This paper describes in detail the design and implementation of various vacuum system for HHFTF.

  8. High Flux Heat Exchanger

    DTIC Science & Technology

    1993-01-01

    called an enhancement surfkce) is bonded to the chip. In both cases, the electronics board is immersed in a dielectric coolant . Bare chip cooling...the stocking of a dielectric coolant , which add to complexity and maintenance costs. 4. High performance heat pipe heat spreaders have demonstrated

  9. Flow-Boiling Critical Heat Flux Experiments Performed in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Hasan, Mohammad M.; Mudawar, Issam

    2005-01-01

    Poor understanding of flow boiling in microgravity has recently emerged as a key obstacle to the development of many types of power generation and advanced life support systems intended for space exploration. The critical heat flux (CHF) is perhaps the most important thermal design parameter for boiling systems involving both heatflux-controlled devices and intense heat removal. Exceeding the CHF limit can lead to permanent damage, including physical burnout of the heat-dissipating device. The importance of the CHF limit creates an urgent need to develop predictive design tools to ensure both the safe and reliable operation of a two-phase thermal management system under the reduced-gravity (like that on the Moon and Mars) and microgravity environments of space. At present, very limited information is available on flow-boiling heat transfer and the CHF under these conditions.

  10. Surface renewal performance to independently estimate sensible and latent heat fluxes in heterogeneous crop surfaces

    NASA Astrophysics Data System (ADS)

    Suvočarev, K.; Shapland, T. M.; Snyder, R. L.; Martínez-Cob, A.

    2014-02-01

    Surface renewal (SR) analysis is an interesting alternative to eddy covariance (EC) flux measurements. We have applied two recent SR approaches, with different theoretical background, that from Castellví (2004), SRCas, and that from Shapland et al. (2012a,b), SRShap. We have applied both models for sensible (H) and latent (LE) heat flux estimation over heterogeneous crop surfaces. For this, EC equipments, including a sonic anemometer CSAT3 and a krypton hygrometer KH20, were located in two zones of drip irrigated orchards of late and early maturing peaches. The measurement period was June-September 2009. The SRCas is based on similarity concepts for independent estimation of the calibration factor (α), which varies with respect to the atmospheric stability. The SRShap is based on analysis of different ramp dimensions, separating the ones that are flux-bearing from the others that are isotropic. According to the results obtained here, there was a high agreement between the 30-min turbulent fluxes independently derived by EC and SRCas. The SRShap agreement with EC was slightly lower. Estimation of fluxes determined by SRCas resulted in higher values (around 11% for LE) with respect to EC, similarly to previously published works over homogeneous canopies. In terms of evapotranspiration, the root mean square error (RMSE) between EC and SR was only 0.07 mm h-1 (for SRCas) and 0.11 mm h-1 (for SRShap) for both measuring spots. According to the energy balance closure, the SRCas method was as reliable as the EC in estimating the turbulent fluxes related to irrigated agriculture and watershed distribution management, even when applied in heterogeneous cropping systems.

  11. Assessment of the performance of the drag and bulk transfer method in estimating sensible and latent heat fluxes in a tropical station

    NASA Astrophysics Data System (ADS)

    Adeniyi, Mojisola Oluwayemisi; Ogunsola, Oluseyi E.

    2012-02-01

    The performance of the general bulk formulation in estimating sensible heat flux at Nigerian Micrometeorological Experimental site was assessed. Reliable sensible heat flux was estimated with the use of accurate diurnal values of transfer coefficient of sensible heat. The performances of one α, two β and a modified α formulations in the estimation of latent heat flux were also assessed at the station. The Lee and Pielke ( β), modified Kondo ( α), Jacquemin and Noilhan ( α) and Noilhan and Planton ( β) parameterizations gave good estimation of latent heat flux. The coefficient of determination ( R 2) of the models between measured and estimated values were greater than 0.7. Low diurnal mean absolute error and root mean squared error values were found between measured and estimated fluxes. All the parameterizations gave reliable latent heat flux when diurnal values of transfer coefficients of moisture were used.

  12. Performance of an Advanced Stirling Convertor Based on Heat Flux Sensor Measurements

    NASA Technical Reports Server (NTRS)

    Wilson, Dcott D.

    2012-01-01

    The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two highefficiency Advanced Stirling Convertors (ASCs), developed by Sunpower, Inc., and NASA Glenn Research Center. The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot-end and cold-end temperatures, and specified electrical power output for a given heat input. It is difficult to measure heat input to Stirling convertors due to the complex geometries of the hot components, temperature limits of sensor materials, and invasive integration of sensors. A thin-film heat flux sensor was used to directly measure heat input to an ASC. The effort succeeded in designing and fabricating unique sensors, which were integrated into a Stirling convertor ground test and exposed to test temperatures exceeding 700 C in air for 10,000 hr. Sensor measurements were used to calculate thermal efficiency for ASC-E (Engineering Unit) #1 and #4. The post-disassembly condition of the sensors is also discussed.

  13. Performance of an Advanced Stirling Convertor Based on Heat Flux Sensor Measurements

    NASA Technical Reports Server (NTRS)

    Wilson, Scott D.

    2012-01-01

    The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs), developed by Sunpower, Inc., and NASA Glenn Research Center. The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot-end and cold-end temperatures, and specified electrical power output for a given heat input. It is difficult to measure heat input to Stirling convertors due to the complex geometries of the hot components, temperature limits of sensor materials, and invasive integration of sensors. A thin-film heat flux sensor was used to directly measure heat input to an ASC. The effort succeeded in designing and fabricating unique sensors, which were integrated into a Stirling convertor ground test and exposed to test temperatures exceeding 700 C in air for 10,000 hr. Sensor measurements were used to calculate thermal efficiency for ASC-E (Engineering Unit) #1 and #4. The post-disassembly condition of the sensors is also discussed.

  14. Photovoltaic Roof Heat Flux

    NASA Astrophysics Data System (ADS)

    Samady, Mezhgan Frishta

    Solar panels were mounted with different designs onto 1:800 scale building models while temperature and radiation were measured. While there have been other studies aimed at finding the optimal angles for solar panels [9], in this study both the angle and the mounting method were tested. The three PV mounting designs that were considered to provide the most insulation to a building's rooftop were flush, offset (control), and angled. The solar panel offset height became a key component for rooftop insulation as well as the performance of the actual solar panel. Experimental results were given to verify the thermal behavior of the heat loads from the different designs of the photovoltaic panel. From the results, the angled PV design needed 16Z more heat extraction than the offset and flush PV design needed 60% more heat extracted than the offset. In addition to the heat transfer analysis, thermal models were performed to incorporate main atmospheric conditions which were based on the effects of PV mounting structure.

  15. Fundamentals of heat measurement. [heat flux transducers

    NASA Technical Reports Server (NTRS)

    Gerashchenko, O. A.

    1979-01-01

    Various methods and devices for obtaining experimental data on heat flux density over wide ranges of temperature and pressure are examined. Laboratory tests and device fabrication details are supplemented by theoretical analyses of heat-conduction and thermoelectric effects, providing design guidelines and information relevant to further research and development. A theory defining the measure of correspondence between transducer signal and the measured heat flux is established for individual (isolated) heat flux transducers subject to space and time-dependent loading. An analysis of the properties of stacked (series-connected) transducers of various types (sandwich-type, plane, and spiral) is used to derive a similarity theory providing general governing relationships. The transducers examined are used in 36 types of derivative devices involving direct heat loss measurements, heat conduction studies, radiation pyrometry, calorimetry in medicine and industry and nuclear reactor dosimetry.

  16. Heat flux solarimeter

    SciTech Connect

    Sartarelli, A.; Vera, S.; Cyrulies, E.; Echarri, R.; Samson, I.

    2010-12-15

    The solarimeter presented in this work is easy to assemble. It is calibrated and its performance is validated by means of Hottel's method. Finally, the curves obtained with this solarimeter are compared to the ones obtained with a commercial solarimeter. This device is based on the evaluation of the heat flow in a metal rod. In consequence, measurements are not affected by ambient temperature variations. On the other hand, there is a linear relationship between the temperatures measured at the rod ends and the incident radiation, as can be concluded both from the theory of its operation and the calibration lines obtained. The results obtained from the global irradiance measurements in the area of Los Polvorines (Buenos Aires Province), together with a preliminary evaluation of the solarimeter's response time, are presented in this work. (author)

  17. Radial heat flux transformer

    NASA Technical Reports Server (NTRS)

    Basiulis, A.; Buzzard, R. J.

    1971-01-01

    Unit moves heat radially from small diameter shell to larger diameter shell, or vice versa, with negligible temperature drop, making device useful wherever heating or cooling of concentrically arranged materials, substances, and structures is desired.

  18. High heat flux loop heat pipes

    NASA Technical Reports Server (NTRS)

    North, Mark T.; Sarraf, David B.; Rosenfeld, John H.; Maidanik, Yuri F.; Vershinin, Sergey

    1997-01-01

    Loop heat pipes (LHPs) can transport very large thermal power loads over long distances, through flexible, small diameter tubes against gravitational heads. In order to overcome the evaporator limit of LHPs, which is of about 0.07 MW/sq m, work was carried out to improve the efficiency by threefold to tenfold. The vapor passage geometry for the high heat flux conditions is shown. A bidisperse wick material within the circumferential vapor passages was used. Along with heat flux enhancement, several underlying issues were demonstrated, including the fabrication of bidisperse powder with controlled properties and the fabrication of a device geometry capable of replacing vapor passages with bidisperse powder.

  19. Numerical Study of High Heat Flux Performances of Flat-Tile Divertor Mock-ups with Hypervapotron Cooling Concept

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Liu, Xiang; Lian, Youyun; Cai, Laizhong

    2015-09-01

    The hypervapotron (HV), as an enhanced heat transfer technique, will be used for ITER divertor components in the dome region as well as the enhanced heat flux first wall panels. W-Cu brazing technology has been developed at SWIP (Southwestern Institute of Physics), and one W/CuCrZr/316LN component of 450 mm×52 mm×166 mm with HV cooling channels will be fabricated for high heat flux (HHF) tests. Before that a relevant analysis was carried out to optimize the structure of divertor component elements. ANSYS-CFX was used in CFD analysis and ABAQUS was adopted for thermal-mechanical calculations. Commercial code FE-SAFE was adopted to compute the fatigue life of the component. The tile size, thickness of tungsten tiles and the slit width among tungsten tiles were optimized and its HHF performances under International Thermonuclear Experimental Reactor (ITER) loading conditions were simulated. One brand new tokamak HL-2M with advanced divertor configuration is under construction in SWIP, where ITER-like flat-tile divertor components are adopted. This optimized design is expected to supply valuable data for HL-2M tokamak. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2011GB110001 and 2011GB110004)

  20. Heat flux limiting sleeves

    DOEpatents

    Harris, William G.

    1985-01-01

    A heat limiting tubular sleeve extending over only a portion of a tube having a generally uniform outside diameter, the sleeve being open on both ends, having one end thereof larger in diameter than the other end thereof and having a wall thickness which decreases in the same direction as the diameter of the sleeve decreases so that the heat transfer through the sleeve and tube is less adjacent the large diameter end of the sleeve than adjacent the other end thereof.

  1. Characterization of the thermal performance of high heat flux systems at the Laser Hardened Materials Evaluation Laboratory

    NASA Astrophysics Data System (ADS)

    Lander, Michael L.; Bagford, John O.; North, Mark T.; Hull, Robert J.

    1996-11-01

    When developing a high-heat-flux system, it is important to be able to test the system under relevant thermal conditions and environmental surroundings. Thermal characterization testing is best performed in parallel with analysis and design. This permits test results to impact materials selection and systems design decisions. This paper describes the thermal testing and characterization capabilities of the Laser Hardened Materials Evaluation Laboratory located at Wright-Patterson Air Force Base, Ohio. The facility features high-power carbon dioxide (CO2$ and neodymium:glass laser systems that can be teamed with vacuum chambers, wind tunnels, mechanical loading machines and/or ambient test sites to create application-specific thermal and environmental conditions local to the material sample or system. Representative results from recently conducted test series are summarized. The test series described demonstrate the successful use of a high power CO2 laser paired with environment simulation capability to : 1) simulate the expected in-service heat load on a newly developed heat transfer device to ensure its efficient operation prior to design completion, 2) simulate the heat load expected for a laser diode array cooler, 3) produce thermal conditions needed to test a radiator concept designed for space-based operation, and 4) produce thermal conditions experienced by materials use din solid rocket motor nozzles. Test diagnostics systems used to collect thermal and mechanical response data from the test samples are also described.

  2. Towards Improved Estimates of Ocean Heat Flux

    NASA Astrophysics Data System (ADS)

    Bentamy, Abderrahim; Hollman, Rainer; Kent, Elisabeth; Haines, Keith

    2014-05-01

    Recommendations and priorities for ocean heat flux research are for instance outlined in recent CLIVAR and WCRP reports, eg. Yu et al (2013). Among these is the need for improving the accuracy, the consistency, and the spatial and temporal resolution of air-sea fluxes over global as well as at region scales. To meet the main air-sea flux requirements, this study is aimed at obtaining and analyzing all the heat flux components (latent, sensible and radiative) at the ocean surface over global oceans using multiple satellite sensor observations in combination with in-situ measurements and numerical model analyses. The fluxes will be generated daily and monthly for the 20-year (1992-2011) period, between 80N and 80S and at 0.25deg resolution. Simultaneous estimates of all surface heat flux terms have not yet been calculated at such large scale and long time period. Such an effort requires a wide range of expertise and data sources that only recently are becoming available. Needed are methods for integrating many data sources to calculate energy fluxes (short-wave, long wave, sensible and latent heat) across the air-sea interface. We have access to all the relevant, recently available satellite data to perform such computations. Yu, L., K. Haines, M. Bourassa, M. Cronin, S. Gulev, S. Josey, S. Kato, A. Kumar, T. Lee, D. Roemmich: Towards achieving global closure of ocean heat and freshwater budgets: Recommendations for advancing research in air-sea fluxes through collaborative activities. INTERNATIONAL CLIVAR PROJECT OFFICE, 2013: International CLIVAR Publication Series No 189. http://www.clivar.org/sites/default/files/ICPO189_WHOI_fluxes_workshop.pdf

  3. Heat Flux Sensors for Infrared Thermography in Convective Heat Transfer

    PubMed Central

    Carlomagno, Giovanni Maria; de Luca, Luigi; Cardone, Gennaro; Astarita, Tommaso

    2014-01-01

    This paper reviews the most dependable heat flux sensors, which can be used with InfraRed (IR) thermography to measure convective heat transfer coefficient distributions, and some of their applications performed by the authors' research group at the University of Naples Federico II. After recalling the basic principles that make IR thermography work, the various heat flux sensors to be used with it are presented and discussed, describing their capability to investigate complex thermo-fluid-dynamic flows. Several applications to streams, which range from natural convection to hypersonic flows, are also described. PMID:25386758

  4. Heat flux sensors for infrared thermography in convective heat transfer.

    PubMed

    Carlomagno, Giovanni Maria; de Luca, Luigi; Cardone, Gennaro; Astarita, Tommaso

    2014-11-07

    This paper reviews the most dependable heat flux sensors, which can be used with InfraRed (IR) thermography to measure convective heat transfer coefficient distributions, and some of their applications performed by the authors' research group at the University of Naples Federico II. After recalling the basic principles that make IR thermography work, the various heat flux sensors to be used with it are presented and discussed, describing their capability to investigate complex thermo-fluid-dynamic flows. Several applications to streams, which range from natural convection to hypersonic flows, are also described.

  5. Structures for handling high heat fluxes

    NASA Astrophysics Data System (ADS)

    Watson, R. D.

    1990-12-01

    The divertor is reconized as one of the main performance limiting components for ITER. This paper reviews the critical issues for structures that are designed to withstand heat fluxes > 5 MW/m 2. High velocity, sub-cooled water with twisted tape inserts for enhanced heat transfer provides a critical heat flux limit of 40-60 MW/m 2. Uncertainties in physics and engineering heat flux peaking factors require that the design heat flux not exceed 10 MW/m 2 to maintain an adequate burnout safety margin. Armor tiles and heat sink materials must have a well matched thermal expansion coefficient to minimize stresses. The divertor lifetime from sputtering erosion is highly uncertain. The number of disruptions specified for ITER must be reduced to achieve a credible design. In-situ plasma spray repair with thick metallic coatings may reduce the problems of erosion. Runaway electrons in ITER have the potential to melt actively cooled components in a single event. A water leak is a serious accident because of steam reactions with hot carbon, beryllium, or tungsten that can mobilize large amounts of tritium and radioactive elements. If the plasma does not shutdown immediately, the divertor can melt in 1-10 s after a loss of coolant accident. Very high reliability of carbon tile braze joints will be required to achieve adequate safety and performance goals. Most of these critical issues will be addressed in the near future by operation of the Tore Supra pump limiters and the JET pumped divertor. An accurate understanding of the power flow out of edge of a DT burning plasma is essential to successful design of high heat flux components.

  6. Latent heat sink in soil heat flux measurements

    USDA-ARS?s Scientific Manuscript database

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  7. Simulation of Lake Surface Heat Fluxes by the Canadian Small Lake Model: Offline Performance Assessment for Future Coupling with a Regional Climate Model

    NASA Astrophysics Data System (ADS)

    Pernica, P.; Guerrero, J. L.; MacKay, M.; Wheater, H. S.

    2014-12-01

    Lakes strongly influence local and regional climate especially in regions where they are abundant. Development of a lake model for the purpose of integration within a regional climate model is therefore a subject of scientific interest. Of particular importance are the heat flux predictions provided by the lake model since they function as key forcings in a fully coupled atmosphere-land-lake system. The first step towards a coupled model is to validate and characterize the accuracy of the lake model over a range of conditions and to identify limitations. In this work, validation results from offline tests of the Canadian Small Lake Model; a deterministic, computationally efficient, 1D integral model, are presented. Heat fluxes (sensible and latent) and surface water temperatures simulated by the model are compared with in situ observations from two lakes; Landing Lake (NWT, Canada) and L239 (ELA, Canada) for the 2007-2009 period. Sensitivity analysis is performed to identify key parameters important for heat flux predictions. The results demonstrate the ability of the 1-D lake model to reproduce both diurnal and seasonal variations in heat fluxes and surface temperatures for the open water period. These results, in context of regional climate modelling are also discussed.

  8. Novel thin-film heat flux sensors

    NASA Technical Reports Server (NTRS)

    Bhatt, Hemanshu; Zeller, Mary; Will, Herbert

    1992-01-01

    A new and simpler design for thin-film heat flux sensors for utilization in high heat flux environments is presented. The design of these sensors consists of a planar differential thermopile made up of a number of thermocouple pairs arranged in a circular array, two different thermal resistance layers deposited on the inside and outside junctions of the thermopile and a high emissivity coating. This design has shown good potential for measuring heat fluxes in severe environments of aerospace propulsion systems.

  9. Dual Active Surface Heat Flux Gage Probe

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.; Kolodziej, Paul

    1995-01-01

    A unique plug-type heat flux gage probe was tested in the NASA Ames Research Center 2x9 turbulent flow duct facility. The probe was fabricated by welding a miniature dual active surface heat flux gage body to the end of a hollow metal cylindrical bolt containing a metal inner tube. Cooling air flows through the inner tube, impinges onto the back of the gage body and then flows out through the annulus formed between the inner tube and the hollow bolt wall. Heat flux was generated in the duct facility with a Huels arc heater. The duct had a rectangular cross section and one wall was fabricated from 2.54 centimeter thick thermal insulation rigid surface material mounted onto an aluminum plate. To measure heat flux, the probe was inserted through the plate and insulating materials with the from of the gage located flush with the hot gas-side insulation surface. Absorbed heat fluxes measured with the probe were compared with absorbed heat fluxes measured with six water-cooled reference calorimeters. These calorimeters were located in a water-cooled metal duct wall which was located across from the probe position. Correspondence of transient and steady heat fluxes measured with the reference calorimeters and heat flux gage probe was generally within a satisfactory plus or minus 10 percent. This good correspondence was achieved even though the much cooler probe caused a large surface temperature disruption of 1000K between the metal gage and the insulation. However, this temperature disruption did not seriously effect the accuracy of the heat flux measurement. A current application for dual active surface heat flux gages is for transient and steady absorbed heat flux, surface temperature and heat transfer coefficient measurements on the surface of an oxidizer turbine inlet deflector operating in a space shuttle test bed engine.

  10. Dual active surface heat flux gage probe

    NASA Astrophysics Data System (ADS)

    Liebert, Curt H.; Kolodziej, Paul

    1995-02-01

    A unique plug-type heat flux gage probe was tested in the NASA Ames Research Center 2x9 turbulent flow duct facility. The probe was fabricated by welding a miniature dual active surface heat flux gage body to the end of a hollow metal cylindrical bolt containing a metal inner tube. Cooling air flows through the inner tube, impinges onto the back of the gage body and then flows out through the annulus formed between the inner tube and the hollow bolt wall. Heat flux was generated in the duct facility with a Huels arc heater. The duct had a rectangular cross section and one wall was fabricated from 2.54 centimeter thick thermal insulation rigid surface material mounted onto an aluminum plate. To measure heat flux, the probe was inserted through the plate and insulating materials with the from of the gage located flush with the hot gas-side insulation surface. Absorbed heat fluxes measured with the probe were compared with absorbed heat fluxes measured with six water-cooled reference calorimeters. These calorimeters were located in a water-cooled metal duct wall which was located across from the probe position. Correspondence of transient and steady heat fluxes measured with the reference calorimeters and heat flux gage probe was generally within a satisfactory plus or minus 10 percent. This good correspondence was achieved even though the much cooler probe caused a large surface temperature disruption of 1000K between the metal gage and the insulation. However, this temperature disruption did not seriously effect the accuracy of the heat flux measurement. A current application for dual active surface heat flux gages is for transient and steady absorbed heat flux, surface temperature and heat transfer coefficient measurements on the surface of an oxidizer turbine inlet deflector operating in a space shuttle test bed engine.

  11. Expanding Taylor bubble under constant heat flux

    NASA Astrophysics Data System (ADS)

    Voirand, Antoine; Benselama, Adel M.; Ayel, Vincent; Bertin, Yves

    2016-09-01

    Modelization of non-isothermal bubbles expanding in a capillary, as a contribution to the understanding of the physical phenomena taking place in Pulsating Heat Pipes (PHPs), is the scope of this paper. The liquid film problem is simplified and solved, while the thermal problem takes into account a constant heat flux density applied at the capillary tube wall, exchanging with the liquid film surrounding the bubble and also with the capillary tube outside medium. The liquid slug dynamics is solved using the Lucas-Washburn equation. Mass and energy balance on the vapor phase allow governing equations of bubble expansion to be written. The liquid and vapor phases are coupled only through the saturation temperature associated with the vapor pressure, assumed to be uniform throughout the bubble. Results show an over-heating of the vapor phase, although the particular thermal boundary condition used here always ensures an evaporative mass flux at the liquid-vapor interface. Global heat exchange is also investigated, showing a strong decreasing of the PHP performance to convey heat by phase change means for large meniscus velocities.

  12. Pyrolytic graphite gauge for measuring heat flux

    NASA Technical Reports Server (NTRS)

    Bunker, Robert C. (Inventor); Ewing, Mark E. (Inventor); Shipley, John L. (Inventor)

    2002-01-01

    A gauge for measuring heat flux, especially heat flux encountered in a high temperature environment, is provided. The gauge includes at least one thermocouple and an anisotropic pyrolytic graphite body that covers at least part of, and optionally encases the thermocouple. Heat flux is incident on the anisotropic pyrolytic graphite body by arranging the gauge so that the gauge surface on which convective and radiative fluxes are incident is perpendicular to the basal planes of the pyrolytic graphite. The conductivity of the pyrolytic graphite permits energy, transferred into the pyrolytic graphite body in the form of heat flux on the incident (or facing) surface, to be quickly distributed through the entire pyrolytic graphite body, resulting in small substantially instantaneous temperature gradients. Temperature changes to the body can thereby be measured by the thermocouple, and reduced to quantify the heat flux incident to the body.

  13. Convective heat flux in a laser-heated thruster

    NASA Technical Reports Server (NTRS)

    Wu, P. K. S.

    1978-01-01

    An analysis is performed to estimate the convective heating to the wall in a laser-heated thruster on the basis of a solution of the laminar boundary-layer equations with variable transport properties. A local similiarity approximation is used, and it is assumed that the gas phase is in equilibrium. For the thruster described by Wu (1976), the temperature and pressure distributions along the nozzle are obtained from the core calculation. The similarity solutions and heat flux are obtained from the freestream conditions of the boundary layer, in order to determine if it is necessary to couple the boundary losses directly to the core calculation. In addition, the effects of mass injection on the convective heat transfer across the boundary layer with large density-viscosity product gradient are examined.

  14. Quantifying streambed advection and conduction heat fluxes

    NASA Astrophysics Data System (ADS)

    Caissie, Daniel; Luce, Charles H.

    2017-02-01

    Groundwater and accompanying heat fluxes are particularly relevant for aquatic habitats as they influence living conditions both within the river and streambed. This study focuses on the theory and the development of new equations to estimate conduction and advection heat fluxes into and out of the bed, correcting some earlier misunderstandings and adding parameterizations that extend our understanding of timing of heat fluxes. The new heat flux equations are illustrated using Catamaran Brook (New Brunswick, Canada) stream/streambed temperature data. We show important relationships between fluxes when the surface water temperature (1) follows a sinusoidal function superimposed on a steady state condition (constant deep streambed temperature) and (2) when sinusoidal variations in stream temperature at two frequencies (annual and diel) are superimposed. When the stream temperature is used as a prescribed boundary condition, the contribution of bed fluid fluxes to stream temperature occurs through the effects of conductive thermal gradients, not through direct contribution/mixing of cold/warm water. Boundary conditions can be modified, however, to account for direct contribution of cold/warm water (e.g., localized upwelling) and consequences for the conduction heat flux. Equations developed allow for prediction of conductive fluxes to the bed during summer driven by diel and annual temperature fluctuations of the stream water and good agreement was observed between analytic solutions and field data. Results from this study provide a better insight into groundwater and heat fluxes which will ultimately result in better stream temperature models and a better management of fisheries resources.

  15. Heat flux viscosity in collisional magnetized plasmas

    SciTech Connect

    Liu, C.; Fox, W.; Bhattacharjee, A.

    2015-05-15

    Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a “heat flux viscosity,” is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.

  16. Miniature Convection Cooled Plug-type Heat Flux Gauges

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1994-01-01

    Tests and analysis of a new miniature plug-type heat flux gauge configuration are described. This gauge can simultaneously measure heat flux on two opposed active surfaces when heat flux levels are equal to or greater than about 0.2 MW/m(sup 2). The performance of this dual active surface gauge was investigated over a wide transient and steady heat flux and temperature range. The tests were performed by radiatively heating the front surface with an argon arc lamp while the back surface was convection cooled with air. Accuracy is about +20 percent. The gauge is responsive to fast heat flux transients and is designed to withstand the high temperature (1300 K), high pressure (15 MPa), erosive and corrosive environments in modern engines. This gauge can be used to measure heat flux on the surfaces of internally cooled apparatus such as turbine blades and combustors used in jet propulsion systems and on the surfaces of hypersonic vehicles. Heat flux measurement accuracy is not compromised when design considerations call for various size gauges to be fabricated into alloys of various shapes and properties. Significant gauge temperature reductions (120 K), which can lead to potential gauge durability improvement, were obtained when the gauges were air-cooled by forced convection.

  17. Comparison of the high temperature heat flux sensor to traditional heat flux gages under high heat flux conditions.

    SciTech Connect

    Blanchat, Thomas K.; Hanks, Charles R.

    2013-04-01

    Four types of heat flux gages (Gardon, Schmidt-Boelter, Directional Flame Temperature, and High Temperature Heat Flux Sensor) were assessed and compared under flux conditions ranging between 100-1000 kW/m2, such as those seen in hydrocarbon fire or propellant fire conditions. Short duration step and pulse boundary conditions were imposed using a six-panel cylindrical array of high-temperature tungsten lamps. Overall, agreement between all gages was acceptable for the pulse tests and also for the step tests. However, repeated tests with the HTHFS with relatively long durations at temperatures approaching 1000ÀC showed a substantial decrease (10-25%) in heat flux subsequent to the initial test, likely due to the mounting technique. New HTHFS gages have been ordered to allow additional tests to determine the cause of the flux reduction.

  18. Gyrokinetic projection of the divertor heat-flux width from present tokamaks to ITER

    DOE PAGES

    Chang, Choong Seock; Ku, Seung -Hoe; Loarte, Alberto; ...

    2017-07-11

    Here, the XGC1 edge gyrokinetic code is used to study the width of the heat-flux to divertor plates in attached plasma condition. The flux-driven simulation is performed until an approximate power balance is achieved between the heat-flux across the steep pedestal pressure gradient and the heat-flux on the divertor plates.

  19. Fabrication of Thin Film Heat Flux Sensors

    NASA Technical Reports Server (NTRS)

    Will, Herbert A.

    1992-01-01

    Prototype thin film heat flux sensors have been constructed and tested. The sensors can be applied to propulsion system materials and components. The sensors can provide steady state and fast transient heat flux information. Fabrication of the sensor does not require any matching of the mounting surface. Heat flux is proportional to the temperature difference across the upper and lower surfaces of an insulation material. The sensor consists of an array of thermocouples on the upper and lower surfaces of a thin insulating layer. The thermocouples for the sensor are connected in a thermopile arrangement. A 100 thermocouple pair heat flux sensor has been fabricated on silicon wafers. The sensor produced an output voltage of 200-400 microvolts when exposed to a hot air heat gun. A 20 element thermocouple pair heat flux sensor has been fabricated on aluminum oxide sheet. Thermocouples are Pt-Pt/Rh with silicon dioxide as the insulating material. This sensor produced an output of 28 microvolts when exposed to the radiation of a furnace operating at 1000 C. Work is also underway to put this type of heat flux sensor on metal surfaces.

  20. Nanoscale heat flux between nanoporous materials.

    PubMed

    Biehs, S-A; Ben-Abdallah, P; Rosa, F S S; Joulain, K; Greffet, J-J

    2011-09-12

    By combining stochastic electrodynamics and the Maxwell-Garnett description for effective media we study the radiative heat transfer between two nanoporous materials. We show that the heat flux can be significantly enhanced by air inclusions, which we explain by: (a) the presence of additional surface waves that give rise to supplementary channels for heat transfer throughout the gap, (b) an increase in the contribution given by the ordinary surface waves at resonance, (c) and the appearance of frustrated modes over a broad spectral range. We generalize the known expression for the nanoscale heat flux for anisotropic metamaterials.

  1. Conformally flat solution with heat flux

    SciTech Connect

    Banerjee, A.; Dutta Choudhury, S. B.; Bhui, B. K.

    1989-07-15

    It is shown that the spherically symmetric solution previously given by Maiti is not the most general conformally flat solution for a shear-free and rotation-free fluid with heat flux. We have presented a more general solution for such a distribution and have considered the conditions of fit at the boundary of a simple spherically symmetric model with heat flux across the boundary with the exterior Vaidya metric.

  2. Critical heat flux test apparatus

    DOEpatents

    Welsh, Robert E.; Doman, Marvin J.; Wilson, Edward C.

    1992-01-01

    An apparatus for testing, in situ, highly irradiated specimens at high temperature transients is provided. A specimen, which has a thermocouple device attached thereto, is manipulated into test position in a sealed quartz heating tube by a robot. An induction coil around a heating portion of the tube is powered by a radio frequency generator to heat the specimen. Sensors are connected to monitor the temperatures of the specimen and the induction coil. A quench chamber is located below the heating portion to permit rapid cooling of the specimen which is moved into this quench chamber once it is heated to a critical temperature. A vacuum pump is connected to the apparatus to collect any released fission gases which are analyzed at a remote location.

  3. The thermal performance of heat pipes with localized heat input

    NASA Technical Reports Server (NTRS)

    Cao, Yiding; Faghri, Amir; Mahefkey, E. T.

    1989-01-01

    The performance of heat pipes with localized heat input including the effects of axial and circumferential heat conduction under high and low working temperatures is investigated. The numerical results show that when heat pipes are spot heated, the peak temperature of the wall is greatly reduced and the surface can be protected from being burned out by the high heat flux. The boiling limitation becomes the most important limitation for this type of heat pipe. Numerical results for block heating a heat pipe with low working temperatures indicate a good agreement with existing experimental data. It is also shown that most of the input heat passes through the wall beneath the heated block.

  4. High heat flux cooling for spacecraft electronics

    SciTech Connect

    Leland, J.E.; Chow, L.C. )

    1991-01-05

    An experimental investigation of flow boiling in a curved channel has been performed to ascertain its value in electronics cooling applications. Results have been obtained for flow velocities of 1 to 5 m/s and subcooling of 0.5 to 40 K. These results were compared to those of straight channel under identical velocity and subcooling conditions. The critical heat flux of the curved channel was found to be greater than that of the straight channel. In some cases the increase was found to be marginal, however. An unexplained temperature shift in the nucleate boiling regime was experienced during some experiments. Because this shift only occurred for the first test of the day, it is thought to be related to the incipience phenomenon often experienced in pool boiling experiments. Finally, true incipience overshoot and nucleate boiling regime hysteresis were found to be negligible.

  5. Critical heat flux predictions in rod bundles

    SciTech Connect

    Kao, S.P.; Kazimi, M.S.

    1983-01-01

    The prediction of critical heat flux (CHF) in rod bundles has been studied with both subchannel and bundle-average methods. The correlations of Biasi, Bowring, CISE-4, and Barnett were considered. The General Electric 9-rod bundle CHF data were used in the comparisons. Calculations were performed by the two-fluid subchannel code THERMIT-2. The results indicate that the subchannel method yields more conservative CHF predictions than the bundleaverage method. This is attributed to the two-phase turbulent mixing phenomenon in the bundle, which can be modeled only on a subchannel basis. The results also indicate that the CISE-4 correlation had the smallest error in prediction of transition boiling for both subchannel and bundle-average methods.

  6. Heat flux measurement in a high enthalpy plasma flow

    NASA Astrophysics Data System (ADS)

    Löhle, Stefan; Battaglia, Jean-Luc; Gardarein, Jean-Laurent; Jullien, Pierre; van Ootegem, Bruno

    2008-11-01

    It is a widely used approach to measure heat flux in harsh environments like high enthalpy plasma flows, fusion plasma and rocket motor combustion chambers based on solving the inverse heat conduction problem in a semi-infinite environment. This approach strongly depends on model parameters and geometrical aspects of the sensor design. In this work the surface heat flux is determined by solving the inverse heat conduction problem using an identified system as a direct model. The identification of the system is performed using calibration measurements with modern laser technique and advanced data handling. The results of the identified thermo-physical system show that a non-integer model appears most adapted to this particular problem. It is concluded that the new method improves the heat flux sensor significantly and furthermore extend its application to very short measurement times.

  7. High heat flux measurements and experimental calibrations/characterizations

    NASA Technical Reports Server (NTRS)

    Kidd, Carl T.

    1992-01-01

    Recent progress in techniques employed in the measurement of very high heat-transfer rates in reentry-type facilities at the Arnold Engineering Development Center (AEDC) is described. These advances include thermal analyses applied to transducer concepts used to make these measurements; improved heat-flux sensor fabrication methods, equipment, and procedures for determining the experimental time response of individual sensors; performance of absolute heat-flux calibrations at levels above 2,000 Btu/cu ft-sec (2.27 kW/cu cm); and innovative methods of performing in-situ run-to-run characterizations of heat-flux probes installed in the test facility. Graphical illustrations of the results of extensive thermal analyses of the null-point calorimeter and coaxial surface thermocouple concepts with application to measurements in aerothermal test environments are presented. Results of time response experiments and absolute calibrations of null-point calorimeters and coaxial thermocouples performed in the laboratory at intermediate to high heat-flux levels are shown. Typical AEDC high-enthalpy arc heater heat-flux data recently obtained with a Calspan-fabricated null-point probe model are included.

  8. Heat-Flux Gage thermophosphor system

    SciTech Connect

    Tobin, K.W.

    1991-08-01

    This document describes the installation, hardware requirements, and application of the Heat-Flux Gage (Version 1.0) software package developed by the Oak Ridge National Laboratory, Applied Technology Division. The developed software is a single component of a thermographic phosphor-based temperature and heat-flux measurement system. The heat-flux transducer was developed by EG G Energy Measurements Systems and consists of a 1- by 1-in. polymethylpentene sheet coated on the front and back with a repeating thermographic phosphor pattern. The phosphor chosen for this application is gadolinium oxysulphide doped with terbium. This compound has a sensitive temperature response from 10 to 65.6{degree}C (50--150{degree}F) for the 415- and 490-nm spectral emission lines. 3 refs., 17 figs.

  9. Heat flux dynamics in low Arctic rivers

    NASA Astrophysics Data System (ADS)

    King, T.; Neilson, B. T.; Kane, D. L.; Overbeck, L. D.; Rasmussen, M. T.

    2016-12-01

    The impacts of climate change on Arctic river temperatures and the resulting influences on biogeochemical cycling and habitat suitability require research into controlling heat fluxes between Arctic rivers and their surroundings. Instrumentation of the Kuparuk River in the foothills of the Brooks Range, Alaska, USA, during the 2013 - 2016 open water seasons provided data required to populate and calibrate an instream temperature model. This model accounts for radiative, sensible, and latent heat fluxes at the air-water interface, conductive and friction heat fluxes at the water-sediment interface, and lateral inflows of heat and mass from surface and subsurface hillslope drainage adjacent to the river. Model outputs reproduce observed river temperature dynamics throughout the watershed under high flows, with radiative heat fluxes dominating the total energy balance and lateral inflows contributing significantly following rainy periods of elevated hillslope drainage. Under low flows, however, observed river temperatures in the headwater portion of the watershed were significantly buffered when compared with simulated river temperatures that produced daily ranges in river temperatures up to 15° C greater than were observed. River temperature observations were reproduced when convective heat fluxes at the water-sediment interface were incorporated, indicating that hyporheic exchange provides significant buffering capacity in Arctic river temperatures under low flows. The influence of hyporheic exchange on river temperature depends on residence times and the proximity of flow paths to the frozen soils below the river bed. Therefore, Arctic river temperatures may be significantly affected by alterations in sub-surface thaw, atmospheric conditions, and hillslope hydrology - all of which are projected to accompany changes in Arctic climate.

  10. Turbine blade and vane heat flux sensor development, phase 2

    NASA Technical Reports Server (NTRS)

    Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

    1985-01-01

    The development of heat flux sensors for gas turbine blades and vanes and the demonstration of heat transfer measurement methods are reported. The performance of the heat flux sensors was evaluated in a cylinder in cross flow experiment and compared with two other heat flux measurement methods, the slug calorimeter and a dynamic method based on fluctuating gas and surface temperature. Two cylinders, each instrumented with an embedded thermocouple sensor, a Gardon gauge, and a slug calorimeter, were fabricated. Each sensor type was calibrated using a quartz lamp bank facility. The instrumented cylinders were then tested in an atmospheric pressure combustor rig at conditions up to gas stream temperatures of 1700K and velocities to Mach 0.74. The test data are compared to other measurements and analytical prediction.

  11. Fine fuel heating by radiant flux

    Treesearch

    David Frankman; Brent W. Webb; Bret W. Butler; Don J. Latham

    2010-01-01

    Experiments were conducted wherein wood shavings and Ponderosa pine needles in quiescent air were subjected to a steady radiation heat flux from a planar ceramic burner. The internal temperature of these particles was measured using fine diameter (0.076mm diameter) type K thermocouples. A narrow angle radiometer was used to determine the emissive power generated by the...

  12. Heat flux concentration through polymeric thermal lenses

    NASA Astrophysics Data System (ADS)

    Kapadia, R. S.; Bandaru, P. R.

    2014-12-01

    A significant contributor to energy inefficiency is the generation as well as the uneven dissipation of heat. Practical methods to adeptly channel heat flux (Q) would then have widespread applications to improved energy utilization and thermal energy management. It would be beneficial to engineer lens-like composite materials (graded in terms of length or thermal conductivity) with augmented attributes for heat control. Here, we propose and demonstrate polymeric composite based Q focusing lenses, architected through geometrical considerations. We indicate a five-fold enhancement of the Q, at the level of ˜2500 W/m2, enabled through such thermal lenses.

  13. Corrections for heat flux measurements taken on launch vehicles

    NASA Astrophysics Data System (ADS)

    Reinarts, Thomas R.; Matson, Monique L.; Walls, Laurie K.

    2002-01-01

    Knowledge of aerothermally induced convective heat transfer and plume induced radiative heat transfer loads is essential to the design of thermal protection systems for launch vehicles. Aerothermal and radiative models are typically calibrated via the data from cylindrical, in-flight, flush-mounted surface heat flux gauges that are exposed to the external thermal and velocity boundary layers as well as thermal radiation. Typically, Schmidt-Boelter gauges, taking advantage of the 1-Dimensional Fourier's law, measure the incident heat flux. This instrumentation, when surrounded by low-conductivity insulation, has an exposed surface temperature significantly lower than the insulation. As a result of this substantial disturbance to the thermal boundary layer, the heat flux incident on the gauge tends to be considerably higher (potentially by factors of 2 or more) than it would have been on the insulation had the calorimeter not been there. In addition, the gauge can receive energy radially from the hotter insulation, contributing to the increase of the indicated heat flux. This paper will present an overview of an effort to model the heat flux gauge under typical flight conditions that includes an installation surrounded by high temperature insulation. The goal is to correct the measurements to reflect the local heat flux on the insulation had the instrument not been present. The three major components of this effort include: 1) a 3-Dimensional computational thermal math model including the internal conduction heat transfer details of a Schmidt-Boelter gauge. 2) a CFD analysis to determine the effects on measurement of the rapidly changing thermal boundary layer over the near step changes in wall temperature, and 3) testing performed on flat plates exposed to an aerothermal environment in the Marshall Space Flight Center (MSFC) Improved Hot Gas Facility (IHGF). A summary of the analytical efforts will be presented, as well as early testing results and preliminary model

  14. A study of performance parameters on drag and heat flux reduction efficiency of combinational novel cavity and opposing jet concept in hypersonic flows

    NASA Astrophysics Data System (ADS)

    Sun, Xi-wan; Guo, Zhen-yun; Huang, Wei; Li, Shi-bin; Yan, Li

    2017-02-01

    The drag reduction and thermal protection system applied to hypersonic re-entry vehicles have attracted an increasing attention, and several novel concepts have been proposed by researchers. In the current study, the influences of performance parameters on drag and heat reduction efficiency of combinational novel cavity and opposing jet concept has been investigated numerically. The Reynolds-average Navier-Stokes (RANS) equations coupled with the SST k-ω turbulence model have been employed to calculate its surrounding flowfields, and the first-order spatially accurate upwind scheme appears to be more suitable for three-dimensional flowfields after grid independent analysis. Different cases of performance parameters, namely jet operating conditions, freestream angle of attack and physical dimensions, are simulated based on the verification of numerical method, and the effects on shock stand-off distance, drag force coefficient, surface pressure and heat flux distributions have been analyzed. This is the basic study for drag reduction and thermal protection by multi-objective optimization of the combinational novel cavity and opposing jet concept in hypersonic flows in the future.

  15. Fabrication of thin film heat flux sensors

    NASA Technical Reports Server (NTRS)

    Will, Herbert

    1991-01-01

    Thin-film heat-flux sensors have been constructed in the form of arrays of thermocouples on upper and lower surfaces of an insulating layer, so that flux values are proportional to the temperature difference across the upper and lower surface of the insulation material. The sensor thermocouples are connected in thermopile arrangement, and the structure is patterned with photolithographic techniques. Both chromel-alumel and Pt-Pt/Rh thermocouples have been devised; the later produced 28 microvolts when exposed to the radiation of a 1000 C furnace.

  16. Thin film heat flux sensors for accurate transient and unidirectional heat transfer analysis

    NASA Astrophysics Data System (ADS)

    Azerou, B.; Garnier, B.; Lahmar, J.

    2012-11-01

    Heat flux measurement is needed in many heat transfer studies. For the best unbiased heat flux sensors (HFS), the heat flux is obtained using temperature measurements at different locations and also an inverse heat conduction method (function specification...) in order to calculate the heat flux. Systematic errors can come from the uncertainty in the wire thermocouples locations and from errors in the knowledge of distances between two consecutive wire thermocouples. The main idea in this work is to use thin film thermoresistances deposited on a flexible thin polymer substrate instead of wire thermocouples welded on metallic sample. The interest of using thin film thermoresistances instead of wire thermocouples is a lower disturbance due to the smaller thickness of the thin film sensors (typically less than 1μm) and a much better knowledge of the distances between the different thin film thermoresistances which are precisely defined in the mask used for the metallic thin film pattern fabrication. In this paper, we present the fabrication of the new heat flux sensor with thin film thermoresistances, the study of the effect of the self heating (due to Joule effect in thermoresistances) and the performances of this new HFS with the comparison with classical HFS using wire thermocouples. For this study, a symmetric experimental setup is used with metallic samples equipped with an etched foil heater and both classical and new HFS. For several heating conditions, it appears that a better accuracy is always obtained with the new HFS using thin film thermoresistances.

  17. Simulation for heat flux mitigation by gas puffing in KSTAR

    NASA Astrophysics Data System (ADS)

    Shim, Seung Bo; Kotov, Vladislav; Hong, Suk-Ho; Detlev, Reiter; Kim, Jin Yong; Na, Yong Su; Lee, Hae June

    2013-10-01

    Control of heat flux is very important to achieve high performance long pulse operation in tokamaks. There are so many efforts to reduce the heat flux like change of divertor structure, snowflake divertor, and RMP, etc. Detachment by gas puffing is used for long time to reduce the heat flux. In this paper edge plasma scenarios of KSTAR are analyzed numerically by well-known B2-Eirene code package(SOLPS4.3). High performance discharges with heating power ~ 8 MW and core flux ~ 1021 s-1 is used. Gas puffed on the outer mid-plane(OMP), both divertors is likely to stay attached. So, gas puffed on the outer target, one is near the private flux region(PFR) and the other is near the scrape-off-layer(SOL). When gas puffed near the SOL is still attached, and it is worse than gas puff from OMP because it is too close to cryo-pump. The case near the PFR shows high recycling region easily compared with OMP case. When one forth gas puffed on the PFR, results are similar with OMP case. But it is still not good for detachment operation. Detachment operation window is too small for the gas puffing on the PFR. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST)(No. 2012-0000579).

  18. Contactless heat flux control with photonic devices

    SciTech Connect

    Ben-Abdallah, Philippe; Biehs, Svend-Age

    2015-05-15

    The ability to control electric currents in solids using diodes and transistors is undoubtedly at the origin of the main developments in modern electronics which have revolutionized the daily life in the second half of 20th century. Surprisingly, until the year 2000 no thermal counterpart for such a control had been proposed. Since then, based on pioneering works on the control of phononic heat currents new devices were proposed which allow for the control of heat fluxes carried by photons rather than phonons or electrons. The goal of the present paper is to summarize the main advances achieved recently in the field of thermal energy control with photons.

  19. The photospheric Poynting flux and coronal heating

    NASA Astrophysics Data System (ADS)

    Welsch, Brian T.

    2015-04-01

    Some models of coronal heating suppose that convective motions at the photosphere shuffle the footpoints of coronal magnetic fields and thereby inject sufficient magnetic energy upward to account for observed coronal and chromospheric energy losses in active regions. Using high-resolution observations of plage magnetic fields made with the Solar Optical Telescope aboard the Hinode satellite, we investigate this idea by estimating the upward transport of magnetic energy-the vertical Poynting flux, Sz-across the photosphere in a plage region. To do so, we combine the following: (i) estimates of photospheric horizontal velocities, vh, determined by local correlation tracking applied to a sequence of line-of-sight magnetic field maps from the Narrowband Filter Imager, with (ii) a vector magnetic field measurement from the SpectroPolarimeter. Plage fields are ideal observational targets for estimating energy injection by convection, because they are (i) strong enough to be measured with relatively small uncertainties, (ii) not so strong that convection is heavily suppressed (as within umbrae), and (iii) unipolar, so Sz in plage is not influenced by mixed-polarity processes (e.g., flux emergence) unrelated to heating in stable, active-region fields. In this plage region, we found that the average Sz varied in space, but was positive (upward) and sufficient to explain coronal heating, with values near (5 ± 1) × 107 erg cm-2 s-1. We find the energy input per unit magnetic flux to be on the order of 105 erg s-1 Mx-1. A comparison of intensity in a Ca II image co-registered with one plage magnetogram shows stronger spatial correlations with both total field strength and unsigned vertical field, |Bz|, than either Sz or horizontal flux density, Bh. The observed Ca II brightness enhancement, however, probably contains a strong contribution from a near-photosphere hot-wall effect, which is unrelated to heating in the solar atmosphere.

  20. Miniature high temperature plug-type heat flux gauges

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1992-01-01

    The objective is to describe continuing efforts to develop methods for measuring surface heat flux, gauge active surface temperature, and heat transfer coefficient quantities. The methodology involves inventing a procedure for fabricating improved plug-type heat flux gauges and also for formulating inverse heat conduction models and calculation procedures. These models and procedures are required for making indirect measurements of these quantities from direct temperature measurements at gauge interior locations. Measurements of these quantities were made in a turbine blade thermal cycling tester (TBT) located at MSFC. The TBT partially simulates the turbopump turbine environment in the Space Shuttle Main Engine. After the TBT test, experiments were performed in an arc lamp to analyze gauge quality.

  1. Distributed Sensible Heat Flux Measurements for Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Brauchli, T.; Lehning, M.; Higgins, C. W.

    2015-12-01

    The sensible heat flux component of the surface energy balance is typically computed using eddy covariance or two point profile measurements while alternative approaches such as the flux variance method based on convective scaling has been much less explored and applied. Flux variance (FV) certainly has a few limitations and constraints but may be an interesting and competitive method in low-cost and power limited wireless sensor networks (WSN) with the advantage of providing spatio-temporal sensible heat flux over the domain of the network. In a first step, parameters such as sampling frequency, sensor response time, and averaging interval are investigated. Then we explore the applicability and the potential of the FV method for use in WSN in a field experiment. Low-cost sensor systems are tested and compared against reference instruments (3D sonic anemometers) to evaluate the performance and limitations of the sensors as well as the method with respect to the standard calculations. Comparison experiments were carried out at several sites to gauge the flux measurements over different surface types (gravel, grass, water) from the low-cost systems. This study should also serve as an example of spatially distributed sensible heat flux measurements.

  2. Heat flux in a granular gas

    NASA Astrophysics Data System (ADS)

    Brey, J. J.; Ruiz-Montero, M. J.

    2012-11-01

    A peculiarity of the hydrodynamic Navier-Stokes equations for a granular gas is the modification of the Fourier law, with the presence of an additional contribution to the heat flux that is proportional to the density gradient. Consequently, the constitutive relation involves, in the case of a one-component granular gas, two transport coefficients: the usual (thermal) heat conductivity and a diffusive heat conductivity. A very simple physical interpretation of this effect, in terms of the mean free path and the mean free time is provided. It leads to the modified Fourier law with an expression for the diffusive Fourier coefficient that differs in a factor of the order of unity from the expression obtained by means of the inelastic Boltzmann equation. Also, some aspects of the Chapman-Enskog computation of the new transport coefficients as well as of the comparison between simulation results and theory are discussed.

  3. The Photospheric Poynting Flux and Coronal Heating

    NASA Astrophysics Data System (ADS)

    Welsch, Brian

    2014-06-01

    Some models of coronal heating suppose that random (cf., coherent) convective motions at the photosphere shuffle the footpoints of coronal magnetic fields and thereby inject sufficient magnetic energy upward to account for observed coronal and chromospheric energy losses in active regions. Using high-resolution observations of plage magnetic fields made with the Solar Optical Telescope aboard the Hinode satellite, we observationally test this idea by estimating the upward transport of magnetic energy --- the vertical Poynting flux, S_z --- across the photosphere in a plage region. To do so, we combine: (i) estimates of photospheric horizontal velocities, v_h, determined by local correlation tracking applied to a sequence of line-of-sight magnetic field maps from the Narrowband Filter Imager, with (ii) a vector magnetic field measurement from the SpectroPolarimeter. Plage fields are ideal observational targets for estimating energy injection by convection, because they are: (i) strong enough to be measured with relatively small uncertainties; (ii) not so strong that convection is heavily suppressed (as within umbrae); and (iii) unipolar, so S_z in plage is not influenced by mixed-polarity processes (e.g., flux emergence) that cannot explain steady heating in stable, active-region fields. In this and a previously analyzed plage region, we found that the average S_z varied between the regions, but was positive (upward) and sufficient to explain coronal heating, with values near 2 x 10^7 erg/ cm^2/ s. We find the energy input per unit magnetic flux to be on the order of a few times 10^4 erg/ s/ Mx. A comparison of intensity in a Ca II image co-registered with one plage magnetogram shows stronger spatial correlation with unsigned vertical field, |B_z|, than either S_z or horizontal flux density, |B_h|.

  4. Role of surface heat fluxes underneath cold pools.

    PubMed

    Gentine, Pierre; Garelli, Alix; Park, Seung-Bu; Nie, Ji; Torri, Giuseppe; Kuang, Zhiming

    2016-01-28

    The role of surface heat fluxes underneath cold pools is investigated using cloud-resolving simulations with either interactive or horizontally homogenous surface heat fluxes over an ocean and a simplified land surface. Over the ocean, there are limited changes in the distribution of the cold pool temperature, humidity, and gust front velocity, yet interactive heat fluxes induce more cold pools, which are smaller, and convection is then less organized. Correspondingly, the updraft mass flux and lateral entrainment are modified. Over the land surface, the heat fluxes underneath cold pools drastically impact the cold pool characteristics with more numerous and smaller pools, which are warmer and more humid and accompanied by smaller gust front velocities. The interactive fluxes also modify the updraft mass flux and reduce convective organization. These results emphasize the importance of interactive surface fluxes instead of prescribed flux boundary conditions, as well as the formulation of surface heat fluxes, when studying convection.

  5. Role of surface heat fluxes underneath cold pools

    PubMed Central

    Garelli, Alix; Park, Seung‐Bu; Nie, Ji; Torri, Giuseppe; Kuang, Zhiming

    2016-01-01

    Abstract The role of surface heat fluxes underneath cold pools is investigated using cloud‐resolving simulations with either interactive or horizontally homogenous surface heat fluxes over an ocean and a simplified land surface. Over the ocean, there are limited changes in the distribution of the cold pool temperature, humidity, and gust front velocity, yet interactive heat fluxes induce more cold pools, which are smaller, and convection is then less organized. Correspondingly, the updraft mass flux and lateral entrainment are modified. Over the land surface, the heat fluxes underneath cold pools drastically impact the cold pool characteristics with more numerous and smaller pools, which are warmer and more humid and accompanied by smaller gust front velocities. The interactive fluxes also modify the updraft mass flux and reduce convective organization. These results emphasize the importance of interactive surface fluxes instead of prescribed flux boundary conditions, as well as the formulation of surface heat fluxes, when studying convection. PMID:27134320

  6. Diamond Microchannel Heat Sink Designs For High Heat Flux Thermal Control

    NASA Astrophysics Data System (ADS)

    Corbin, Michael V.; DeBenedictis, Matthew M.; James, David B.; LeBlanc, Stephen P.; Paradis, Leo R.

    2002-08-01

    Directed energy weapons, wide band gap semiconductor based radars, and other powerful systems present significant thermal control challenges to component designers. heat Flux levels approaching 2000 W/cm(2) are encountered at the base of laser diodes, and levels as high as 500 WI /cm(2) are expected in laser slabs and power amplifier tube collectors. These impressive heat flux levels frequently combine with strict operating temperature requirements to further compound the thermal control problem. Many investigators have suggested the use of diamond heat spreaders to reduce flux levels at or near to its source, and some have suggested that diamond microchannel heat sinks ultimately may play a significant role in the solution of these problems. Design engineers at Raytheon Company have investigated the application of all-diamond microchannel heat sinks to representative high heat flux problems and have found the approach promising. Diamond microchannel fabrication feasibility has been demonstrated; integration into packaging systems and the accompanying material compatibility issues have been addressed; and thermal and hydrodynamic performance predictions have been made for selected, possible applications. An example of a practical, all diamond microchannel heat sink has been fabricated, and another is in process and will be performance tested. The heat sink assembly is made entirely of optical quality, CVD diamond and is of sufficient strength to withstand the thermal and pressure-induced mechanical loads associated with manufacture and use in tactical weapons environment. The work presented describes the development program's accomplishments to date, and highlights many of the areas for future study.

  7. The Photosheric Poynting Flux and Coronal Heating

    NASA Astrophysics Data System (ADS)

    Welsch, B. T.

    2014-12-01

    Some models of coronal heating suppose that convective motions at thephotosphere shuffle the footpoints of coronal magnetic fields andthereby inject sufficient magnetic energy upward to account forobserved coronal and chromospheric energy losses in active regions.Using high-resolution observations of plage magnetic fields made withthe Solar Optical Telescope aboard the Hinode satellite, weinvestigate this idea by estimating the upward transport of magneticenergy --- the vertical Poynting flux, S_z --- across the photospherein a plage region. To do so, we combine: (i) estimates ofphotospheric horizontal velocities, v_h, determined by localcorrelation tracking applied to a sequence of line-of-sight magneticfield maps from the Narrowband Filter Imager, with (ii) a vectormagnetic field measurement from the SpectroPolarimeter. Plage fieldsare ideal observational targets for estimating energy injection byconvection, because they are: (i) strong enough to be measured withrelatively small uncertainties; (ii) not so strong that convection isheavily suppressed (as within umbrae); and (iii) unipolar, so S_z inplage is not influenced by mixed-polarity processes (e.g., fluxemergence) unrelated to heating in stable, active-region fields. Inthis plage region, we found that the average S_z varied in space, butwas positive (upward) and sufficient to explain coronal heating, withvalues near (5 +/- 1) x 107 erg / cm2 / s. We find the energy inputper unit magnetic flux to be on the order of 105 erg / s / Mx. Acomparison of intensity in a Ca II image co-registered with one plagemagnetogram shows stronger spatial correlations with both total fieldstrength and unsigned vertical field, |B_z|, than either S_z orhorizontal flux density, B_h. The observed Ca II brightnessenhancement, however, probably contains a strong contribution from anear-photosphere hot-wall effect, which is unrelated to heating in thesolar atmosphere.

  8. Time and Space Resolved Heat Flux Measurements During Nucleate Boiling with Constant Heat Flux Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Yerramilli, Vamsee K.; Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Kim, Jungho

    2005-01-01

    The lack of temporally and spatially resolved measurements under nucleate bubbles has complicated efforts to fully explain pool-boiling phenomena. The objective of this current work was to acquire time and space resolved temperature distributions under nucleating bubbles on a constant heat flux surface using a microheater array with 100x 100 square microns resolution, then numerically determine the wall to liquid heat flux. This data was then correlated with high speed (greater than l000Hz) visual recordings of The bubble growth and departure from the heater surface acquired from below and from the side of the heater. The data indicate that microlayer evaporation and contact line heat transfer are not major heat transfer mechanisms for bubble growth. The dominant heat transfer mechanism appears to be transient conduction into the liquid as the liquid rewets the wall during the bubble departure process.

  9. Soil profile method for soil thermal diffusivity, conductivity and heat flux:Comparison to soil heat flux plates

    USDA-ARS?s Scientific Manuscript database

    Diffusive heat flux at the soil surface is commonly determined as a mean value over a time period using heat flux plates buried at some depth (e.g., 5 to 8 cm) below the surface with a correction to surface flux based on the change in heat storage during the corresponding time period in the soil lay...

  10. Hysteretic Superconducting Heat-Flux Quantum Modulator

    NASA Astrophysics Data System (ADS)

    Guarcello, Claudio; Solinas, Paolo; Di Ventra, Massimiliano; Giazotto, Francesco

    2017-04-01

    We discuss heat transport in a thermally biased superconducting quantum-interference device (SQUID) in the presence of an external magnetic flux, when a non-negligible inductance of the SQUID ring is taken into account. A properly sweeping driving flux causes the thermal current to modulate and behave hysteretically. The response of this device is analyzed as a function of both the hysteresis parameter and the degree of asymmetry of the SQUID, highlighting the parameter range over which hysteretic behavior is observable. Markedly, the temperature of the SQUID also shows hysteretic evolution, with sharp transitions characterized by temperature jumps up to, e.g., approximately 0.02 K for a realistic Al-based setup. In view of these results, the proposed device can effectively find an application as a temperature-based superconducting memory element, working even at gigahertz frequencies by suitably choosing the superconductor on which the device is based.

  11. Critical heat flux of subcooled flow boiling with water for high heat flux application

    NASA Astrophysics Data System (ADS)

    Inasaka, Fujio; Nariai, Hideki

    1993-11-01

    Subcooled flow boiling in water is thought to be advantageous in removing high heat load of more than 10 MW/m2. Characteristics of the critical heat flux (CHF), which determines the upper limit of heat removal, are very important for the design of cooling systems. In this paper, studies on subcooled flow boiling CHF, which have been conducted by the authors, are reported. Experiments were conducted using direct current heating of stainless steel tube. For uniform heating conditions, CHF increment in small diameter tubes (1 - 3 mm inside diameter) and the CHF characteristics in tubes with internal twisted tapes were investigated, and also the existing CHF correlations for ordinary tubes (more than 3 mm inside diameter) were evaluated. For peripherally non-uniform heating conditions using the tube, whose wall thickness was partly reduced, the CHF for swirl flow was higher than the CHF under uniform heating conditions with an increase of the non-uniformity factor.

  12. Heat flux measurements on ceramics with thin film thermocouples

    NASA Technical Reports Server (NTRS)

    Holanda, Raymond; Anderson, Robert C.; Liebert, Curt H.

    1993-01-01

    Two methods were devised to measure heat flux through a thick ceramic using thin film thermocouples. The thermocouples were deposited on the front and back face of a flat ceramic substrate. The heat flux was applied to the front surface of the ceramic using an arc lamp Heat Flux Calibration Facility. Silicon nitride and mullite ceramics were used; two thicknesses of each material was tested, with ceramic temperatures to 1500 C. Heat flux ranged from 0.05-2.5 MW/m2(sup 2). One method for heat flux determination used an approximation technique to calculate instantaneous values of heat flux vs time; the other method used an extrapolation technique to determine the steady state heat flux from a record of transient data. Neither method measures heat flux in real time but the techniques may easily be adapted for quasi-real time measurement. In cases where a significant portion of the transient heat flux data is available, the calculated transient heat flux is seen to approach the extrapolated steady state heat flux value as expected.

  13. Plug-type heat flux gauge

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H. (Inventor); Koch, John, Jr. (Inventor)

    1991-01-01

    A plug-type heat flux gauge formed in a material specimen and having a thermoplug integrally formed in the material specimen, and a method for making the same are disclosed. The thermoplug is surrounded by a concentric annulus, through which thermocouple wires are routed. The end of each thermocouple wire is welded to the thermoplug, with each thermocouple wire welded at a different location along the length of the thermoplug. The thermoplug and concentric annulus may be formed in the material specimen by electrical discharge machining and trepanning procedures.

  14. Longitudinal spin Seebeck coefficient: heat flux vs. temperature difference method

    NASA Astrophysics Data System (ADS)

    Sola, A.; Bougiatioti, P.; Kuepferling, M.; Meier, D.; Reiss, G.; Pasquale, M.; Kuschel, T.; Basso, V.

    2017-04-01

    The determination of the longitudinal spin Seebeck effect (LSSE) coefficient is currently plagued by a large uncertainty due to the poor reproducibility of the experimental conditions used in its measurement. In this work we present a detailed analysis of two different methods used for the determination of the LSSE coefficient. We have performed LSSE experiments in different laboratories, by using different setups and employing both the temperature difference method and the heat flux method. We found that the lack of reproducibility can be mainly attributed to the thermal contact resistance between the sample and the thermal baths which generate the temperature gradient. Due to the variation of the thermal resistance, we found that the scaling of the LSSE voltage to the heat flux through the sample rather than to the temperature difference across the sample greatly reduces the uncertainty. The characteristics of a single YIG/Pt LSSE device obtained with two different setups was (1.143 ± 0.007) 10-7 Vm/W and (1.101 ± 0.015) 10-7 Vm/W with the heat flux method and (2.313 ± 0.017) 10-7 V/K and (4.956 ± 0.005) 10-7 V/K with the temperature difference method. This shows that systematic errors can be considerably reduced with the heat flux method.

  15. Longitudinal spin Seebeck coefficient: heat flux vs. temperature difference method.

    PubMed

    Sola, A; Bougiatioti, P; Kuepferling, M; Meier, D; Reiss, G; Pasquale, M; Kuschel, T; Basso, V

    2017-04-25

    The determination of the longitudinal spin Seebeck effect (LSSE) coefficient is currently plagued by a large uncertainty due to the poor reproducibility of the experimental conditions used in its measurement. In this work we present a detailed analysis of two different methods used for the determination of the LSSE coefficient. We have performed LSSE experiments in different laboratories, by using different setups and employing both the temperature difference method and the heat flux method. We found that the lack of reproducibility can be mainly attributed to the thermal contact resistance between the sample and the thermal baths which generate the temperature gradient. Due to the variation of the thermal resistance, we found that the scaling of the LSSE voltage to the heat flux through the sample rather than to the temperature difference across the sample greatly reduces the uncertainty. The characteristics of a single YIG/Pt LSSE device obtained with two different setups was (1.143 ± 0.007) 10(-7) Vm/W and (1.101 ± 0.015) 10(-7) Vm/W with the heat flux method and (2.313 ± 0.017) 10(-7) V/K and (4.956 ± 0.005) 10(-7) V/K with the temperature difference method. This shows that systematic errors can be considerably reduced with the heat flux method.

  16. Longitudinal spin Seebeck coefficient: heat flux vs. temperature difference method

    PubMed Central

    Sola, A.; Bougiatioti, P.; Kuepferling, M.; Meier, D.; Reiss, G.; Pasquale, M.; Kuschel, T.; Basso, V.

    2017-01-01

    The determination of the longitudinal spin Seebeck effect (LSSE) coefficient is currently plagued by a large uncertainty due to the poor reproducibility of the experimental conditions used in its measurement. In this work we present a detailed analysis of two different methods used for the determination of the LSSE coefficient. We have performed LSSE experiments in different laboratories, by using different setups and employing both the temperature difference method and the heat flux method. We found that the lack of reproducibility can be mainly attributed to the thermal contact resistance between the sample and the thermal baths which generate the temperature gradient. Due to the variation of the thermal resistance, we found that the scaling of the LSSE voltage to the heat flux through the sample rather than to the temperature difference across the sample greatly reduces the uncertainty. The characteristics of a single YIG/Pt LSSE device obtained with two different setups was (1.143 ± 0.007) 10−7 Vm/W and (1.101 ± 0.015) 10−7 Vm/W with the heat flux method and (2.313 ± 0.017) 10−7 V/K and (4.956 ± 0.005) 10−7 V/K with the temperature difference method. This shows that systematic errors can be considerably reduced with the heat flux method. PMID:28440288

  17. Reconnection Between Twisted Flux Tubes - Implications for Coronal Heating

    NASA Astrophysics Data System (ADS)

    Knizhnik, K. J.; Antiochos, S. K.; DeVore, C. R.; Klimchuk, J. A.; Wyper, P. F.

    2015-12-01

    The nature of the heating of the Sun's corona has been a long-standing unanswered problem in solar physics. Beginning with the work of Parker (1972), many authors have argued that the corona is continuously heated through numerous small-scale reconnection events known as nanoflares. In these nanoflare models, stressing of magnetic flux tubes by photospheric motions causes the field to become misaligned, producing current sheets in the corona. These current sheets then reconnect, converting the free energy stored in the magnetic field into heat. In this work, we use the Adaptively Refined MHD Solver (ARMS) to perform 3D MHD simulations that dynamically resolve regions of strong current to study the reconnection between twisted flux tubes in a plane-parallel Parker configuration. We investigate the energetics of the process, and show that the flux tubes accumulate stress gradually before undergoing impulsive reconnection. We study the motion of the individual field lines during reconnection, and demonstrate that the connectivity of the configuration becomes extremely complex, with multiple current sheets being formed, which could lead to enhanced heating. In addition, we show that there is considerable interaction between the twisted flux tubes and the surrounding untwisted field, which contributes further to the formation of current sheets. The implications for observations will be discussed. This work was funded by a NASA Earth and Space Science Fellowship, and by the NASA TR&T Program.

  18. Corrections for Heat Flux Measurements Taken on Launch Vehicles

    NASA Astrophysics Data System (ADS)

    Reinarts, Thomas R.; Ford, Danielle M.

    2004-02-01

    Knowledge of aerothermally induced convective heat transfer and plume induced radiative heat transfer loads is essential to the design of thermal protection systems (TPS) for launch vehicles. Aerothermal and radiative models are typically calibrated via the data from cylindrical, in-flight, flush-mounted surface heat flux gauges that are exposed to the external thermal and velocity boundary layers as well as thermal radiation. Typically, Schmidt-Boelter gauges, taking advantage of the 1-Dimensional Fourier's law, measure the incident heat flux. This instrumentation, when surrounded by low-conductivity insulation, has an exposed surface temperature significantly lower than the insulation. As a result of this substantial disturbance to the thermal boundary layer, the heat flux incident on the gauge tends to be considerably higher (potentially by factors of 2 or more) than it would have been on the insulation had the calorimeter not been there. In addition, the gauge can receive energy radially from the hotter insulation, contributing to the increase of the indicated heat flux. This paper will present an overview of an effort to model the heat flux gauge under typical flight conditions that includes an installation surrounded by high temperature insulation. The goal is to correct the measurements to reflect the local heat flux on the insulation had the instrument not been present. The three major components of this effort include: 1) a three-dimensional computational thermal math model including the internal conduction heat transfer details of a Schmidt-Boelter gauge, 2) a two-dimensional Navier-Stokes computational fluid dynamics (CFD) analysis to determine the effects on measurement of the rapidly changing thermal boundary layer over the near step changes in wall temperature, and 3) testing performed on flat plates exposed to an aerothermal environment in the Marshall Space Flight Center (MSFC) Improved Hot Gas Facility (IHGF). A brief summary of calibration issues

  19. Critical heat flux in subcooled flow boiling

    NASA Astrophysics Data System (ADS)

    Hall, David Douglas

    The critical heat flux (CHF) phenomenon was investigated for water flow in tubes with particular emphasis on the development of methods for predicting CHF in the subcooled flow boiling regime. The Purdue University Boiling and Two-Phase Flow Laboratory (PU-BTPFL) CHF database for water flow in a uniformly heated tube was compiled from the world literature dating back to 1949 and represents the largest CHF database ever assembled with 32,544 data points from over 100 sources. The superiority of this database was proven via a detailed examination of previous databases. The PU-BTPFL CHF database is an invaluable tool for the development of CHF correlations and mechanistic models that are superior to existing ones developed with smaller, less comprehensive CHF databases. In response to the many inaccurate and inordinately complex correlations, two nondimensional, subcooled CHF correlations were formulated, containing only five adjustable constants and whose unique functional forms were determined without using a statistical analysis but rather using the parametric trends observed in less than 10% of the subcooled CHF data. The correlation based on inlet conditions (diameter, heated length, mass velocity, pressure, inlet quality) was by far the most accurate of all known subcooled CHF correlations, having mean absolute and root-mean-square (RMS) errors of 10.3% and 14.3%, respectively. The outlet (local) conditions correlation was the most accurate correlation based on local CHF conditions (diameter, mass velocity, pressure, outlet quality) and may be used with a nonuniform axial heat flux. Both correlations proved more accurate than a recent CHF look-up table commonly employed in nuclear reactor thermal hydraulic computer codes. An interfacial lift-off, subcooled CHF model was developed from a consideration of the instability of the vapor-liquid interface and the fraction of heat required for liquid-vapor conversion as opposed to that for bulk liquid heating. Severe

  20. Dynamic ignition regime of condensed system by radiate heat flux

    NASA Astrophysics Data System (ADS)

    Arkhipov, V. A.; Zolotorev, N. N.; Korotkikh, A. G.; Kuznetsov, V. T.

    2017-05-01

    The main ignition characteristics of high-energy materials are the ignition time and critical heat flux allowing evaluation of the critical conditions for ignition, fire and explosive safety for the test solid propellants. The ignition process is typically studied in stationary conditions of heat input at constant temperature of the heating surface, environment or the radiate heat flux on the sample surface. In real conditions, ignition is usually effected at variable time-dependent values of the heat flux. In this case, the heated layer is formed on the sample surface in dynamic conditions and significantly depends on the heat flux change, i.e. increasing or decreasing falling heat flux in the reaction period of the propellant sample. This paper presents a method for measuring the ignition characteristics of a high-energy material sample in initiation of the dynamic radiant heat flux, which includes the measurement of the ignition time when exposed to a sample time varying radiant heat flux given intensity. In case of pyroxyline containing 1 wt. % of soot, it is shown that the ignition times are reduced by 20-50 % depending on the initial value of the radiant flux density in initiation by increasing or decreasing radiant heat flux compared with the stationary conditions of heat supply in the same ambient conditions.

  1. Thin Film Heat Flux Sensors: Design and Methodology

    NASA Technical Reports Server (NTRS)

    Fralick, Gustave C.; Wrbanek, John D.

    2013-01-01

    Thin Film Heat Flux Sensors: Design and Methodology: (1) Heat flux is one of a number of parameters, together with pressure, temperature, flow, etc. of interest to engine designers and fluid dynamists, (2) The measurement of heat flux is of interest in directly determining the cooling requirements of hot section blades and vanes, and (3)In addition, if the surface and gas temperatures are known, the measurement of heat flux provides a value for the convective heat transfer coefficient that can be compared with the value provided by CFD codes.

  2. Tests of a robust eddy correlation system for sensible heat flux

    NASA Astrophysics Data System (ADS)

    Blanford, J. H.; Gay, L. W.

    1992-03-01

    Sensible heat flux estimates from a simple, one-propeller eddy correlation system (OPEC) were compared with those from a sonic anemometer eddy correlation system (SEC). In accordance with similarity theory, the performance of the OPEC system improved with increasing height of the sensor above the surface. Flux totals from the two systems at sites with adequate fetch were in excellent agreement after frequency response corrections were applied. The propeller system appears suitable for long periods of unattended measurement. The sensible heat flux measurements can be combined with net radiation and soil heat flux measurements to estimate latent heat as a residual in the surface energy balance.

  3. Method for limiting heat flux in double-wall tubes

    DOEpatents

    Hwang, Jaw-Yeu

    1982-01-01

    A method of limiting the heat flux in a portion of double-wall tubes including heat treating the tubes so that the walls separate when subjected to high heat flux and supplying an inert gas mixture to the gap at the interface of the double-wall tubes.

  4. Collisionality scaling of the electron heat flux in ETG turbulence

    NASA Astrophysics Data System (ADS)

    Colyer, G. J.; Schekochihin, A. A.; Parra, F. I.; Roach, C. M.; Barnes, M. A.; Ghim, Y.-c.; Dorland, W.

    2017-05-01

    In electrostatic simulations of MAST plasma at electron-gyroradius scales, using the local flux-tube gyrokinetic code GS2 with adiabatic ions, we find that the long-time saturated electron heat flux (the level most relevant to energy transport) decreases as the electron collisionality decreases. At early simulation times, the heat flux ‘quasi-saturates’ without any strong dependence on collisionality, and with the turbulence dominated by streamer-like radially elongated structures. However, the zonal fluctuation component continues to grow slowly until much later times, eventually leading to a new saturated state dominated by zonal modes and with the heat flux proportional to the collision rate, in approximate agreement with the experimentally observed collisionality scaling of the energy confinement in MAST. We outline an explanation of this effect based on a model of ETG turbulence dominated by zonal-nonzonal interactions and on an analytically derived scaling of the zonal-mode damping rate with the electron-ion collisionality. Improved energy confinement with decreasing collisionality is favourable towards the performance of future, hotter devices.

  5. Exploring ISEE-3 magnetic cloud polarities with electron heat fluxes

    NASA Astrophysics Data System (ADS)

    Kahler, S. W.; Crooker, N. U.; Gosling, J. T.

    1999-06-01

    We have used solar wind electron heat fluxes to determine the magnetic polarities of the interplanetary magnetic fields (IMF) during the ISEE-3 observations in 1978-1982. That period included 14 magnetic clouds (MCs) identified by Zhang and Burlaga. The MCs have been modeled as single magnetic flux ropes, and it is generally assumed that they are magnetically closed structures with each end of the flux rope connected to the Sun. The flux rope model is valid only if the magnetic polarity of each MC does not change during the passage of ISEE-3 through the MC. We test this model with the heat flux data, using the dominant heat flux in bidirectional electron heat fluxes to determine the MC polarities. The polarity changes within at least 2, and possibly 6, of the 14 MCs, meaning that those MCs can not fit the model of a single flux rope.

  6. Heat flux measurement in SSME turbine blade tester

    NASA Astrophysics Data System (ADS)

    Liebert, Curt H.

    1990-11-01

    Surface heat flux values were measured in the turbine blade thermal cycling tester located at NASA-Marshall. This is the first time heat flux has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat flux data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat flux gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat flux measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat flux effects that might be observed on degraded vanes are discussed.

  7. Heat flux measurement in SSME turbine blade tester

    NASA Astrophysics Data System (ADS)

    Liebert, Curt H.

    Surface heat flux values were measured in the turbine blade thermal cycling tester located at NASA-Marshall. This is the first time heat flux has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat flux data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat flux gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat flux measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat flux effects that might be observed on degraded vanes are discussed.

  8. Heat flux measurement in SSME turbine blade tester

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1990-01-01

    Surface heat flux values were measured in the turbine blade thermal cycling tester located at NASA-Marshall. This is the first time heat flux has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat flux data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat flux gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat flux measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat flux effects that might be observed on degraded vanes are discussed.

  9. Heat flux measurement in SSME turbine blade tester

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1990-01-01

    Surface heat flux values were measured in the turbine blade thermal cycling tester located at NASA-Marshall. This is the first time heat flux has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat flux data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat flux gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat flux measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat flux effects that might be observed on degraded vanes are discussed.

  10. Heat flux instrumentation for HYFLITE thermal protection system

    NASA Astrophysics Data System (ADS)

    Diller, T. E.

    1994-12-01

    Tasks performed in this project were defined in a September 9, 1994 meeting of representatives of Vatell, NASA Lewis and Virginia Tech. The overall objective agreed upon in the meeting was 'to demonstrate the viability of thin film techniques for heat flux and temperature sensing in HYSTEP thermal protection systems'. We decided to attempt a combination of NASA's and Vatell's best heat flux sensor technology in a sensor which would be tested in the Vortek facility at Lewis early in 1995. The NASA concept for thermocouple measurement of surface temperature was adopted, and Vatell methods for fabrication of sensors on small diameter substrates of aluminum nitride were used to produce a sensor. This sensor was then encapsulated in a NARloy-Z housing. Various improvements to the Vatell substrate design were explored without success. The basic NASA and Vatell sensor layouts were analyzed by finite element modeling, in an attempt to better understand the effects of material properties, dimensions and thermal differential element location on sensor symmetry, bandwidth and sensitivity. This analysis showed that, as long as the thermal resistivity of the thermal differential element material is much larger (10X) than that of the substrate material, the simplest arrangement of layer is best. During calibration of the sensor produced in this project, undesirable side-effects of combining the heat flux and temperature sensor return leads were observed. The sensor did not cleanly separate the heat flux and temperature signals, as sensors with four leads have consistently done before. Task 7 and 8 discussed in the meeting will be performed with a continuation of funding in 1995. The following is a discussion of each of the tasks performed as outlined in the statement of work dated september 26, 1994. Task 1A was added to cover further investigation into the NASA sensor concept.

  11. Heat flux instrumentation for HYFLITE thermal protection system

    NASA Technical Reports Server (NTRS)

    Diller, T. E.

    1994-01-01

    Tasks performed in this project were defined in a September 9, 1994 meeting of representatives of Vatell, NASA Lewis and Virginia Tech. The overall objective agreed upon in the meeting was 'to demonstrate the viability of thin film techniques for heat flux and temperature sensing in HYSTEP thermal protection systems'. We decided to attempt a combination of NASA's and Vatell's best heat flux sensor technology in a sensor which would be tested in the Vortek facility at Lewis early in 1995. The NASA concept for thermocouple measurement of surface temperature was adopted, and Vatell methods for fabrication of sensors on small diameter substrates of aluminum nitride were used to produce a sensor. This sensor was then encapsulated in a NARloy-Z housing. Various improvements to the Vatell substrate design were explored without success. The basic NASA and Vatell sensor layouts were analyzed by finite element modeling, in an attempt to better understand the effects of material properties, dimensions and thermal differential element location on sensor symmetry, bandwidth and sensitivity. This analysis showed that, as long as the thermal resistivity of the thermal differential element material is much larger (10X) than that of the substrate material, the simplest arrangement of layer is best. During calibration of the sensor produced in this project, undesirable side-effects of combining the heat flux and temperature sensor return leads were observed. The sensor did not cleanly separate the heat flux and temperature signals, as sensors with four leads have consistently done before. Task 7 and 8 discussed in the meeting will be performed with a continuation of funding in 1995. The following is a discussion of each of the tasks performed as outlined in the statement of work dated september 26, 1994. Task 1A was added to cover further investigation into the NASA sensor concept.

  12. High heat flux engineering in solar energy applications

    SciTech Connect

    Cameron, C.P.

    1993-07-01

    Solar thermal energy systems can produce heat fluxes in excess of 10,000 kW/m{sup 2}. This paper provides an introduction to the solar concentrators that produce high heat flux, the receivers that convert the flux into usable thermal energy, and the instrumentation systems used to measure flux in the solar environment. References are incorporated to direct the reader to detailed technical information.

  13. From local force-flux relationships to internal dissipations and their impact on heat engine performance: the illustrative case of a thermoelectric generator.

    PubMed

    Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph

    2013-08-01

    We present an in-depth analysis of the sometimes understated role of the principle of energy conservation in linear irreversible thermodynamics. Our case study is that of a thermoelectric generator (TEG), which is a heat engine of choice in irreversible thermodynamics, owing to the coupling between the electrical and heat fluxes. We show why Onsager's reciprocal relations must be considered locally and how internal dissipative processes emerge from the extension of these relations to a global scale: The linear behavior of a heat engine at the local scale is associated with a dissipation process that must partake in the global energy balance. We discuss the consequences of internal dissipations on the so-called efficiency at maximum power, in the light of our comparative analyses of exoreversibility and endoreversibility on the one hand and of two classes of heat engines, autonomous and periodically driven, on the other hand. Finally, basing our analysis on energy conservation, we also discuss recent works which claim the possibility to overcome the traditional boundaries on efficiency imposed by finite-time thermodynamics in thermoelectric systems with broken time-reversal symmetry; this we do by introducing a "thermal" thermopower and an "electrical" thermopower which permits an analysis of the thermoelectric response of the TEG considering a possible dissymmetry between the electrical/thermal and the thermal/electrical couplings.

  14. Wood gasification at fire level heat fluxes

    SciTech Connect

    Ohlemiller, T.J.; Kashiwagi, T.; Werner, K.

    1987-08-01

    This study was motivated by a need to understand the source of pollutant species emitted by wood burning stoves; the results are relevant also to fire research. The study examines the products generated when wood is heated in controlled conditions, without flaming, in atmospheres of varying oxygen concentration (0-21% O/sub 2/ in N/sub 2/). Small wood samples (typically 4 x 4 cm exposed face, 2-4 cm thick; mainly white pine and red oak, but also two tests with yellow pine) were subjected to uniform radiative heat fluxes (2-7.8 W/cm/sup 2/) on one face. Sample weight was followed in some tests and sample temperature (5 thermocouples in depth) in others since the two measurements could not be made together. In all tests, all evolved products were either monitored (H/sub 2/O, CO, CO/sub 2/, total hydrocarbons not condensible at -40C) or trapped and analyzed (condensible organic species).

  15. Extremely high heat fluxes beneath impinging liquid jets

    NASA Astrophysics Data System (ADS)

    Liu, X.; Lienhard, J. H., V.

    1993-05-01

    Measurements of jet-impingement heat fluxes up to 400 MW/sq m were obtained using a specially designed experimental arrangement where a thin metal plate was heated from one side with a plasma arc and cooled from the other side with an unsubmerged impinging water jet produced by a 34 MPa piston pump supplying a large cylindrical plenum. The results of this study, where heating was confined to the stagnation region, show no evidence of a critical heat flux, even up to the maximum power applied. The large fluxes were limited only by wall failure and the power of the heating source, and not by liquid-side thermal resistance.

  16. Transient critical heat flux and blowdown heat-transfer studies

    SciTech Connect

    Leung, J.C.

    1980-05-01

    Objective of this study is to give a best-estimate prediction of transient critical heat flux (CHF) during reactor transients and hypothetical accidents. To accomplish this task, a predictional method has been developed. Basically it involves the thermal-hydraulic calculation of the heated core with boundary conditions supplied from experimental measurements. CHF predictions were based on the instantaneous ''local-conditions'' hypothesis, and eight correlations (consisting of round-tube, rod-bundle, and transient correlations) were tested against most recent blowdown heat-transfer test data obtained in major US facilities. The prediction results are summarized in a table in which both CISE and Biasi correlations are found to be capable of predicting the early CHF of approx. 1 s. The Griffith-Zuber correlation is credited for its prediction of the delay CHF that occurs in a more tranquil state with slowly decaying mass velocity. In many instances, the early CHF can be well correlated by the x = 1.0 criterion; this is certainly indicative of an annular-flow dryout-type crisis. The delay CHF occurred at near or above 80% void fraction, and the success of the modified Zuber pool-boiling correlation suggests that this CHF is caused by flooding and pool-boiling type hydrodynamic crisis.

  17. High heat flux transport by microbubble emission boiling

    NASA Astrophysics Data System (ADS)

    Suzuki, Koichi

    2007-10-01

    In highly subcooled flow boiling, coalescing bubbles on the heating surface collapse to many microbubbles in the beginning of transition boiling and the heat flux increases higher than the ordinary critical heat flux. This phenomenon is called Microbubble Emission Boiling, MEB. It is generated in subcooled flow boiling and the maximum heat flux reaches about 1 kW/cm2(10 MW/m2) at liquid subcooling of 40 K and liquid velocity of 0.5 m/s for a small heating surface of 10 mm×10 mm which is placed at the bottom surface of horizontal rectangular channel. The high pressure in the channel is observed at collapse of the coalescing bubbles and it is closely related the size of coalescing bubbles. Periodic pressure waves are observed in MEB and the heat flux increases linearly in proportion to the pressure frequency. The frequency is considered the frequency of liquid-solid exchange on the heating surface. For the large sized heating surface of 50 mm length×20 mm width, the maximum heat flux obtained is 500 W/cm2 (5 MW/m2) at liquid subcooling of 40 K and liquid velocity of 0.5 m/s. This is considerably higher heat flux than the conventional cooling limit in power electronics. It is difficult to remove the high heat flux by MEB for a longer heating surface than 50 mm by single channel type. A model of advanced cooling device is introduced for power electronics by subcooled flow boiling with impinging jets. Themaxumum cooling heat flux is 500 W/cm2 (5 MW/m2). Microbubble emission boiling is useful for a high heat flux transport technology in future power electronics used in a fuel-cell power plant and a space facility.

  18. Critical heat flux in a multi-minichannel heat sink. Effect of the heated length-on-diameter ratio

    NASA Astrophysics Data System (ADS)

    Mastrullo, R.; Mauro, A. W.; Viscito, L.

    2017-01-01

    This paper exhibits saturated CHF experimental values obtained with R134a and R1234yf, working at saturation temperatures from 25 °C up to 65 °C (i.e. reduced pressures from 0.16, 0.20 and up to 0.46, 0.54, respectively). The mass flux was let to vary from 150 up to 350 kg/m2 s. All tests were performed with an aluminum multi-minichannel heat sink, made up of seven rectangular ducts, each of them 2 mm wide, 1 mm high and 35 mm long. Two heated lengths of 25 and 35 mm were structured, in order to study two different Lh/Deq ratios. The results show that critical heat flux is enhanced with increasing the mass flux and decreasing the saturation temperature. A greater Lh/Deq ratio leads instead to lower CHF values.

  19. Critical Heat Flux of Butanol Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Nishiguchi, Shotaro; Shoji, Masahiro

    It is known that the addition of small amount of alcohol such as butanol to water enhances the CHF. Such aqueous solution is actively applied to heat transfer devices such as heat pipes and microchannel cooling systems, however, the fundamental characters of boiling have not been fully understood. In the present research, the experiment of boiling heat transfer is performed on a heated wire by employing butanol aqueous solution as a typical test solution and by changing concentration 1-butanol and subcooling in a wide range. Bubbling aspects were observed using high-speed video camera. It is found from the experiment that CHF is 2 to 3 times higher than that of pure water and generating bubbles are tiny even at the saturated condition. The dependence of CHF on subcooling is found to be curious showing that CHF decreases first, takes a minimum, and then increases with increasing subcooling. These results suggest that the butanol aqueous solution is a promising liquid for the application of boiling to a small-scaled cooling device.

  20. Experimental and Numerical Characterization of High Heat Fluxes During Transient Blackbody Calibrations

    NASA Technical Reports Server (NTRS)

    Abdelmessih, Amanie N.; Horn, Thomas J.

    2008-01-01

    High heat fluxes are encountered in numerous applications, such as hypersonic vehicles in flight, fires, and engines, Calibration of heat flux gages may be performed in a dual cavity cylindrical blackbody resulting in a transient calibration environment. To characterize the transient heat fluxes. experiments were performed on a dual cavity cylindrical blackbody at nominal temperatures varying from 800 C to 1900 C in increments of 100 C. Based on experiments, the optimum heat flux sensor insertion location as measured from the center partition was determined. The pre-insertion steady state axial temperature profile is compared experimentally, numerically, and analytically. The effect of convection in the blackbody cavity during the insertion is calculated and found to be less than 2 per cent. Also, an empirical correlation for predicting the emissivity of the blackbody is included. Detailed transient thermal models have been developed to simulate the heat flux calibration process at two extreme fluxes. The high (1MW/sq m) and relatively low (70 kw/sq m) fluxes are reported in this article. The transient models show the effect of inserting a heat flux gage at room temperature on the thermal equilibrium of the blackbody at 1800 C and 800 C nominal temperatures, respectively. Also, heat flux sensor outputs are derived from computed sensor temperature distributions and compared to experimental results.

  1. Reynolds stress and heat flux in spherical shell convection

    NASA Astrophysics Data System (ADS)

    Käpylä, P. J.; Mantere, M. J.; Guerrero, G.; Brandenburg, A.; Chatterjee, P.

    2011-07-01

    Context. Turbulent fluxes of angular momentum and enthalpy or heat due to rotationally affected convection play a key role in determining differential rotation of stars. Their dependence on latitude and depth has been determined in the past from convection simulations in Cartesian or spherical simulations. Here we perform a systematic comparison between the two geometries as a function of the rotation rate. Aims: Here we want to extend the earlier studies by using spherical wedges to obtain turbulent angular momentum and heat transport as functions of the rotation rate from stratified convection. We compare results from spherical and Cartesian models in the same parameter regime in order to study whether restricted geometry introduces artefacts into the results. In particular, we want to clarify whether the sharp equatorial profile of the horizontal Reynolds stress found in earlier Cartesian models is also reproduced in spherical geometry. Methods: We employ direct numerical simulations of turbulent convection in spherical and Cartesian geometries. In order to alleviate the computational cost in the spherical runs, and to reach as high spatial resolution as possible, we model only parts of the latitude and longitude. The rotational influence, measured by the Coriolis number or inverse Rossby number, is varied from zero to roughly seven, which is the regime that is likely to be realised in the solar convection zone. Cartesian simulations are performed in overlapping parameter regimes. Results: For slow rotation we find that the radial and latitudinal turbulent angular momentum fluxes are directed inward and equatorward, respectively. In the rapid rotation regime the radial flux changes sign in accordance with earlier numerical results, but in contradiction with theory. The latitudinal flux remains mostly equatorward and develops a maximum close to the equator. In Cartesian simulations this peak can be explained by the strong "banana cells". Their effect in the

  2. Investigation of Instabilities and Heat Transfer Phenomena in Supercritical Fuels at High Heat Flux and Temperatures

    NASA Technical Reports Server (NTRS)

    Linne, Diane L.; Meyer, Michael L.; Braun, Donald C.; Keller, Dennis J.

    2000-01-01

    A series of heated tube experiments was performed to investigate fluid instabilities that occur during heating of supercritical fluids. In these tests, JP-7 flowed vertically through small diameter tubes at supercritical pressures. Test section heated length, diameter, mass flow rate, inlet temperature, and heat flux were varied in an effort to determine the range of conditions that trigger the instabilities. Heat flux was varied up to 4 BTU/sq in./s, and test section wall temperatures reached as high as 1950 F. A statistical model was generated to explain the trends and effects of the control variables. The model included no direct linear effect of heat flux on the occurrence of the instabilities. All terms involving inlet temperature were negative, and all terms involving mass flow rate were positive. Multiple tests at conditions that produced instabilities provided inconsistent results. These inconsistencies limit the use of the model as a predictive tool. Physical variables that had been previously postulated to control the onset of the instabilities, such as film temperature, velocity, buoyancy, and wall-to-bulk temperature ratio, were evaluated here. Film temperatures at or near critical occurred during both stable and unstable tests. All tests at the highest velocity were stable, but there was no functional relationship found between the instabilities and velocity, or a combination of velocity and temperature ratio. Finally, all of the unstable tests had significant buoyancy at the inlet of the test section, but many stable tests also had significant buoyancy forces.

  3. Heat flux splitter for near-field thermal radiation

    SciTech Connect

    Ben-Abdallah, P.; Belarouci, A.; Frechette, L.; Biehs, S.-A.

    2015-08-03

    We demonstrate the possibility to efficiently split the near-field heat flux exchanged between graphene nano-disks by tuning their doping. This result paves the way for the development of an active control of propagation directions for heat fluxes exchanged in the near field throughout integrated nanostructured networks.

  4. Thin Film Heat Flux Sensor of Improved Design

    NASA Technical Reports Server (NTRS)

    Fralick, Gus; Wrbanek, John; Blaha, Charles

    2002-01-01

    A new design for a thin film heat flux sensor is presented. It is easier to fabricate than previous designs, for a given heat flux has an order of magnitude larger signal, and is more easily scalable than previous designs. Transient and steady state data are also presented.

  5. Investigation of saturated critical heat flux in a single, uniformly heated microchannel

    SciTech Connect

    Wojtan, Leszek; Revellin, Remi; Thome, John R.

    2006-08-15

    A series of tests have been performed to determine the saturated critical heat flux (CHF) in 0.5 and 0.8mm internal diameter microchannel tubes as a function of refrigerant mass velocity, heated length, saturation temperature and inlet liquid subcooling. The tested refrigerants were R-134a and R-245fa and the heated length of microchannel was varied between 20 and 70mm. The results show a strong dependence of CHF on mass velocity, heated length and microchannel diameter but no influence of liquid subcooling (2-15{sup o}C) was observed. The experimental results have been compared to the well-known CHF single-channel correlation of Y. Katto and H. Ohno [An improved version of the generalized correlation of critical heat flux for the forced convective boiling in uniformly heated vertical tubes, Int. J. Heat and Mass Transfer 27 (9) (1984) 1641-1648] and the multichannel correlation of W. Qu and I. Mudawar [Measurement and correlation of critical heat flux in two-phase microchannel heat sinks, Int. J. Heat and Mass Transfer 47 (2004) 2045-2059]. The comparison shows that the correlation of Katto-Ohno predicts microchannel data with a mean absolute error of 32.8% with only 41.2% of the data falling within a +/-15% error band. The correlation of Qu and Mudawar shows the same trends as the CHF data but significantly overpredicts them. Based on the present experimental data, a new microscale version of the Katto-Ohno correlation for the prediction of CHF during saturated boiling in microchannels has been proposed. (author)

  6. Observational & modeling analysis of surface heat and moisture fluxes

    SciTech Connect

    Smith, E.

    1995-09-01

    An observational and modeling study was conducted to help assess how well current GCMs are predicting surface fluxes under the highly variable cloudiness and flow conditions characteristic of the real atmosphere. The observational data base for the study was obtained from a network of surface flux stations operated during the First ISLSCP Field Experiment (FIFE). The study included examination of a surface-driven secondary circulation in the boundary layer resulting from a persistent cross-site gradient in soil moisture, to demonstrate the sensitivity of boundary layer dynamics to heterogeneous surface fluxes, The performance of a biosphere model in reproducing the measured surface fluxes was evaluated with and without the use of satellite retrieval of three key canopy variables with RMS uncertainties commensurate with those of the measurements themselves. Four sensible heat flux closure schemes currently being used in GCMs were then evaluated against the FIFE observations. Results indicate that the methods by which closure models are calibrated lead to exceedingly large errors when the schemes are applied to variable boundary layer conditions. 4 refs., 2 figs.

  7. Tracking heat flux sensors for concentrating solar applications

    DOEpatents

    Andraka, Charles E; Diver, Jr., Richard B

    2013-06-11

    Innovative tracking heat flux sensors located at or near the solar collector's focus for centering the concentrated image on a receiver assembly. With flux sensors mounted near a receiver's aperture, the flux gradient near the focus of a dish or trough collector can be used to precisely position the focused solar flux on the receiver. The heat flux sensors comprise two closely-coupled thermocouple junctions with opposing electrical polarity that are separated by a thermal resistor. This arrangement creates an electrical signal proportional to heat flux intensity, and largely independent of temperature. The sensors are thermally grounded to allow a temperature difference to develop across the thermal resistor, and are cooled by a heat sink to maintain an acceptable operating temperature.

  8. Flow and heat transfer of ferrofluids over a flat plate with uniform heat flux

    NASA Astrophysics Data System (ADS)

    Khan, W. A.; Khan, Z. H.; Haq, R. U.

    2015-04-01

    The present work is dedicated to analyze the flow and heat transport of ferrofluids along a flat plate subjected to uniform heat flux and slip velocity. A magnetic field is applied in the transverse direction to the plate. Moreover, three different kinds of magnetic nanoparticles (Fe3O4, CoFe2O4, Mn-ZnFe2O4 are incorporated within the base fluid. We have considered two different kinds of base fluids (kerosene and water) having poor thermal conductivity as compared to solid magnetic nanoparticles. Self-similar solutions are obtained and are compared with the available data for special cases. A simulation is performed for each ferrofluid mixture by considering the dominant effects of slip and uniform heat flux. It is found that the present results are in an excellent agreement with the existing literature. The variation of skin friction and heat transfer is also performed at the surface of the plate and then the better heat transfer and of each mixture is analyzed. Kerosene-based magnetite Fe3O4 provides the higher heat transfer rate at the wall as compared to the kerosene-based cobalt ferrite and Mn-Zn ferrite. It is also concluded that the primary effect of the magnetic field is to accelerate the dimensionless velocity and to reduce the dimensionless surface temperature as compared to the hydrodynamic case, thereby increasing the skin friction and the heat transfer rate of ferrofluids.

  9. Modeling of a heat sink and high heat flux vapor chamber

    NASA Astrophysics Data System (ADS)

    Vadnjal, Aleksander

    An increasing demand for a higher heat flux removal capability within a smaller volume for high power electronics led us to focus on a novel cold plate design. A high heat flux evaporator and micro channel heat sink are the main components of a cold plate which is capable of removing couple of 100 W/cm2. In order to describe performance of such porous media device a proper modeling has to be addressed. A universal approach based on the volume average theory (VAT) to transport phenomena in porous media is shown. An approach on how to treat the closure for momentum and energy equations is addressed and a proper definition for friction factors and heat transfer coefficients are discussed. A numerical scheme using a solution to Navier-Stokes equations over a representative elementary volume (REV) and the use of VAT is developed to show how to compute friction factors and heat transfer coefficients. The calculation show good agreement with the experimental data. For the heat transfer coefficient closure, a proper average for both fluid and solid is investigated. Different types of heating are also investigated in order to determine how it influences the heat transfer coefficient. A higher heat fluxes in small area condensers led us to the micro channels in contrast to the classical heat fin design. A micro channel can have various shapes to enhance heat transfer, but the shape that will lead to a higher heat flux removal with a moderate pumping power needs to be determined. The standard micro-channel terminology is usually used for channels with a simple cross section, e.g. square, round, triangle, etc., but here the micro channel cross section is going to be expanded to describe more complicated and interconnected micro scale channel cross sections. The micro channel geometries explored are pin fins (in-line and staggered) and sintered porous micro channels. The problem solved here is a conjugate problem involving two heat transfer mechanisms; (1) porous media

  10. Development of heat flux sensors for turbine airfoils

    NASA Astrophysics Data System (ADS)

    Atkinson, William H.; Cyr, Marcia A.; Strange, Richard R.

    1985-10-01

    The objectives of this program are to develop heat flux sensors suitable for installation in hot section airfoils of advanced aircraft turbine engines and to experimentally verify the operation of these heat flux sensors in a cylinder in a cross flow experiment. Embedded thermocouple and Gardon gauge sensors were developed and fabricated into both blades and vanes. These were then calibrated using a quartz lamp bank heat source and finally subjected to thermal cycle and thermal soak testing. These sensors were also fabricated into cylindrical test pieces and tested in a burner exhaust to verify heat flux measurements produced by these sensors. The results of the cylinder in cross flow tests are given.

  11. A flux correction method for the conjugate heat transfer problem

    SciTech Connect

    He, M.; Bishop, P.J.; Minardi, A.; Kassab, A.J.

    1995-12-31

    A computational method, the flux correction method, is proposed to deal with the conjugate heat transfer problem, which uses a coupled FDM/BEM iteration scheme. The convective heat transfer in the fluid is solved using the BEM. The two solutions are coupled by enforcing continuity of temperature and heat flux at the solid-fluid interfaces. The proposed method is tested using available experimental data. For the considered cases of flow in a parallel plate channel subjected to constant heat flux or constant temperature, good agreements are observed.

  12. Dimensional Analysis of Thermoelectric Modules Under Constant Heat Flux

    NASA Astrophysics Data System (ADS)

    Suzuki, Ryosuke O.; Fujisaka, Takeyuki; Ito, Keita O.; Meng, Xiangning; Sui, Hong-Tao

    2015-01-01

    Thermoelectric power generation is examined in the case of radiative heating. A constant heat flux is assumed in addition to consideration of the Seebeck effect, Peltier effect, and Joule heating with temperature-dependent material properties. Numerical evaluations are conducted using a combination of the finite-volume method and an original simultaneous solver for the heat transfer, thermoelectric, and electric transportation phenomena. Comparison with experimental results shows that the new solver could work well in the numerical calculations. The calculations predict that the Seebeck effect becomes larger for longer thermoelectric elements because of the larger temperature difference. The heat transfer to the cold surface is critical to determine the junction temperatures under a constant heat flux from the hot surface. The negative contribution from Peltier cooling and heating can be minimized when the current is smaller for longer elements. Therefore, a thicker TE module can generate more electric power even under a constant heat flux.

  13. Constraints on geothermal heat flux under the Greenland ice sheet

    NASA Astrophysics Data System (ADS)

    Purucker, M. E.; Nicholas, J. B.; Sabaka, T. J.

    2012-12-01

    The geothermal heat flux depends on geologic conditions such as crustal heat production, mantle heat flux, and the tectonic history of the crust, all of which vary spatially. Underneath ice sheets, the geothermal heat flux influences the basal ice. Heat flux is an important boundary condition in ice sheet modeling. Using magnetic data to constrain heat flux is possible because the magnetic properties of rocks are temperature dependent until they reach the Curie temperature. In the absence of remanent magnetism, the crustal magnetic signal can be described either as a spatially varying magnetic susceptibility or a spatially varying magnetic crustal thickness. Our assumed thermal model uses a steady state, one-dimensional heat conduction and constant thermal conductivity, and assumes that the lower boundary of the magnetic crust is the Curie isotherm. To account for radioactive heat production in the crust, a model of exponentially decreasing heat production with depth is applied. Based on models of the lithospheric magnetic field from CHAMP, and the recently launched Swarm mission, this technique utilizes the 3SMAC thermal and compositional model as a starting model, and modifies it in an iterative fashion with the observed lithospheric magnetic field until the magnetic field produced by the model matches that field to within a specified error tolerance. This is done globally at a horizontal scale comparable to the spacecraft altitude, and in the 2nd stage the model heat flux is calculated based on a 1-D heat conduction equation. We validate our heat flux estimates by assessing the possible contributions from remanent magnetism, from unmodeled external magnetic fields, and from the assumptions utilized in the heat flux calculations. Our updated technique now uses improved regularizations (Tikhonov) and variance component estimation and we are in the process of updating the oceanic remanence model based on Muller et al. (2008). The technique has applications to

  14. Water and heat fluxes in desert soils: 2. Numerical simulations

    NASA Astrophysics Data System (ADS)

    Scanlon, Bridget R.; Milly, P. C. D.

    1994-03-01

    Transient one-dimensional fluxes of soil water (liquid and vapor) and heat in response to 1 year of atmospheric forcing were simulated numerically for a site in the Chihuahuan Desert of Texas. The model was initialized and evaluated using the monitoring data presented in a companion paper (Scanlon, this issue). Soil hydraulic and thermal properties were estimated a priori from a combination of laboratory measurements, models, and other published information. In the first simulation, the main drying curves were used to describe soil water retention, and hysteresis was ignored. Remarkable consistency was found between computed and measured water potentials and temperatures. Attenuation and phase shift of the seasonal cycle of water potentials below the shallow subsurface active zone (0.0- to 0.3-m depth) were similar to those of temperatures, suggesting that water potential fluctuations were driven primarily by temperature changes. Water fluxes in the upper 0.3 m of soil were dominated by downward and upward liquid fluxes that resulted from infiltration of rain and subsequent evaporation from the surface. Upward flux was vapor dominated only in the top several millimeters of the soil during periods of evaporation. Below a depth of 0.3 m, water fluxes varied slowly and were dominated by downward thermal vapor flux that decreased with depth, causing a net accumulation of water. In a second simulation, nonhysteretic water retention was instead described by the estimated main wetting curves; the resulting differences in fluxes were attributed to lower initial water contents (given fixed initial water potential) and unsaturated hydraulic conductivities that were lower than they were in the first simulation. Below a depth of 0.3 m, the thermal vapor fluxes dominated and were similar to those in the first simulation. Two other simulations were performed, differing from the first only in the prescription of different (wetter) initial water potentials. These three simulations

  15. Supercritical convection, critical heat flux, and coking characteristics of propane

    NASA Technical Reports Server (NTRS)

    Rousar, D. C.; Gross, R. S.; Boyd, W. C.

    1984-01-01

    The heat transfer characteristics of propane at subcritical and supercritical pressure were experimentally evaluated using electrically heated Monel K-500 tubes. A design correlation for supercritical heat transfer coefficient was established using the approach previously applied to supercritical oxygen. Flow oscillations were observed and the onset of these oscillations at supercritical pressures was correlated with wall-to-bulk temperature ratio and velocity. The critical heat flux measured at subcritical pressure was correlated with the product of velocity and subcooling. Long duration tests at fixed heat flux conditions were conducted to evaluate coking on the coolant side tube wall and coking rates comparable to RP-1 were observed.

  16. Supercritical convection, critical heat flux, and coking characteristics of propane

    NASA Technical Reports Server (NTRS)

    Rousar, D. C.; Gross, R. S.; Boyd, W. C.

    1984-01-01

    The heat transfer characteristics of propane at subcritical and supercritical pressure were experimentally evaluated using electrically heated Monel K-500 tubes. A design correlation for supercritical heat transfer coefficient was established using the approach previously applied to supercritical oxygen. Flow oscillations were observed and the onset of these oscillations at supercritical pressures was correlated with wall-to-bulk temperature ratio and velocity. The critical heat flux measured at subcritical pressure was correlated with the product of velocity and subcooling. Long duration tests at fixed heat flux conditions were conducted to evaluate coking on the coolant side tube wall and coking rates comparable to RP-1 were observed.

  17. Wind stress and heat fluxes over a Brazilian Coastal Upwelling

    NASA Astrophysics Data System (ADS)

    Dourado, Marcelo; Candella, Rogério

    2017-04-01

    Coastal upwelling zones have been intensively studied in the last decades especially due to their importance to the biological cycle. The coastal upwelling system of the Cabo Frio region (east coast of the Rio de Janeiro state, Brazil) keeps the surface water cold during most part of the year, what induces a stable atmospheric boundary layer associated to northeast winds. The main goal of this study is to investigate the wind stress and heat fluxes exchanges between the ocean and the atmosphere in that area. For this purpose, a set of hourly data meteorological and oceanographic data collected by a Wavescan metocean buoy anchored at 23o59S; 42oW, were used, as well as solar radiation and relative humidity from a terrestrial meteorological station from the Instituto Nacional de Meteorologia (InMet). COARE 3.0 algorithm was used to calculate the latent and sensible heat fluxes. In this discussion, positive values represent fluxes towards the ocean. The average net heat flux over our study period is 88 W m-2. The reduction of the net heat flux is due to the increase of the ocean latent heat loss, although a reduction in incoming shortwave radiation and an increase in ocean long wave cooling also contributes. The latent heat is 20 times larger than the sensible heat flux, but the mean value of the latent heat flux, 62 W m-2, is half the typical value found in open ocean. The temporal variability of both sensible and latent heat fluxes reflects their dependence on wind speed and air-sea temperature differences. When upwelling events, here periods when diurnal SST is lower than 18oC, are compared with undisturbed (without upwelling) events, it can be noted the sensible heat fluxes are positives and 10 times greater in magnitude. This is related to an increment, during these upwelling events, of the air-sea temperature difference and an increasing of the wind speed. The cold waters of the upwelling increase the air-sea temperature gradient and, also, the horizontal land

  18. Optimization-based design of a heat flux concentrator.

    PubMed

    Peralta, Ignacio; Fachinotti, Víctor D; Ciarbonetti, Ángel A

    2017-01-13

    To gain control over the diffusive heat flux in a given domain, one needs to engineer a thermal metamaterial with a specific distribution of the generally anisotropic thermal conductivity throughout the domain. Until now, the appropriate conductivity distribution was usually determined using transformation thermodynamics. By this way, only a few particular cases of heat flux control in simple domains having simple boundary conditions were studied. Thermal metamaterials based on optimization algorithm provides superior properties compared to those using the previous methods. As a more general approach, we propose to define the heat control problem as an optimization problem where we minimize the error in guiding the heat flux in a given way, taking as design variables the parameters that define the variable microstructure of the metamaterial. In the present study we numerically demonstrate the ability to manipulate heat flux by designing a device to concentrate the thermal energy to its center without disturbing the temperature profile outside it.

  19. Optimization-based design of a heat flux concentrator

    PubMed Central

    Peralta, Ignacio; Fachinotti, Víctor D.; Ciarbonetti, Ángel A.

    2017-01-01

    To gain control over the diffusive heat flux in a given domain, one needs to engineer a thermal metamaterial with a specific distribution of the generally anisotropic thermal conductivity throughout the domain. Until now, the appropriate conductivity distribution was usually determined using transformation thermodynamics. By this way, only a few particular cases of heat flux control in simple domains having simple boundary conditions were studied. Thermal metamaterials based on optimization algorithm provides superior properties compared to those using the previous methods. As a more general approach, we propose to define the heat control problem as an optimization problem where we minimize the error in guiding the heat flux in a given way, taking as design variables the parameters that define the variable microstructure of the metamaterial. In the present study we numerically demonstrate the ability to manipulate heat flux by designing a device to concentrate the thermal energy to its center without disturbing the temperature profile outside it. PMID:28084451

  20. Optimization-based design of a heat flux concentrator

    NASA Astrophysics Data System (ADS)

    Peralta, Ignacio; Fachinotti, Víctor D.; Ciarbonetti, Ángel A.

    2017-01-01

    To gain control over the diffusive heat flux in a given domain, one needs to engineer a thermal metamaterial with a specific distribution of the generally anisotropic thermal conductivity throughout the domain. Until now, the appropriate conductivity distribution was usually determined using transformation thermodynamics. By this way, only a few particular cases of heat flux control in simple domains having simple boundary conditions were studied. Thermal metamaterials based on optimization algorithm provides superior properties compared to those using the previous methods. As a more general approach, we propose to define the heat control problem as an optimization problem where we minimize the error in guiding the heat flux in a given way, taking as design variables the parameters that define the variable microstructure of the metamaterial. In the present study we numerically demonstrate the ability to manipulate heat flux by designing a device to concentrate the thermal energy to its center without disturbing the temperature profile outside it.

  1. A framework for critical heat flux prediction in high heat flux, high subcooling components

    SciTech Connect

    Hechanova, A.E.; Kazimi, M.S.; Meyer, J.E.

    1995-12-31

    The critical heat flux (CHF) limits relevant to the design of plasma facing components in tokamak fusion reactors are considered. Highly subcooled water in unobstructed pipe flow are investigated using experiments and computational models. The experiments employ water flowing through a 9.5 mm bore in a 19 mm x 19 mm copper monoblock. Single-sized heating of the block is achieved by passing an electric current through a 51 mm long plasma sprayed thin layer (0.4 mm) of tungsten overlaying a thin film (0.1 mm) of plasma sprayed ceramic on an outer wall. In the analysis, the heat transfer coefficient on the coolant-side wall relies on extrapolation of existing nucleate boiling correlations but is validated using outer wall temperature measurements and a heat conduction model. The experimental results are combined with a CHF data base from several sources to enhance the generality of the proposed CHF correlation. The CHF data base parameter ranges are as follows: Peclet numbers between 7 {times}10{sup 4} to 3.2 {times} 10{sup 6}, coolant channel diameter between 5 and 25 mm, pressure between 1 and 7 MPa, and equilibrium quality between {minus}0.49 and {minus}0.07. The proposed correlation bounds the CHF data base as a lower limit and, thus, is an appropriate conservative limit for design applications.

  2. Experimental feasibility study of a thermoelectric heat flux gage

    NASA Technical Reports Server (NTRS)

    Vanfossen, G. J.; Lopez, I.

    1983-01-01

    An experiment was conducted to determine the feasibility of using a commercially available thermoelectric device as a heat flux gage at near ambient conditions. In certain research applications, the thermoelectric heat flux gage can provide a relatively simple means to model a warm fluid cold wall convection environment. The experiment showed that heat flux through the gage could be correlated within 2.5 percent with a simple algebraic equation which considered the thermoelectric current through the device and the hot and cold side temperatures.

  3. Soil heat flux determined from diel water content and temperature variations

    USDA-ARS?s Scientific Manuscript database

    Soil heat flux for a measurement interval is commonly determined using heat flux plates buried at some depth below the surface. The heat flux values are adjusted to represent the soil surface heat flux by determining the heat stored in the layer between the plate and surface. Heat storage is calcula...

  4. Modeling epoxy foams exposed to fire-like heat fluxes.

    SciTech Connect

    Hobbs, Michael L.

    2004-11-01

    A decomposition chemistry and heat transfer model to predict the response of removable epoxy foam (REF) exposed to fire-like heat fluxes is described. The epoxy foam was created using a perfluorohexane blowing agent with a surfactant. The model includes desorption of the blowing agent and surfactant, thermal degradation of the epoxy polymer, polymer fragment transport, and vapor-liquid equilibrium. An effective thermal conductivity model describes changes in thermal conductivity with reaction extent. Pressurization is modeled assuming: (1) no strain in the condensed-phase, (2) no resistance to gas-phase transport, (3) spatially uniform stress fields, and (4) no mass loss from the system due to venting. The model has been used to predict mass loss, pressure rise, and decomposition front locations for various small-scale and large-scale experiments performed by others. The framework of the model is suitable for polymeric foams with absorbed gases.

  5. Progress in the measurement of SSME turbine heat flux with plug-type sensors

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1991-01-01

    Data reduction was completed for tests of plug-type heat flux sensors (gauges) in a turbine blade thermal cycling tester (TBT) that is located at NASA/Marshall Space Flight Center, and a typical gauge is illustrated. This is the first time that heat flux has been measured in a Space Shuttle Main Engine (SSME) Turbopump Turbine environment. The development of the concept for the gauge was performed in a heat flux measurement facility at Lewis. In this facility, transient and steady state absorbed surface heat flux information was obtained from transient temperature measurements taken at points within the gauge. A schematic of the TBT is presented, and plots of the absorbed surface heat flux measured on the three blades tested in the TBT are presented. High quality heat flux values were measured on all three blades. The experiments demonstrated that reliable and durable gauges can be repeatedly fabricated into the airfoils. The experiment heat flux data are being used for verification of SSME analytical stress, boundary layer, and heat transfer design models. Other experimental results and future plans are also presented.

  6. Infrared radiometric technique for rapid quantitative evaluation of heat flux distribution over large areas

    NASA Technical Reports Server (NTRS)

    Glazer, Stuart; Siebes, Georg

    1989-01-01

    This paper describes a novel approach for rapid, quantitative measurement of spatially distributed heat flux incident on a plane. The technique utilizes the spatial temperature distribution on an opaque thin film at the location of interest, as measured by an imaging infrared radiometer. Knowledge of film radiative properties, plus quantitative estimates of convection cooling permit the steady state energy balance at any location on the film sheet to be solved for the incident heat flux. Absolute accuracies on the order of 10-15 percent have been obtained in tests performed in air. The method is particularly useful for evaluation of spatial heat flux uniformity from distributed heat sources over large areas. It has recently been used in several applications at the Jet Propulsion Laboratory, including flux uniformity measurements from large distributed quartz lamp arrays used during thermal vacuum testing of several spacecraft components, and flux mapping of a low power NdYg laser beam.

  7. Approaching the limits of two-phase boiling heat transfer: High heat flux and low superheat

    NASA Astrophysics Data System (ADS)

    Palko, J. W.; Zhang, C.; Wilbur, J. D.; Dusseault, T. J.; Asheghi, M.; Goodson, K. E.; Santiago, J. G.

    2015-12-01

    We demonstrate capillary fed porous copper structures capable of dissipating over 1200 W cm-2 in boiling with water as the working fluid. Demonstrated superheats for this structure are dramatically lower than those previously reported at these high heat fluxes and are extremely insensitive to heat input. We show superheats of less than 10 K at maximum dissipation and varying less than 5 K over input heat flux ranges of 1000 W cm-2. Fabrication of the porous copper layers using electrodeposition around a sacrificial template allows fine control of both microstructure and bulk geometry, producing structures less than 40 μm thick with active region lateral dimensions of 2 mm × 0.3 mm. The active region is volumetrically Joule heated by passing an electric current through the porous copper bulk material. We analyze the heat transfer performance of the structures and suggest a strong influence of pore size on superheat. We compare performance of the current structure to existing wick structures.

  8. Tropical Gravity Wave Momentum Fluxes and Latent Heating Distributions

    NASA Technical Reports Server (NTRS)

    Geller, Marvin A.; Zhou, Tiehan; Love, Peter T.

    2015-01-01

    Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations forGWmomentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model's land-sea differences in convective latent heating.

  9. Simulating Heat Flux and Bubble Nucleation using Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Karayiannis, Tassos; Smith, Edward; Sefiane, Khellil; Matar, Omar

    2016-11-01

    Modelling the heat flux in multiphase flow situations must account for nucleation of bubbles, non-linear heat transfer coefficients, complex molecular interaction at the surface, detailed surface textures as well as build up of material on the surface. These complex factors combine to define the well known boiling curve, which characterises the heat flux for a given temperature gradient. Understanding and optimisation of this boiling curve, and its critical heat flux (CHF), is a problem of great importance. Molecular dynamics (MD), by modelling the motion of the individual molecules, can replicate the bubble nucleation and heat flux. Details of the wall-fluid interaction are represented with complex textures and the surface materials can be explicitly reproduced. In this talk, MD simulation results are presented for bubble nucleation and heat flux. The heat flux is matched to experimental results and the process of nucleation explored for both fractal and textured surfaces. The unique insights from the molecular scale are discussed and potential applications including surface design and coupled molecular to continuum simulation are presented. EPSRC UK platform Grant MACIPh (EP/L020564/1).

  10. Tropical Gravity Wave Momentum Fluxes and Latent Heating Distributions

    NASA Technical Reports Server (NTRS)

    Geller, Marvin A.; Zhou, Tiehan; Love, Peter T.

    2015-01-01

    Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations forGWmomentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model's land-sea differences in convective latent heating.

  11. Baseline high heat flux and plasma facing materials for fusion

    NASA Astrophysics Data System (ADS)

    Ueda, Y.; Schmid, K.; Balden, M.; Coenen, J. W.; Loewenhoff, Th.; Ito, A.; Hasegawa, A.; Hardie, C.; Porton, M.; Gilbert, M.

    2017-09-01

    In fusion reactors, surfaces of plasma facing components (PFCs) are exposed to high heat and particle flux. Tungsten and Copper alloys are primary candidates for plasma facing materials (PFMs) and coolant tube materials, respectively, mainly due to high thermal conductivity and, in the case of tungsten, its high melting point. In this paper, recent understandings and future issues on responses of tungsten and Cu alloys to fusion environments (high particle flux (including T and He), high heat flux, and high neutron doses) are reviewed. This review paper includes; Tritium retention in tungsten (K. Schmid and M. Balden), Impact of stationary and transient heat loads on tungsten (J.W. Coenen and Th. Loewenhoff), Helium effects on surface morphology of tungsten (Y. Ueda and A. Ito), Neutron radiation effects in tungsten (A. Hasegawa), and Copper and copper alloys development for high heat flux components (C. Hardie, M. Porton, and M. Gilbert).

  12. Thin-Film Resistance Heat-Flux Sensors

    NASA Technical Reports Server (NTRS)

    Fralick, Gustave C.; Wrbanek, John D.; Blaha, Charles A.

    2005-01-01

    Thin-film heat-flux sensors of a proposed type would offer advantages over currently available thin-film heat flux sensors. Like a currently available thin-film heat-flux sensor, a sensor according to the proposal would be based on measurement of voltages related to the temperatures of thin metal films on the hotter and colder faces of a layer of an electrically insulating and moderately thermally conductive material. The heat flux through such a device is proportional to the difference between the temperatures and to the thermal conductivity of the layer. The advantages of the proposed sensors over the commercial ones would arise from the manner in which the temperature-related voltages would be generated and measured.

  13. Wind-Speed—Surface-Heat-Flux Feedback in Dust Devils

    NASA Astrophysics Data System (ADS)

    Ito, Junshi; Niino, Hiroshi

    2016-11-01

    Strong winds associated with dust devils can induce locally large heat fluxes from the surface, and resulting enhanced buoyancy may further intensify the dust devils. This positive wind—surface-heat-flux feedback is studied using a large-eddy simulation of a convective boundary layer. A comparison of the results with and without the feedback process for the same environment demonstrates the significance of the feedback process for simulated dust devils.

  14. Divertor Heat Flux Mitigation in the National Spherical Torus Experiment

    SciTech Connect

    Soukhanovskii, V A; Maingi, R; Gates, D A; Menard, J E; Paul, S F; Raman, R; Roquemore, A L; Bell, M G; Bell, R E; Boedo, J A; Bush, C E; Kaita, R; Kugel, H W; LeBlanc, B P; Mueller, D

    2008-08-04

    Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly-shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6 MW m{sup -2} to 0.5-2 MW m{sup -2} in small-ELM 0.8-1.0 MA, 4-6 MW neutral beam injection-heated H-mode discharges. A self-consistent picture of outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.

  15. Anthropogenic heat flux estimation from space: first results

    NASA Astrophysics Data System (ADS)

    Chrysoulakis, Nektarios; Heldens, Wieke; Gastellu-Etchegorry, Jean-Philippe; Grimmond, Sue; Feigenwinter, Christian; Lindberg, Fredrik; Del Frate, Fabio; Klostermann, Judith; Mitraka, Zina; Esch, Thomas; Albitar, Ahmad; Gabey, Andrew; Parlow, Eberhard; Olofson, Frans

    2016-04-01

    While Earth Observation (EO) has made significant advances in the study of urban areas, there are several unanswered science and policy questions to which it could contribute. To this aim the recently launched Horizon 2020 project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of EO to retrieve anthropogenic heat flux, as a key component in the urban energy budget. The anthropogenic heat flux is the heat flux resulting from vehicular emissions, space heating and cooling of buildings, industrial processing and the metabolic heat release by people. Optical, thermal and SAR data from existing satellite sensors are used to improve the accuracy of the radiation balance spatial distribution calculation, using also in-situ reflectance measurements of urban materials are for calibration. EO-based methods are developed for estimating turbulent sensible and latent heat fluxes, as well as urban heat storage flux and anthropogenic heat flux spatial patterns at city scale and local scale by employing an energy budget closure approach. Independent methods and models are engaged to evaluate the derived products and statistical analyses provide uncertainty measures as well. Ultimate goal of the URBANFLUXES is to develop a highly automated method for estimating urban energy budget components to use with Copernicus Sentinel data, enabling its integration into applications and operational services. Thus, URBANFLUXES prepares the ground for further innovative exploitation of European space data in scientific activities (i.e. Earth system modelling and climate change studies in cities) and future and emerging applications (i.e. sustainable urban planning) by exploiting the improved data quality, coverage and revisit times of the Copernicus data. The URBANFLUXES products will therefore have the potential to support both sustainable planning strategies to improve the quality of life in cities, as well as Earth system models to

  16. Characterization of local heat fluxes around ICRF antennas on JET

    SciTech Connect

    Campergue, A.-L.; Jacquet, P.; Monakhov, I.; Arnoux, G.; Brix, M.; Sirinelli, A.; Milanesio, D.; Colas, L.; Collaboration: JET-EFDA Contributors

    2014-02-12

    When using Ion Cyclotron Range of Frequency (ICRF) heating, enhanced power deposition on Plasma-Facing Components (PFCs) close to the antennas can occur. Experiments have recently been carried out on JET with the new ITER-Like-Wall (ILW) to characterize the heat fluxes on the protection of the JET ICRF antennas, using Infra-Red (IR) thermography measurement. The measured heat flux patterns along the poloidal limiters surrounding powered antennas were compared to predictions from a simple RF sheath rectification model. The RF electric field, parallel to the static magnetic field in front of the antenna, was evaluated using the TOPICA code, integrating a 3D flattened model of the JET A2 antennas. The poloidal density variation in front of the limiters was obtained from the mapping of the Li-beam or edge reflectometry measurements using the flux surface geometry provided by EFIT equilibrium reconstruction. In many cases, this simple model can well explain the position of the maximum heat flux on the different protection limiters and the heat-flux magnitude, confirming that the parallel RF electric field and the electron plasma density in front of the antenna are the main driving parameters for ICRF-induced local heat fluxes.

  17. Explosive Boiling at Very Low Heat Fluxes: A Microgravity Phenomenon

    NASA Technical Reports Server (NTRS)

    Hasan, M. M.; Lin, C. S.; Knoll, R. H.; Bentz, M. D.

    1993-01-01

    The paper presents experimental observations of explosive boiling from a large (relative to bubble sizes) flat heating surface at very low heat fluxes in microgravity. The explosive boiling is characterized as either a rapid growth of vapor mass over the entire heating surface due to the flashing of superheated liquid or a violent boiling spread following the appearance of single bubbles on the heating surface. Pool boiling data with saturated Freon 113 was obtained in the microgravity environment of the space shuttle. The unique features of the experimental results are the sustainability of high liquid superheat for long periods and the occurrence of explosive boiling at low heat fluxes (0.2 to 1.2 kW/sq m). For a heat flux of 1.0 kW/sq m a wall superheat of 17.9 degrees C was attained in ten minutes of heating. This was followed by an explosive boiling accompanied with a pressure spike and a violent bulk liquid motion. However, at this heat flux the vapor blanketing the heating surface could not be sustained. Stable nucleate boiling continued following the explosive boiling.

  18. Applicability of uniform heat flux Nusselt number correlations to thermosyphon heat exchangers for solar water heaters

    SciTech Connect

    Dahl, S.; Davidson, J.

    1999-05-01

    Nusselt numbers are measured in three counterflow tube-in-shell heat exchangers with flow rates and temperatures representative of thermosyphon operation in solar water heating systems. Mixed convection heat transfer correlations for these tube-in-shell heat exchangers were previously developed in Dahl and Davidson (1998) from data obtained in carefully controlled experiments with uniform heat flux at the tube walls. The data presented in this paper confirm that the uniform heat flux correlations apply under more realistic conditions. Water flows in the shell and 50 percent ethylene glycol circulates in the tubes. Actual Nusselt numbers are within 15 percent of the values predicted for a constant heat flux boundary condition. The data reconfirm the importance of mixed convection in determining heat transfer rates. Under most operating conditions, natural convection heat transfer accounts for more than half of the total heat transfer rate.

  19. Applicability of uniform heat flux Nusselt number correlations to thermosyphon heat exchangers for solar water heaters

    SciTech Connect

    Dahl, S.; Davidson, J.

    1999-07-01

    Nusselt numbers are measured in three counterflow tube-in-shell heat exchangers with flow rates and temperatures representative of thermosyphon operation in solar water heating systems. Mixed convection heat transfer correlations for these tube-in-shell heat exchangers were previously developed in Dahl and Davidson (1998) from data obtained in carefully controlled experiments with uniform heat flux at the tube walls. The data presented in this paper confirm that the uniform heat flux correlations apply under more realistic conditions. Water flows in the shell and 50% ethylene glycol is circulated in the tubes. Actual Nusselt numbers are within 15% of the values predicted for a constant heat flux boundary condition. The data reconfirm the importance of mixed convection in determining heat transfer rates. Under most operating conditions, natural convection heat transfer accounts for more than half of the total heat transfer rate.

  20. Characterization of ion fluxes and heat fluxes for PMI relevant conditions on Proto-MPEX

    NASA Astrophysics Data System (ADS)

    Beers, Clyde; Shaw, Guinevere; Biewer, Theodore; Rapp, Juergen

    2016-10-01

    Plasma characterization, in particular, particle flux and electron and ion temperature distributions nearest to an exposed target, are critical to quantifying Plasma Surface Interaction (PSI). In the Proto-Material Plasma Exposure eXperiment (Proto-MPEX), the ion fluxes and heat fluxes are derived from double Langmuir Probes (DLP) and Thomson Scattering in front of the target assuming Bohm conditions at the sheath entrance. Power fluxes derived from ne and Te measurements are compared to heat fluxes measured with IR thermography. The comparison will allow conclusions on the sheath heat transmission coefficient to be made experimentally. Different experimental conditions (low and high density plasmas (0.5 - 6 x 1019 m-3) with different magnetic configuration are compared. This work was supported by the U.S. D.O.E. contract DE-AC05-00OR22725.

  1. Calibrator tests of heat flux gauges mounted in SSME blades

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1989-01-01

    Measurements of heat flux to space shuttle main engine (SSME) turbine blade surfaces are being made in the Lewis heat flux calibration facility. Surface heat flux information is obtained from transient temperature measurements taken at points within the gauge. A 100-kW Vortek arc lamp is used as a source of thermal radiant energy. Thermoplugs, with diameters of about 0.190 cm and lengths varying from about 0.190 to 0.320 cm, are being investigated. The thermoplug is surrounded on all surfaces except the active surface by a pocket of air located in the circular annulus and under the back cover. Since the thermoplug is insulated, it is assumed that heat is conducted in a one-dimensional manner from the hot active surface to the cooler back side of the thermoplug. It is concluded that the miniature plug-type gauge concept is feasible for measurement of blade surface heat flux. It is suggested that it is important to measure heat flux near the hub on the suction surface and at the throat on SSME blades rotating in engines because stress and heat transfer coefficients are high in this region.

  2. Surface Energy Heat Fluxes Using Remotely Sensed Parameters

    NASA Technical Reports Server (NTRS)

    Toll, David L.; Vukovich, Fred M.; Pontikes, Elizabeth G.

    1997-01-01

    Realistic estimates of surface energy heat fluxes are needed for the study of water and energy interactions between the land and atmosphere. The primary objective of this work is to study the estimation of surface heat energy fluxes using remote sensing derived parameters under different spatial and temporal conditions. Surface energy fluxes and remote sensing derived data from two sources were analyzed. First, we used surface heat flux, remote sensing, and ancillary data from the International Satellite Land Surface Climatology Project (ISLSCP), mapped at a 1 deg. x 1 deg. grid. Second, we used NOAA AVHRR (1 km), weather station, and ancillary data to derive estimates of surface latent and sensible heat energy fluxes over a 100 sq kilometers area for three test sites: 1) First ISLSCP Field Experiment (FIFE) grassland site, Konza Prairie, Kansas; 2) Howland, Maine Forest Ecosystem Dynamics Site; and 3) Walnut Gulch, scrubland site, surrounding Tombstone, Arizona. Satellite derived estimates of land surface temperature, surface albedo, and spectral vegetation index are used in selected models to provide estimates of surface heat fluxes. Analysis of results from the 1 deg. x 1 deg. grid for North America indicated there were similar, overall correlations between sensible and latent heat energy fluxes versus remotely sensed vegetation index and ground temperature during dry and wet year conditions. However, there were significant differences in correlations between years when stratified by land cover class. Analysis of 100 km x 100 km data (1 km resolution) indicated partitioning the areas in to primary versus secondary cover, with the secondary cover comprising less than 5% of the area, significantly improved surface heat energy flux estimates.

  3. Intercomparison of Latent Heat Fluxes Over Global Oceans

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.; Chou, Ming-Dah

    2003-01-01

    Turbulent fluxes of momentum, moisture, and heat at the air-sea interface are essential for climate studies. Version 2 Goddard Satellite-based Surface Turbulent Fluxes (GSSTF2) has been derived from the Special Sensor Microwave/Imager (SSM/I) radiance measurements. This dataset, covering the period July 1987-December 2000 over global oceans, has a spatial resolution of 1 deg x 1 deg lat-long and a temporal resolution of 1 day. Turbulent fluxes are derived from the SSM/I surface winds and surface air humidity, as well as the 2-m air and sea surface temperatures (SST) of the NCEP/NCAR reanalysis, using a bulk aerodynamic algorithm based on the surface layer similarity theory. The GSSTF2 bulk flux model, and retrieved daily wind stress, latent heat flux, wind speed, and surface air humidity validate well with ship observations of ten field experiments over the tropical and midlatitude oceans during 1991-99. The global distributions of 1988-2000 annual- and seasonal-mean turbulent fluxes show reasonable patterns related to the atmospheric general circulation and seasonal variations. Latent heat fluxes and related input parameters over global oceans during 1992-93 have been compared among GSSTF1 (version 1), GSSTF2, HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP/NCAR reanalysis, and one based on COADS (Comprehensive Ocean-Atmosphere Data Set). Our analyses suggest that the GSSTF2 latent heat flux, surface air humidity, surface wind, and SST are quite realistic compared to the other four flux datasets examined. However, significant differences are found among these five flux datasets. The GSSTF2, available at http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/hydrology/hd_gsstf2.O.html, is useful for climate studies.

  4. Charring rate of wood exposed to a constant heat flux

    Treesearch

    R. H. White; H. C. Tran

    1996-01-01

    A critical factor in the fire endurance of a wood member is its rate of charring. Most available charring rate data have been obtained using the time-temperature curves of the standard fire resistance tests (ASTM E 119 and ISO 834) to define the fire exposure. The increased use of heat release calorimeters using exposures of constant heat flux levels has broadened the...

  5. Institute for High Heat Flux Removal (IHHFR). Phases I, II, and III

    SciTech Connect

    Boyd, Ronald D.

    2014-08-31

    The IHHFR focused on interdisciplinary applications as it relates to high heat flux engineering issues and problems which arise due to engineering systems being miniaturized, optimized, or requiring increased high heat flux performance. The work in the IHHFR focused on water as a coolant and includes: (1) the development, design, and construction of the high heat flux flow loop and facility; (2) test section development, design, and fabrication; and, (3) single-side heat flux experiments to produce 2-D boiling curves and 3-D conjugate heat transfer measurements for single-side heated test sections. This work provides data for comparisons with previously developed and new single-side heated correlations and approaches that address the single-side heated effect on heat transfer. In addition, this work includes the addition of single-side heated circular TS and a monoblock test section with a helical wire insert. Finally, the present work includes: (1) data base expansion for the monoblock with a helical wire insert (only for the latter geometry), (2) prediction and verification using finite element, (3) monoblock model and methodology development analyses, and (4) an alternate model development for a hypervapotron and related conjugate heat transfer controlling parameters.

  6. Infrared Radiometery and Heat Flux Calculation for a Helicon Plasma

    NASA Astrophysics Data System (ADS)

    Berisford, Daniel; Lee, Charles A.; Raja, L. L.; Bengtson, Roger D.

    2006-10-01

    Using an infrared camera, we measured the external temperature of a quartz tube containing a 1 kW helicon Argon plasma. An Inframetrics model 600 IR camera connected to a computer DAQ system records the temperature evolution of the quartz tube surface in the vicinity of the antenna during and after the pulse. Using these measurements, we estimated the heat flux profile from the plasma into the quartz tube walls. A MATLAB code uses pre- and post- pulse snapshot images from the video to estimate the heat flux into the quartz from the plasma. Initial results have shown a broad heating profile with localized power input into the quartz under the helical antenna. We find approximately 30% of the total RF power deposited into the tube as heat, and heating directly under the antenna accounts for about 30% of this heat input.

  7. Critical heat flux and boiling heat transfer to water in a 3-mm-diameter horizontal tube.

    SciTech Connect

    Yu, W.; Wambsganss, M. W.; Hull, J. R.; France, D. M.

    2000-12-04

    Boiling of the coolant in an engine, by design or by circumstance, is limited by the critical heat flux phenomenon. As a first step in providing relevant engine design information, this study experimentally addressed both rate of boiling heat transfer and conditions at the critical point of water in a horizontal tube of 2.98 mm inside diameter and 0.9144 m heated length. Experiments were performed at system pressure of 203 kPa, mass fluxes in range of 50 to 200 kg/m{sup z}s, and inlet temperatures in range of ambient to 80 C. Experimental results and comparisons with predictive correlations are presented.

  8. An Experimental Feasibility Study of a Thermoelectric Heat Flux Gage.

    DTIC Science & Technology

    1983-01-01

    STANDARDS-1963-A /e !I -7 p- F r 𔃾f * 4 Wm , 4J#, Ooe £44 AlA -~~ *3 fv+~ 4, I4 YAW - ie AN EXPERIENTAL FEASIBILITY STUDY OF A THERMOELECTRIC HEAT FLUX GAGE...in passages beneath the surface while a heated gas flowed ITED TED Current, A over the surface. Gardon type gages then measured the SH o i rlocal...it was R Resistence parameter, ohms thought these devices could be used as a heat flux gage in moderate temperature research applications where the

  9. Numerical Analysis of a Radiant Heat Flux Calibration System

    NASA Technical Reports Server (NTRS)

    Jiang, Shanjuan; Horn, Thomas J.; Dhir, V. K.

    1998-01-01

    A radiant heat flux gage calibration system exists in the Flight Loads Laboratory at NASA's Dryden Flight Research Center. This calibration system must be well understood if the heat flux gages calibrated in it are to provide useful data during radiant heating ground tests or flight tests of high speed aerospace vehicles. A part of the calibration system characterization process is to develop a numerical model of the flat plate heater element and heat flux gage, which will help identify errors due to convection, heater element erosion, and other factors. A 2-dimensional mathematical model of the gage-plate system has been developed to simulate the combined problem involving convection, radiation and mass loss by chemical reaction. A fourth order finite difference scheme is used to solve the steady state governing equations and determine the temperature distribution in the gage and plate, incident heat flux on the gage face, and flat plate erosion. Initial gage heat flux predictions from the model are found to be within 17% of experimental results.

  10. QUANTIFICATION OF HEAT FLUX FROM A REACTING THERMITE SPRAY

    SciTech Connect

    Eric Nixon; Michelle Pantoya

    2009-07-01

    Characterizing the combustion behaviors of energetic materials requires diagnostic tools that are often not readily or commercially available. For example, a jet of thermite spray provides a high temperature and pressure reaction that can also be highly corrosive and promote undesirable conditions for the survivability of any sensor. Developing a diagnostic to quantify heat flux from a thermite spray is the objective of this study. Quick response sensors such as thin film heat flux sensors can not survive the harsh conditions of the spray, but more rugged sensors lack the response time for the resolution desired. A sensor that will allow for adequate response time while surviving the entire test duration was constructed. The sensor outputs interior temperatures of the probes at known locations and utilizes an inverse heat conduction code to calculate heat flux values. The details of this device are discussed and illustrated. Temperature and heat flux measurements of various thermite spray conditions are reported. Results indicate that this newly developed energetic material heat flux sensor provides quantitative data with good repeatability.

  11. Estimation of surface heat and moisture fluxes over a prairie grassland. 4. Impact of satellite remote sensing of slow canopy variables on performance of a hybrid biosphere model

    SciTech Connect

    Crosson, W.L. ); Smith, E.A.; Cooper, H.J. )

    1993-03-20

    The authors present the results of a series of numerical experiments using the Ex-BATS biosphere model, which is an adaptation of Dickinson's biosphere-atmosphere transfer scheme (BATS). These simulations are used to assess how the model performs when remotely sensed data are used to estimate three key canopy variables. These canopy variables, which effectively represent the slowly changing boundary conditions of a vegetated surface, consist of the total surface albedo, leaf area index, and the nondiurnally varying component of stomatal resistance, referred to as stressed stomatal resistance. The surface albedo is retrieved from NOAA-AVHRR (advanced very high resolution radiometer) channel 1 spectral reflectance information in conjunction with a directional reflectance model which accounts for the strong diurnal variations in surface reflectance. A 4-channel vegetation index also retrieved from AVHRR measurements is used to estimate the leaf area index. A similar index derived from high-resolution SPOT visible and near-infrared information has been used to describe the spatial variations in such indices which impact the retrieval of the leaf area index. Satellite retrieval of stomatal resistance is based on split-window skin temperatures from AVHRR channels 4 and 5 from the afternoon overpass ([approximately]1630 LT). It was found that although stomatal resistance has little correlation with the diurnal amplitude of skin temperature, it is closely related to the daily maximum of skin temperature. Numerical experiments have been conducted to examine model sensitivity to each of these canopy variables. The rms measurement-model flux differences in every numerical trial were within 6 W m[sup [minus]2] of the rms differences obtained for the simulations performed using measured albedo and leaf area index. Measured stomatal resistance values were obtained using an inversion form of the model. 35 refs., 16 figs., 1 tab.

  12. Turbine blade and vane heat flux sensor development, phase 1

    NASA Astrophysics Data System (ADS)

    Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

    1984-08-01

    Heat flux sensors available for installation in the hot section airfoils of advanced aircraft gas turbine engines were developed. Two heat flux sensors were designed, fabricated, calibrated, and tested. Measurement techniques are compared in an atmospheric pressure combustor rig test. Sensors, embedded thermocouple and the Gordon gauge, were fabricated that met the geometric and fabricability requirements and could withstand the hot section environmental conditions. Calibration data indicate that these sensors yielded repeatable results and have the potential to meet the accuracy goal of measuring local heat flux to within 5%. Thermal cycle tests and thermal soak tests indicated that the sensors are capable of surviving extended periods of exposure to the environment conditions in the turbine. Problems in calibration of the sensors caused by severe non-one dimensional heat flow were encountered. Modifications to the calibration techniques are needed to minimize this problem and proof testing of the sensors in an engine is needed to verify the designs.

  13. Turbine blade and vane heat flux sensor development, phase 1

    NASA Technical Reports Server (NTRS)

    Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

    1984-01-01

    Heat flux sensors available for installation in the hot section airfoils of advanced aircraft gas turbine engines were developed. Two heat flux sensors were designed, fabricated, calibrated, and tested. Measurement techniques are compared in an atmospheric pressure combustor rig test. Sensors, embedded thermocouple and the Gordon gauge, were fabricated that met the geometric and fabricability requirements and could withstand the hot section environmental conditions. Calibration data indicate that these sensors yielded repeatable results and have the potential to meet the accuracy goal of measuring local heat flux to within 5%. Thermal cycle tests and thermal soak tests indicated that the sensors are capable of surviving extended periods of exposure to the environment conditions in the turbine. Problems in calibration of the sensors caused by severe non-one dimensional heat flow were encountered. Modifications to the calibration techniques are needed to minimize this problem and proof testing of the sensors in an engine is needed to verify the designs.

  14. Critical heat flux estimation for annular channel geometry

    NASA Astrophysics Data System (ADS)

    Pagh, Richard T.

    Critical Heat Flux (CHF) is an important safety parameter for the design of nuclear reactors. The most commonly used predictive tool for determination of CHF is a look-up table developed using tube data with an average hydraulic test diameter of 8 mm. There exist in the world today nuclear reactors whose geometry is annular, not tubular, and whose hydraulic diameter is significantly smaller than 8 mm. In addition, any sub-channel thermal hydraulic model of fuel assemblies is annular and not tubular. Comparisons were made between this predictive tool and annular correlations developed from test data. These comparisons showed the look-up table over-predicts the CHF values for annular channels, thus questioning its ability to perform correct safety evaluations. Since no better tool exists to predict CHF for annular geometry, an effort was undertaken to produce one. A database of open literature annular CHF values was created as a basis for this new tool. By compiling information from eighteen sources and requiring that the data be inner wall, unilaterally, uniformly heated with no spacers or heat transfer enhancement devices, a database of 1630 experimental values was produced. After a review of the data in the database, a new look-up table was created. A look-up table provides localized control of the prediction to overcome sparseness of data. Using Shepard's Method as the extrapolation technique, a regular mesh look-up table was produced using four main variables: pressure, quality, mass flux, and hydraulic diameter. The root mean square error of this look-up table was found to be 0.8267. However, by fixing the hydraulic diameter locations to the database values, the root mean square error was further reduced to 0.2816. This look-up table can now predict CHF values for annular channels over a wide range of fluid conditions.

  15. Corrections of Heat Flux Measurements on Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Reinarts, Thomas R.; Matson, Monique L.; Walls, Laurie K.

    2002-01-01

    Knowledge of aerothermally induced convective heat transfer is important in the design of thermal protection systems for launch vehicles. Aerothermal models are typically calibrated via the data from circular, in-flight, flush-mounted surface heat flux gauges exposed to the thermal and velocity boundary layers of the external flow. Typically, copper or aluminum Schmidt- Boelter gauges, which take advantage of the one-dimensional Fourier's law of heat conduction, are used to measure the incident heat flux. This instrumentation, when surrounded by low-conductivity insulation, has a wall temperature significantly lower than the insulation. As a result of this substantial disturbance to the thermal boundary layer, the heat flux incident on the gauge tends to be considerably higher than it would have been on the insulation had the calorimeter not been there. In addition, radial conductive heat transfer from the hotter insulation can cause the calorimeter to indicate heat fluxes higher than actual. An overview of an effort to develop and calibrate gauge correction techniques for both of these effects will be presented.

  16. Methodology for calibration and use of heat flux transducers

    NASA Astrophysics Data System (ADS)

    Ducharme, Michel B.; Frim, John

    1991-05-01

    The direct assessment of heat flux from the body is a basic measurement in thermal physiology. Heat flux transducers (HFTs) are being used increasingly for that purpose under different environmental conditions. However, questions have been raised regarding the accuracy of the manufacturer's constant of calibration, and also about the effect of the thermal resistance of the device on the true thermal flux from the skin. Two different types of waterproofed HFTs were checked for their calibration using the Rapid-k thermal conductivity instrument. A detailed description of the methodology used during the calibration is given. A model capable of simulating a large range of tissue insulation was used to study the effect of the underlying tissue insulation on the relative error in thermal flux due to the thermal resistance of the HFTs. The data show that the deviation from the true value of thermal flux increases with the reciprocal of the underlying tissue insulation (r = 0.99, p less than 0.001). The underestimation of the heat flux through the skin measured by an HFT is minimal when the device is used on vasoconstricted skin in cool subjects (3 to 13 pct. error), but becomes important when used on warm vasodilated subjects (29 to 35 pct. error), and even more important on metallic skin mannequins (greater than 60 pct. error). In order to optimize the accuracy of the heat flux measurements by HFTs, it is important to recalibrate the HFTs and to correct the heat flux values for the thermal resistance of the HFT when used on vasodilated tissues.

  17. Hamiltonian magnetic reconnection with parallel electron heat flux dynamics

    NASA Astrophysics Data System (ADS)

    Grasso, D.; Tassi, E.

    2015-10-01

    > We analyse, both analytically and numerically, a two-dimensional six-field fluid model for collisionless magnetic reconnection, accounting for temperature and heat flux fluctuations along the direction of the magnetic guide field. We show that the model possesses a Hamiltonian structure with a non-canonical Poisson bracket. This bracket is characterized by the presence of six infinite families of Casimirs, associated with Lagrangian invariants. This reveals that the model can be reformulated as a system of advection equations, thus generalizing previous results obtained for Hamiltonian isothermal fluid models for reconnection. Numerical simulations indicate that the presence of heat flux and temperature fluctuations yields slightly larger growth rates and similar saturated island amplitudes, with respect to the isothermal models. For values of the sonic Larmor radius much smaller than the electron skin depth, heat flux fluctuations tend to be suppressed and temperature fluctuations follow density fluctuations. Increasing the sonic Larmor radius results in an increasing fraction of magnetic energy converted into heat flux, at the expense of temperature fluctuations. In particular, heat flux fluctuations tend to become relevant along the magnetic island separatrices. The qualitative structures associated with the electron field variables are also reinterpreted in terms of the rotation of the Lagrangian invariants of the system.

  18. Heat flux sensor research and development: The cool film calorimeter

    NASA Technical Reports Server (NTRS)

    Abtahi, A.; Dean, P.

    1990-01-01

    The goal was to meet the measurement requirement of the NASP program for a gauge capable of measuring heat flux into a 'typical' structure in a 'typical' hypersonic flight environment. A device is conceptually described that has fast response times and is small enough to fit in leading edge or cowl lip structures. The device relies heavily on thin film technology. The main conclusion is the description of the limitations of thin film technology both in the art of fabrication and in the assumption that thin films have the same material properties as the original bulk material. Three gauges were designed and fabricated. Thin film deposition processes were evaluated. The effect of different thin film materials on the performance and fabrication of the gauge was studied. The gauges were tested in an arcjet facility. Survivability and accuracy were determined under various hostile environment conditions.

  19. High heat flux experiments of saddle type divertor module

    NASA Astrophysics Data System (ADS)

    Suzuki, Satoshi; Akiba, Masato; Araki, Masanori; Satoh, Kazuyoshi; Yokoyama, Kenji; Dairaku, Masayuki

    1994-09-01

    JAERI has been extensively developing plasma facing components for next tokomak devices. The authors have developed a saddle type divertor module which consists of saddle-shaped armor tiles brazed on metal heat sink. This paper presents the experimental and analytical results of thermal cycling experiments of the saddle type divertor module. The divertor module has unidirectional CFC armor tiles brazed on OFHC copper heat sink. A twisted tape was inserted in the cooling tube to enhance the heat transfer. In the experiments, thermal response of the divertor module was monitored by an infrared camera and thermocouples. The maximum incident heat flux was 24.5 MW/m 2 for a duration of 30 s. No degradation of thermal response was observed during the experiment. As a result, the saddle type divertor module successfully endured at an incident heat flux of over 20 MW/m 2 under steady state conditions for 1000 cycles.

  20. A Comparative Study for Flow of Viscoelastic Fluids with Cattaneo-Christov Heat Flux

    PubMed Central

    Hayat, Tasawar; Muhammad, Taseer; Alsaedi, Ahmed; Mustafa, Meraj

    2016-01-01

    This article examines the impact of Cattaneo-Christov heat flux in flows of viscoelastic fluids. Flow is generated by a linear stretching sheet. Influence of thermal relaxation time in the considered heat flux is seen. Mathematical formulation is presented for the boundary layer approach. Suitable transformations lead to a nonlinear differential system. Convergent series solutions of velocity and temperature are achieved. Impacts of various influential parameters on the velocity and temperature are sketched and discussed. Numerical computations are also performed for the skin friction coefficient and heat transfer rate. Our findings reveal that the temperature profile has an inverse relationship with the thermal relaxation parameter and the Prandtl number. Further the temperature profile and thermal boundary layer thickness are lower for Cattaneo-Christov heat flux model in comparison to the classical Fourier’s law of heat conduction. PMID:27176779

  1. A Comparative Study for Flow of Viscoelastic Fluids with Cattaneo-Christov Heat Flux.

    PubMed

    Hayat, Tasawar; Muhammad, Taseer; Alsaedi, Ahmed; Mustafa, Meraj

    2016-01-01

    This article examines the impact of Cattaneo-Christov heat flux in flows of viscoelastic fluids. Flow is generated by a linear stretching sheet. Influence of thermal relaxation time in the considered heat flux is seen. Mathematical formulation is presented for the boundary layer approach. Suitable transformations lead to a nonlinear differential system. Convergent series solutions of velocity and temperature are achieved. Impacts of various influential parameters on the velocity and temperature are sketched and discussed. Numerical computations are also performed for the skin friction coefficient and heat transfer rate. Our findings reveal that the temperature profile has an inverse relationship with the thermal relaxation parameter and the Prandtl number. Further the temperature profile and thermal boundary layer thickness are lower for Cattaneo-Christov heat flux model in comparison to the classical Fourier's law of heat conduction.

  2. Mass, heat and freshwater fluxes in the South Indian Ocean

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng

    1986-01-01

    Six hydrographic sections were used to examine the circulation and property fluxes in the South Indian Ocean from 10 to 32 deg S. The calculations were made by applying an inverse method to the data. In the interior of the South Indian Ocean, the geostrophic flow is generally northward. At 18 deg S, the northward interior mass flux is balanced by the southward Ekman mass flux at the surface, whereas at 32 deg S the northward interior mass flux is balanced by the southward mass flux of the Agulhas Current. There is a weak, southward mass flux of 6 x 10 to the 9th kg/s in the Mozambique Channel. The rate of water exchange between the Pacific Ocean and the Indian Ocean is dependent on the choice of the initial reference level used in the inverse calculation. The choice of 1500 m, the depth of the deep oxygen minimum, has led to a flux of water from the Pacific Ocean to the Indian Ocean at a rate of 6.6 x 10 to the 9th kg/s. Heat flux calculations indicate that the Indian Ocean is exporting heat to the rest of the world's oceans at a rate of -0.69 x 10 to the 15th W at 18 deg S and -0.25 x 10 to the 15th W at 32 deg S (negative values being southward).

  3. Initial Tile Temperature and Heat Flux Measurements in NSTX

    NASA Astrophysics Data System (ADS)

    Maingi, Rajesh; Kugel, Henry; Roquemore, Lane; Lasnier, Charles; Johnson, Dave

    1999-11-01

    Due to their compact nature, spherical tori are projected to experience higher peak heat flux than conventional aspect ratio tokamaks of comparable heating power. For NSTX, it has been predicted[1,2] that the peak heat flux in double-null divertor configuration could reach between 10-15 MW/m2, and single-null operation would result in even higher peak heat flux. To test these predictions and support physics operations, two infrared television cameras (Inframetrics 525) have been installed on NSTX to monitor real-time tile heating and surface heat flux. The data are analyzed in real-time with a frame grabber (IMAXX) and software, and these data are also archived on videotape for future analysis. The first set of measurements will focus on thermal emission from the RF antenna, the center stack, and divertor regions. Initial data and comparison with the earlier predictions will be presented. 1 R.Maingi, et. al., "Estimates of Scrape-Off Layer and Divertor Parameters in NSTX", Proc. 1996 Int’l Workshop on the Spherical Torus, Abingdon, U.K., Dec. 4-6, 1996. 2 R. Maingi, et. al., "2-D Edge Plasma Transport Calculations for NSTX", Proc. 1997 Int’l Workshop on the Spherical Torus, St. Petersburg, Russia, Sept. 3-5, 1997.

  4. Measurements of ocean surface kinematics and heat flux

    NASA Astrophysics Data System (ADS)

    Veron, Fabrice; Melville, Ken

    2003-11-01

    The top few meters of the oceanic boundary layer play a critical role in the transfers of momentum, gas, mass and heat between the atmosphere and the ocean. These exchanges must necessarily transfer through the surface, and presumably, the rates at which they do are influence by the dynamics of the surface layer. Heat flux in particular is regulated by the thin surface thermal layer which, at most, is only a few millimeter thick. We are specifically interested in the structure of the thermal layer and the influence of the surface turbulence on the flux of heat through the air-sea boundary. Using active and passive infrared imaging, we were able to collect high temporal and spatial resolution images, yielding the Lagrangian surface velocity and temperature fields over small areas of a few square meters. We have applied cross-correlation techniques (typically used for Particle Image Velocimetry) on the passive infrared images and obtained high-resolution surface velocity fields. Using the displacement and the distortion of the actively laid down heat pattern, we also have been able to recover the surface velocity, shear strain, vorticity, and divergence. In addition, the data show that the heat flux appears to be correlated the surface vorticity. With the penetration depth of infrared radiation at these wavelengths being a few microns, these techniques appear to be extremely promising for measuring ocean surface turbulence confined within the thermal boundary layer. We will discuss the results in the context of air sea heat flux and ocean surface turbulence.

  5. The measurement of heat flux from initiators in solid propellant rocket igniters

    NASA Astrophysics Data System (ADS)

    Subba Rao, S. V.; Ramesh, N.; Pillai, B. C.

    The use of ribbon thermocouples to measure the heat flux from the initiator jet of a solid propellant rocket igniter and received by the booster charge is reported. Heat flux histories are given. All the heat flux curves showed a sharp peak within a short operation of 1 ms. Peak heat flux values extended up to 16,000 W/sq cm.

  6. Long-term evolution of anthropogenic heat fluxes into a subsurface urban heat island.

    PubMed

    Menberg, Kathrin; Blum, Philipp; Schaffitel, Axel; Bayer, Peter

    2013-09-03

    Anthropogenic alterations in urban areas influence the thermal environment causing elevated atmospheric and subsurface temperatures. The subsurface urban heat island effect is observed in several cities. Often shallow urban aquifers exist with thermal anomalies that spread laterally and vertically, resulting in the long-term accumulation of heat. In this study, we develop an analytical heat flux model to investigate possible drivers such as increased ground surface temperatures (GSTs) at artificial surfaces and heat losses from basements of buildings, sewage systems, subsurface district heating networks, and reinjection of thermal wastewater. By modeling the anthropogenic heat flux into the subsurface of the city of Karlsruhe, Germany, in 1977 and 2011, we evaluate long-term trends in the heat flux processes. It revealed that elevated GST and heat loss from basements are dominant factors in the heat anomalies. The average total urban heat flux into the shallow aquifer in Karlsruhe was found to be ∼759 ± 89 mW/m(2) in 1977 and 828 ± 143 mW/m(2) in 2011, which represents an annual energy gain of around 1.0 × 10(15) J. However, the amount of thermal energy originating from the individual heat flux processes has changed significantly over the past three decades.

  7. Analysis of edge stability for models of heat flux width

    DOE PAGES

    Makowski, Michael A.; Lasnier, Charles J.; Leonard, Anthony W.; ...

    2017-05-12

    Detailed measurements of the ne, and Te, and Ti profiles in the vicinity of the separatrix of ELMing H-mode discharges have been used to examine plasma stability at the extreme edge of the plasma and assess stability dependent models of the heat flux width. The results are strongly contrary to the critical gradient model, which posits that a ballooning instability determines a gradient scale length related to the heat flux width. The results of this analysis are not sensitive to the choice of location to evaluate stability. Significantly, it is also found that the results are completely consistent with themore » heuristic drift model for the heat flux width. Here the edge pressure gradient scales with plasma density and is proportional to the pressure gradient inferred from the equilibrium in accordance with the predictions of that theory.« less

  8. Remote high-temperature insulatorless heat-flux gauge

    DOEpatents

    Noel, B.W.

    1993-12-28

    A remote optical heat-flux gauge for use in extremely high temperature environments is described. This application is possible because of the use of thermographic phosphors as the sensing media, and the omission of the need for an intervening layer of insulator between phosphor layers. The gauge has no electrical leads, but is interrogated with ultraviolet or laser light. The luminescence emitted by the two phosphor layers, which is indicative of the temperature of the layers, is collected and analyzed in order to determine the heat flux incident on the surface being investigated. The two layers of thermographic phosphor must be of different materials to assure that the spectral lines collected will be distinguishable. Spatial heat-flux measurements can be made by scanning the light across the surface of the gauge. 3 figures.

  9. Remote high-temperature insulatorless heat-flux gauge

    DOEpatents

    Noel, Bruce W.

    1993-01-01

    A remote optical heat-flux gauge for use in extremely high temperature environments is described. This application is possible because of the use of thermographic phosphors as the sensing media, and the omission of the need for an intervening layer of insulator between phosphor layers. The gauge has no electrical leads, but is interrogated with ultraviolet or laser light. The luminescence emitted by the two phosphor layers, which is indicative of the temperature of the layers, is collected and analyzed in order to determine the heat flux incident on the surface being investigated. The two layers of thermographic phosphor must be of different materials to assure that the spectral lines collected will be distinguishable. Spatial heat-flux measurements can be made by scanning the light across the surface of the gauge.

  10. Thermal evaluation of uranium silicide miniplates irradiated at high heat flux

    SciTech Connect

    Donna P. Guillen

    2012-09-01

    The Gas Test Loop (GTL)-1 irradiation experiment was conducted in the Advanced Test Reactor (ATR) to assess corrosion performance of proposed booster fuel at heat flux levels ~30% above the design operating condition. Sixteen miniplates fabricated from 25% enriched, high-density (4.8 g U/cm3) U3Si2/Al dispersion fuel with 6061 aluminum cladding were subjected to peak beginning of cycle (BOC) heat fluxes ranging from 411 to 593 W/cm2. No adverse impacts to the miniplates were observed at these high heat flux levels. A detailed finite element model was constructed to calculate temperatures and heat flux for an as-run cycle average effective ATR south lobe power of 25.4 MW(t). Miniplate heat flux levels and fuel, cladding, hydroxide, and coolant–hydroxide interface temperatures were calculated using the average hydroxide thickness on each miniplate measured during post-irradiation examination. The purpose of this study was to obtain a best estimate of the as-run experiment temperatures to aid in establishing acceptable heat flux levels and designing fuel qualification experiments for this fuel type.

  11. Boiling inside tubes: Critical heat flux for upward flow in uniformly heated vertical tubes

    NASA Astrophysics Data System (ADS)

    1986-11-01

    ESDU 85041 recommended a procedure for estimating the heat flux at different locations along a heated tube through which a boiling liquid is flowing, assuming that the wall is wetted by the liquid. The purpose of this Data Item (ESDU 86032) is to enable the reader to check, in the case of flow up a uniformly heated vertical tube, that the heat flux does not exceed the critical value above which the liquid would not wet the wall. This point marks the onset of dryout accompanied by an increase in resistance to heat transfer and the possible onset of corrosion and overheating of the tube. The open literature contains many experimental values of the critical heat flux (CHF) in flow up electrically heated vertical tubes, mostly with water or R.12. These results have been used to check various procedures for predicting CHF with flow up vertical tubes. The recommended procedure is given in detail and illustrated in an example.

  12. Estimating interfacial thermal conductivity in metamaterials through heat flux mapping

    SciTech Connect

    Canbazoglu, Fatih M.; Vemuri, Krishna P.; Bandaru, Prabhakar R.

    2015-04-06

    The variability of the thickness as well as the thermal conductivity of interfaces in composites may significantly influence thermal transport characteristics and the notion of a metamaterial as an effective medium. The consequent modulations of the heat flux passage are analytically and experimentally examined through a non-contact methodology using radiative imaging, on a model anisotropic thermal metamaterial. It was indicated that a lower Al layer/silver interfacial epoxy ratio of ∼25 compared to that of a Al layer/alumina interfacial epoxy (of ∼39) contributes to a smaller deviation of the heat flux bending angle.

  13. DIRECT MEASUREMENT OF HEAT FLUX FROM COOLING LAKE THERMAL IMAGERY

    SciTech Connect

    Garrett, A; Eliel Villa-Aleman, E; Robert Kurzeja, R; Malcolm Pendergast, M; Timothy Brown, T; Saleem Salaymeh, S

    2007-12-19

    Laboratory experiments show a linear relationship between the total heat flux from a water surface to air and the standard deviation of the surface temperature field, {sigma}, derived from thermal images of the water surface over a range of heat fluxes from 400 to 1800 Wm{sup -2}. Thermal imagery and surface data were collected at two power plant cooling lakes to determine if the laboratory relationship between heat flux and {sigma} exists in large heated bodies of water. The heat fluxes computed from the cooling lake data range from 200 to 1400 Wm{sup -2}. The linear relationship between {sigma} and Q is evident in the cooling lake data, but it is necessary to apply band pass filtering to the thermal imagery to remove camera artifacts and non-convective thermal gradients. The correlation between {sigma} and Q is improved if a correction to the measured {sigma} is made that accounts for wind speed effects on the thermal convection. Based on more than a thousand cooling lake images, the correlation coefficients between {sigma} and Q ranged from about 0.8 to 0.9.

  14. Influence of surface kinematics on air-sea heat flux

    NASA Astrophysics Data System (ADS)

    Veron, Fabrice; Melville, Ken

    2004-11-01

    The top few meters of the oceanic boundary layer play a critical role in the transfers of momentum, gas, mass and heat between the atmosphere and the ocean. These exchanges must necessarily transfer through the surface, and presumably, the rates at which they do are influence by the dynamics of the surface layer. Heat flux in particular is regulated by the thin surface thermal layer which, at most, is only a few millimeter thick. We are specifically interested in the influence of small coherent structures of the surface turbulence on the heat flux. Using active and passive infrared imaging, we measured the evolution the surface velocity and temperature fields over small areas of a few square meters. High-resolution surface Eulerian velocity fields using cross-correlation techniques (PIV) are obtained. Using active marking of the surface with an infrared CO2 laser, we have not only shown that it is possible to directly recover the Langrangian surface velocity, but also, by marking appropriate patterns on the surface we have been able to measure the shear strain, vorticity, and surface divergence. With the penetration depth of infrared radiation at these wavelengths being a few microns, these techniques appear to be quite apt for direct measurements of ocean surface turbulence. We have also found that the flux of heat through the surface appears to be influenced by the surface wave field. We will discuss the results in the context of air sea heat flux and ocean surface turbulence.

  15. Heat flux instrumentation for Hyflite thermal protection system

    NASA Technical Reports Server (NTRS)

    Diller, T. E.

    1994-01-01

    Using Thermal Protection Tile core samples supplied by NASA, the surface characteristics of the FRCI, TUFI, and RCG coatings were evaluated. Based on these results, appropriate methods of surface preparation were determined and tested for the required sputtering processes. Sample sensors were fabricated on the RCG coating and adhesion was acceptable. Based on these encouraging results, complete Heat Flux Microsensors were fabricated on the RCG coating. The issue of lead attachment was addressed with the annnealing and welding methods developed at NASA Lewis. Parallel gap welding appears to be the best method of lead attachment with prior heat treatment of the sputtered pads. Sample Heat Flux Microsensors were submitted for testing in the NASA Ames arc jet facility. Details of the project are contained in two attached reports. One additional item of interest is contained in the attached AIAA paper, which gives details of the transient response of a Heat Flux Microsensors in a shock tube facility at Virginia Tech. The response of the heat flux sensor was measured to be faster than 10 micro-s.

  16. SPECTRAL data-based estimation of soil heat flux

    USGS Publications Warehouse

    Singh, R.K.; Irmak, A.; Walter-Shea, Elizabeth; Verma, S.B.; Suyker, A.E.

    2011-01-01

    Numerous existing spectral-based soil heat flux (G) models have shown wide variation in performance for maize and soybean cropping systems in Nebraska, indicating the need for localized calibration and model development. The objectives of this article are to develop a semi-empirical model to estimate G from a normalized difference vegetation index (NDVI) and net radiation (Rn) for maize (Zea mays L.) and soybean (Glycine max L.) fields in the Great Plains, and present the suitability of the developed model to estimate G under similar and different soil and management conditions. Soil heat fluxes measured in both irrigated and rainfed fields in eastern and south-central Nebraska were used for model development and validation. An exponential model that uses NDVI and Rn was found to be the best to estimate G based on r2 values. The effect of geographic location, crop, and water management practices were used to develop semi-empirical models under four case studies. Each case study has the same exponential model structure but a different set of coefficients and exponents to represent the crop, soil, and management practices. Results showed that the semi-empirical models can be used effectively for G estimation for nearby fields with similar soil properties for independent years, regardless of differences in crop type, crop rotation, and irrigation practices, provided that the crop residue from the previous year is more than 4000 kg ha-1. The coefficients calibrated from particular fields can be used at nearby fields in order to capture temporal variation in G. However, there is a need for further investigation of the models to account for the interaction effects of crop rotation and irrigation. Validation at an independent site having different soil and crop management practices showed the limitation of the semi-empirical model in estimating G under different soil and environment conditions.

  17. Liquid Argon Maximm Convective Heat Flux vs. Liquid Depth

    SciTech Connect

    Peterson, T.; /Fermilab

    1990-01-12

    In order to help answer questions about the magnitude of heat flux to the liquid argon in a liquid argon calorimeter which could cause boiling (bubbles), calculations estimating the heat flux which can be removed by free convection were made in February, 1988. These calculations are intended to be an estimate of the heat flux above which boiling would occur. No formal writeup was made of these calculations, although the graph dated 3 Feb 88 and revised (adding low-velocity forced convection lines) 19 Feb 88 was presented in several meetings and widely distributed. With this description of the calculations, copies of the original graph and calculations are being added to the D0 Engineering Note files. The liquid argon surface is in equilibrium with argon vapor at a pressure of 1.3 bar, so the surface is at 89.70 K. The liquid is entirely at this surface temperature throughout the bulk of the volume, except locally where it is warmed by a solid surface at a higher temperature than the bulk liquid. This surface temperature is taken to be the boiling temperature of argon at the pressure corresponding to 1.3 bar plus the liquid head; hence it is a function of depth below the surface. The free and forced convection correlations used are 'from Kreith, 'Heat Transfer', for heated flat plates in a large (i.e., no other objects nearby enough to disturb the flow) uniform volume of fluid. Heat flux is a function of plate size, really length along the flow path (since a boundary layer increases in thickness starting from the leading edge of the plate), and orientation (i.e., vertical or horizontal). The maximum heat flux which can be carried away by free convection (i.e., the heat flux above which boiling occurs) is .001 W/sq.cm. at 4 inches below the surface and 0.1 to 0.2 W/sq.cm. 15 feet below the surface. Forced convection over a 1 cm plate with a fluid velocity of 1 cm/sec, or a 10 cm plate at 10 cm/sec, is about like free convection. The line for much higher heat flux is

  18. Turbulent heat flux measurements in a transitional boundary layer

    NASA Technical Reports Server (NTRS)

    Sohn, K. H.; Zaman, K. B. M. Q.; Reshotko, E.

    1992-01-01

    During an experimental investigation of the transitional boundary layer over a heated flat plate, an unexpected result was encountered for the turbulent heat flux (bar-v't'). This quantity, representing the correlation between the fluctuating normal velocity and the temperature, was measured to be negative near the wall under certain conditions. The result was unexpected as it implied a counter-gradient heat transfer by the turbulent fluctuations. Possible reasons for this anomalous result were further investigated. The possible causes considered for this negative bar-v't' were: (1) plausible measurement error and peculiarity of the flow facility, (2) large probe size effect, (3) 'streaky structure' in the near wall boundary layer, and (4) contributions from other terms usually assumed negligible in the energy equation including the Reynolds heat flux in the streamwise direction (bar-u't'). Even though the energy balance has remained inconclusive, none of the items (1) to (3) appear to be contributing directly to the anomaly.

  19. Thermotronics: Towards Nanocircuits to Manage Radiative Heat Flux

    NASA Astrophysics Data System (ADS)

    Ben-Abdallah, Philippe; Biehs, Svend-Age

    2017-02-01

    The control of electric currents in solids is at the origin of the modern electronics revolution that has driven our daily life since the second half of 20th century. Surprisingly, to date, there is no thermal analogue for a control of heat flux. Here, we summarise the very last developments carried out in this direction to control heat exchanges by radiation both in near and far-field in complex architecture networks.

  20. Convectively Driven Heat Flux Heterogeneity in Europa's Mantle

    NASA Astrophysics Data System (ADS)

    Travis, Bryan; Schubert, G.; Palguta, J.

    2006-09-01

    Features on the surface of Europa may reflect non-uniform heating in an underlying ocean due to variations in heat flux at the mantle surface. Pore water convection can generate a spatially heterogeneous heat flux in a fractured, permeable mantle, as illustrated in 2-D computer simulations of the thermal evolution of Europa. The model uses three layers - core, silicate mantle, and H2O (liquid and frozen). Processes active in the model include radiogenic heating, tidal dissipative heating (TDH), thermal diffusion, latent heat of melting and pore water convection. Starting from a cold Europa, radiogenic heating and TDH produce a temperature profile ranging from a peak near 1150 oC in the deep interior to 15 oC at the mantle surface, overlain by an 80 km deep ocean layer at 3 oC, capped by an ice shell approximately 20 km thick. This structure provides initial conditions for our pore water convection simulation. Mantle permeability is based on Earth values. An initial, very strong flow gives way to a weaker quasi-steady pattern of convection in the mantle's porosity. Plumes rise from the mantle at a roughly 10o spacing, through the ocean layer up to the base of the ice. These are typically 50 - 100 km wide at the base of the ice. Plume heat flux is 10-12 W/m2 during the initial transient, but later drops to about 0.5 - 1.5 W/m2. Heating at the base of the ice shell is spatially heterogeneous, but only strong enough to produce significant melt-through during the initial transient. However, strong spatial heterogeneity of basal heating of the ice shell could significantly influence convection in the ice phase. This work was supported by a grant from the Institute of Geophysics and Planetary Physics at Los Alamos National Laboratory and by the NASA Planetary Geology and Geophysics Program.

  1. Contagious Coronal Heating from Recurring Emergence of Magnetic Flux

    NASA Astrophysics Data System (ADS)

    Moore, R. L.; Falconer, D. A.; Sterling, A. C.

    2002-01-01

    For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emergence within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the flux emergence. 4. There are episodes of enhanced coronal heating in surrounding magnetic fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged flux within an old active region entails far reaching adjustments in the 3D magnetic field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We Also Note That The Reason For The recurrence of flux emergence in old active regions may be that active-region flux tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

  2. Contagious Coronal Heating from Recurring Emergence of Magnetic Flux

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Falconer, David; Sterling, Alphonse; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emerge= within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the flux emergence. 4. There are episodes of enhanced coronal heating in surrounding magnetic fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged flux within an old active region entails far reaching adjustments in the 3D magnetic field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We also note that the reason for the recurrence of flux emergence in old active regions may be that active region flux tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

  3. Contagious Coronal Heating from Recurring Emergence of Magnetic Flux

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Falconer, David; Sterling, Alphonse; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emerge= within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the flux emergence. 4. There are episodes of enhanced coronal heating in surrounding magnetic fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged flux within an old active region entails far reaching adjustments in the 3D magnetic field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We also note that the reason for the recurrence of flux emergence in old active regions may be that active region flux tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

  4. Critical Heat Flux In Inclined Rectangular Narrow Long Channel

    SciTech Connect

    J. L. Rempe; S. W. Noh; Y. H. Kim; K. Y. Suh; F.B.Cheung; S. B. Kim

    2005-05-01

    In the TMI-2 accident, the lower part of the reactor pressure vessel had been overheated and then rather rapidly cooled down, as was later identified in a vessel investigation project. This accounted for the possibility of gap cooling feasibility. For this reason, several investigations were performed to determine the critical heat flux (CHF) from the standpoint of invessel retention. The experiments are conducted to investigate the general boiling phenomena, and the triggering mechanism for the CHF in a narrow gap using a 5 x 105 mm2 crevice type heater assembly and de-mineralized water. The test parameters include the gap size of 5 mm, and the surface orientation angles from the downward facing position (180o) to the vertical position (90o). The orientation angle affects the bubble layer and escape from the narrow gap. The CHF is less than that in a shorter channel, compared with the previous experiments having a heated length of 35 mmin the copper test section.

  5. Dependence of divertor heat flux widths on heating power, flux expansion, and plasma current in the NSTX

    SciTech Connect

    Maingi, Rajesh; Soukhanovskii, V. A.; Ahn, J.W.

    2011-01-01

    We report the dependence of the lower divertor surface heat flux profiles, measured from infrared thermography and mapped magnetically to the mid-plane on loss power into the scrape-off layer (P{sub LOSS}), plasma current (I{sub p}), and magnetic flux expansion (f{sub exp}), as well as initial results with lithium wall conditioning in NSTX. Here we extend previous studies [R. Maingi et al., J. Nucl. Mater. 363-365 (2007) 196-200] to higher triangularity similar to 0.7 and higher I{sub p} {le} 1.2 MA. First we note that the mid-plane heat flux width mapped to the mid-plane, {lambda}{sub q}{sup mid} is largely independent of P{sub LOSS} for P{sub LOSS} {ge} 4 MW. {lambda}{sub q}{sup mid} is also found to be relatively independent of f{sub exp}; peak heat flux is strongly reduced as f{sub exp} is increased, as expected. Finally, {lambda}{sub q}{sup mid} is shown to strongly contract with increasing I{sub p} such that {lambda}{sub q}{sup mid} {alpha} I{sub p}{sup -1.6} with a peak divertor heat flux of q{sub div,peak} similar to 15 MW/m{sup 2} when I{sub p} = 1.2 MA and P{sub LOSS} similar to 6 MW. These relationships are then used to predict the divertor heat flux for the planned NSTX-Upgrade, with heating power between 10 and 15 MW, B{sub t} = 1.01 and I{sub p}= 2.0 MA for 5 s.

  6. Coronal Heating and the Magnetic Flux Content of the Network

    NASA Astrophysics Data System (ADS)

    Moore, R. L.; Falconer, D. A.; Porter, J. G.; Hathaway, D. H.

    2003-05-01

    We investigate the heating of the quiet corona by measuring the increase of coronal luminosity with the amount of magnetic flux in the underlying network at solar minimum when there were no active regions on the face of the Sun. The coronal luminosity is measured from Fe IX/X-Fe XII pairs of coronal images from SOHO/EIT. The network magnetic flux content is measured from SOHO/MDI magnetograms. We find that the luminosity of the corona in our quiet regions increases roughly in proportion to the square root of the magnetic flux content of the network and roughly in proportion to the length of the perimeter of the network magnetic flux clumps. From (1) this result, (2) other observations of many fine-scale explosive events at the edges of network flux clumps, and (3) a demonstration that it is energetically feasible for the heating of the corona in quiet regions to be driven by explosions of granule-sized sheared-core magnetic bipoles embedded in the edges of network flux clumps, we infer that in quiet regions that are not influenced by active regions the corona is mainly heated by such magnetic activity in the edges of the network flux clumps. Our observational results together with our feasibility analysis allow us to predict that (1) at the edges of the network flux clumps there are many transient sheared-core bipoles of the size and lifetime of granules and having transverse field strengths > 100 G, (2) 30 of these bipoles are present per supergranule, and (3) most spicules are produced by explosions of these bipoles. This work was supported by NASA's Office of Space Science through its Solar and Heliospheric Physics Supporting Research and Technology Program and its Sun-Earth Connection Guest Investigator Program.

  7. Reflectance-Based Estimation of Soil Heat Fluxes in the Texas High Plains

    NASA Astrophysics Data System (ADS)

    Gowda, P. H.; Colaizzi, P. D.; O'Shaughnessy, S.; Ha, W.; Howell, T. A.

    2010-12-01

    Soil heat flux (G) is one of the terms required for estimating evapotranspiration rates using an energy balance. Numerous reflectance-based models are available in the literature for estimating G fluxes. However, these models have shown wide variation in their performance. Therefore, operational ET remote sensing programs may require locally developed/calibrated models for accurately estimating G. The objective of this study was to develop and evaluate reflectance-based empirical G models for the semi-arid Texas High Plains. Soil heat flux was measured at 0.15 hz interval and averaged every 15 minutes at five different locations within a 4.7 ha lysimeter field with Pullman clay loam soil during the 2010 summer growing season. The field was planted to soybean and managed under dryland conditions. In each location, G was measured at 8 cm depth with two Campbell Scientific HFT3 soil heat flux plates. Soil temperature was measured at 2 and 6 cm above the soil heat flux plates. Soil moisture was measured in the 2-8 cm layer using Acclima SDI-12 sensors. Hourly G fluxes at the surface were calculated by adding the measured G fluxes at 8 cm to the energy stored above the heat flux plates. A multispectral radiometer (MSR, CROPSCAN, Inc.) and hand-held thermometer (EVEREST Interscience Inc.) measured surface reflectance in red and near infrared bandwidths and surface temperature (ST), respectively, daily at 11:30 AM CST to be consistent with the Landsat 5 overpass time. Fraction crop cover (FC) was measured by digital photographs taken twice a week. A set of G models was developed for estimating hourly fluxes based on measured reflectance, net radiation, ST, NDVI, and FC,. Resulting models were compared for performance with existing models available in the literature. In this presentation, we will discuss our G models for the Texas High Plains and the statistical results.

  8. Heat flux measurements for use in physiological and clothing research.

    PubMed

    Niedermann, R; Psikuta, A; Rossi, R M

    2014-08-01

    Scientists use passive heat flow meters to measure body heat exchanges with the environment. In recent years, several such sensors have been developed and concerns about their proper calibration have been addressed. However, calibration methods have differed in the geometry of the heated device as well as in the heat transfer mechanism. Therefore, a comparison of calibration methods is needed in order to understand the obtained differences in calibration lines. We chose three commercially available heat flux sensors and placed them on four different heated devices: a hot plate, double hot plate, nude cylinder and a cylinder covered with a spacer material. We found differences between the calibration line of the manufacturer and our own measurements, especially when forced convection was involved as the main heat transfer mechanism. The results showed clearly that the calibration method should be chosen according to the intended purpose of use. In addition, we recommend use a thin, light heat flux sensor with good thermal conduction in human subject studies.

  9. Heat flux measurements for use in physiological and clothing research

    NASA Astrophysics Data System (ADS)

    Niedermann, R.; Psikuta, A.; Rossi, R. M.

    2014-08-01

    Scientists use passive heat flow meters to measure body heat exchanges with the environment. In recent years, several such sensors have been developed and concerns about their proper calibration have been addressed. However, calibration methods have differed in the geometry of the heated device as well as in the heat transfer mechanism. Therefore, a comparison of calibration methods is needed in order to understand the obtained differences in calibration lines. We chose three commercially available heat flux sensors and placed them on four different heated devices: a hot plate, double hot plate, nude cylinder and a cylinder covered with a spacer material. We found differences between the calibration line of the manufacturer and our own measurements, especially when forced convection was involved as the main heat transfer mechanism. The results showed clearly that the calibration method should be chosen according to the intended purpose of use. In addition, we recommend use a thin, light heat flux sensor with good thermal conduction in human subject studies.

  10. Spatial resolution of subsurface anthropogenic heat fluxes in cities

    NASA Astrophysics Data System (ADS)

    Benz, Susanne; Bayer, Peter; Menberg, Kathrin; Blum, Philipp

    2015-04-01

    Urban heat islands in the subsurface contain large quantities of energy in the form of elevated groundwater temperatures caused by anthropogenic heat fluxes (AHFS) into the subsurface. Hence, the objective of this study is to exemplarily quantify these AHFS and the generated thermal powers in two German cities, Karlsruhe and Cologne. A two-dimensional (2D) statistical analytical model of the vertical subsurface anthropogenic heat fluxes across the unsaturated zone was developed. The model consists of a so-called Local Monte Carlo approach that introduces a spatial representation of the following sources of AHFS: (1) elevated ground surface temperatures, (2) basements, (3) sewage systems, (4) sewage leakage, (5) subway tunnels, and (6) district heating networks. The results show that district heating networks induce the largest local AHFS with values larger than 60 W/m2 and one order of magnitude higher than the other evaluated heat sources. Only sewage pipes and basements reaching into the groundwater cause equally high heat fluxes, with maximal values of 40.37 W/m2 and 13.60 W/m2, respectively. While dominating locally, the district heating network is rather insignificant for the citywide energy budget in both urban subsurfaces. Heat from buildings (1.51 ± 1.36 PJ/a in Karlsruhe; 0.31 ± 0.14 PJ/a in Cologne) and elevated GST (0.34 ± 0.10 PJ/a in Karlsruhe; 0.42 ± 0.13 PJ/a in Cologne) are dominant contributors to the anthropogenic thermal power of the urban aquifer. In Karlsruhe, buildings are the source of 70% of the annual heat transported into the groundwater, which is mainly caused by basements reaching into the groundwater. A variance analysis confirms these findings: basement depth is the most influential factor to citywide thermal power in the studied cities with high groundwater levels. The spatial distribution of fluxes, however, is mostly influenced by the prevailing thermal gradient across the unsaturated zone. A relatively cold groundwater

  11. Multi Function Heat Pulse Probes (MFHPP) to Estimate Ground Heat Flux and Reduce Surface Energy Budget Errors

    NASA Astrophysics Data System (ADS)

    Ciocca, Francesco; Sharma, Varun; Lunati, Ivan; Parlange, Marc B.

    2013-04-01

    Ground heat flux plays a crucial role in surface energy budget: an incorrect estimation of energy storage and heat fluxes in soils occur when probes such as heat flux plates are adopted, and these mistakes can account for up to 90% of the residual variance (Higgins, GRL, 2012). A promising alternative to heat flux plates is represented by Multi Function Heat Pulse Probes (MFHPP). They have proven to be accurate in thermal properties and heat fluxes estimation (e.g. Cobos, VZJ, 2003) and can be used to monitor and quantify subsurface evaporation in field experiments (Xiao et al., VZJ, 2011). We perform a laboratory experiment with controlled temperature in a small Plexiglas column (20cm diameter and 40cm height). The column is packed with homogeneously saturated sandy soil and equipped with three MFHPPs in the upper 4cm and thermocouples and dielectric soil moisture probes deeper. This configuration allows for accurate and simultaneous ground heat flux, soil moisture and subsurface evaporation measurements. Total evaporation is monitored using a precision scale, while an infrared gun and a long wave radiometer measure the soil skin temperature and the outgoing long-short wave radiation, respectively. A fan and a heat lamp placed above the column allow to mimick on a smaller and more controlled scale the field conditions induced by the diurnal cycle. At a reference height above the column relative humidity, wind speed and air temperature are collected. Results are interpreted by means of numerical simulations performed with an ad-hoc-developed numerical model that simulates coupled heat and moisture transfer in soils and is used to match and interpolate the temperature and soil moisture values got at finite depths within the column. Ground heat fluxes are then estimated by integrating over almost continuous, numerically simulated temperature profiles, which avoids errors due to use of discrete data (Lunati et al., WRR, 2012) and leads to a more reliable estimate of

  12. Spatial and temporal variation of the surface temperature and heat flux for saturated pool nucleate boiling at lower heat fluxes

    SciTech Connect

    Unal, C.; Pasamehmetoglu, K.O.

    1993-10-01

    The spatial and temporal variations of local surface temperature and heat flux for saturated pool nucleate boiling are investigated parametrically using a numerical model. The numerical model consisted of solving the three-dimensional transient heat conduction equation within the heater subjected to nucleate boiling over its upper surface. The surface topography model to distribute the cavities over the boiling surface used a Monte Carlo scheme. All cavities were assumed to be conical in shape. The cavity radii are obtained using an exponential probability density function with a known mean value. Local surface temperatures showed significant spatial and temporal variations, depending upon the surface topography and the heater material and thickness. However, the surface-averaged temperature showed practically no temporal variation. The temporal variations in local temperatures caused the surface-averaged heat flux to vary significantly. The temporal variations in the surface-averaged heat flux were similar for smooth and rough and thick and thin copper and nickel plates. Results indicated that the use of a classical energy balance equation to evaluate the surface heat flux must consider the spatial variation of the temperature. Results also showed that any thermocouple embedded beneath the surface of the heater does not follow the temporal variations at the surface.

  13. Forced Convection Boiling and Critical Heat Flux of Ethanol in Electrically Heated Tube Tests

    NASA Technical Reports Server (NTRS)

    Meyer, Michael L.; Linne, Diane L.; Rousar, Donald C.

    1998-01-01

    Electrically heated tube tests were conducted to characterize the critical heat flux (transition from nucleate to film boiling) of subcritical ethanol flowing at conditions relevant to the design of a regeneratively cooled rocket engine thrust chamber. The coolant was SDA-3C alcohol (95% ethyl alcohol, 5% isopropyl alcohol by weight), and tests were conducted over the following ranges of conditions: pressure from 144 to 703 psia, flow velocities from 9.7 to 77 ft/s, coolant subcooling from 33 to 362 F, and critical heat fluxes up to 8.7 BTU/in(exp 2)/sec. For the data taken near 200 psia, critical heat flux was correlated as a function of the product of velocity and fluid subcooling to within +/- 20%. For data taken at higher pressures, an additional pressure term is needed to correlate the critical heat flux. It was also shown that at the higher test pressures and/or flow rates, exceeding the critical heat flux did not result in wall burnout. This result may significantly increase the engine heat flux design envelope for higher pressure conditions.

  14. Pool boiling of distilled water over tube bundle with variable heat flux

    NASA Astrophysics Data System (ADS)

    Swain, Abhilas; Mohanty, Rajiva Lochan; Das, Mihir Kumar

    2017-02-01

    The experimental investigation of saturated pool boiling heat transfer of distilled water over plain tube bundle, under uniform and varying heat flux condition along the height are presented in this article. Experiments are carried out under various heat flux configurations applied to rows of tube bundles and pitch distance to diameter ratios of 1.25, 1.6 and 1.95. The wall superheats and pool boiling heat transfer coefficients over individual rows are determined. The pool boiling heat transfer coefficients for variable heat flux and uniform heat flux conditions are compared. The results indicate that the bundle effect is found to exist for uniform as well as variable heat flux under all operating conditions in the present investigation. The variable heat flux resulted in range of wall superheat being highest for decreasing heat flux from bottom to top and lowest for increasing heat flux from bottom to top.

  15. Pool boiling of distilled water over tube bundle with variable heat flux

    NASA Astrophysics Data System (ADS)

    Swain, Abhilas; Mohanty, Rajiva Lochan; Das, Mihir Kumar

    2017-08-01

    The experimental investigation of saturated pool boiling heat transfer of distilled water over plain tube bundle, under uniform and varying heat flux condition along the height are presented in this article. Experiments are carried out under various heat flux configurations applied to rows of tube bundles and pitch distance to diameter ratios of 1.25, 1.6 and 1.95. The wall superheats and pool boiling heat transfer coefficients over individual rows are determined. The pool boiling heat transfer coefficients for variable heat flux and uniform heat flux conditions are compared. The results indicate that the bundle effect is found to exist for uniform as well as variable heat flux under all operating conditions in the present investigation. The variable heat flux resulted in range of wall superheat being highest for decreasing heat flux from bottom to top and lowest for increasing heat flux from bottom to top.

  16. Soil heat flux measurements in an open forest

    NASA Astrophysics Data System (ADS)

    van der Meulen, M. W. J.; Klaassen, W.

    1996-05-01

    The soil surface heat flux in an open oak forest was determined at four locations to account for the heterogeneity of the forest. Soil temperatures and soil water content were measured at several depths and an integration method with three layers was used. The thickness of the bottom layer was determined with a spectral method. The soil surface heat flux was compared with the net radiation above the canopy for four typical days in 1995. These data were fitted linearly. The slope of this parameterisation was 0.092, with a leaf area index of 2.5 (fully-leafed canopy). This result was compared with four other studies. To produce an exponential fit of the slope against the leaf area index the Beer-Bouguer law for radiation extinction in canopies and a soil surface heat flux proportional to the net radiation at the forest floor was used. An extinction coefficient of 0.36 was found. This result is recommended for future studies, if soil surface heat flux is requested and net radiation data above the canopy as well as leaf area index are available.

  17. Light-intensity modulator withstands high heat fluxes

    NASA Technical Reports Server (NTRS)

    Maples, H. G.; Strass, H. K.

    1966-01-01

    Mechanism modulates and controls the intensity of luminous radiation in light beams associated with high-intensity heat flux. This modulator incorporates two fluid-cooled, externally grooved, contracting metal cylinders which when rotated about their longitudinal axes present a circular aperture of varying size depending on the degree of rotation.

  18. Experiments of Transient Condensation Heat Transfer on the Heat Flux Senor

    NASA Astrophysics Data System (ADS)

    Wang, Xuwen; Liu, Qiusheng; Zhu, Zhiqiang; Chen, Xue

    2015-09-01

    The influence of transient heat transfer in different condensation condition was investigated experimentally in the present paper. Getting condensation heat and mass transfer regularity and characteristics in space can provide theoretical basis for thermodynamic device such as heat pipes, loop heat pipes and capillary pumped loops as well as other fluid management engineering designing. In order to study the condensation process in space, an experimental study has been carried out on the ground for space experiment. The results show that transit heat transfer coefficient of film condensation is related to the condensation film width, the flow condition near the two phase interface and the pressure of the vapor and non-condensable gas in chamber. On the ground, the condensation heat flux on vertical surface is higher than it on horizontal surface. The transit heat flux of film condensation is affected by the temperature of superheated vapor, the temperature of condensation surface and non-condensable gas pressure. Condensation heat flux with vapor forced convection is many times more than it with natural convection. All of heat flux for both vapor forced convection and natural convection condensation in limited chamber declines dramatically over time. The present experiment is preliminary work for our future space experiments of the condensation and heat transfer process onboard the Chinese Spacecraft "TZ-1" to be launched in 2016.

  19. Maximum allowable heat flux for a submerged horizontal tube bundle

    SciTech Connect

    McEligot, D.M.

    1995-08-14

    For application to industrial heating of large pools by immersed heat exchangers, the socalled maximum allowable (or {open_quotes}critical{close_quotes}) heat flux is studied for unconfined tube bundles aligned horizontally in a pool without forced flow. In general, we are considering boiling after the pool reaches its saturation temperature rather than sub-cooled pool boiling which should occur during early stages of transient operation. A combination of literature review and simple approximate analysis has been used. To date our main conclusion is that estimates of q inch chf are highly uncertain for this configuration.

  20. Viscous relaxation of Ganymede's impact craters: Constraints on heat flux

    USGS Publications Warehouse

    Bland, Michael; Singer, Kelsi N.; McKinnon, William B.; Schenk, Paul M.

    2017-01-01

    Measurement of crater depths in Ganymede’s dark terrain have revealed substantial numbers of unusually shallow craters indicative of viscous relaxation [see companion paper: Singer, K.N., Schenk, P. M., Bland, M.T., McKinnon, W.B., (2017). Relaxed impact craters on Ganymede: Regional variations and high heat flow. Icarus, submitted]. These viscously relaxed craters provide insight into the thermal history of the dark terrain: the rate of relaxation depends on the size of the crater and the thermal structure of the lithosphere. Here we use finite element simulations of crater relaxation to constrain the heat flux within the dark terrain when relaxation occurred. We show that the degree of viscous relaxation observed cannot be achieved through radiogenic heating alone, even if all of the relaxed craters are ancient and experienced the high radiogenic fluxes present early in the satellite’s history. For craters with diameter ≥ 10 km, heat fluxes of 40–50 mW m-2−2"> can reproduce the observed crater depths, but only if the fluxes are sustained for ∼1 Gyr. These craters can also be explained by shorter-lived “heat pulses” with magnitudes of ∼100 mW m-2−2"> and timescales of 10–100 Myr. At small crater diameters (4 km) the observed shallow depths are difficult to achieve even when heat fluxes as high as 150 mW m-2−2"> are sustained for 1 Gyr. The extreme thermal conditions required to viscously relax small craters may indicate that mechanisms other than viscous relaxation, such as topographic degradation, are also in play at small crater diameters. The timing of the relaxation event(s) is poorly constrained due to the sparsity of adequate topographic information, though it likely occurred in Ganymede’s middle history (neither recently, nor shortly after satellite formation). The consistency between the timing and magnitude of the heat fluxes derived here and those inferred from other tectonic features suggests that a single event

  1. Measurement of a surface heat flux and temperature

    NASA Technical Reports Server (NTRS)

    Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

    1994-01-01

    The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The

  2. Measurement of a surface heat flux and temperature

    NASA Astrophysics Data System (ADS)

    Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

    1994-04-01

    The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The

  3. Azimuthal Stress and Heat Flux In Radiatively Inefficient Accretion Flows

    NASA Astrophysics Data System (ADS)

    Devlen, Ebru

    2016-07-01

    Radiatively Inefficient Accretion Flows (RIAFs) have low radiative efficiencies and/or low accretion rates. The accreting gas may retain most of its binding energy in the form of heat. This lost energy for hot RIAFs is one of the problems heavily worked on in the literature. RIAF observations on the accretion to super massive black holes (e.g., Sagittarius A* in the center of our Galaxy) have shown that the observational data are not consistent with either advection-dominated accretion flow (ADAF) or Bondi models. For this reason, it is very important to theoretically comprehend the physical properties of RIAFs derived from observations with a new disk/flow model. One of the most probable candidates for definition of mass accretion and the source of excess heat energy in RIAFs is the gyroviscous modified magnetorotational instability (GvMRI). Dispersion relation is derived by using MHD equations containing heat flux term based on viscosity in the energy equation. Numerical solutions of the disk equations are done and the growth rates of the instability are calculated. This additional heat flux plays an important role in dissipation of energy. The rates of the angular momentum and heat flux which are obtained from numerical calculations of the turbulence brought about by the GVMRI are also discussed.

  4. Heat Flux in the Strong-Wind Nocturnal Boundary Layer

    NASA Astrophysics Data System (ADS)

    Mahrt, L.

    2016-11-01

    Sonic anemometer measurements are analyzed from two primary field programs and 12 supplementary sites to examine the behaviour of the turbulent heat flux near the surface with high wind speeds in the nocturnal boundary layer. On average, large downward heat flux is found for high wind speeds for most of the sites where some stratification is maintained in spite of relatively intense vertical mixing. The stratification for high wind speeds is found to be dependent on wind direction, suggesting the importance of warm-air advection, even for locally homogenous sites. Warm-air advection is also inferred from a large imbalance of the heat budget of the air for strong winds. Shortcomings of our study are noted.

  5. Numerical study of the effects of boundary conditions on the measurement and calibration of gardon type heat flux sensors

    NASA Technical Reports Server (NTRS)

    Krane, M.; Dybbs, A.

    1987-01-01

    To monitor the high-intensity heat flux conditions that occur in the space shuttle main engine (SSME), it is necessary to use specifically designed heat flux sensors. These sensors, which are of the Gardon-type, are exposed on the measuring face to high-intensity radiative and convective heat fluxes and on the other face to convective cooling. To improve the calibration and measurement accuracy of these gauges, researchers are studing the effect that the thermal boundary conditions have on gauge performance. In particular, they are studying how convective cooling effects the field inside the sensor and the measured heat flux. The first phase of this study involves a numerical study of these effects. Subsequent phases will involve experimental verification. A computer model of the heat transfer around a Garden-type heat flux sensor was developed. Two specific geometries are being considered are: (1) heat flux sensor mounted on a flat-plate; and (2) heat flux sensor mounted at the stagnation point of a circular cylinder. Both of these configurations are representative of the use of heat flux sensors in the components of the SSME. The purpose of the analysis is to obtain a temperature distribution as a function of the boundary conditions.

  6. Global Intercomparison of 12 Land Surface Heat Flux Estimates

    NASA Technical Reports Server (NTRS)

    Jimenez, C.; Prigent, C.; Mueller, B.; Seneviratne, S. I.; McCabe, M. F.; Wood, E. F.; Rossow, W. B.; Balsamo, G.; Betts, A. K.; Dirmeyer, P. A.; hide

    2011-01-01

    A global intercomparison of 12 monthly mean land surface heat flux products for the period 1993-1995 is presented. The intercomparison includes some of the first emerging global satellite-based products (developed at Paris Observatory, Max Planck Institute for Biogeochemistry, University of California Berkeley, University of Maryland, and Princeton University) and examples of fluxes produced by reanalyses (ERA-Interim, MERRA, NCEP-DOE) and off-line land surface models (GSWP-2, GLDAS CLM/ Mosaic/Noah). An intercomparison of the global latent heat flux (Q(sub le)) annual means shows a spread of approx 20 W/sq m (all-product global average of approx 45 W/sq m). A similar spread is observed for the sensible (Q(sub h)) and net radiative (R(sub n)) fluxes. In general, the products correlate well with each other, helped by the large seasonal variability and common forcing data for some of the products. Expected spatial distributions related to the major climatic regimes and geographical features are reproduced by all products. Nevertheless, large Q(sub le)and Q(sub h) absolute differences are also observed. The fluxes were spatially averaged for 10 vegetation classes. The larger Q(sub le) differences were observed for the rain forest but, when normalized by mean fluxes, the differences were comparable to other classes. In general, the correlations between Q(sub le) and R(sub n) were higher for the satellite-based products compared with the reanalyses and off-line models. The fluxes were also averaged for 10 selected basins. The seasonality was generally well captured by all products, but large differences in the flux partitioning were observed for some products and basins.

  7. Global Intercomparison of 12 Land Surface Heat Flux Estimates

    NASA Technical Reports Server (NTRS)

    Jimenez, C.; Prigent, C.; Mueller, B.; Seneviratne, S. I.; McCabe, M. F.; Wood, E. F.; Rossow, W. B.; Balsamo, G.; Betts, A. K.; Dirmeyer, P. A.; Fisher, J. B.; Jung, M.; Kanamitsu, M.; Reichle, R. H.; Reichstein, M.; Rodell, M.; Sheffield, J.; Tu, K.; Wang, K.

    2011-01-01

    A global intercomparison of 12 monthly mean land surface heat flux products for the period 1993-1995 is presented. The intercomparison includes some of the first emerging global satellite-based products (developed at Paris Observatory, Max Planck Institute for Biogeochemistry, University of California Berkeley, University of Maryland, and Princeton University) and examples of fluxes produced by reanalyses (ERA-Interim, MERRA, NCEP-DOE) and off-line land surface models (GSWP-2, GLDAS CLM/ Mosaic/Noah). An intercomparison of the global latent heat flux (Q(sub le)) annual means shows a spread of approx 20 W/sq m (all-product global average of approx 45 W/sq m). A similar spread is observed for the sensible (Q(sub h)) and net radiative (R(sub n)) fluxes. In general, the products correlate well with each other, helped by the large seasonal variability and common forcing data for some of the products. Expected spatial distributions related to the major climatic regimes and geographical features are reproduced by all products. Nevertheless, large Q(sub le)and Q(sub h) absolute differences are also observed. The fluxes were spatially averaged for 10 vegetation classes. The larger Q(sub le) differences were observed for the rain forest but, when normalized by mean fluxes, the differences were comparable to other classes. In general, the correlations between Q(sub le) and R(sub n) were higher for the satellite-based products compared with the reanalyses and off-line models. The fluxes were also averaged for 10 selected basins. The seasonality was generally well captured by all products, but large differences in the flux partitioning were observed for some products and basins.

  8. Experimental investigation of heat transfer and burnout in condition of nonuniform megawatt heat fluxes

    SciTech Connect

    Komendantov, A.S.; Kuzma-Kichta, Y.A.; Vasil'eva, L.T.; Ovodkov, A.A. )

    1991-01-01

    In this paper burnout is investigated in tubes under nonuniform heating on the perimeter. Data on heat transfer and critical heat flux (q{sub chf}) in the case of water were obtained for ranges of mass velocity {rho}w = 200--3000 kg/m{sup 2} s, pressure p = 1--1 MPa, and inlet water temperature T = 25--98{degrees}C. The test section was a horizontal copper tube of 21 mm outer diameter, 8 mm inner diameter with a technically smooth surface and heat transfer-intensifying twisted tape and porous sintered coating. The test section was heated by bombardment with electrons. It is established that a redistribution of heat fluxes and an increase of wall temperature fluctuations occur at burnout. The range of regime parameters to prevent burnout of a heat transfer surface is determined.

  9. High performance flexible heat pipes

    NASA Technical Reports Server (NTRS)

    Shaubach, R. M.; Gernert, N. J.

    1985-01-01

    A Phase I SBIR NASA program for developing and demonstrating high-performance flexible heat pipes for use in the thermal management of spacecraft is examined. The program combines several technologies such as flexible screen arteries and high-performance circumferential distribution wicks within an envelope which is flexible in the adiabatic heat transport zone. The first six months of work during which the Phase I contract goal were met, are described. Consideration is given to the heat-pipe performance requirements. A preliminary evaluation shows that the power requirement for Phase II of the program is 30.5 kilowatt meters at an operating temperature from 0 to 100 C.

  10. High performance flexible heat pipes

    NASA Technical Reports Server (NTRS)

    Shaubach, R. M.; Gernert, N. J.

    1985-01-01

    A Phase I SBIR NASA program for developing and demonstrating high-performance flexible heat pipes for use in the thermal management of spacecraft is examined. The program combines several technologies such as flexible screen arteries and high-performance circumferential distribution wicks within an envelope which is flexible in the adiabatic heat transport zone. The first six months of work during which the Phase I contract goal were met, are described. Consideration is given to the heat-pipe performance requirements. A preliminary evaluation shows that the power requirement for Phase II of the program is 30.5 kilowatt meters at an operating temperature from 0 to 100 C.

  11. Constraints on hydrothermal heat flux through the oceanic lithosphere from global heat flow

    NASA Technical Reports Server (NTRS)

    Stein, Carol A.; Stein, Seth

    1994-01-01

    A significant discrepancy exists between the heat flow measured at the seafloor and the higher values predicted by thermal models of the cooling lithosphere. This discrepancy is generally interpreted as indicating that the upper oceanic crust is cooled significantly by hydrothermal circulation. The magnitude of this heat flow discrepancy is the primary datum used to estimate the volume of hydrothermal flow, and the variation in the discrepancy with lithospheric age is the primary constraint on how the hydrothermal flux is divided between near-ridge and off-ridge environments. The resulting estimates are important for investigation of both the thermal structure of the lithosphere and the chemistry of the oceans. We reevaluate the magnitude and age variation of the discrepancy using a global heat flow data set substantially larger than in earlier studies, and the GDHI (Global Depth and Heat Flow) model that better predicts the heat flow. We estimate that of the predicted global oceanic heat flux of 32 x 10(exp 12) W, 34% (11 x 10(exp 12) W) occurs by hydrothermal flow. Approximately 30% of the hydrothermal heat flux occurs in crust younger than 1 Ma, so the majority of this flux is off-ridge. These hydrothermal heat flux estimates are upper bounds, because heat flow measurements require sediment at the site and so are made preferentially at topographic lows, where heat flow may be depressed. Because the water temperature for the near-ridge flow exceeds that for the off-ridge flow, the near-ridge water flow will be even a smaller fraction of the total water flow. As a result, in estimating fluxes from geochemical data, use of the high water temperatures appropriate for the ridge axis may significantly overestimate the heat flux for an assumed water flux or underestimate the water flux for an assumed heat flux. Our data also permit improved estimates of the 'sealing' age, defined as the age where the observed heat flow approximately equals that predicted, suggesting

  12. Constraints on hydrothermal heat flux through the oceanic lithosphere from global heat flow

    NASA Technical Reports Server (NTRS)

    Stein, Carol A.; Stein, Seth

    1994-01-01

    A significant discrepancy exists between the heat flow measured at the seafloor and the higher values predicted by thermal models of the cooling lithosphere. This discrepancy is generally interpreted as indicating that the upper oceanic crust is cooled significantly by hydrothermal circulation. The magnitude of this heat flow discrepancy is the primary datum used to estimate the volume of hydrothermal flow, and the variation in the discrepancy with lithospheric age is the primary constraint on how the hydrothermal flux is divided between near-ridge and off-ridge environments. The resulting estimates are important for investigation of both the thermal structure of the lithosphere and the chemistry of the oceans. We reevaluate the magnitude and age variation of the discrepancy using a global heat flow data set substantially larger than in earlier studies, and the GDHI (Global Depth and Heat Flow) model that better predicts the heat flow. We estimate that of the predicted global oceanic heat flux of 32 x 10(exp 12) W, 34% (11 x 10(exp 12) W) occurs by hydrothermal flow. Approximately 30% of the hydrothermal heat flux occurs in crust younger than 1 Ma, so the majority of this flux is off-ridge. These hydrothermal heat flux estimates are upper bounds, because heat flow measurements require sediment at the site and so are made preferentially at topographic lows, where heat flow may be depressed. Because the water temperature for the near-ridge flow exceeds that for the off-ridge flow, the near-ridge water flow will be even a smaller fraction of the total water flow. As a result, in estimating fluxes from geochemical data, use of the high water temperatures appropriate for the ridge axis may significantly overestimate the heat flux for an assumed water flux or underestimate the water flux for an assumed heat flux. Our data also permit improved estimates of the 'sealing' age, defined as the age where the observed heat flow approximately equals that predicted, suggesting

  13. Dispersion of Heat Flux Sensors Manufactured in Silicon Technology

    PubMed Central

    Ziouche, Katir; Lejeune, Pascale; Bougrioua, Zahia; Leclercq, Didier

    2016-01-01

    In this paper, we focus on the dispersion performances related to the manufacturing process of heat flux sensors realized in CMOS (Complementary metal oxide semi-conductor) compatible 3-in technology. In particular, we have studied the performance dispersion of our sensors and linked these to the physical characteristics of dispersion of the materials used. This information is mandatory to ensure low-cost manufacturing and especially to reduce production rejects during the fabrication process. The results obtained show that the measured sensitivity of the sensors is in the range 3.15 to 6.56 μV/(W/m2), associated with measured resistances ranging from 485 to 675 kΩ. The dispersions correspond to a Gaussian-type distribution with more than 90% determined around average sensitivity Se¯ = 4.5 µV/(W/m2) and electrical resistance R¯ = 573.5 kΩ within the interval between the average and, more or less, twice the relative standard deviation. PMID:27294929

  14. Simulation of surface heat fluxes of Typhoon Songda (Chedeng) 2011 using WRF-ARW model

    NASA Astrophysics Data System (ADS)

    Muhammad; Lestari, R. I.; Mulia, F.; Ilhamsyah, Y.; Jalil, Z.; Rizwan

    2017-02-01

    Heat fluxes particularly latent heat is important to drive the development, formation, and intensification of Typhoon Songda (Chedeng). The research was carried out by performing WRF ARW. Three domains with finest resolution at 3.2-km in domain three were utilized in the model. The model involved significant physics parameters, e.g., Kain-Fritsch in the cumulus scheme, Yonsei university in the PBL scheme, and WRF Single-Moment 3-class in the microphysics scheme . The analysis focused on May 26th upon mature stage of Songda (Chedeng). The result showed that the simulation of the eye, three-dimensional structure of internal wind flow, and surface heat fluxes were well-performed. The intensity of Songda (Chedeng) was represented by azimuthal velocity. It showed that the maximum wind was 72 ms-1 occurred at the eye wall at critical radius of 20-km from the eye center where large portion of latent heat available in the area. Significant variation of surface sensible and latent heat fluxes were occurred between the inner and outer core. Thus, it affected to develop a strong horizontal temperature gradient which further intensify the cyclonic inward penetration into the inner core. In terms of disaster risk reduction, this study bring benefit to assist operational weather forecaster to produce good short-range forecasts of the Typhoon intensities. If the surface heat fluxes increase gradually, early warning system on typhoon intensities that will affect over particular region is then released.

  15. Heat flux: thermohydraulic investigation of solar air heaters used in agro-industrial applications

    NASA Astrophysics Data System (ADS)

    Rahmati Aidinlou, H.; Nikbakht, A. M.

    2017-03-01

    A new design of solar air heater simulator is presented to comply with the extensive applications inagro-industry. A wise installation of increased heat transfer surface area provided uniform and efficient heat diffusion over the duct. Nusselt number and friction factor have been investigated based on the constant roughness parameters such as relative roughness height (e/D), relative roughness pitch (P/e), angle of attack (α) and aspect ratio with Reynolds numbers ranging from 5000 to 19,000 in the fully developed region. Heat fluxes of 800, 900 and 1000 Wm-2 were provided. The enhancement in friction factor is observed to be 3.1656, 3.47 and 3.0856 times, and for the Nusselt number either, augmentation is calculated to be 1.4437, 1.4963 and 1.535 times, respectively, over the smooth duct for 800, 900 and 1000 Wm-2 heat fluxes. Thermohydraulic performance is plotted versus the Reynolds number based on the aforementioned roughness parameters at varying heat fluxes. The results show up that thermohydraulic performance is found to be maximum for 1000 Wm-2 at the average Reynolds number of 5151. Based on the results, we can verify that the introduced solar simulator can help analyzing and developing solar collector installations at the simulated heat fluxes.

  16. A low-frequency wave motion mechanism enables efficient energy transport in carbon nanotubes at high heat fluxes.

    PubMed

    Zhang, Xiaoliang; Hu, Ming; Poulikakos, Dimos

    2012-07-11

    The great majority of investigations of thermal transport in carbon nanotubes (CNTs) in the open literature focus on low heat fluxes, that is, in the regime of validity of the Fourier heat conduction law. In this paper, by performing nonequilibrium molecular dynamics simulations we investigated thermal transport in a single-walled CNT bridging two Si slabs under constant high heat flux. An anomalous wave-like kinetic energy profile was observed, and a previously unexplored, wave-dominated energy transport mechanism is identified for high heat fluxes in CNTs, originated from excited low frequency transverse acoustic waves. The transported energy, in terms of a one-dimensional low frequency mechanical wave, is quantified as a function of the total heat flux applied and is compared to the energy transported by traditional Fourier heat conduction. The results show that the low frequency wave actually overtakes traditional Fourier heat conduction and efficiently transports the energy at high heat flux. Our findings reveal an important new mechanism for high heat flux energy transport in low-dimensional nanostructures, such as one-dimensional (1-D) nanotubes and nanowires, which could be very relevant to high heat flux dissipation such as in micro/nanoelectronics applications.

  17. Physical mechanisms of heat, momentum and turbulence fluxes

    NASA Technical Reports Server (NTRS)

    Theon, John S.

    1987-01-01

    In a qualitative way, the physical mechanisms which generate fluxes of heat, momentum, and turbulence in the atmosphere are discussed. This material is presented to acquaint people with the Earth science aspects of turbulence as important processes in the atmosphere. To attempt to describe turbulent fluxes of heat, momentum, and moisture in precise mathematical detail becomes an intractable problem. It is burdened by an eighth order set of equations involving more variables than equations. It is a closure problem which requires complicated assumptions that are not necessarily always satisfied, variable boundary conditions, and sparse observational data. Therefore, we must approach the problem in a simplified manner to obtain any kind of solution involving the variables of shear, stress, and heat, moisture, and momentum fluxes. There are other problems, of course, in which the inclusion of the planetary boundary layer is extremely important. Air pollution studies, air-sea exchanges, mesoscale models, and so on, must account for the planetary layer in very specific terms. Some of the physical mechanisms that are involved in generating fluxes are described.

  18. Spectral estimates of net radiation and soil heat flux

    USGS Publications Warehouse

    Daughtry, C.S.T.; Kustas, W.P.; Moran, M.S.; Pinter, P. J.; Jackson, R. D.; Brown, P.W.; Nichols, W.D.; Gay, L.W.

    1990-01-01

    Conventional methods of measuring surface energy balance are point measurements and represent only a small area. Remote sensing offers a potential means of measuring outgoing fluxes over large areas at the spatial resolution of the sensor. The objective of this study was to estimate net radiation (Rn) and soil heat flux (G) using remotely sensed multispectral data acquired from an aircraft over large agricultural fields. Ground-based instruments measured Rn and G at nine locations along the flight lines. Incoming fluxes were also measured by ground-based instruments. Outgoing fluxes were estimated using remotely sensed data. Remote Rn, estimated as the algebraic sum of incoming and outgoing fluxes, slightly underestimated Rn measured by the ground-based net radiometers. The mean absolute errors for remote Rn minus measured Rn were less than 7%. Remote G, estimated as a function of a spectral vegetation index and remote Rn, slightly overestimated measured G; however, the mean absolute error for remote G was 13%. Some of the differences between measured and remote values of Rn and G are associated with differences in instrument designs and measurement techniques. The root mean square error for available energy (Rn - G) was 12%. Thus, methods using both ground-based and remotely sensed data can provide reliable estimates of the available energy which can be partitioned into sensible and latent heat under nonadvective conditions. ?? 1990.

  19. Entropy flux and anomalous axial heat transport at the nanoscale

    NASA Astrophysics Data System (ADS)

    Sellitto, A.; Cimmelli, V. A.; Jou, D.

    2013-02-01

    The form and the role of the entropy flux in the thermodynamic analysis of the transport equations are essentially open questions in nonequilibrium thermodynamics. In particular, nonlocal heat-transport equations at nanoscale may exhibit some peculiar behaviors which seem to violate well-known statements of the second law of thermodynamics. Here we examine one of these behaviors in axial heat transport from the perspective of a generalized entropy flux, i.e., J(s)=q/T+k, and show that such a generalization allows it to be consistent with the second law. In contrast with previous formal analyses, this paper provides an explicit form for the nonclassical part of the entropy flux, that is, k=ℓ2/(λT2)∇qT·q and links it to a concrete physical phenomenon which is accessible to current experimental possibilities for systems with sufficiently long mean-free path ℓ, whereas for short enough ℓ the classical results are recovered. The derivation of the nonclassical part of the entropy flux is obtained within the frame of extended irreversible thermodynamics from two different perspectives, namely, a 13-field theory with higher-order fluxes and a 4-field theory with higher-order gradients.

  20. Scaling Relationships for ELM Diverter Heat Flux on DIII D

    NASA Astrophysics Data System (ADS)

    Peters, E. A.; Makowski, M. A.; Leonard, A. W.

    2015-11-01

    Edge Localized Modes (ELMs) are periodic plasma instabilities that occur during H-mode operation in tokamaks. Left unmitigated, these instabilities result in concentrated particle and heat fluxes at the divertor and stand to cause serious damage to the plasma facing components of tokamaks. The purpose of this research is to find scaling relationships that predict divertor heat flux due to ELMs based on plasma parameters at the time of instability. This will be accomplished by correlating characteristic ELM parameters with corresponding plasma measurements and analyzing the data for trends. One early assessment is the effect of the heat transmission coefficient ? on the in/out asymmetry of the calculated ELM heat fluxes. Using IR camera data, further assessments in this study will continue to emphasize in/out asymmetry in ELMs, as this has important implications for ITER operation. Work supported in part by the US DOE, DE-AC52-07NA27344, DE-FC02-04ER54698, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships Program (SULI).

  1. A Review of Boiling Heat Transfer Processes at High Heat Flux

    DTIC Science & Technology

    1991-04-01

    the limit of nucleate boiling (point C) and point 0 which is known as the Leidenfrost point. The path between the points is dependent on numerous...heat flux controlled system. 4 Point Elies on a portion of the boiling curve known as film boiling. Beginning at the Leidenfrost point (point D) heat

  2. A 2-D imaging heat-flux gauge

    SciTech Connect

    Noel, B.W.; Borella, H.M. ); Beshears, D.L.; Sartory, W.K.; Tobin, K.W.; Williams, R.K. ); Turley, W.D. . Santa Barbara Operations)

    1991-07-01

    This report describes a new leadless two-dimensional imaging optical heat-flux gauge. The gauge is made by depositing arrays of thermorgraphic-phosphor (TP) spots onto the faces of a polymethylpentene is insulator. In the first section of the report, we describe several gauge configurations and their prototype realizations. A satisfactory configuration is an array of right triangles on each face that overlay to form squares when the gauge is viewed normal to the surface. The next section of the report treats the thermal conductivity of TPs. We set up an experiment using a comparative longitudinal heat-flow apparatus to measure the previously unknown thermal conductivity of these materials. The thermal conductivity of one TP, Y{sub 2}O{sub 3}:Eu, is 0.0137 W/cm{center dot}K over the temperature range from about 300 to 360 K. The theories underlying the time response of TP gauges and the imaging characteristics are discussed in the next section. Then we discuss several laboratory experiments to (1) demonstrate that the TP heat-flux gauge can be used in imaging applications; (2) obtain a quantum yield that enumerates what typical optical output signal amplitudes can be obtained from TP heat-flux gauges; and (3) determine whether LANL-designed intensified video cameras have sufficient sensitivity to acquire images from the heat-flux gauges. We obtained positive results from all the measurements. Throughout the text, we note limitations, areas where improvements are needed, and where further research is necessary. 12 refs., 25 figs., 4 tabs.

  3. High heat flux testing capabilities at Sandia National Laboratories - New Mexico

    SciTech Connect

    Youchison, D.L.; McDonald, J.M.; Wold, L.S.

    1994-12-31

    High heat flux testing for the United States fusion power program is the primary mission of the Plasma Materials Test Facility (PMTF) located at Sandia National Laboratories - New Mexico. This facility, which is owned by the United States Department of Energy, has been in operation for over 17 years and has provided much of the high heat flux data used in the design and evaluation of plasma facing components for many of the world`s magnetic fusion, tokamak experiments. In addition to domestic tokamaks such as Tokamak Fusion Test Reactor (TFTR) at Princeton and the DIII-D tokamak at General Atomics, components for international experiments like TEXTOR, Tore-Supra, and JET also have been tested at the PMTF. High heat flux testing spans a wide spectrum including thermal shock tests on passively cooled materials, thermal response and thermal fatigue tests on actively cooled components, critical heat flux-burnout tests, braze reliability tests and safety related tests. The objective of this article is to provide a brief overview of the high heat flux testing capabilities at the PMTF and describe a few of the experiments performed over the last year.

  4. Simulation of tokamak SOL and divertor region including heat flux mitigation by gas puffing

    NASA Astrophysics Data System (ADS)

    Park, Jin-Woo; Na, Yong-Su; Hong, Sang Hee; Ahn, Joon-Wook; Kim, Deok-Kyu; Han, Hyunsun; Shim, Seong Bo; Lee, Hae June

    2012-08-01

    Two-dimensional (2D), scrape-off layer (SOL)-divertor transport simulations are performed using the integrated plasma-neutral-impurity code KTRAN developed at Seoul National University. Firstly, the code is applied to reproduce a National Spherical Torus eXperiment (NSTX) discharge by using the prescribed transport coefficients and the boundary conditions obtained from the experiment. The plasma density, the heat flux on the divertor plate, and the D α emission rate profiles from the numerical simulation are found to follow experimental trends qualitatively. Secondly, predictive simulations are carried out for the baseline operation mode in Korea Superconducting Tokamak Advanced Research (KSTAR) to predict the heat flux on the divertor target plates. The stationary peak heat flux in the KSTAR baseline operation mode is expected to be 6.5 MW/m2 in the case of an orthogonal divertor. To study the mitigation of the heat flux, we investigated the puffing effects of deuterium and argon gases. The puffing position is assumed to be in front of the strike point at the outer lower divertor plate. In the simulations, mitigation of the peak heat flux at the divertor target plates is found to occur when the gas puffing rate exceeds certain values, ˜1.0 × 1020 /s and ˜5.0 × 1018 /s for deuterium and argon, respectively. Multi-charged impurity transport is also investigated for both NSTX and KSTAR SOL and divertor regions.

  5. Modelling sub-daily latent heat fluxes from a small reservoir

    NASA Astrophysics Data System (ADS)

    McGloin, Ryan; McGowan, Hamish; McJannet, David; Burn, Stewart

    2014-11-01

    Accurate methods of latent heat flux quantification are essential for water management and for use in hydrological and meteorological models. Currently the effect of small lakes in most numerical weather prediction modelling systems is either entirely ignored or crudely parameterized. In order to test methods for modelling hourly latent heat flux from small water bodies, this study compares results from several modelling approaches to values measured by the eddy covariance method at an agricultural reservoir in southeast Queensland, Australia. Mass transfer estimates of LE calculated using the theoretical mass transfer model and using the Tanny et al. (2008) and Sacks et al. (1994) bulk transfer coefficients showed the best relationship with measured values under a range of meteorological conditions. The theoretical model showed the strongest correlation with measured values, while the Tanny et al. (2008) and Sacks et al. (1994) models had regression equation slopes with the closest proximity to 1. Latent heat fluxes estimated using the Granger and Hedstrom (2011) evaporation model, that was specifically developed for use at small reservoirs, showed a poor relationship with measured values, particularly in stable atmospheric conditions. The 1-dimensional hydrodynamics model, DYRESM, was used to obtain predictions of hourly latent heat flux without the use of water surface temperature measurements. DYRESM estimates of latent heat flux showed a slightly worse relationship with measured values than those predicted using the traditional mass transfer models (which used measurements of water surface temperature). However, DYRESM performed considerably better than the Granger and Hedstrom (2011) model.

  6. A Simple Scheme for Estimating Turbulent Heat Flux over Landfast Arctic Sea Ice from Dry Snow to Advanced Melt

    NASA Astrophysics Data System (ADS)

    Raddatz, R. L.; Papakyriakou, T. N.; Else, B. G.; Swystun, K.; Barber, D. G.

    2015-05-01

    We describe a dynamic-parameter aggregation scheme to estimate hourly turbulent heat fluxes over landfast sea ice during the transition from winter to spring. Hourly albedo measurements are used to track the morphology of the surface as it evolved from a fairly smooth homogeneous dry snow surface to a rougher heterogeneous surface with spatially differential melting and melt ponds. The estimates of turbulent heat fluxes for 928 h are compared with eddy-covariance measurements. The model performance metrics (W m) for sensible heat flux were found to be: mean bias , root-mean-square error 6 and absolute accuracy 4, and for latent heat flux near zero, 3 and 2, respectively. The correlation coefficient between modelled and measured sensible heat fluxes was 0.82, and for latent heat fluxes 0.88. The turbulent heat fluxes were estimated more accurately without adjustments than with adjustments for atmospheric stability based on the bulk Richardson number. Overall, and across all metrics for both sensible and latent heat fluxes, the dynamic-parameter aggregation scheme outperformed the static Community Ice (C-ICE) scheme, part of the Community Climate System model, applied to the same winter-to-spring transition period.

  7. Do Cyclones Steer Surface Turbulent Heat Fluxes in Mid Latitude Oceans?

    NASA Astrophysics Data System (ADS)

    Tilinina, N.; Gulev, S.; Gavrikov, A.

    2015-12-01

    Surface turbulent heat fluxes are responsible for variability of surface ocean heat budget on synoptic and interannual scales. This variability is driven by variations of near surface atmospheric characteristics controlled in midlatitudes by atmospheric cyclones. We focus on understanding the mechanisms of synoptic variability of surface turbulent fluxes and on the origins of extreme turbulent fluxes and their impact on the atmospheric dynamics. The main questions addressed in this study are (i) what are the large scale atmospheric conditions associated with extreme ocean surface fluxes and are they related to cyclones, (ii) what is the role of extreme surface fluxes in the variability of oceanic heat content, and (iii) which characteristics of atmospheric cyclones are sensitive to the surface ocean flux signals? To answer these questions, we derived characteristics of the extreme surface fluxes from their empirical probability distributions from the NCEP-CFSR reanalysis, 1979-onwards and analyse them together with cyclone characteristics over the midlatitudinal North Atlantic. Cyclone tracking has been performed using state of the art numerical tracking algorithm applied to the reanalysis SLP at 6-hourly resolution. We argue that the presence of the high pressure system following to the rare part of propagating cyclone is a critical condition for the formation of extreme surface ocean fluxes which are associated with the cyclone-anticyclone interaction zone rather than with cyclone per se. We also demonstrate that the fraction of oceanic heat loss due to extremes linked to the atmospheric circulation. Locally this fraction can be as large as 50%. We also show that over the Gulf Stream more than 60% of cyclogenesis were associated with extreme surface fluxes.

  8. Round-Robin Test of Heat Flux Sensors

    NASA Astrophysics Data System (ADS)

    Turzo-Andras, E.; Blokland, H.; Hammerschmidt, U.; Rudtsch, S.; Stacey, C.; Krös, C.; Magyarlaki, T.; Nemeth, S.

    2011-12-01

    The first intercomparison on the density of heat flow-rate measurements has been organized by MKEH (Hungarian Trade Licensing Office, Metrology Division) within the framework of EUROMET (Project No. 426). This round-robin test gives evidence about the measurement capabilities of the local realizations of a density of a heat flow-rate scale up to 100 W · m-2. Two types of heat flux plate sensors differing in their size were circulated among partner laboratories. Each one of the six partners calibrated the sensors using its own calibration system, a guarded hot plate or a heat flow meter apparatus. This article compares all the results of the round-robin test and gives the mutual differences among the partners. The participants could benefit from the measurement results by improving, in case of need, their calibration methods and procedures and by reducing their uncertainties. The impact of this comparison will go directly to the users in industry.

  9. Surface heat flux feedback controlled impurity seeding experiments with Alcator C-Mod’s high-Z vertical target plate divertor: performance, limitations and implications for fusion power reactors

    NASA Astrophysics Data System (ADS)

    Brunner, D.; Wolfe, S. M.; LaBombard, B.; Kuang, A. Q.; Lipschultz, B.; Reinke, M. L.; Hubbard, A.; Hughes, J.; Mumgaard, R. T.; Terry, J. L.; Umansky, M. V.; The Alcator C-Mod Team

    2017-08-01

    The Alcator C-Mod team has recently developed a feedback system to measure and control surface heat flux in real-time. The system uses real-time measurements of surface heat flux from surface thermocouples and a pulse-width modulated piezo valve to inject low-Z impurities (typically N2) into the private flux region. It has been used in C-Mod to mitigate peak surface heat fluxes  >40 MW m-2 down to  <10 MW m-2 while maintaining excellent core confinement, H 98  >  1. While the system works quite well under relatively steady conditions, use of it during transients has revealed important limitations on feedback control of impurity seeding in conventional vertical target plate divertors. In some cases, the system is unable to avoid plasma reattachment to the divertor plate or the formation of a confinement-damaging x-point MARFE. This is due to the small operational window for mitigated heat flux in the parameters of incident plasma heat flux, plasma density, and impurity density as well as the relatively slow response of the impurity gas injection system compared to plasma transients. Given the severe consequences for failure of such a system to operate reliably in a reactor, there is substantial risk that the conventional vertical target plate divertor will not provide an adequately controllable system in reactor-class devices. These considerations motivate the need to develop passively stable, highly compliant divertor configurations and experimental facilities that can test such possible solutions.

  10. Critical heat flux (CHF) phenomenon on a downward facing curved surface

    SciTech Connect

    Cheung, F.B.; Haddad, K.H.; Liu, Y.C.

    1997-06-01

    This report describes a theoretical and experimental study of the boundary layer boiling and critical heat flux phenomena on a downward facing curved heating surface, including both hemispherical and toroidal surfaces. A subscale boundary layer boiling (SBLB) test facility was developed to measure the spatial variation of the critical heat flux and observe the underlying mechanisms. Transient quenching and steady-state boiling experiments were performed in the SBLB facility under both saturated and subcooled conditions to obtain a complete database on the critical heat flux. To complement the experimental effort, an advanced hydrodynamic CHF model was developed from the conservation laws along with sound physical arguments. The model provides a clear physical explanation for the spatial variation of the CHF observed in the SBLB experiments and for the weak dependence of the CHF data on the physical size of the vessel. Based upon the CHF model, a scaling law was established for estimating the local critical heat flux on the outer surface of a heated hemispherical vessel that is fully submerged in water. The scaling law, which compares favorably with all the available local CHF data obtained for various vessel sizes, can be used to predict the local CHF limits on large commercial-size vessels. This technical information represents one of the essential elements that is needed in assessing the efficacy of external cooling of core melt by cavity flooding as a severe accident management strategy. 83 figs., 3 tabs.

  11. Recent High Heat Flux Tests on W-Rod-Armored Mockups

    SciTech Connect

    NYGREN,RICHARD E.; YOUCHISON,DENNIS L.; MCDONALD,JIMMIE M.; LUTZ,THOMAS J.; MISZKIEL,MARK E.

    2000-07-18

    In the authors initial high heat flux tests on small mockups armored with W rods, done in the small electron beam facility (EBTS) at Sandia National Laboratories, the mockups exhibited excellent thermal performance. However, to reach high heat fluxes, they reduced the heated area to only a portion ({approximately}25%) of the sample. They have now begun tests in their larger electron beam facility, EB 1200, where the available power (1.2 MW) is more than enough to heat the entire surface area of the small mockups. The initial results indicate that, at a given power, the surface temperatures of rods in the EB 1200 tests is somewhat higher than was observed in the EBTS tests. Also, it appears that one mockup (PW-10) has higher surface temperatures than other mockups with similar height (10mm) W rods, and that the previously reported values of absorbed heat flux on this mockup were too high. In the tests in EB 1200 of a second mockup, PW-4, absorbed heat fluxes of {approximately}22MW/m{sup 2} were reached but the corresponding surface temperatures were somewhat higher than in EBTS. A further conclusion is that the simple 1-D model initially used in evaluating some of the results from the EBTS testing was not adequate, and 3-D thermal modeling will be needed to interpret the results.

  12. Estimation of surface heat and moisture fluxes over a prairie grassland. IV - Impact of satellite remote sensing of slow canopy variables on performance of a hybrid biosphere model

    NASA Technical Reports Server (NTRS)

    Crosson, William L.; Smith, Eric A.; Cooper, Harry J.

    1993-01-01

    Numerical experiments are conducted using the Ex-BATS model of Crosson and Weng (1993), which is an adaptation the Dickinson (1983, 1984) and Dickinson et al. (1986) biosphere model BATS. The purpose of these experiments is the assessment of the Ex-BATS performance when using remotely sensed data for the estimation of three key canopy variables retrieved from NOAA-AVHRR measurements: the total surface albedo, the leaf area index (LAI), and the nondiurnally varying component of stomatal resistance, r(s). The results of the simulations, which cover the entire FIFE 1987 time period, show that the satellite retrievals of r(s) are only 20 to 30 percent less accurate than the idealized results of the control experiment. The performance of the model which used satellite retrieval of the surface albedo and LAI was essentially equivalent to the hypothetical version.

  13. A novel thin-film temperature and heat-flux microsensor for heat transfer measurements in microchannels.

    PubMed

    Hamadi, David; Garnier, Bertrand; Willaime, Herve; Monti, Fabrice; Peerhossaini, Hassan

    2012-02-07

    Temperature and heat-flux measurement at the microscale for convective heat-transfer studies requires highly precise, minimally intrusive sensors. For this purpose, a new generic temperature and heat-flux sensor was designed, calibrated and tested. The sensor allows measurement of temperature and heat flux distributions along the direction of flow. It is composed of forty gold thermoresistances, 85 nm thick, deposited on both sides of a borosilicate substrate. Their sensitivities are about 37.8 μV K(-1), close to those of a K-type wire thermocouple. Using a thermoelectrical model, temperature biases due to the Joule effect were calculated using the current crossing each thermoresistance and the heat-transfer coefficient. Finally, heat-transfer measurements were performed with deionized water flowing in a straight PDMS microchannel for various Reynolds numbers. The Nusselt number was obtained for microchannels of 50 to 10 μm span. The results were found to be in good agreement with classical Nu-Re macroscopic correlations.

  14. Geodesic acoustic mode in anisotropic plasma with heat flux

    SciTech Connect

    Ren, Haijun

    2015-10-15

    Geodesic acoustic mode (GAM) in an anisotropic tokamak plasma is investigated in fluid approximation. The collisionless anisotropic plasma is described within the 16-momentum magnetohydrodynamic (MHD) fluid closure model, which takes into account not only the pressure anisotropy but also the anisotropic heat flux. It is shown that the GAM frequency agrees better with the kinetic result than the standard Chew-Goldberger-Low (CGL) MHD model. When zeroing the anisotropy, the 16-momentum result is identical with the kinetic one to the order of 1/q{sup 2}, while the CGL result agrees with the kinetic result only on the leading order. The discrepancies between the results of the CGL fluid model and the kinetic theory are well removed by considering the heat flux effect in the fluid approximation.

  15. Method of fission heat flux determination from experimental data

    DOEpatents

    Paxton, Frank A.

    1999-01-01

    A method is provided for determining the fission heat flux of a prime specimen inserted into a specimen of a test reactor. A pair of thermocouple test specimens are positioned at the same level in the holder and a determination is made of various experimental data including the temperature of the thermocouple test specimens, the temperature of bulk water channels located in the test holder, the gamma scan count ratios for the thermocouple test specimens and the prime specimen, and the thicknesses of the outer clads, the fuel fillers, and the backclad of the thermocouple test specimen. Using this experimental data, the absolute value of the fission heat flux for the thermocouple test specimens and prime specimen can be calculated.

  16. A microscale thermophoretic turbine driven by external diffusive heat flux.

    PubMed

    Yang, Mingcheng; Liu, Rui; Ripoll, Marisol; Chen, Ke

    2014-11-21

    We propose a theoretical prototype of a micro-scale turbine externally driven by diffusive heat flux without the need for macroscopic particle flux, which is in sharp contrast to conventional turbines. The prototypes are described analytically and validated by computer simulations. Our results indicate that a micro-scale turbine composed of anisotropic blades can rotate unidirectionally in an external temperature gradient due to the anisotropic thermophoresis effect. The rotational direction and speed depend on the temperature gradient, the geometry and the thermophoretic properties of the turbine. The proposed thermophoretic turbines can be experimentally realized and implemented on micro-devices such as computer-chips to recover waste heat or to facilitate cooling.

  17. Geodesic acoustic mode in anisotropic plasma with heat flux

    NASA Astrophysics Data System (ADS)

    Ren, Haijun

    2015-10-01

    Geodesic acoustic mode (GAM) in an anisotropic tokamak plasma is investigated in fluid approximation. The collisionless anisotropic plasma is described within the 16-momentum magnetohydrodynamic (MHD) fluid closure model, which takes into account not only the pressure anisotropy but also the anisotropic heat flux. It is shown that the GAM frequency agrees better with the kinetic result than the standard Chew-Goldberger-Low (CGL) MHD model. When zeroing the anisotropy, the 16-momentum result is identical with the kinetic one to the order of 1/q2, while the CGL result agrees with the kinetic result only on the leading order. The discrepancies between the results of the CGL fluid model and the kinetic theory are well removed by considering the heat flux effect in the fluid approximation.

  18. Mechanisms governing radial heat fluxes in tokamak plasma

    SciTech Connect

    Razumova, K. A. Timchenko, N. N.; Dnestrovskij, A. Yu.; Lysenko, S. E.

    2016-09-15

    A method for analyzing the characteristics of turbulence responsible for radial heat transport is proposed. The method is based on the previously proposed hypotheses (to a great extent, confirmed experimentally) concerning the consistency of normalized pressure profiles in tokamak plasmas and the mechanism of internal transport barrier formation. Using the proposed approach, it is shown that, under an external action on the plasma, when the plasma heat flux onto the wall grows, the spectrum of turbulent modes broadens due to the excitation of modes with lower poloidal numbers m. Thus, in contrast to the conventional diffusion approach, the transport coefficient depends on the flux intensity. A mechanism of formation of internal transport barriers is proposed.

  19. Establishing more truth in space-time integration of surface turbulent heat fluxes

    NASA Astrophysics Data System (ADS)

    Gulev, Sergey; Belyaev, Konstantin

    2016-04-01

    Space-time integration of surface turbulent heat fluxes is important for obtaining area-averaged budget estimates and for producing climatologies of surface fluxes. Uncertainty of the integration or averaging of fluxes in space and in time are especially high when the data are sparse as in the case of the use of information from Voluntary Observing Ships (VOS) which are characterized by inhomogeneous sampling density in contrast to NWP products and satellite data sets. In order to minimize sampling impact onto local and larger scale surface flux averages we suggest an approach based upon analysis of surface fluxes in the coordinates of steering parameters (vertical surface temperature and humidity gradients on one hand and wind speed on the other). These variables are distributed according to the Modified Fisher-Tippett (MFT) distribution (temperature and humidity gradients) and Weibull distribution (wind speed) which imply a 2-dimentional distribution for the fluxes. Since the fluxes in these coordinates are determined in a unique manner (within a chosen bulk transfer algorithm), they can be easily integrated in the space of 2-dimentional distribution in order to get the averaged values dependent on the parameters of the MFT and Weibull distributions. Conceptually, the approach is similar to that oceanographers apply for analysing volumetric T,S-diagrams of water mass properties. We developed an algorithm for applying this approach and also provided the analysis of integrated surface fluxes for different regions of the North Atlantic for which heat flux estimates can be obtained from oceanographic cross-sections. Analysis was performed for the last 5 decades. 2-dimensitonal diagrams also make it possible to analyse temporal variability of integrated surface fluxes in the dimension of steering parameters and to further compare estimates with changes in the ocean heat content.

  20. A comparison of critical heat flux in tubes and bilaterally heated annuli

    SciTech Connect

    Doerffer, S.; Groeneveld, D.C.; Cheng, S.C.

    1995-09-01

    This paper examines the critical heat flux (CHF) behaviour for annular flow in bilaterally heated annuli and compares it to that in tubes and unilaterally heated annuli. It was found that the differences in CHF between bilaterally and unilaterally heated annuli or tubes strongly depend on pressure and quality. the CHF in bilaterally heated annuli can be predicted by tube CHF prediction methods for the simultaneous CHF occurrence at both surfaces, and the following flow conditions: pressure 7-10 MPa, mass flux 0.5-4.0 Mg/m{sup 2}s and critical quality 0.23-0.9. The effect on CHF of the outer-to-inner surface heat flux ratio, was also examined. The prediction of CHF for bilaterally heated annuli was based on the droplet-diffusion model proposed by Kirillov and Smogalev. While their model refers only to CHF occurrence at the inner surface, we extended it to cases where CHF occurs at the outer surface, and simultaneously at both surfaces, thus covering all cases of CHF occurrence in bilaterally heated annuli. From the annuli CHF data of Becker and Letzter, we derived empirical functions required by the model. the proposed equations provide good accuracy for the CHF data used in this study. Moreover, the equations can predict conditions at which CHF occurs simultaneously at both surfaces. Also, this method can be used for cases with only one heated surface.

  1. Spray cooling heat-transfer with subcooled trichlorotrifluoroethane (Freon-113) for vertical constant heat flux surfaces

    SciTech Connect

    Kendall, C.M.; Holman, J.P.

    1996-06-06

    Experiments were done using subcooled Freon-113 sprayed vertically downward. Local and average heat transfers were investigated fro Freon-113 sprays with 40 C subcooling, droplet sizes 200-1250{mu}m, and droplet breakup velocities 5-29 m/s. Full-cone type nozzles were used to generate the spray. Test assemblies consisted of 1 to 6 7.62 cm vertical constant heat flux surfaces parallel with each other and aligned horizontally. Distance between heated surfaces was varied from 6.35 to 76.2 mm. Steady state heat fluxes as high as 13 W/cm{sup 2} were achieved. Dependence on the surface distance from axial centerline of the spray was found. For surfaces sufficiently removed from centerline, local and average heat transfers were identical and correlated by a power relation of the form seen for normal-impact sprays which involves the Weber number, a nondimensionalized temperature difference, and a mass flux parameter. For surfaces closer to centerline, the local heat transfer depended on vertical location on the surface while the average heat transfer was described by a semi-log correlation involving the same parameters. The heat transfer was independent of the distance (gap) between the heated surfaces for the gaps investigated.

  2. Heat flux calibration of a near earth spacecraft temperature alarm system in rarefied flow

    NASA Technical Reports Server (NTRS)

    Caruso, P. S., Jr.

    1974-01-01

    Description of the aerodynamic molecular beam testing performed on the near earth spacecraft temperature alarm system that is designed to provide in-flight temperature information useful for safeguarding scientific equipment during perigee maneuvers. The temperature/heat flux calibration results obtained are summarized.

  3. Solid propellant combustion response to oscillatory radiant heat flux

    NASA Technical Reports Server (NTRS)

    Strand, L. D.; Weil, M. T.; Cohen, N. S.

    1989-01-01

    A progress report is given on a research project to use the microwave Doppler velocimeter technique to measure the combustion response to an oscillating thermal radiation source (CO2 laser). The test technique and supporting analyses are described, and the results are presented for an initial test series on the nonmetallized, composite propellant, Naval Weapons Center formulation A-13. It is concluded that in-depth transmission of radiant heat flux is not a factor at the CO2 laser wave length.

  4. Development of advanced high-temperature heat flux sensors

    NASA Technical Reports Server (NTRS)

    Atkinson, W. H.; Strange, R. R.

    1982-01-01

    Various configurations of high temperature, heat flux sensors were studied to determine their suitability for use in experimental combustor liners of advanced aircraft gas turbine engines. It was determined that embedded thermocouple sensors, laminated sensors, and Gardon gauge sensors, were the most viable candidates. Sensors of all three types were fabricated, calibrated, and endurance tested. All three types of sensors met the fabricability survivability, and accuracy requirements established for their application.

  5. Heat flux induced dryout and rewet in thin films

    NASA Technical Reports Server (NTRS)

    Stroes, Gustave; Fricker, Darren; Issacci, Farrokh; Catton, Ivan

    1990-01-01

    Heat flux induced dryout of thin liquid films on an inclined copper plate was studied. Rewet of the dried out area is also considered. The four fluids used to form the thin films exhibited very different dryout and rewet characteristics. The contact angle and hysteresis effects were found to be important, but they must be considered in context with other parameters. No single variable was found to independently determine the pattern of dryout and rewet.

  6. Sea Spray Effects on Surface Heat and Moisture Fluxes

    DTIC Science & Technology

    2016-06-07

    have also contributed to the recent ONR “whitepaper” that describes an initiative for comprehensive research on coupled air and sea boundary layers...transferring heat and moisture across the air -sea interface, especially in high winds. Ultimately, we hope to develop simple parameterizations for...these air -sea fluxes for use in large-scale models, especially those simulating tropical and extra-tropical storms. OBJECTIVES The ultimate goal of this

  7. Effect of heat flux on differential rotation in turbulent convection.

    PubMed

    Kleeorin, Nathan; Rogachevskii, Igor

    2006-04-01

    We studied the effect of the turbulent heat flux on the Reynolds stresses in a rotating turbulent convection. To this end we solved a coupled system of dynamical equations which includes the equations for the Reynolds stresses, the entropy fluctuations, and the turbulent heat flux. We used a spectral tau approximation in order to close the system of dynamical equations. We found that the ratio of the contributions to the Reynolds stresses caused by the turbulent heat flux and the anisotropic eddy viscosity is of the order of approximately 10(L rho/l0)2, where l0 is the maximum scale of turbulent motions and L rho is the fluid density variation scale. This effect is crucial for the formation of the differential rotation and should be taken into account in the theories of the differential rotation of the Sun, stars, and planets. In particular, we demonstrated that this effect may cause the differential rotation which is comparable with the typical solar differential rotation.

  8. Vapor Shielding of Solid Targets Exposed to High Heat Flux

    NASA Astrophysics Data System (ADS)

    Pshenov, A. A.; Eksaeva, A. A.; Krasheninnikov, S. I.; Marenkov, E. D.

    The thickness of Tungsten monoblocks composing the future ITER divertor is supposed to be 8 mm only. Therefore, severe erosion caused by high heat fluxes during transients, such as Type I ELMs and disruptions, is a limiting factor to PFCs lifespan. Under the influence of extreme heat fluxes expected during ITER transients serious surface modification of the Tungsten monoblocks is anticipated. Moreover, melting of a thin surface layer is likely to happen. Melt motion contributes seriously to the material erosion. The other sources of erosion are melt splashing, in the form of droplet ejection, and evaporation. These mechanics lead to a cold dense secondary plasma region formation near the irradiated surface. Intense re-radiation of the incoming plasma flow energy in the secondary plasma layer results in a significant reduction of the heat flux reaching the target surface. Accounting for this vapor shielding effect is essential to estimate the surface erosion under influence of intense plasma flow properly. In this paper a simple model capable of reproducing one of the key features of vapor shielding, namely the saturation of the energy absorbed by the target, is proposed. This model allows for an approximate analytical solution that indicates parameters the saturation energy depends on. The model is validated against the experimental data obtained at MK-200 pulse plasma accelerator.

  9. Ground heat flux and power sources of low-enthalpy geothermal systems

    NASA Astrophysics Data System (ADS)

    Bayer, Peter; Blum, Philipp; Rivera, Jaime A.

    2015-04-01

    Geothermal heat pumps commonly extract energy from the shallow ground at depths as low as approximately 400 m. Vertical borehole heat exchangers are often applied, which are seasonally operated for decades. During this lifetime, thermal anomalies are induced in the ground and surface-near aquifers, which often grow over the years and which alleviate the overall performance of the geothermal system. As basis for prediction and control of the evolving energy imbalance in the ground, focus is typically set on the ground temperatures. This is reflected in regulative temperature thresholds, and in temperature trends, which serve as indicators for renewability and sustainability. In our work, we examine the fundamental heat flux and power sources, as well as their temporal and spatial variability during geothermal heat pump operation. The underlying rationale is that for control of ground temperature evolution, knowledge of the primary heat sources is fundamental. This insight is also important to judge the validity of simplified modelling frameworks. For instance, we reveal that vertical heat flux from the surface dominates the basal heat flux towards a borehole. Both fluxes need to be accounted for as proper vertical boundary conditions in the model. Additionally, the role of horizontal groundwater advection is inspected. Moreover, by adopting the ground energy deficit and long-term replenishment as criteria for system sustainability, an uncommon perspective is adopted that is based on the primary parameter rather than induced local temperatures. In our synthetic study and dimensionless analysis, we demonstrate that time of ground energy recovery after system shutdown may be longer than what is expected from local temperature trends. In contrast, unrealistically long recovery periods and extreme thermal anomalies are predicted without account for vertical ground heat fluxes and only when the energy content of the geothermal reservoir is considered.

  10. Local Heat Flux Measurements with Single Element Coaxial Injectors

    NASA Technical Reports Server (NTRS)

    Jones, Gregg; Protz, Christopher; Bullard, Brad; Hulka, James

    2006-01-01

    To support the mission for the NASA Vision for Space Exploration, the NASA Marshall Space Flight Center conducted a program in 2005 to improve the capability to predict local thermal compatibility and heat transfer in liquid propellant rocket engine combustion devices. The ultimate objective was to predict and hence reduce the local peak heat flux due to injector design, resulting in a significant improvement in overall engine reliability and durability. Such analyses are applicable to combustion devices in booster, upper stage, and in-space engines, as well as for small thrusters with few elements in the injector. In this program, single element and three-element injectors were hot-fire tested with liquid oxygen and ambient temperature gaseous hydrogen propellants at The Pennsylvania State University Cryogenic Combustor Laboratory from May to August 2005. Local heat fluxes were measured in a 1-inch internal diameter heat sink combustion chamber using Medtherm coaxial thermocouples and Gardon heat flux gauges. Injectors were tested with shear coaxial and swirl coaxial elements, including recessed, flush and scarfed oxidizer post configurations, and concentric and non-concentric fuel annuli. This paper includes general descriptions of the experimental hardware, instrumentation, and results of the hot-fire testing for three of the single element injectors - recessed-post shear coaxial with concentric fuel, flush-post swirl coaxial with concentric fuel, and scarfed-post swirl coaxial with concentric fuel. Detailed geometry and test results will be published elsewhere to provide well-defined data sets for injector development and model validatation.

  11. Surface Heat Flux Corrections for Global Ocean Forecasts

    NASA Astrophysics Data System (ADS)

    Garraffo, Z. D.; Hogan, P. J.; Mehra, A.; Rivin, I.; Balasubramaniyan, B.; Spindler, T. D.; Kim, H. C.; Paturi, S.

    2016-02-01

    RTOFS (Real Time Ocean Forecast System) - Global is the first global eddy resolving ocean forecast system implemented operationally at NOAA/NWS/NCEP in close collaboration with US Navy. Recently upgraded version 1.1 (which was developed and validated at NRL) uses the Hybrid Coordinates Ocean Model (HYCOM) at 1/12 degree coupled with Los Alamos Community sea ICE model (CICE). The forecast system runs once a day and produces forecasts from the daily initialization fields produced at NAVOCEANO (NAVal OCEANographic Office) which use NCODA (Navy Coupled Ocean Data Assimilation), a 3DVAR data assimilation methodology (Cummings and Smedstad, 2013). After a two-day spin up with hourly NCEP's Global Data Assimilation System (GDAS) atmospheric fluxes with the ocean model in forecast mode, the daily forecast cycle is forced with 3-hourly momentum, radiation and precipitation fluxes from NCEP's Global Forecast System fields for the next eight days. Following flux-corrections efforts at NRL (Metzger et al. 2013, NRL report), heat flux corrections are computed for the RTOFS v1.1 configuration. To assess sensitivity to upgrades in GFS/GDAS and HYCOM, these radiative corrections are compared with forecasts produced with other versions of NCEP forcing. Impacts of flux corrections in SST errors will be discussed.

  12. Modeling of aerodynamic heat flux and thermoelastic behavior of nose caps of hypersonic vehicles

    NASA Astrophysics Data System (ADS)

    Persova, Marina G.; Soloveichik, Yury G.; Belov, Vasiliy K.; Kiselev, Dmitry S.; Vagin, Denis V.; Domnikov, Petr A.; Patrushev, Ilya I.; Kurskiy, Denis N.

    2017-07-01

    In this paper, the problem of numerical modeling of thermoelastic behavior of nose caps of hypersonic vehicles at different angles of attack is considered. 3D finite element modeling is performed by solving the coupled heat and elastic problems taking into account thermal and mechanical properties variations with temperature. A special method for calculating the aerodynamic heat flux entering the nose cap from its surface is proposed. This method is characterized by very low computational costs and allows calculating the aerodynamic heat flux at different values of the Mach number and angles of attack which may vary during the aerodynamic heating. The numerical results obtained by the proposed approach are compared with the numerical results and experimental data obtained by other authors. The developed approach has been used for studying the impact of the angle of attack on the thermoelastic behavior of nose caps main components.

  13. Prototype thin-film thermocouple/heat-flux sensor for a ceramic-insulated diesel engine

    NASA Technical Reports Server (NTRS)

    Kim, Walter S.; Barrows, Richard F.

    1988-01-01

    A platinum versus platinum-13 percent rhodium thin-film thermocouple/heat-flux sensor was devised and tested in the harsh, high-temperature environment of a ceramic-insulated, low-heat-rejection diesel engine. The sensor probe assembly was developed to provide experimental validation of heat transfer and thermal analysis methodologies applicable to the insulated diesel engine concept. The thin-film thermocouple configuration was chosen to approximate an uninterrupted chamber surface and provide a 1-D heat-flux path through the probe body. The engine test was conducted by Purdue University for Integral Technologies, Inc., under a DOE-funded contract managed by NASA Lewis Research Center. The thin-film sensor performed reliably during 6 to 10 hr of repeated engine runs at indicated mean surface temperatures up to 950 K. However, the sensor suffered partial loss of adhesion in the thin-film thermocouple junction area following maximum cyclic temperature excursions to greater than 1150 K.

  14. Critical heat flux maxima during boiling crisis on textured surfaces

    NASA Astrophysics Data System (ADS)

    Dhillon, Navdeep Singh; Buongiorno, Jacopo; Varanasi, Kripa K.

    2015-09-01

    Enhancing the critical heat flux (CHF) of industrial boilers by surface texturing can lead to substantial energy savings and global reduction in greenhouse gas emissions, but fundamentally this phenomenon is not well understood. Prior studies on boiling crisis indicate that CHF monotonically increases with increasing texture density. Here we report on the existence of maxima in CHF enhancement at intermediate texture density using measurements on parametrically designed plain and nano-textured micropillar surfaces. Using high-speed optical and infrared imaging, we study the dynamics of dry spot heating and rewetting phenomena and reveal that the dry spot heating timescale is of the same order as that of the gravity and liquid imbibition-induced dry spot rewetting timescale. Based on these insights, we develop a coupled thermal-hydraulic model that relates CHF enhancement to rewetting of a hot dry spot on the boiling surface, thereby revealing the mechanism governing the hitherto unknown CHF enhancement maxima.

  15. Modern perspectives on measuring and interpreting seafloor heat flux

    USGS Publications Warehouse

    Harris, Reid N.; Fisher, A.; Ruppel, C.; Martinez, F.

    2008-01-01

    There has been a resurgence of interest in marine heat flow in the past 10–15 years, coinciding with fundamental achievements in understanding the Earth's thermal state and quantifying the dynamics and impacts of material and energy fluxes within and between the lithosphere and hydrosphere. At the same time, technical capabilities have dwindled to the point that no U.S. academic institution currently operates a seagoing heat flow capacity.In September 2007, a workshop was convened in Salt Lake City with sponsorship from the U.S. National Science Foundation (NSF) and participation by scientists and engineers from North America, Europe, and Asia. The primary goals of the workshop were to (1) assess high-priority scientific and technical needs and (2) to evaluate options for developing and maintaining essential capabilities in marine heat flow for the U.S. scientific community.

  16. Critical heat flux maxima during boiling crisis on textured surfaces.

    PubMed

    Dhillon, Navdeep Singh; Buongiorno, Jacopo; Varanasi, Kripa K

    2015-09-08

    Enhancing the critical heat flux (CHF) of industrial boilers by surface texturing can lead to substantial energy savings and global reduction in greenhouse gas emissions, but fundamentally this phenomenon is not well understood. Prior studies on boiling crisis indicate that CHF monotonically increases with increasing texture density. Here we report on the existence of maxima in CHF enhancement at intermediate texture density using measurements on parametrically designed plain and nano-textured micropillar surfaces. Using high-speed optical and infrared imaging, we study the dynamics of dry spot heating and rewetting phenomena and reveal that the dry spot heating timescale is of the same order as that of the gravity and liquid imbibition-induced dry spot rewetting timescale. Based on these insights, we develop a coupled thermal-hydraulic model that relates CHF enhancement to rewetting of a hot dry spot on the boiling surface, thereby revealing the mechanism governing the hitherto unknown CHF enhancement maxima.

  17. Critical heat flux maxima during boiling crisis on textured surfaces

    PubMed Central

    Dhillon, Navdeep Singh; Buongiorno, Jacopo; Varanasi, Kripa K.

    2015-01-01

    Enhancing the critical heat flux (CHF) of industrial boilers by surface texturing can lead to substantial energy savings and global reduction in greenhouse gas emissions, but fundamentally this phenomenon is not well understood. Prior studies on boiling crisis indicate that CHF monotonically increases with increasing texture density. Here we report on the existence of maxima in CHF enhancement at intermediate texture density using measurements on parametrically designed plain and nano-textured micropillar surfaces. Using high-speed optical and infrared imaging, we study the dynamics of dry spot heating and rewetting phenomena and reveal that the dry spot heating timescale is of the same order as that of the gravity and liquid imbibition-induced dry spot rewetting timescale. Based on these insights, we develop a coupled thermal-hydraulic model that relates CHF enhancement to rewetting of a hot dry spot on the boiling surface, thereby revealing the mechanism governing the hitherto unknown CHF enhancement maxima. PMID:26346098

  18. Calculation of heating values for the high flux isotope reactor

    SciTech Connect

    Peterson, J.; Ilas, G.

    2012-07-01

    Calculating the amount of energy released by a fission reaction (fission Q value) and the heating rate distribution in a nuclear reactor is an important part of the safety analysis. However, these calculations can become very complex. One of the codes that can be used for this type of analyses is the Monte Carlo transport code MCNP5. Currently it is impossible to calculate the Q value and heating rate disposition for delayed beta and delayed gamma particles directly from MCNP5. The purpose of this paper is to outline a rigorous method for indirectly calculating the Q values and heating rates in the High Flux Isotope Reactor (HFIR), based on previous similar studies carried out for very high-temperature reactor configurations. This method has been applied in this study to calculate heating rates for the beginning of cycle (BOC) and end-of-cycle (EOC) states of HFIR. In addition, the BOC results obtained for HFIR are compared with corresponding results for the Advanced Test Reactor. The fission Q value for HFIR was calculated as 200.2 MeV for the BOC and 201.3 MeV for the EOC. It was also determined that 95.1% and 95.4% of the heat was deposited within the HFIR fuel plates for the BOC and EOC models, respectively. This methodology can also be used for heating rate calculations for HFIR experiments. (authors)

  19. Heat Transfer in the Turbulent Incompressible Boundary Layer. 3; Arbitrary Wall Temperature and Heat Flux

    NASA Technical Reports Server (NTRS)

    Reynolds, W. C.; Kays, W. M.; Kline, S. J.

    1958-01-01

    Superposition techniques are used to calculate the rate of heat transfer from a flat plate to a turbulent incompressible boundary layer for several cases of variable surface temperature. The predictions of a number of these calculations are compared with experimental heat- transfer rates, and good agreement is obtained. A simple computing procedure for determining the heat-transfer rates from surfaces with arbitrary wall-temperature distributions is presented and illustrated by two examples. The inverse problem of determining the temperature distribution from an arbitrarily prescribed heat flux is also treated, both experimentally and analytically.

  20. Heat Fluxes and CO2 Variations Measured over a Tidal Flat

    NASA Astrophysics Data System (ADS)

    Kim, Parksa; Kim, Kwangho; Kim, Minseong; Seo, Seongwoon; Kang, Donghwan; Kwon, Byunghyuk

    2014-05-01

    In order to analyze the characteristics of momentum, heat fluxes and carbon dioxide variations in a tidal flat, observations were performed in Suncheon bay, Korea. Measured heat data was classified by surface condition for daytime inundation and daytime exposure. Since the sediment temperature extremely increased when the surface is exposed, the difference of temperature between the air and the surface was larger. Thus, it is clear that sensible heat flux and latent heat flux increase when the surface is exposed. CO2 was intensively measured around the sunset when the variation of temperature is large. CO2 flux was less absorbed during daytime when the surface was immersed, while it was more absorbed during daytime when the surface was exposed. When the soil temperature increases during daytime exposure, micro phytobenthos make a great photosynthesis. It causes a large absorption of CO2 and it can explain the reason that a large absorption of CO2 during daytime exposure. This shows that tidal flat actively operate as a sink of CO2. Also, it support that the surface change in tidal flat make an influence on CO2 exchange process. Understanding CO2 exchange variations in tidal flat will be useful in climate change problems. Research on heat balance and carbon dioxide variations will help to understand not only the variations of local weather process but also the variations of global climate process.

  1. Measurement of Heat Flux and Heat Transfer Coefficient Due to Spray Application for the Die Casting Process

    SciTech Connect

    Sabau, Adrian S

    2007-01-01

    Lubricant spray application experiments were conducted for the die casting process. The heat flux was measured in situ using a differential thermopile sensor for three application techniques. First, the lubricant was applied under a constant flowrate while the nozzle was held in the same position. Second, the lubricant was applied in a pulsed, static manner, in which the nozzle was held over the same surface while it was turned on and off several times. Third, the lubricant was applied in a sweeping manner, in which the nozzle was moved along the die surface while it was held open. The experiments were conducted at several die temperatures and at sweep speeds of 20, 23, and 68 cm/s. The heat flux data, which were obtained with a sensor that was located in the centre of the test plate, were presented and discussed. The sensor can be used to evaluate lubricants, monitor the consistency of die lubrication process, and obtain useful process data, such as surface temperature, heat flux, and heat transfer coefficients. The heat removed from the die surface during lubricant application is necessary for (a) designing the cooling channels in the die, i.e. their size and placement, and (b) performing accurate numerical simulations of the die casting process.

  2. 2D divertor heat flux distribution using a 3D heat conduction solver in National Spherical Torus Experiment.

    PubMed

    Gan, K F; Ahn, J-W; Park, J-W; Maingi, R; McLean, A G; Gray, T K; Gong, X; Zhang, X D

    2013-02-01

    The divertor heat flux footprint in tokamaks is often observed to be non-axisymmetric due to intrinsic error fields, applied 3D magnetic fields or during transients such as edge localized modes. Typically, only 1D radial heat flux profiles are analyzed; however, analysis of the full 2D divertor measurements provides opportunities to study the asymmetric nature of the deposited heat flux. To accomplish this an improved 3D Fourier analysis method has been successfully applied in a heat conduction solver (TACO) to determine the 2D heat flux distribution at the lower divertor surface in the National Spherical Torus Experiment (NSTX) tokamak. This advance enables study of helical heat deposition onto the divertor. In order to account for heat transmission through poorly adhered surface layers on the divertor plate, a heat transmission coefficient, defined as the surface layer thermal conductivity divided by the thickness of the layer, was introduced to the solution of heat conduction equation. This coefficient is denoted as α and a range of values were tested in the model to ensure a reliable heat flux calculation until a specific value of α led to the constant total deposited energy in the numerical solution after the end of discharge. A comparison between 1D heat flux profiles from TACO and from a 2D heat flux calculation code, THEODOR, shows good agreement. Advantages of 2D heat flux distribution over the conventional 1D heat flux profile are also discussed, and examples of 2D data analysis in the study of striated heat deposition pattern as well as the toroidal degree of asymmetry of peak heat flux and heat flux width are demonstrated.

  3. Solar Flux Deposition And Heating Rates In Jupiter's Atmosphere

    NASA Astrophysics Data System (ADS)

    Perez-Hoyos, Santiago; Sánchez-Lavega, A.

    2009-09-01

    We discuss here the solar downward net flux in the 0.25 - 2.5 µm range in the atmosphere of Jupiter and the associated heating rates under a number of vertical cloud structure scenarios focusing in the effect of clouds and hazes. Our numerical model is based in the doubling-adding technique to solve the radiative transfer equation and it includes gas absorption by CH4, NH3 and H2, in addition to Rayleigh scattering by a mixture of H2 plus He. Four paradigmatic Jovian regions have been considered (hot-spots, belts, zones and Polar Regions). The hot-spots are the most transparent regions with downward net fluxes of 2.5±0.5 Wm-2 at the 6 bar level. The maximum solar heating is 0.04±0.01 K/day and occurs above 1 bar. Belts and zones characterization result in a maximum net downward flux of 0.5 Wm-2 at 2 bar and 0.015 Wm-2 at 6 bar. Heating is concentrated in the stratospheric and tropospheric hazes. Finally, Polar Regions are also explored and the results point to a considerable stratospheric heating of 0.04±0.02 K/day. In all, these calculations suggest that the role of the direct solar forcing in the Jovian atmospheric dynamics is limited to the upper 1 - 2 bar of the atmosphere except in the hot-spot areas. Acknowledgments: This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07.

  4. Shear heating as the origin of the plumes and heat flux on Enceladus.

    PubMed

    Nimmo, F; Spencer, J R; Pappalardo, R T; Mullen, M E

    2007-05-17

    Enceladus, a small icy satellite of Saturn, has active plumes jetting from localized fractures ('tiger stripes') within an area of high heat flux near the south pole. The plume characteristics and local high heat flux have been ascribed either to the presence of liquid water within a few tens of metres of the surface, or the decomposition of clathrates. Neither model addresses how delivery of internal heat to the near-surface is sustained. Here we show that the most likely explanation for the heat and vapour production is shear heating by tidally driven lateral (strike-slip) fault motion with displacement of approximately 0.5 m over a tidal period. Vapour produced by this heating may escape as plumes through cracks reopened by the tidal stresses. The ice shell thickness needed to produce the observed heat flux is at least 5 km. The tidal displacements required imply a Love number of h2 > 0.01, suggesting that the ice shell is decoupled from the silicate interior by a subsurface ocean. We predict that the tiger-stripe regions with highest relative temperatures will be the lower-latitude branch of Damascus, Cairo around 60 degrees W longitude and Alexandria around 150 degrees W longitude.

  5. New technique of the local heat flux measurement in combustion chambers of steam boilers

    NASA Astrophysics Data System (ADS)

    Taler, Jan; Taler, Dawid; Sobota, Tomasz; Dzierwa, Piotr

    2011-12-01

    A new method for measurement of local heat flux to water-walls of steam boilers was developed. A flux meter tube was made from an eccentric tube of short length to which two longitudinal fins were attached. These two fins prevent the boiler setting from heating by a thermal radiation from the combustion chamber. The fins are not welded to the adjacent water-wall tubes, so that the temperature distribution in the heat flux meter is not influenced by neighbouring water-wall tubes. The thickness of the heat flux tube wall is larger on the fireside to obtain a greater distance between the thermocouples located inside the wall which increases the accuracy of heat flux determination. Based on the temperature measurements at selected points inside the heat flux meter, the heat flux absorbed by the water-wall, heat transfer coefficient on the inner tube surface and temperature of the water-steam mixture was determined.

  6. Self-pressurization of a flightweight liquid hydrogen storage tank subjected to low heat flux

    NASA Technical Reports Server (NTRS)

    Hasan, M. M.; Lin, C. S.; Vandresar, N. T.

    1991-01-01

    Results are presented for an experimental investigation of self-pressurization and thermal stratification of a 4.89 cu m liquid hydrogen (LH2) storage tank subjected to low heat flux (0.35, 2.0, and 3.5 W/sq m) under normal gravity conditions. Tests were performed at fill levels of 83 to 84 percent (by volume). The LH2 tank was representative of future spacecraft tankage, having a low mass-to-volume ratio and high performance multilayer thermal insulation. Results show that the pressure rise rate and thermal stratification increase with increasing heat flux. At the lowest heat flux, the pressure rise rate is comparable to the homogenous rate, while at the highest heat flux, the rate is more than three times the homogeneous rate. It was found that initial conditions have a significant impact on the initial pressure rise rate. The quasi-steady pressure rise rates are nearly independent of the initial condition after an initial transient period has passed.

  7. Boundary layer structure over areas of heterogeneous heat fluxes

    SciTech Connect

    Doran, J.C. ); Barnes, F.J. ); Coulter, R.L. ); Crawford, T.L. . Air Resources Lab. Atmospheric Turbulence and Diffusion Div.)

    1993-01-01

    In general circulation models (GCMs), some properties of a grid element are necessarily considered homogeneous. That is, for each grid volume there is associated a particular combination of boundary layer depth, vertical profiles of wind and temperature, surface fluxes of sensible and latent heat, etc. In reality, all of these quantities may exhibit significant spatial variations within the grid area, and the larger the area the greater the likely variations. In balancing the benefits of higher resolution against increased computational time and expense, it is useful to consider what the consequences of such subgrid-scale variability may be. Moveover, in interpreting the results of a simulation, one must be able to define an appropriate average value over a grid. There are two aspects of this latter problem: (1) in observations, how does one take a set of discrete or volume-averaged measurements and relate these to properties of the entire domain, and (2) in computations, how can subgrid-scale features be accounted for in the model parameterizations To address these and related issues, two field campaigns were carried out near Boardman, Oregon, in June 1991 and 1992. These campaigns were designed to measure the surface fluxes of latent and sensible heat over adjacent areas with strongly contrasting surface types and to measure the response of the boundary layer to those fluxes. This paper discuses some initial findings from those campaigns.

  8. Boundary layer structure over areas of heterogeneous heat fluxes

    SciTech Connect

    Doran, J.C. ); Barnes, F.J. ); Coulter, R.L. ); Crawford, T.L. . Air Resources Lab. Atmospheric Turbulence and Diffusion Div.)

    1993-01-01

    In general circulation models (GCMs), some properties of a grid element are necessarily considered homogeneous. That is, for each grid volume there is associated a particular combination of boundary layer depth, vertical profiles of wind and temperature, surface fluxes of sensible and latent heat, etc. In reality, all of these quantities may exhibit significant spatial variations the grid area, and the larger the area the greater the likely variations. In balancing the benefits of higher resolution against increased computational time and expense, it is useful to consider what the consequences of such subgrid-scale variability may be. Moreover, in interpreting the results of a simulation, one must be able to define an appropriate average value over a grid. There are two aspects of this latter problem: (1) in observations, how does one take a set of discrete or volume-averaged measurements and relate these to properties of the entire domain, and (2) in computations, how can subgrid-scale features be accounted for in the model parameterizations To address these and related issues, two field campaigns were carried out near Boardman, Oregon, in June 1991 and 1992. These campaigns were designed to measure the surface fluxes of latent and sensible heat over adjacent areas with strongly contrasting surface types and to measure the response of the boundary layer to those fluxes. This paper discusses some initial findings from those campaigns.

  9. Boundary layer structure over areas of heterogeneous heat fluxes

    SciTech Connect

    Doran, J.C.; Barnes, F.J.; Coulter, R.L.; Crawford, T.L.

    1993-04-01

    In general circulation models (GCMs), some properties of a grid element are necessarily considered homogeneous. That is, for each grid volume there is associated a particular combination of boundary layer depth, vertical profiles of wind and temperature, surface fluxes of sensible and latent heat, etc. In reality, all of these quantities may exhibit significant spatial variations within the grid area, and the larger the area the greater the likely variations. In balancing the benefits of higher resolution against increased computational time and expense, it is useful to consider what the consequences of such subgrid-scale variability may be. Moveover, in interpreting the results of a simulation, one must be able to define an appropriate average value over a grid. There are two aspects of this latter problem: (1) in observations, how does one take a set of discrete or volume-averaged measurements and relate these to properties of the entire domain, and (2) in computations, how can subgrid-scale features be accounted for in the model parameterizations? To address these and related issues, two field campaigns were carried out near Boardman, Oregon, in June 1991 and 1992. These campaigns were designed to measure the surface fluxes of latent and sensible heat over adjacent areas with strongly contrasting surface types and to measure the response of the boundary layer to those fluxes. This paper discuses some initial findings from those campaigns.

  10. Boundary layer structure over areas of heterogeneous heat fluxes

    SciTech Connect

    Doran, J.C.; Barnes, F.J.; Coulter, R.L.; Crawford, T.L.

    1993-01-01

    In general circulation models (GCMs), some properties of a grid element are necessarily considered homogeneous. That is, for each grid volume there is associated a particular combination of boundary layer depth, vertical profiles of wind and temperature, surface fluxes of sensible and latent heat, etc. In reality, all of these quantities may exhibit significant spatial variations the grid area, and the larger the area the greater the likely variations. In balancing the benefits of higher resolution against increased computational time and expense, it is useful to consider what the consequences of such subgrid-scale variability may be. Moreover, in interpreting the results of a simulation, one must be able to define an appropriate average value over a grid. There are two aspects of this latter problem: (1) in observations, how does one take a set of discrete or volume-averaged measurements and relate these to properties of the entire domain, and (2) in computations, how can subgrid-scale features be accounted for in the model parameterizations? To address these and related issues, two field campaigns were carried out near Boardman, Oregon, in June 1991 and 1992. These campaigns were designed to measure the surface fluxes of latent and sensible heat over adjacent areas with strongly contrasting surface types and to measure the response of the boundary layer to those fluxes. This paper discusses some initial findings from those campaigns.

  11. Critical heat flux on micro-structured zircaloy surfaces for flow boiling of water at low pressures

    SciTech Connect

    Haas, C.; Miassoedov, A.; Schulenberg, T.; Wetzel, T.

    2012-07-01

    The influence of surface structure on critical heat flux for flow boiling of water was investigated for Zircaloy tubes in a vertical annular test section. The objectives were to find suitable surface modification processes for Zircaloy tubes and to test their critical heat flux performance in comparison to the smooth tube. Surface structures with micro-channels, porous layer, oxidized layer, and elevations in micro- and nano-scale were produced on a section of a Zircaloy cladding tube. These modified tubes were tested in an internally heated vertical annulus with a heated length of 326 mm and an inner and outer diameter of 9.5 and 18 mm. The experiments were performed with mass fluxes of 250 and 400 kg/(m{sup 2}s), outlet pressures between 120 and 300 kPa, and constant inlet subcooling enthalpy of 167 kJ/kg. Only a small influence of modified surface structures on critical heat flux was observed for the pressure of 120 kPa in the present test section geometry. However, with increasing pressure the critical heat flux could increase up to 29% using the surface structured tubes with micro-channels, porous and oxidized layers. Capillary effects and increased nucleation site density are assumed to improve the critical heat flux performance. (authors)

  12. Monitoring Delamination of Thermal Barrier Coatings During Interrupted High-Heat-Flux Laser Testing using Luminescence Imaging

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

    2011-01-01

    This presentation showed progress made in extending luminescence-base delamination monitoring to TBCs exposed to high heat fluxes, which is an environment that much better simulates actual turbine engine conditions. This was done by performing upconversion luminescence imaging during interruptions in laser testing, where a high-power CO2 laser was employed to create the desired heat flux. Upconverison luminescence refers to luminescence where the emission is at a higher energy (shorter wavelength) than the excitation. Since there will be negligible background emission at higher energies than the excitation, this methods produces superb contrast. Delamination contrast is produced because both the excitation and emission wavelengths are reflected at delamination cracks so that substantially higher luminescence intensity is observed in regions containing delamination cracks. Erbium was selected as the dopant for luminescence specifically because it exhibits upconversion luminescence. The high power CO2 10.6 micron wavelength laser facility at NASA GRC was used to produce the heat flux in combination with forced air backside cooling. Testing was performed at a lower (95 W/sq cm) and higher (125 W/sq cm) heat flux as well as furnace cycling at 1163C for comparison. The lower heat flux showed the same general behavior as furnace cycling, a gradual, "spotty" increase in luminescence associated with debond progression; however, a significant difference was a pronounced incubation period followed by acceleration delamination progression. These results indicate that extrapolating behavior from furnace cycling measurements will grossly overestimate remaining life under high heat flux conditions. The higher heat flux results were not only accelerated, but much different in character. Extreme bond coat rumpling occurred, and delamination propagation extended over much larger areas before precipitating macroscopic TBC failure. This indicates that under the higher heat flux (and

  13. Investigation of the impact of anthropogenic heat flux within an urban land surface model and PILPS-urban

    NASA Astrophysics Data System (ADS)

    Best, M. J.; Grimmond, C. S. B.

    2016-10-01

    Results from the first international urban model comparison experiment (PILPS-Urban) suggested that models which neglected the anthropogenic heat flux within the surface energy balance performed at least as well as models that include the source term, but this could not be explained. The analyses undertaken show that the results from PILPS-Urban were masked by the signal from including vegetation, which was identified in PILPS-Urban as being important. Including the anthropogenic heat flux does give improved performance, but the benefit is small for the site studied given the relatively small magnitude of this flux relative to other terms in the surface energy balance. However, there is no further benefit from including temporal variations in the flux at this site. The importance is expected to increase at sites with a larger anthropogenic heat flux and greater temporal variations.

  14. Heat acclimation improves exercise performance

    PubMed Central

    Lorenzo, Santiago; Halliwill, John R.; Sawka, Michael N.

    2010-01-01

    This study examined the impact of heat acclimation on improving exercise performance in cool and hot environments. Twelve trained cyclists performed tests of maximal aerobic power (V̇o2max), time-trial performance, and lactate threshold, in both cool [13°C, 30% relative humidity (RH)] and hot (38°C, 30% RH) environments before and after a 10-day heat acclimation (∼50% V̇o2max in 40°C) program. The hot and cool condition V̇o2max and lactate threshold tests were both preceded by either warm (41°C) water or thermoneutral (34°C) water immersion to induce hyperthermia (0.8–1.0°C) or sustain normothermia, respectively. Eight matched control subjects completed the same exercise tests in the same environments before and after 10 days of identical exercise in a cool (13°C) environment. Heat acclimation increased V̇o2max by 5% in cool (66.8 ± 2.1 vs. 70.2 ± 2.3 ml·kg−1·min−1, P = 0.004) and by 8% in hot (55.1 ± 2.5 vs. 59.6 ± 2.0 ml·kg−1·min−1, P = 0.007) conditions. Heat acclimation improved time-trial performance by 6% in cool (879.8 ± 48.5 vs. 934.7 ± 50.9 kJ, P = 0.005) and by 8% in hot (718.7 ± 42.3 vs. 776.2 ± 50.9 kJ, P = 0.014) conditions. Heat acclimation increased power output at lactate threshold by 5% in cool (3.88 ± 0.82 vs. 4.09 ± 0.76 W/kg, P = 0.002) and by 5% in hot (3.45 ± 0.80 vs. 3.60 ± 0.79 W/kg, P < 0.001) conditions. Heat acclimation increased plasma volume (6.5 ± 1.5%) and maximal cardiac output in cool and hot conditions (9.1 ± 3.4% and 4.5 ± 4.6%, respectively). The control group had no changes in V̇o2max, time-trial performance, lactate threshold, or any physiological parameters. These data demonstrate that heat acclimation improves aerobic exercise performance in temperate-cool conditions and provide the scientific basis for employing heat acclimation to augment physical training programs. PMID:20724560

  15. Critical heat flux and dynamics of boiling in nanofluids at stepwise heat release

    NASA Astrophysics Data System (ADS)

    Moiseev, M. I.; Kuznetsov, D. V.

    2016-10-01

    In this paper results of an experimental study on critical heat flux and dynamics of boiling crisis onset in nanofluids at stepwise heat generation are presented. Freon R21 with three types of nanoparticles - SiO2, Cu and Al2O3 was used as test fluid. Critical heat fluxes and temperatures of boiling initiation were obtained. It was shown that the addition of nanoparticles increased CHF at stepwise heat generation by up to 21%. Under conditions of the experiment transition to film boiling occurred via evaporation fronts. Data on propagation velocity and structure of evaporation fronts were obtained; the spectral analysis of fluctuations of the evaporation front interface was carried out. The characteristic frequencies and amplitudes of interface fluctuations were determined depending on the velocity of evaporation front propagation. It was shown that the addition of nano-sized particles significantly affects development of interface instability and increases the front velocity.

  16. Particle and heat flux measurements in PDX edge plasmas

    SciTech Connect

    Budny, R.; Manos, D.

    1983-12-01

    This paper describes the use of novel combined Langmuir-calorimeter probes to measure edge plasma conditions near the midplane in PDX. The probes consisted of up to five Langmuir probes and up to two calorimeters. Single and double probe characteristics yield n/sub e/ and T/sub e/ which are compared with that derived from a triple probe analysis. The calorimeters measure heat flux in the electron and ion drift directions. This paper presents time-resolved radial profiles of n/sub e/, T/sub e/, V/sub F/ (floating potential), and P (heat flux) during high power neutral beam-heated, single-null discharges and circular scoop limiter discharges. The temporal dependence of these quantities displays the previous observed behavior with respect to gross discharge characteristics; however, an additional dependence on confinement mode has been observed. During the H-mode of energy confinement, a transient depression of n/sub e/, T/sub e/, and P occurs in the scrape-off plasma.

  17. Microconvection in vertical channel at given heat flux

    NASA Astrophysics Data System (ADS)

    Bekezhanova, V. B.; Shefer, I. A.

    2016-10-01

    A problem on stability of the viscous heat-conducting liquid flow in the vertical channel at given heat flux on the permeable solid walls is studied. The two-dimensional flow is described by an exact invariant solution of the microconvection equations. The investigation of the exact solution allows one to find out the extent of influence of the thermal load, gravity and the system geometry on the flow structure. Stability of the solution is investigated in the framework of the linear theory. The spectrum of the spatial characteristic perturbations is analyzed in the space of problem parameters. Typical forms of the hydrodynamic and thermal disturbances are presented and dependence of characteristics of the arising structures on the thermal load and gravity is established. Convective cells, hydrothermal rolls and polygonal structures can appear in the channel. By weak gravity the hydrothermal rolls are not formed. Changing heat flux and disturbance wave length lead to deformation of the cells and complication of the spatial form of the structures.

  18. Investigation of heat flux deposition on divertor target on the Large Helical Device with EMC3-EIRENE modelling

    NASA Astrophysics Data System (ADS)

    Dai, Shuyu; Kobayashi, M.; Kawamura, G.; Masuzaki, S.; Tanaka, H.; Suzuki, Y.; Feng, Y.; Wang, D. Z.; the LHD Experimental Group

    2017-08-01

    The measured divertor heat flux profiles are compared to the EMC3-EIRENE simulations for two different times of an LHD discharge, corresponding to higher and lower edge temperatures. The relation between the three-dimensional magnetic field structure and the heat flux distributions on the divertor has been analysed. The modelled heat flux for the lower plasma temperature case has a better agreement with the experimental result obtained by the Langmuir probes, which shows a qualitative reproduction of the experimental profile shape. However, the heat flux distribution for the high plasma temperature case shows a different behaviour between the simulation results and the experimental measurements. The detailed analysis of the heat flux distribution for the higher temperature case which has a larger discrepancy has been performed, both quantitatively and qualitatively. The radiation of the eroded impurity from divertor target plates has a minor effect on the heat flux distribution. Non-uniform cross-field transport coefficients are used in the simulations and its impact on the heat flux distributions is discussed for the case of the high plasma temperature.

  19. A Three Component Model to Estimate Sensible Heat Flux Over Sparse Shrubs in Nevada

    USGS Publications Warehouse

    Chehbouni, A.; Nichols, W.D.; Njoku, E.G.; Qi, J.; Kerr, Y.H.; Cabot, F.

    1997-01-01

    It is now recognized that accurate partitioning of available energy into sensible and latent heat flux is crucial to understanding surface-atmosphere interactions. This issue is more complicated in arid and semi-arid regions where the relative contribution to surface fluxes from the soil and vegetation may vary significantly throughout the day and throughout the season. The objective of this paper is to present a three-component model to estimate sensible heat flux over heterogeneous surfaces. The surface was represented with two adjacent compartments. The first compartment is made up of two components, shrubs and shaded soil; the second compartment consists of bare, unshaded soil. Data collected at two different sites in Nevada during the summers of 1991 and 1992 were used to evaluate model performance. The results show that the present model is sufficiently general to yield satisfactory results for both sites.

  20. Copper alloys for high heat flux structure applications

    SciTech Connect

    Zinkle, S.J.; Fabritsiev, S.A.

    1994-09-01

    The mechanical and physical properties of copper alloys are reviewed and compared with the requirements for high heat flux structural applications in fusion reactors. High heat flux structural materials must possess a combination of high thermal conductivity and high mechanical strength. The three most promising copper alloys at the present time are oxide dispersion-strengthened copper (Cu-Al{sub 2}O{sub 3}) and two precipitation-hardened copper alloys (Cu-Cr-Zr and Cu-Ni-Be). These three alloys are capable of room temperature yield strengths >400 MPa and thermal conductivities up to 350 W/m-K. All of these alloys require extensive cold working to achieve their optimum strength. Precipitation-hardened copper alloys such Cu-Cr-Zr are susceptible to softening due to precipitate overaging and recrystallization during brazing, whereas the dislocation structure in Cu-Al{sub 2}O{sub 3} remains stabilized during typical high temperature brazing cycles. All three alloys exhibit good resistance to irradiation-induced softening and void swelling at temperatures below 300{degrees}C. The precipitation-strengthened allows typically soften during neutron irradiation at temperatures above about 300{degrees}C and therefore should only be considered for applications operating at temperatures <300{degrees}C. Dispersion-strengthened copper may be used up to temperatures in excess of 500{degrees}C. Based on the available data, dispersion-strengthened copper (Cu-Al{sub 2}O{sub 3}) is considered to be the best candidate for high heat flux structural applications.

  1. Heat flux through a geothermally heated fluidized bed at the bottom of a lake.

    PubMed

    Sanchez, Xavier; Roget, Elena; Planella, Jesus

    2009-07-01

    Heat fluxes and the underground inflow through a natural fluidized bed within the main sub-basin of Lake Banyoles are studied and parameterized. In the upper part of this fluidized bed, at a depth of about 30 m, the vertical gradients of particle concentration and temperature are very sharply located within an interface a few centimeters thick. Within this interface (lutocline), the depths where the temperature and the concentration gradients are maximum match exactly. On the other hand, the lutocline determines a flat, horizontal surface dividing the water column into a hot, turbid medium at the bottom and clear, colder, bulk water above. Through this interface the flow regime also varies from being laminar just below it, to turbulent due to convective processes developing above it. More precisely, in studied main sub-basin a buoyant plume develops above the lutocline, as a result of the heat flux, and affects the lake's water quality due to particles dragged along by it. In this paper it is proposed to determine the temperature at the depth of maximum gradient within the interface by means of measured temperature profiles, and consider the stationary heat transport equation in the laminar region below it, in order to obtain the water velocity and the heat flux. Heat flux parameterization is given based on a large number of thermal high-resolution profiles, covering six campaigns in different years and seasons. Furthermore, and in consideration of the fact that high-resolution thermal profiles are not always available, some alternative parameterizations for the heat flux are presented based only on the temperature of the fluidized bed and that of the lower hypolimnion.

  2. Transectional heat transfer in thermoregulating bigeye tuna (Thunnus obesus) - a 2D heat flux model.

    PubMed

    Boye, Jess; Musyl, Michael; Brill, Richard; Malte, Hans

    2009-11-01

    We developed a 2D heat flux model to elucidate routes and rates of heat transfer within bigeye tuna Thunnus obesus Lowe 1839 in both steady-state and time-dependent settings. In modeling the former situation, we adjusted the efficiencies of heat conservation in the red and the white muscle so as to make the output of the model agree as closely as possible with observed cross-sectional isotherms. In modeling the latter situation, we applied the heat exchanger efficiencies from the steady-state model to predict the distribution of temperature and heat fluxes in bigeye tuna during their extensive daily vertical excursions. The simulations yielded a close match to the data recorded in free-swimming fish and strongly point to the importance of the heat-producing and heat-conserving properties of the white muscle. The best correspondence between model output and observed data was obtained when the countercurrent heat exchangers in the blood flow pathways to the red and white muscle retained 99% and 96% (respectively) of the heat produced in these tissues. Our model confirms that the ability of bigeye tuna to maintain elevated muscle temperatures during their extensive daily vertical movements depends on their ability to rapidly modulate heating and cooling rates. This study shows that the differential cooling and heating rates could be fully accounted for by a mechanism where blood flow to the swimming muscles is either exclusively through the heat exchangers or completely shunted around them, depending on the ambient temperature relative to the body temperature. Our results therefore strongly suggest that such a mechanism is involved in the extensive physiological thermoregulatory abilities of endothermic bigeye tuna.

  3. Critical heat flux in locally heated liquid film moving under the action of gas flow in a mini-channel

    NASA Astrophysics Data System (ADS)

    Tkachenko, E. M.; Zaitsev, D. V.; Orlik, E. V.; Kabov, O. A.

    2016-10-01

    Thin and ultra thin liquid films driven by a forced gas/vapor flow (stratified or annular flows), i.e. shear-driven liquid films in a narrow channel, is one of the promising candidate for the thermal management of advanced semiconductor devices with high local heat release. In experiments performed in this paper with locally heated shear-driven liquid films of water the effect of various conditions, such as flow rates of liquid and gas and channel height, on critical heat flux (CHF) was investigated. In experiments the record value of CHF as high as 540 W/cm2 has been achieved. The heat spreading into the substrate and the heat loses into the atmosphere in total don't exceed 30% at heat fluxes higher than 200 W/cm2. Comparison of shear-driven liquid films and gravity-driven liquid films showed that CHF in shear-driven films up to 10 times higher than in gravity-driven liquid films. Thus, prospect of using shear- driven films of water in modern cooling systems of semiconductor devices was confirmed.

  4. Applicability of copper alloys for DEMO high heat flux components

    NASA Astrophysics Data System (ADS)

    Zinkle, Steven J.

    2016-02-01

    The current state of knowledge of the mechanical and thermal properties of high-strength, high conductivity Cu alloys relevant for fusion energy high heat flux applications is reviewed, including effects of thermomechanical and joining processes and neutron irradiation on precipitation- or dispersion-strengthened CuCrZr, Cu-Al2O3, CuNiBe, CuNiSiCr and CuCrNb (GRCop-84). The prospects for designing improved versions of wrought copper alloys and for utilizing advanced fabrication processes such as additive manufacturing based on electron beam and laser consolidation methods are discussed. The importance of developing improved structural materials design criteria is also noted.

  5. Method of producing a plug-type heat flux gauge

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H. (Inventor); Koch, John, Jr. (Inventor)

    1992-01-01

    A method of making a plug-type heat flux gauge in a material specimen in which a thermoplug is integrally formed in the specimen is disclosed. The thermoplug and concentric annulus are formed in the material specimen by electrical discharge machining and trepanning procedures. The thermoplug is surrounded by a concentric annulus through which thermocouple wires are routed. The end of each thermocouple wire is welded to the thermoplug, with each thermocouple wire welded at a different location along the length of the thermoplug.

  6. USE OF PELTIER COOLERS AS SOIL HEAT FLUX TRANSDUCERS.

    USGS Publications Warehouse

    Weaver, H.L.; Campbell, G.S.

    1985-01-01

    Peltier coolers were modified and calibrated to serve as soil heat flux transducers. The modification was to fill their interiors with epoxy. The average calibration constant on 21 units was 13. 6 plus or minus 0. 8 kW m** minus **2 V** minus **1 at 20 degree C. This sensitivity is about eight times that of the two thermopile transducers with which comparisons were made. The thermal conductivity of the Peltier cooler transducers was 0. 4 W m** minus **1 degree C** minus **1, which is comparable to that of dry soil.

  7. Critical heat flux correlation through the alternating conditional expectation algorithm

    SciTech Connect

    Han Gon Kim; Lee, J.C.

    1996-12-31

    Because most critical heat flux (CHF) correlations have specific ranges of application, lookup table techniques and artificial neural networks have been recently used to predict CHF for a broad range of variables. In this paper, the alternating conditional expectation (ACE) algorithm is used to generate a new CHF correlation applicable to a wide range of forced convective boiling parameters. As a generalized regression tool, the ACE algorithm does not require an initial guess for the functional form, and it guarantees the convergence of the solution.

  8. Influences of biomass heat and biochemical energy storages on the land surface fluxes and radiative temperature

    NASA Astrophysics Data System (ADS)

    Gu, Lianhong; Meyers, Tilden; Pallardy, Stephen G.; Hanson, Paul J.; Yang, Bai; Heuer, Mark; Hosman, Kevin P.; Liu, Qing; Riggs, Jeffery S.; Sluss, Dan; Wullschleger, Stan D.

    2007-01-01

    The interest of this study was to develop an initial assessment on the potential importance of biomass heat and biochemical energy storages for land-atmosphere interactions, an issue that has been largely neglected so far. We conducted flux tower observations and model simulations at a temperate deciduous forest site in central Missouri in the summer of 2004. The model used was the comprehensive terrestrial ecosystem Fluxes and Pools Integrated Simulator (FAPIS). We first examined FAPIS performance by testing its predictions with and without the representation of biomass energy storages against measurements of surface energy and CO2 fluxes. We then evaluated the magnitudes and temporal patterns of the biomass energy storages calculated by FAPIS. Finally, the effects of biomass energy storages on land-atmosphere exchanges of sensible and latent heat fluxes and variations of land surface radiative temperature were investigated by contrasting FAPIS simulations with and without these storage terms. We found that with the representation of the two biomass energy storage terms, FAPIS predictions agreed with flux tower measurements fairly well; without the representation, however, FAPIS performance deteriorated for all predicted surface energy flux terms although the effect on the predicted CO2 flux was minimal. In addition, we found that the biomass heat storage and biochemical energy storage had clear diurnal patterns with typical ranges from -50 to 50 and -3 to 20 W m-2, respectively; these typical ranges were exceeded substantially when there were sudden changes in atmospheric conditions. Furthermore, FAPIS simulations without the energy storages produced larger sensible and latent heat fluxes during the day but smaller fluxes (more negative values) at night as compared with simulations with the energy storages. Similarly, without-storage simulations had higher surface radiative temperature during the day but lower radiative temperature at night, indicating that the

  9. Inverse determination of heat flux into a gun barrel using temperature sensors

    NASA Astrophysics Data System (ADS)

    Jablonski, Jonathan A.; Jablonski, Melissa N.

    2017-05-01

    A mathematical model is developed to describe the thermal response of a temperature sensor located within a gun barrel, which accounts for the time-constant of the sensor and a measurement bias. The model is inversely solved to estimate the total heat flux applied to the bore surface as well as the transient history of the applied heat flux for a given thermal response of a temperature sensor. A parametric study is conducted to determine the influence of sensor time-constant, sensor location within the gun barrel, and measurement bias on the accuracy of the estimated heat flux as applied to a 155mm gun barrel. It is found that the accuracy of the estimated heat flux improves as the time-constant of the sensor decreases, the sensor is located closer to the bore surface, and the measurement bias decreases. A regression model is provided to estimate that accuracy and it is shown how a typical thermocouple would perform at various locations through the thickness of the gun barrel.

  10. Effect of Triangular Fins on Critical Heat Flux in Ethanol-cooled Combustion Chamber

    NASA Astrophysics Data System (ADS)

    Takegoshi, Masao; Suzuki, Ryosuke; Saito, Toshihito; Ono, Fumiei; Hiraiwa, Tetsuo; Tomioka, Sadatake

    A pressure-fed engine with a regeneratively-cooled combustion chamber is studied in JAXA. Operation chamber pressure is approximately 1 MPa. A proposed propellant combination is liquid oxygen and ethanol. However, it is necessary to understand the critical heat flux when ethanol is used as a coolant for regeneratively-cooled combustion chamber because the saturation pressure of it is 6.3 MPa. In general, it is known that the cooling wall with fins improves the cooling performance. In this study, the effect of triangular fins on critical heat flux of ethanol in ethanol-cooled combustion chamber was investigated. As the result, it was found that the critical heat flux of cooling wall with triangular fins was 23 % higher than that of that without fin in the same velocity condition of the coolant. The critical heat flux increases by the triangular fins on the cooling surface due to the effect of the combination cooling with film boiling and nucleate boiling.

  11. Dependence of Convective Heat Flux Calculations on Roughness Lengths

    NASA Technical Reports Server (NTRS)

    Schieldge, John P.

    1995-01-01

    The zero plane displacement height (d) and aerodynamic roughness length (z0) can be determined separately for momentum, heat, and humidity by using a procedure based on the Levenberg-Marquardt method for solving non-linear equations. This procedure is used to analyze profile data previously collected by Lo (1977) in a forested area in Canada and by Morgan et al (1971) on a field at the University of California at Davis (UCD) in the United States. The UCD data base is used to show the effects of allowing for different roughness lengths (zom,z0h,z0q) in calculating sensible and latent heat flux densities from bulk transfer coefficients.

  12. Radial impurity flux measuring method with plasma heating in general geometry

    NASA Astrophysics Data System (ADS)

    Espinosa, Silvia; Catto, Peter J.

    2017-10-01

    Devising a means to measure the radial impurity flux across the pedestal could be used to reduce impurity accumulation, if not prevent it while providing natural fueling, and thus improving fusion performance in tokamaks. We employ a novel solution procedure that takes advantage of the poloidal flow measurement to obtain the radial impurity flux directly from available diagnostics, such as charge exchange recombination spectroscopy and Thomson scattering. In the absence of our procedure, a computationally demanding kinetic calculation of the full bulk ion response would be required at finite aspect ratio for the flux surface shape of interest. The more general form of the model considered here permits large toroidal impurity flow on the order of the impurity thermal speed. Moreover, it allows plasma heating techniques to be employed to actively modify the poloidal variation of the potential to adjust the location of impurity accumulation and thereby alter the radial impurity flux.

  13. Using Gravity Inversion to Estimate Antarctic Geothermal Heat Flux

    NASA Astrophysics Data System (ADS)

    Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; (Sasha) Golynsky, A. V.; Rogozhina, Irina

    2014-05-01

    New modelling studies for Greenland have recently underlined the importance of GHF for long-term ice sheet behaviour (Petrunin et al. 2013). Revised determinations of top basement heat-flow for Antarctica and adjacent rifted continental margins using gravity inversion mapping of crustal thickness and continental lithosphere thinning (Chappell & Kusznir 2008), using BedMap2 data have provided improved estimates of geothermal heat flux (GHF) in Antarctica where it is very poorly known. Continental lithosphere thinning and post-breakup residual thicknesses of continental crust determined from gravity inversion have been used to predict the preservation of continental crustal radiogenic heat productivity and the transient lithosphere heat-flow contribution within thermally equilibrating rifted continental and oceanic lithosphere. The sensitivity of present-day Antarctic top basement heat-flow to initial continental radiogenic heat productivity, continental rift and margin breakup age has been examined. Recognition of the East Antarctic Rift System (EARS), a major Permian to Cretaceous age rift system that appears to extend from the continental margin at the Lambert Rift to the South Pole region, a distance of 2500 km (Ferraccioli et al. 2011) and is comparable in scale to the well-studied East African rift system, highlights that crustal variability in interior Antarctica is much greater than previously assumed. GHF is also important to understand proposed ice accretion at the base of the EAIS in the GSM and its links to sub-ice hydrology (Bell et al. 2011). References Bell, R.E., Ferraccioli, F., Creyts, T.T., Braaten, D., Corr, H., Das, I., Damaske, D., Frearson, N., Jordan, T., Rose, K., Studinger, M. & Wolovick, M. 2011. Widespread persistent thickening of the East Antarctic Ice Sheet by freezing from the base. Science, 331 (6024), 1592-1595. Chappell, A.R. & Kusznir, N.J. 2008. Three-dimensional gravity inversion for Moho depth at rifted continental margins

  14. Corrections for Convective Heat Flux Gauges Subjected to a Surface Temperature Discontinuity

    NASA Technical Reports Server (NTRS)

    Kandula, M.; Reinarts, T.; Voska, N. (Technical Monitor)

    2002-01-01

    A two-dimensional Navier-Stokes computational fluid dynamics (CFD) analysis has been carried out in an effort to determine the convective heat transfer corrections for circular heat flux gauges subjected to a surface temperature discontinuity. Solutions were obtained at a Reynolds number Of 1 x 10(exp 6) and a Mach number of 4. The CFD results are compared with the existing correlations for the correction factors. In general, the CFD corrections exceed those provided by the correlations. The discrepancy increases with increasing upstream surface temperature, thus indicating the role of property variations, which are not accounted for in the correlations. A quasi-two-dimensional analysis is also performed to treat the cylindrical geometry of the heat flux gauges by area-averaging the computed two-dimensional results from CFD.

  15. The Surface Heat Flux as a Function of Ground Cover for Climate Models

    NASA Technical Reports Server (NTRS)

    Vukovich, Fred M.; Wayland, Robert; Toll, David

    1997-01-01

    Surface heat fluxes were examined as a function of surface properties and meteorological conditions in a 100 km x 100 km grid square at 1-km spatial resolution centered at the location of the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE), the Forest Ecosystem Dynamics site in central Maine, and a semiarid rangeland site around Walnut Gulch, Arizona. This investigation treats the surface heat flux variability within a GCM grid box to provide insight into methods for treating that variability in climate models. The heat fluxes were calculated using NOAA AVHRR and available meteorological data. The average heat fluxes that were estimated using the various area ground-cover representations were compared with the ensemble average heat fluxes for the entire area, which were assumed to be the best representation of the heat fluxes for the areas. Average beat fluxes were estimated for the entire 100 km x 100 km area based on a single ground-cover representation, and the mean error for the area sensible heat flux was about 10% and for the area latent heat flux, 21%. The estimation error was reduced, and in some cases significantly reduced, when the area heat fluxes were estimated by partitioning the area according to significant ground cover. The most significant effect of the partitioning was on the latent heat flux estimates.

  16. Nonlinear aspects of high heat flux nucleate boiling heat transfer. Part 2, Results

    SciTech Connect

    Sadasivan, P.; Unal, C.; Nelson, R.

    1994-04-01

    This paper describes the results of a study aimed at understanding nonlinear aspects of the macrolayer-controlled heat transfer process associated with high heat flux nucleate boiling and the critical heat flux. Simulations of realistic heater surfaces have been carried out by detailed microscopic modeling of the surfaces. Individual nucleation sites are allowed to activate or deactivate depending on the thermal conditions that prevail at the site. The results indicate that significant spatial and temporal temperature variations can occur on the surface, and that thermal interactions among sites can result in some sites operating extremely intermittently. Surface-averaged temperatures show highly nonlinear behavior. This suggests the possibility of the system exhibiting chaotic behavior under appropriate experimental conditions. It is proposed that such nonlinear behavior is one of the reasons why mechanistic predictive capabilities for the boiling process have remained elusive.

  17. Calibration of High Heat Flux Sensors at NIST

    PubMed Central

    Murthy, A. V.; Tsai, B. K.; Gibson, C. E.

    1997-01-01

    An ongoing program at the National Institute of Standards and Technology (NIST) is aimed at improving and standardizing heat-flux sensor calibration methods. The current calibration needs of U.S. science and industry exceed the current NIST capability of 40 kW/m2 irradiance. In achieving this goal, as well as meeting lower-level non-radiative heat flux calibration needs of science and industry, three different types of calibration facilities currently are under development at NIST: convection, conduction, and radiation. This paper describes the research activities associated with the NIST Radiation Calibration Facility. Two different techniques, transfer and absolute, are presented. The transfer calibration technique employs a transfer standard calibrated with reference to a radiometric standard for calibrating the sensors using a graphite tube blackbody. Plans for an absolute calibration facility include the use of a spherical blackbody and a cooled aperture and sensor-housing assembly to calibrate the sensors in a low convective environment. PMID:27805156

  18. Diamond thin film temperature and heat-flux sensors

    NASA Technical Reports Server (NTRS)

    Aslam, M.; Yang, G. S.; Masood, A.; Fredricks, R.

    1995-01-01

    Diamond film temperature and heat-flux sensors are developed using a technology compatible with silicon integrated circuit processing. The technology involves diamond nucleation, patterning, doping, and metallization. Multi-sensor test chips were designed and fabricated to study the thermistor behavior. The minimum feature size (device width) for 1st and 2nd generation chips are 160 and 5 micron, respectively. The p-type diamond thermistors on the 1st generation test chip show temperature and response time ranges of 80-1270 K and 0.29-25 microseconds, respectively. An array of diamond thermistors, acting as heat flux sensors, was successfully fabricated on an oxidized Si rod with a diameter of 1 cm. Some problems were encountered in the patterning of the Pt/Ti ohmic contacts on the rod, due mainly to the surface roughness of the diamond film. The use of thermistors with a minimum width of 5 micron (to improve the spatial resolution of measurement) resulted in lithographic problems related to surface roughness of diamond films. We improved the mean surface roughness from 124 nm to 30 nm by using an ultra high nucleation density of 10(exp 11)/sq cm. To deposit thermistors with such small dimensions on a curved surface, a new 3-D diamond patterning technique is currently under development. This involves writing a diamond seed pattern directly on the curved surface by a computer-controlled nozzle.

  19. Chromospheric heating due to internetwork magnetic flux cancellations

    NASA Astrophysics Data System (ADS)

    Gosic, Milan; de la Cruz Rodriguez, Jaime; De Pontieu, Bart; Bellot Rubio, Luis; Ortiz, Ada; Esteban Pozuelo, Sara

    2017-08-01

    The heating of the solar chromosphere is one of the most intriguing unanswered problems in solar physics. It is believed that this phenomenon may significantly be supported by small-scale internetwork (IN) magnetic fields. Indeed, cancellations of IN magnetic flux patches might be an efficient way to transport flux and energy from the photosphere to the chromosphere. Because of this, it is essential to determine where they occur, the rates at which they proceed, and understand their influence on the chromosphere. Here we study the spatial and temporal evolution of IN cancelling patches using high resolution, multiwavelength, coordinated observations obtained with the Interface Region Imaging Spectrograph (IRIS) and the Swedish 1-m Solar Telescope (SST). Employing multi-line inversions of the Mg II h&k lines we show that cancelling events, while occurring ubiquitously over IN regions, produce clear signatures of heating in the upper atmospheric layers. Using the RADYN code we determine the energy released due to cancellations of IN elements and discuss about their impact on the dynamics and energetics of the solar chromosphere.

  20. Structural design criteria for high heat flux components.

    SciTech Connect

    Majumdar, S.

    1999-07-14

    The high temperature design rules of the ITER Structural Design Criteria (ISDC), are applied to first wall designs with high heat flux. The maximum coolant pressure and surface heat flux capabilities are shown to be determined not only by the mechanical properties of the first wall material but also by the details of the blanket design. In a high power density self-cooled lithium blanket, the maximum primary stress in the first wall is controlled by many of the geometrical parameters of the blanket, such as, first wall span, first wall curvature, first wall thickness, side wall thickness, and second wall thickness. The creep ratcheting lifetime of the first wall is also shown to be controlled by many of the same geometrical parameters as well as the coolant temperature. According to most high temperature design codes, the time-dependent primary membrane stress allowable are based on the average temperature (ignoring thermal stress). Such a procedure may sometimes be unconservative, particularly for embrittled first walls with large temperature gradients. The effect of secondary (thermal) stresses on the accumulation of creep deformation is illustrated with a vanadium alloy flat plate first wall design.

  1. Heat Flux and Wall Temperature Estimates for the NASA Langley HIFiRE Direct Connect Rig

    NASA Technical Reports Server (NTRS)

    Cuda, Vincent, Jr.; Hass, Neal E.

    2010-01-01

    An objective of the Hypersonic International Flight Research Experimentation (HIFiRE) Program Flight 2 is to provide validation data for high enthalpy scramjet prediction tools through a single flight test and accompanying ground tests of the HIFiRE Direct Connect Rig (HDCR) tested in the NASA LaRC Arc Heated Scramjet Test Facility (AHSTF). The HDCR is a full-scale, copper heat sink structure designed to simulate the isolator entrance conditions and isolator, pilot, and combustor section of the HIFiRE flight test experiment flowpath and is fully instrumented to assess combustion performance over a range of operating conditions simulating flight from Mach 5.5 to 8.5 and for various fueling schemes. As part of the instrumentation package, temperature and heat flux sensors were provided along the flowpath surface and also imbedded in the structure. The purpose of this paper is to demonstrate that the surface heat flux and wall temperature of the Zirconia coated copper wall can be obtained with a water-cooled heat flux gage and a sub-surface temperature measurement. An algorithm was developed which used these two measurements to reconstruct the surface conditions along the flowpath. Determinations of the surface conditions of the Zirconia coating were conducted for a variety of conditions.

  2. An Investigation of the Compatibility of Radiation and Convection Heat Flux Measurements

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1996-01-01

    A method for determining time-resolved absorbed surface heat flux and surface temperature in radiation and convection environments is described. The method is useful for verification of aerodynamic, heat transfer and durability models. A practical heat flux gage fabrication procedure and a simple one-dimensional inverse heat conduction model and calculation procedure are incorporated in this method. The model provides an estimate of the temperature and heat flux gradient in the direction of heat transfer through the gage. This paper discusses several successful time-resolved tests of this method in hostile convective heating and cooling environments.

  3. In Situ Monitoring of Soil Thermal Properties and Heat Flux during Freezing and Thawing

    USDA-ARS?s Scientific Manuscript database

    When soil freezes or thaws, latent heat fluxes occur and conventional methods for monitoring soil heat flux are inaccurate, often wildly so. This prevents the forcing of surface energy balance closure that is used in Bowen ratio flux measurements and the assessment of closure that is used as a check...

  4. A modified force-restore approach to modeling snow-surface heat fluxes

    Treesearch

    Charles H. Luce; David G. Tarboton

    2001-01-01

    Accurate modeling of the energy balance of a snowpack requires good estimates of the snow surface temperature. The snow surface temperature allows a balance between atmospheric heat fluxes and the conductive flux into the snowpack. While the dependency of atmospheric fluxes on surface temperature is reasonably well understood and parameterized, conduction of heat from...

  5. Estimating land surface heat flux using radiometric surface temperature without the need for an extra resistance

    NASA Astrophysics Data System (ADS)

    Su, H.; Yang, Y.; Liu, S.

    2015-12-01

    Remotely-sensed land surface temperature (LST) is a key variable in energy balance and is widely used for estimating regional heat flux. However, the inequality between LST and aerodynamic surface temperature (Taero) poses a great challenge for regional heat flux estimation in one -source energy balance models. In this study, a one-source model for land (OSML) was proposed to estimate regional surface heat flux without a need for an empirical extra resistance. The proposed OSML employs both a conceptual VFC/LST trapezoid model and the electrical analogue formula of sensible heat flux (H) to estimate the radiometric-convective resistance (rae) by using a quartic equation. To evaluate the performance of OSML, the model was applied to the Soil Moisture-Atmosphere Coupling Experiment (SMACEX), using a remotely-sensed data set at a regional scale. Validated against tower observations, the root mean square deviation (RMSD) of H and latent heat flux (LE) from OSML was 47 W/m2 and 51 W/m2, which is comparable to other published studies. OSML and SEBS (Surface Energy Balance System) compared under the same available energy indicated that LE estimated by OSML is comparable to that derived from the SEBS model. In conducting further inter-comparisons of rae, the aerodynamic resistance derived from SEBS (ra_SEBS), and aerodynamic resistance (ra) derived from Brutsaert et al. (2005) in corn and soybean fields, we found that rae and ra_SEBS are comparable. Most importantly, our study indicates that the OSML method is applicable without having to acquire wind speed or to specify aerodynamic surface characteristics and that it is applicable to heterogeneous areas.

  6. Design and calibration of a novel transient radiative heat flux meter for a spacecraft thermal test.

    PubMed

    Sheng, Chunchen; Hu, Peng; Cheng, Xiaofang

    2016-06-01

    Radiative heat flux measurement is significantly important for a spacecraft thermal test. To satisfy the requirements of both high accuracy and fast response, a novel transient radiative heat flux meter was developed. Its thermal receiver consists of a central thermal receiver and two thermal guarded annular plates, which ensure the temperature distribution of the central thermal receiver to be uniform enough for reasonably applying lumped heat capacity method in a transient radiative heat flux measurement. This novel transient radiative heat flux meter design can also take accurate measurements regardless of spacecraft surface temperature and incident radiation spectrum. The measurement principle was elaborated and the coefficients were calibrated. Experimental results from testing a blackbody furnace and an Xenon lamp show that this novel transient radiative heat flux meter can be used to measure transient radiative heat flux up to 1400 W/m(2) with high accuracy and the response time of less than 10 s.

  7. Organization of ice flow by localized regions of elevated geothermal heat flux

    NASA Astrophysics Data System (ADS)

    Pittard, M. L.; Galton-Fenzi, B. K.; Roberts, J. L.; Watson, C. S.

    2016-04-01

    The impact of localized regions of elevated geothermal heat flux on ice sheet dynamics is largely unknown. Simulations of ice dynamics are produced using poorly resolved and low-resolution estimates of geothermal heat flux. Observations of crustal heat production within the continental crust underneath the Lambert-Amery glacial system in East Antarctica indicate that high heat flux regions of at least 120 mW m-2 exist. Here we investigate the influence of simulated but plausible, localized regions of elevated geothermal heat flux on ice dynamics using a numerical ice sheet model of the Lambert-Amery glacial system. We find that high heat flux regions have a significant effect across areas of slow-moving ice with the influence extending both upstream and downstream of the geothermal anomaly, while fast-moving ice is relatively unaffected. Our results suggest that localized regions of elevated geothermal heat flux may play an important role in the organization of ice sheet flow.

  8. Design and calibration of a novel transient radiative heat flux meter for a spacecraft thermal test

    NASA Astrophysics Data System (ADS)

    Sheng, Chunchen; Hu, Peng; Cheng, Xiaofang

    2016-06-01

    Radiative heat flux measurement is significantly important for a spacecraft thermal test. To satisfy the requirements of both high accuracy and fast response, a novel transient radiative heat flux meter was developed. Its thermal receiver consists of a central thermal receiver and two thermal guarded annular plates, which ensure the temperature distribution of the central thermal receiver to be uniform enough for reasonably applying lumped heat capacity method in a transient radiative heat flux measurement. This novel transient radiative heat flux meter design can also take accurate measurements regardless of spacecraft surface temperature and incident radiation spectrum. The measurement principle was elaborated and the coefficients were calibrated. Experimental results from testing a blackbody furnace and an Xenon lamp show that this novel transient radiative heat flux meter can be used to measure transient radiative heat flux up to 1400 W/m2 with high accuracy and the response time of less than 10 s.

  9. Design and calibration of a novel transient radiative heat flux meter for a spacecraft thermal test

    SciTech Connect

    Sheng, Chunchen; Hu, Peng Cheng, Xiaofang

    2016-06-15

    Radiative heat flux measurement is significantly important for a spacecraft thermal test. To satisfy the requirements of both high accuracy and fast response, a novel transient radiative heat flux meter was developed. Its thermal receiver consists of a central thermal receiver and two thermal guarded annular plates, which ensure the temperature distribution of the central thermal receiver to be uniform enough for reasonably applying lumped heat capacity method in a transient radiative heat flux measurement. This novel transient radiative heat flux meter design can also take accurate measurements regardless of spacecraft surface temperature and incident radiation spectrum. The measurement principle was elaborated and the coefficients were calibrated. Experimental results from testing a blackbody furnace and an Xenon lamp show that this novel transient radiative heat flux meter can be used to measure transient radiative heat flux up to 1400 W/m{sup 2} with high accuracy and the response time of less than 10 s.

  10. Development of advanced high-temperature heat flux sensors. Phase 2: Verification testing

    NASA Technical Reports Server (NTRS)

    Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

    1985-01-01

    A two-phase program is conducted to develop heat flux sensors capable of making heat flux measurements throughout the hot section of gas turbine engines. In Phase 1, three types of heat flux sensors are selected; embedded thermocouple, laminated, and Gardon gauge sensors. A demonstration of the ability of these sensors to operate in an actual engine environment is reported. A segmented liner of each of two combustors being used in the Broad Specification Fuels Combustor program is instrumented with the three types of heat flux sensors then tested in a high pressure combustor rig. Radiometer probes are also used to measure the radiant heat loads to more fully characterize the combustor environment. Test results show the heat flux sensors to be in good agreement with radiometer probes and the predicted data trends. In general, heat flux sensors have strong potential for use in combustor development programs.

  11. Estimating Antarctic Geothermal Heat Flux using Gravity Inversion

    NASA Astrophysics Data System (ADS)

    Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; Golynsky, A. V.; Sasha Rogozhina, Irina

    2013-04-01

    Geothermal heat flux (GHF) in Antarctica is very poorly known. We have determined (Vaughan et al. 2012) top basement heat-flow for Antarctica and adjacent rifted continental margins using gravity inversion mapping of crustal thickness and continental lithosphere thinning (Chappell & Kusznir 2008). Continental lithosphere thinning and post-breakup residual thicknesses of continental crust determined from gravity inversion have been used to predict the preservation of continental crustal radiogenic heat productivity and the transient lithosphere heat-flow contribution within thermally equilibrating rifted continental and oceanic lithosphere. The sensitivity of present-day Antarctic top basement heat-flow to initial continental radiogenic heat productivity, continental rift and margin breakup age has been examined. Knowing GHF distribution for East Antarctica and the Gamburtsev Subglacial Mountains (GSM) region in particular is critical because: 1) The GSM likely acted as key nucleation point for the East Antarctic Ice Sheet (EAIS); 2) the region may contain the oldest ice of the EAIS - a prime target for future ice core drilling; 3) GHF is important to understand proposed ice accretion at the base of the EAIS in the GSM and its links to sub-ice hydrology (Bell et al. 2011). An integrated multi-dataset-based GHF model for East Antarctica is planned that will resolve the wide range of estimates previously published using single datasets. The new map and existing GHF distribution estimates available for Antarctica will be evaluated using direct ice temperature measurements obtained from deep ice cores, estimates of GHF derived from subglacial lakes, and a thermodynamic ice-sheet model of the Antarctic Ice Sheet driven by past climate reconstructions and each of analysed heat flow maps, as has recently been done for the Greenland region (Rogozhina et al. 2012). References Bell, R.E., Ferraccioli, F., Creyts, T.T., Braaten, D., Corr, H., Das, I., Damaske, D., Frearson, N

  12. Thermal barrier coatings (TBC's) for high heat flux thrust chambers

    NASA Astrophysics Data System (ADS)

    Bradley, Christopher M.

    The last 30 years materials engineers have been under continual pressure to develop materials with a greater temperature potential or to produce configurations that can be effectively cooled or otherwise protected at elevated temperature conditions. Turbines and thrust chambers produce some of the harshest service conditions for materials which lead to the challenges engineers face in order to increase the efficiencies of current technologies due to the energy crisis that the world is facing. The key tasks for the future of gas turbines are to increase overall efficiencies to meet energy demands of a growing world population and reduce the harmful emissions to protect the environment. Airfoils or blades tend to be the limiting factor when it comes to the performance of the turbine because of their complex design making them difficult to cool as well as limitations of their thermal properties. Key tasks for space transportation it to lower costs while increasing operational efficiency and reliability of our space launchers. The important factor to take into consideration is the rocket nozzle design. The design of the rocket nozzle or thrust chamber has to take into account many constraints including external loads, heat transfer, transients, and the fluid dynamics of expanded hot gases. Turbine engines can have increased efficiencies if the inlet temperature for combustion is higher, increased compressor capacity and lighter weight materials. In order to push for higher temperatures, engineers need to come up with a way to compensate for increased temperatures because material systems that are being used are either at or near their useful properties limit. Before thermal barrier coatings were applied to hot-section components, material alloy systems were able to withstand the service conditions necessary. But, with the increased demand for performance, higher temperatures and pressures have become too much for those alloy systems. Controlled chemistry of hot

  13. Heat Acclimation Improves Exercise Performance

    DTIC Science & Technology

    2010-01-01

    environments. Twelve trained cyclists performed tests of maximal aerobic power ( VO2max ), time-trial performance, and lactate threshold, in both cool [13...C, 30% relative humidity (RH)] and hot (38°C, 30% RH) environments before and after a 10-day heat acclimation (~50% VO2max in 40°C) program. The hot...and cool condition VO2max and lactate threshold tests were both preceded by either warm (41° C) water or thermoneutral (34°C) water immersion to

  14. Analysis of the Effects of Vitiates on Surface Heat Flux in Ground Tests of Hypersonic Vehicles

    NASA Technical Reports Server (NTRS)

    Cuda, Vincent; Gaffney, Richard L

    2008-01-01

    To achieve the high enthalpy conditions associated with hypersonic flight, many ground test facilities burn fuel in the air upstream of the test chamber. Unfortunately, the products of combustion contaminate the test gas and alter gas properties and the heat fluxes associated with aerodynamic heating. The difference in the heating rates between clean air and a vitiated test medium needs to be understood so that the thermal management system for hypersonic vehicles can be properly designed. This is particularly important for advanced hypersonic vehicle concepts powered by air-breathing propulsion systems that couple cooling requirements, fuel flow rates, and combustor performance by flowing fuel through sub-surface cooling passages to cool engine components and preheat the fuel prior to combustion. An analytical investigation was performed comparing clean air to a gas vitiated with methane/oxygen combustion products to determine if variations in gas properties contributed to changes in predicted heat flux. This investigation started with simple relationships, evolved into writing an engineering-level code, and ended with running a series of CFD cases. It was noted that it is not possible to simultaneously match all of the gas properties between clean and vitiated test gases. A study was then conducted selecting various combinations of freestream properties for a vitiated test gas that matched clean air values to determine which combination of parameters affected the computed heat transfer the least. The best combination of properties to match was the free-stream total sensible enthalpy, dynamic pressure, and either the velocity or Mach number. This combination yielded only a 2% difference in heating. Other combinations showed departures of up to 10% in the heat flux estimate.

  15. ANL ITER high-heat-flux blanket-module heat transfer experiments. Fusion Power Program

    SciTech Connect

    Kasza, K.E.

    1992-02-01

    An Argonne National Laboratory facility for conducting tests on multilayered slab models of fusion blanket designs is being developed; some of its features are described. This facility will allow testing under prototypic high heat fluxes, high temperatures, thermal gradients, and variable mechanical loadings in a helium gas environment. Steady and transient heat flux tests are possible. Electrical heating by a two-sided, thin stainless steel (SS) plate electrical resistance heater and SS water-cooled cold panels placed symmetrically on both sides of the heater allow achievement of global one-dimensional heat transfer across blanket specimen layers sandwiched between the hot and cold plates. The heat transfer characteristics at interfaces, as well as macroscale and microscale thermomechanical interactions between layers, can be studied in support of the ITER engineering design effort. The engineering design of the test apparatus has shown that it is important to use multidimensional thermomechanical analysis of sandwich-type composites to adequately analyze heat transfer. This fact will also be true for the engineering design of ITER.

  16. ANL ITER high-heat-flux blanket-module heat transfer experiments

    SciTech Connect

    Kasza, K.E.

    1992-02-01

    An Argonne National Laboratory facility for conducting tests on multilayered slab models of fusion blanket designs is being developed; some of its features are described. This facility will allow testing under prototypic high heat fluxes, high temperatures, thermal gradients, and variable mechanical loadings in a helium gas environment. Steady and transient heat flux tests are possible. Electrical heating by a two-sided, thin stainless steel (SS) plate electrical resistance heater and SS water-cooled cold panels placed symmetrically on both sides of the heater allow achievement of global one-dimensional heat transfer across blanket specimen layers sandwiched between the hot and cold plates. The heat transfer characteristics at interfaces, as well as macroscale and microscale thermomechanical interactions between layers, can be studied in support of the ITER engineering design effort. The engineering design of the test apparatus has shown that it is important to use multidimensional thermomechanical analysis of sandwich-type composites to adequately analyze heat transfer. This fact will also be true for the engineering design of ITER.

  17. Numerical and experimental analyses of the radiant heat flux produced by quartz heating systems

    NASA Astrophysics Data System (ADS)

    Turner, Travis L.; Ash, Robert L.

    1994-03-01

    A method is developed for predicting the radiant heat flux distribution produced by tungsten filament, tubular fused-quartz envelope heating systems with reflectors. The method is an application of Monte Carlo simulation, which takes the form of a random walk or ray tracing scheme. The method is applied to four systems of increasing complexity, including a single lamp without a reflector, a single lamp with a Hat reflector, a single lamp with a parabolic reflector, and up to six lamps in a six-lamp contoured-reflector heating unit. The application of the Monte Carlo method to the simulation of the thermal radiation generated by these systems is discussed. The procedures for numerical implementation are also presented. Experiments were conducted to study these quartz heating systems and to acquire measurements of the corresponding empirical heat flux distributions for correlation with analysis. The experiments were conducted such that several complicating factors could be isolated and studied sequentially. Comparisons of the experimental results with analysis are presented and discussed. Good agreement between the experimental and simulated results was obtained in all cases. This study shows that this method can be used to analyze very complicated quartz heating systems and can account for factors such as spectral properties, specular reflection from curved surfaces, source enhancement due to reflectors and/or adjacent sources, and interaction with a participating medium in a straightforward manner.

  18. Numerical and experimental analyses of the radiant heat flux produced by quartz heating systems

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.; Ash, Robert L.

    1994-01-01

    A method is developed for predicting the radiant heat flux distribution produced by tungsten filament, tubular fused-quartz envelope heating systems with reflectors. The method is an application of Monte Carlo simulation, which takes the form of a random walk or ray tracing scheme. The method is applied to four systems of increasing complexity, including a single lamp without a reflector, a single lamp with a Hat reflector, a single lamp with a parabolic reflector, and up to six lamps in a six-lamp contoured-reflector heating unit. The application of the Monte Carlo method to the simulation of the thermal radiation generated by these systems is discussed. The procedures for numerical implementation are also presented. Experiments were conducted to study these quartz heating systems and to acquire measurements of the corresponding empirical heat flux distributions for correlation with analysis. The experiments were conducted such that several complicating factors could be isolated and studied sequentially. Comparisons of the experimental results with analysis are presented and discussed. Good agreement between the experimental and simulated results was obtained in all cases. This study shows that this method can be used to analyze very complicated quartz heating systems and can account for factors such as spectral properties, specular reflection from curved surfaces, source enhancement due to reflectors and/or adjacent sources, and interaction with a participating medium in a straightforward manner.

  19. Latent Heat and Sensible Heat Fluxes Simulation in Maize Using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Safa, B.

    2015-12-01

    Latent Heat (LE) and Sensible Heat (H) flux are two major components of the energy balance at the earth's surface which play important roles in the water cycle and global warming. There are various methods for their estimation or measurement. Eddy covariance is a direct and accurate technique for their measurement. Some limitations lead to prevention of the extensive use of the eddy covariance technique. Therefore, simulation approaches can be utilized for their estimation. ANNs are the information processing systems, which can inspect the empirical data and investigate the relations (hidden rules) among them, and then make the network structure. In this study, multi-layer perceptron neural network trained by the steepest descent Back-Propagation (BP) algorithm was tested to simulate LE and H flux above two maize sites (rain-fed & irrigated) near Mead, Nebraska. Network training and testing was fulfilled using hourly data of including year, local time of day (DTime), leaf area index (LAI), soil water content (SWC) in 10 and 25 cm depths, soil temperature (Ts) in 10 cm depth, air temperature (Ta), vapor pressure deficit (VPD), wind speed (WS), irrigation and precipitation (P), net radiation (Rn), and the fraction of incoming Photosynthetically Active Radiation (PAR) absorbed by the canopy (fPAR), which were selected from days of year (DOY) 169 to 222 for 2001, 2003, 2005, 2007, and 2009. The results showed high correlation between actual and estimated data; the R² values for LE flux in irrigated and rain-fed sites were 0.9576, and 0.9642; and for H flux 0.8001, and 0.8478, respectively. Furthermore, the RMSE values ranged from 0.0580 to 0.0721 W/m² for LE flux and from 0.0824 to 0.0863 W/m² for H flux. In addition, the sensitivity of the fluxes with respect to each input was analyzed over the growth stages. Thus, the most powerful effects among the inputs for LE flux were identified net radiation, leaf area index, vapor pressure deficit, wind speed, and for H

  20. Comprehensive Analysis of Convective Heat Transfer in Parallel Plate Microchannel with Viscous Dissipation and Constant Heat Flux Boundary Conditions

    NASA Astrophysics Data System (ADS)

    Kushwaha, Hari Mohan; Sahu, Santosh Kumar

    2017-10-01

    This paper reports the hydrodynamically and thermally fully developed, laminar, incompressible, forced convective heat transfer characteristics of gaseous flows through a parallel plate microchannel with different constant heat flux boundary conditions. The first order velocity slip and viscous dissipation effects are considered in the analysis. Here, three different thermal boundary conditions such as: both plates kept at different constant heat fluxes, both plates kept at equal constant heat fluxes and one plate kept at constant heat flux and other one insulated are considered for the analysis. The deviation in Nusselt number between the model that considers both first order velocity slip and temperature jump and the one that considers only velocity slip is reported. Also, the effect of various heat flux ratios on the Nusselt number is reported in this analysis. In addition, the deviation in Nusselt number between first and second order slip model is discussed in this study.

  1. Radial heat flux limits in potassium heat pipes: An experimental and analytical investigation

    SciTech Connect

    Woloshun, K.A.; Sena, J.T.; Keddy, E.S.; Merrigan, M.A.

    1989-01-01

    A radial flux limit of 147 W/cm{sup 2} at the wetted inner tube wall has been demonstrated with a Nb-1%Zr/K heat pipe, a flux 5 times greater than the previously accepted safe design level of 25-30 W/cm{sup 2}. The wick structure was an annular gap type fabricated from 100 {times} 100 mesh Nb-1%Zr screen. Rigorous fabrication and cleaning procedures are believed to be critical to good wetting, resulting in significantly reduced active nucleation site size and a higher boiling limit. The procedure used to clean this heat pipe included acid wash, Freon-TF degrease, ethanol wash, high-vacuum firing, and operation as a lithium heat pipe. A heat pipe boiling limit model, based on the active nucleation site radius, is described. An active nucleation site radius of 6 {times} 10{sup -6} m (2.4 {times} 10{sup -4} in) correlates the radial flux boiling limit measured in these tests. 4 refs., 2 figs.

  2. The surface latent heat flux anomalies related to major earthquake

    NASA Astrophysics Data System (ADS)

    Jing, Feng; Shen, Xuhui; Kang, Chunli; Xiong, Pan; Hong, Shunying

    2011-12-01

    SLHF (Surface Latent Heat Flux) is an atmospheric parameter, which can describe the heat released by phase changes and dependent on meteorological parameters such as surface temperature, relative humidity, wind speed etc. There is a sharp difference between the ocean surface and the land surface. Recently, many studies related to the SLHF anomalies prior to earthquakes have been developed. It has been shown that the energy exchange enhanced between coastal surface and atmosphere prior to earthquakes can increase the rate of the water-heat exchange, which will lead to an obviously increases in SLHF. In this paper, two earthquakes in 2010 (Haiti earthquake and southwest of Sumatra in Indonesia earthquake) have been analyzed using SLHF data by STD (standard deviation) threshold method. It is shows that the SLHF anomaly may occur in interpolate earthquakes or intraplate earthquakes and coastal earthquakes or island earthquakes. And the SLHF anomalies usually appear 5-6 days prior to an earthquake, then disappear quickly after the event. The process of anomaly evolution to a certain extent reflects a dynamic energy change process about earthquake preparation, that is, weak-strong-weak-disappeared.

  3. A Comparison of Latent Heat Fluxes over Global Oceans for Four Flux Products

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.

    2003-01-01

    To improve our understanding of global energy and water cycle variability, and to improve model simulations of climate variations, it is vital to have accurate latent heat fluxes (LHF) over global oceans. Monthly LHF, 10-m wind speed (U10m), 10-m specific humidity (Q10h), and sea-air humidity difference (Qs-Q10m) of GSSTF2 (version 2 Goddard Satellite-based Surface Turbulent Fluxes) over global Oceans during 1992-93 are compared with those of HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP (NCEP/NCAR reanalysis). The mean differences, standard deviations of differences, and temporal correlation of these monthly variables over global Oceans during 1992-93 between GSSTF2 and each of the three datasets are analyzed. The large-scale patterns of the 2yr-mean fields for these variables are similar among these four datasets, but significant quantitative differences are found. The temporal correlation is higher in the northern extratropics than in the south for all variables, with the contrast being especially large for da Silva as a result of more missing ship data in the south. The da Silva has extremely low temporal correlation and large differences with GSSTF2 for all variables in the southern extratropics, indicating that da Silva hardly produces a realistic variability in these variables. The NCEP has extremely low temporal correlation (0.27) and large spatial variations of differences with GSSTF2 for Qs-Q10m in the tropics, which causes the low correlation for LHF. Over the tropics, the HOAPS LHF is significantly smaller than GSSTF2 by approx. 31% (37 W/sq m), whereas the other two datasets are comparable to GSSTF2. This is because the HOAPS has systematically smaller LHF than GSSTF2 in space, while the other two datasets have very large spatial variations of large positive and negative LHF differences with GSSTF2 to cancel and to produce smaller regional-mean differences. Our analyses suggest that the GSSTF2 latent heat flux

  4. A new heat flux model for the Antarctic Peninsula incorporating spatially variable upper crustal radiogenic heat production

    NASA Astrophysics Data System (ADS)

    Burton-Johnson, A.; Halpin, J. A.; Whittaker, J. M.; Graham, F. S.; Watson, S. J.

    2017-06-01

    A new method for modeling heat flux shows that the upper crust contributes up to 70% of the Antarctic Peninsula's subglacial heat flux and that heat flux values are more variable at smaller spatial resolutions than geophysical methods can resolve. Results indicate a higher heat flux on the east and south of the Peninsula (mean 81 mW m-2) where silicic rocks predominate, than on the west and north (mean 67 mW m-2) where volcanic arc and quartzose sediments are dominant. While the data supports the contribution of heat-producing element-enriched granitic rocks to high heat flux values, sedimentary rocks can be of comparative importance dependent on their provenance and petrography. Models of subglacial heat flux must utilize a heterogeneous upper crust with variable radioactive heat production if they are to accurately predict basal conditions of the ice sheet. Our new methodology and data set facilitate improved numerical model simulations of ice sheet dynamics.Plain Language SummaryAs the climate changes, the Antarctic ice sheet represents the single largest potential source of sea level rise. However, one key parameter controlling how the ice sheet flows remains poorly constrained: the effect of <span class="hlt">heat</span> derived from the Earth's geology on the base of the ice sheet (known as subglacial <span class="hlt">heat</span> <span class="hlt">flux</span>). Although this may not seem like a lot of <span class="hlt">heat</span>, under slow-flowing ice, this "<span class="hlt">heat</span> <span class="hlt">flux</span>" can control how well the ice sheet can flow over the rocks and even lead to melting of the ice at its base. Current models for Antarctica's <span class="hlt">heat</span> <span class="hlt">flux</span> use geophysics to determine how thin the crust is and consequently how easily <span class="hlt">heat</span> from the Earth's mantle can warm the surface. We show here that <span class="hlt">heat</span> produced by radioactive decay within the Earth's crust can have an even greater and much more variable contribution to the subglacial <span class="hlt">heat</span> <span class="hlt">flux</span> than estimated by these previous models. We present a new methodology allowing this crustal <span class="hlt">heat</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPT10081S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPT10081S"><span>Particle and <span class="hlt">heat</span> <span class="hlt">flux</span> estimates in Proto-MPEX in Helicon Mode with IR imaging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Showers, M. A.; Biewer, T. M.; Caughman, J. B. O.; Donovan, D. C.; Goulding, R. H.; Rapp, J.</p> <p>2016-10-01</p> <p>The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory (ORNL) is a linear plasma device developing the plasma source concept for the Material Plasma Exposure eXperiment (MPEX), which will address plasma material interaction (PMI) science for future fusion reactors. To better understand how and where energy is being lost from the Proto-MPEX plasma during ``helicon mode'' operations, particle and <span class="hlt">heat</span> <span class="hlt">fluxes</span> are quantified at multiple locations along the machine length. Relevant diagnostics include infrared (IR) cameras, four double Langmuir probes (LPs), and in-vessel thermocouples (TCs). The IR cameras provide temperature measurements of Proto-MPEX's plasma-facing dump and target plates, located on either end of the machine. The change in surface temperature is measured over the duration of the plasma shot to determine the <span class="hlt">heat</span> <span class="hlt">flux</span> hitting the plates. The IR cameras additionally provide 2-D thermal load distribution images of these plates, highlighting Proto-MPEX plasma behaviors, such as hot spots. The LPs and TCs provide additional plasma measurements required to determine particle and <span class="hlt">heat</span> <span class="hlt">fluxes</span>. Quantifying axial variations in <span class="hlt">fluxes</span> will help identify machine operating parameters that will improve Proto-MPEX's <span class="hlt">performance</span>, increasing its PMI research capabilities. This work was supported by the U.S. D.O.E. contract DE-AC05-00OR22725.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A33M..04H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A33M..04H"><span>An Analysis of Inter-annual Variability and Uncertainty of Continental Surface <span class="hlt">Heat</span> <span class="hlt">Fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, S. Y.; Deng, Y.; Wang, J.</p> <p>2016-12-01</p> <p>The inter-annual variability and the corresponding uncertainty of land surface <span class="hlt">heat</span> <span class="hlt">fluxes</span> during the first decade of the 21st century are re-evaluated at continental scale based on the <span class="hlt">heat</span> <span class="hlt">fluxes</span> estimated by the maximum entropy production (MEP) model. The MEP model predicted <span class="hlt">heat</span> <span class="hlt">fluxes</span> are constrained by surface radiation <span class="hlt">fluxes</span>, automatically satisfy surface energy balance, and are independent of temperature/moisture gradient, wind speed, and roughness lengths. The surface radiation <span class="hlt">fluxes</span> and temperature data from Clouds and the Earth's Radiant Energy System and the surface specific humidity data from Modern-Era Retrospective analysis for Research and Applications were used to reproduce the global surface <span class="hlt">heat</span> <span class="hlt">fluxes</span> with land-cover data from the NASA Energy and Water cycle Study (NEWS). Our analysis shows that the annual means of continental latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> have increasing trends associated with increasing trends in surface net radiative <span class="hlt">fluxes</span>. The sensible <span class="hlt">heat</span> <span class="hlt">fluxes</span> also have increasing trends over most continents except for South America. Ground <span class="hlt">heat</span> <span class="hlt">fluxes</span> have little trends. The continental-scale analysis of the MEP <span class="hlt">fluxes</span> are compared with other existing global surface <span class="hlt">fluxes</span> data products and the implications of the results for inter-annual to decadal variability of regional surface energy budget are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010086596&hterms=508&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D508','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010086596&hterms=508&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D508"><span>Coronal <span class="hlt">Heating</span> and the Magnetic <span class="hlt">Flux</span> Content of the Network</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.; Whitaker, Ann F. (Technical Monitor)</p> <p>2001-01-01</p> <p>Previously, from analysis of SOHO/EIT coronal images in combination with Kitt Peak magnetograms (Falconer et al 1998, ApJ, 501, 386-396), we found that the quiet corona is the sum of two components: the e-scale corona and the coronal network. The large-scale corona consists of all coronal-temperature (T approx. 10(exp 6) K) structures larger than supergranules (>approx.30,000 km). The coronal network (1) consists of all coronal-temperature structures smaller than supergranules, (2) is rooted in and loosely traces the photospheric magnetic network, (3) has its brightest features seated on polarity dividing fines (neutral lines) in the network magnetic <span class="hlt">flux</span>, and (4) produces only about 5% of the total coronal emission in quiet regions. The <span class="hlt">heating</span> of the coronal network is apparently magnetic in origin. Here, from analysis of EIT coronal images of quiet regions in combination with magnetograms of the same quiet regions from SOHO/MDI and from Kitt Peak, we examine the other 95% of the quiet corona and its relation to the underlying magnetic network. We find: (1) Dividing the large-scale corona into its bright and dim halves divides the area into bright "continents" and dark "oceans" having spans of 2-4 supergranules. (2) These patterns are also present in the photospheric magnetograms: the network is stronger under the bright half and weaker under the dim half. (3) The radiation from the large-scale corona increases roughly as the cube root of the magnetic <span class="hlt">flux</span> content of the underlying magnetic network. In contrast, Fisher et A (1998, ApJ, 508, 985-998) found that the coronal radiation from an active region increases roughly linearly with the magnetic <span class="hlt">flux</span> content of the active region. We assume, as is widely held, that nearly all of the large-scale corona is magnetically rooted in the network. Our results, together with the result of Fisher et al (1999), suggest that either the coronal <span class="hlt">heating</span> in quiet regions has a large non-magnetic component, or, if the <span class="hlt">heating</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUSM..SH31D06F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUSM..SH31D06F"><span>Coronal <span class="hlt">Heating</span> and the Magnetic <span class="hlt">Flux</span> Content of the Network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.</p> <p>2001-05-01</p> <p>Previously, from analysis of SOHO/EIT coronal images in combination with Kitt Peak magnetograms (Falconer et al 1998, ApJ, 501, 386-396), we found that the quiet corona is the sum of two components: the large-scale corona and the coronal network. The large-scale corona consists of all coronal-temperature ( million-degree) structures larger than the width of a chromospheric network lane (> 10,000 km). The coronal network (1) consists of all coronal-temperature structures of the scale of the network lanes and smaller (< 10,000 km), (2) is rooted in and loosely traces the photospheric magnetic network, (3) has its brightest features seated on polarity dividing lines (neutral lines) in the network magnetic <span class="hlt">flux</span>, and (4) produces only about 5% of the total coronal emission in quiet regions. The <span class="hlt">heating</span> of the coronal network is apparently magnetic in origin. Here, from analysis of EIT coronal images of quiet regions in combination with magnetograms of the same quiet regions from SOHO/MDI and from Kitt Peak, we examine the other 95% of the quiet corona and its relation to the underlying magnetic network. We find: (1) Dividing the large-scale corona into its bright and dim halves divides the area into bright "continents" and dark "oceans" having spans of 2-4 supergranules. (2) These patterns are also present in the photospheric magnetograms: the network is stronger under the bright half and weaker under the dim half. (3) The radiation from the large-scale corona increases roughly as the cube root of the magnetic <span class="hlt">flux</span> content of the underlying magnetic network. In contrast, Fisher et al (1998, ApJ, 508, 985-998) found that the coronal radiation from an active region increases roughly linearly with the magnetic <span class="hlt">flux</span> content of the active region. We assume, as is widely held, that nearly all of the large-scale corona is magnetically rooted in the network. Our results, together with the result of Fisher et al (1998), suggest that either the coronal <span class="hlt">heating</span> in quiet regions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003PhDT.........4E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003PhDT.........4E"><span>Hydrothermal <span class="hlt">fluxes</span> of solutes, carbon, and <span class="hlt">heat</span> to Himalayan rivers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evans, Matthew Jared</p> <p></p> <p>Hot springs flow along the base of the Himalayan front in the Narayani river basin of central Nepal. The springs flow near the Main Central Thrust (MCT), in a zone characterized by active uplift and high incision and erosion rates. Water-rock interaction at depth results in hydrothermal fluids with high solute loads. Himalayan rivers flowing through the zones of geothermal activity are enriched in cations, chloride, radiogenic strontium, and germanium. We use a comprehensive sample set of hot spring and river waters to asses the impact of the springs on the chemistry of the Narayani, and to investigate subsurface processes which control the hydrothermal fluid chemistry. Quantification of the hydrothermal <span class="hlt">fluxes</span> of solutes, carbon dioxide, and <span class="hlt">heat</span> to the surface depends on hot spring discharge. A chemical mass balance estimate using the high germanium concentrations in the springs yields hot spring discharge near 0.5% of the river discharge. The chemistry of the springs indicates that 12 to 100% of the total alkalinity in the springs is derived from silicates, and hot springs collectively deliver 20% of the silicate alkalinity in the Narayani. High germanium-silicon ratios in the springs can be modeled as a combination of thermodynamic equilibrium effects and Rayleigh fractionation during quartz precipitation. Active degassing and high dissolved carbon dioxide concentrations indicate that the springs are a source of CO2. High delta 13C values in the springs can be modeled with a metamorphic source and extensive sub-surface degassing. CO2 released during metamorphic decarbonation reactions is entrained in the meteoric water of the hydrothermal system. The CO2 <span class="hlt">flux</span> from the springs is comparable to the total uptake of CO2 by silicate weathering in the Narayani drainage, which suggests that the Himalayan orogen may be a net source of CO2 to the atmosphere. Hydrothermal <span class="hlt">heat</span> loss is near 745 +/- 313 megawatts. The high <span class="hlt">heat</span> <span class="hlt">flux</span> is the result of tectonic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910021158','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910021158"><span>A laser-induced <span class="hlt">heat</span> <span class="hlt">flux</span> technique for convective <span class="hlt">heat</span> transfer measurements in high speed flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.</p> <p>1991-01-01</p> <p>A technique is developed to measure the local convective <span class="hlt">heat</span> transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local <span class="hlt">heat</span> <span class="hlt">flux</span> at the model test surface, and an infrared camera system determines the local temperature distribution due to the <span class="hlt">heating</span>. From this temperature distribution and an analysis of the <span class="hlt">heating</span> process, a local convective <span class="hlt">heat</span> transfer coefficient is determined. The technique was used to measure the local surface convective <span class="hlt">heat</span> transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective <span class="hlt">heat</span> transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective <span class="hlt">heat</span> transfer coefficients in high speed flow fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920071694&hterms=heat+magidi&qs=Ntf%3DTitle%257Cheat%257Cmode%2Bmatchall%257C2%257C%257CAuthor-Name%257Cmagidi%257Cmode%2Bmatchall%257C2%26N%3D0%26No%3D60','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920071694&hterms=heat+magidi&qs=Ntf%3DTitle%257Cheat%257Cmode%2Bmatchall%257C2%257C%257CAuthor-Name%257Cmagidi%257Cmode%2Bmatchall%257C2%26N%3D0%26No%3D60"><span>A laser-induced <span class="hlt">heat</span> <span class="hlt">flux</span> technique for convective <span class="hlt">heat</span> transfer measurements in high speed flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.</p> <p>1991-01-01</p> <p>A technique is developed to measure the local convective <span class="hlt">heat</span> transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local <span class="hlt">heat</span> <span class="hlt">flux</span> at the model test surface, and an infrared camera system determines the local temperature distribution due to the <span class="hlt">heating</span>. From this temperature distribution and an analysis of the <span class="hlt">heating</span> process, a local convective <span class="hlt">heat</span> transfer coefficient is determined. The technique was used to measure the local surface convective <span class="hlt">heat</span> transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective <span class="hlt">heat</span> transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective <span class="hlt">heat</span> transfer coefficients in high-speed flowfields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920071694&hterms=convective+heat&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dconvective%2Bheat','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920071694&hterms=convective+heat&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dconvective%2Bheat"><span>A laser-induced <span class="hlt">heat</span> <span class="hlt">flux</span> technique for convective <span class="hlt">heat</span> transfer measurements in high speed flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.</p> <p>1991-01-01</p> <p>A technique is developed to measure the local convective <span class="hlt">heat</span> transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local <span class="hlt">heat</span> <span class="hlt">flux</span> at the model test surface, and an infrared camera system determines the local temperature distribution due to the <span class="hlt">heating</span>. From this temperature distribution and an analysis of the <span class="hlt">heating</span> process, a local convective <span class="hlt">heat</span> transfer coefficient is determined. The technique was used to measure the local surface convective <span class="hlt">heat</span> transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective <span class="hlt">heat</span> transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective <span class="hlt">heat</span> transfer coefficients in high-speed flowfields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70186946','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70186946"><span><span class="hlt">Heat</span> <span class="hlt">flux</span> from magmatic hydrothermal systems related to availability of fluid recharge</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Harvey, M. C.; Rowland, J.V.; Chiodini, G.; Rissmann, C.F.; Bloomberg, S.; Hernandez, P.A.; Mazot, A.; Viveiros, F.; Werner, Cynthia A.</p> <p>2015-01-01</p> <p>Magmatic hydrothermal systems are of increasing interest as a renewable energy source. Surface <span class="hlt">heat</span> <span class="hlt">flux</span> indicates system resource potential, and can be inferred from soil CO2 <span class="hlt">flux</span> measurements and fumarole gas chemistry. Here we compile and reanalyze results from previous CO2 <span class="hlt">flux</span> surveys worldwide to compare <span class="hlt">heat</span> <span class="hlt">flux</span> from a variety of magma-hydrothermal areas. We infer that availability of water to recharge magmatic hydrothermal systems is correlated with <span class="hlt">heat</span> <span class="hlt">flux</span>. Recharge availability is in turn governed by permeability, structure, lithology, rainfall, topography, and perhaps unsurprisingly, proximity to a large supply of water such as the ocean. The relationship between recharge and <span class="hlt">heat</span> <span class="hlt">flux</span> interpreted by this study is consistent with recent numerical modeling that relates hydrothermal system <span class="hlt">heat</span> output to rainfall catchment area. This result highlights the importance of recharge as a consideration when evaluating hydrothermal systems for electricity generation, and the utility of CO2 <span class="hlt">flux</span> as a resource evaluation tool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160009728','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160009728"><span>Hybrid <span class="hlt">Heat</span> Pipes for Lunar and Martian Surface and High <span class="hlt">Heat</span> <span class="hlt">Flux</span> Space Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ababneh, Mohammed T.; Tarau, Calin; Anderson, William G.; Farmer, Jeffery T.; Alvarez-Hernandez, Angel R.</p> <p>2016-01-01</p> <p>Novel hybrid wick <span class="hlt">heat</span> pipes are developed to operate against gravity on planetary surfaces, operate in space carrying power over long distances and act as thermosyphons on the planetary surface for Lunar and Martian landers and rovers. These hybrid <span class="hlt">heat</span> pipes will be capable of operating at the higher <span class="hlt">heat</span> <span class="hlt">flux</span> requirements expected in NASA's future spacecraft and on the next generation of polar rovers and equatorial landers. In addition, the sintered evaporator wicks mitigate the start-up problems in vertical gravity aided <span class="hlt">heat</span> pipes because of large number of nucleation sites in wicks which will allow easy boiling initiation. ACT, NASA Marshall Space Flight Center, and NASA Johnson Space Center, are working together on the Advanced Passive Thermal experiment (APTx) to test and validate the operation of a hybrid wick VCHP with warm reservoir and HiK"TM" plates in microgravity environment on the ISS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017HMT....53.2663X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017HMT....53.2663X"><span>Analytical study of flow and <span class="hlt">heat</span> transfer in an annular porous medium subject to asymmetrical <span class="hlt">heat</span> <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Huijin; Zhao, Changying; Vafai, Kambiz</p> <p>2017-08-01</p> <p>Fully developed forced convective <span class="hlt">heat</span> transfer in an annulus filled with a porous medium subject to asymmetrical <span class="hlt">heating</span> is investigated analytically with different models in this work. The classic Darcy and Brinkman models were employed for the fluid flow, while the local thermal equilibrium (LTE) and the local thermal non-equilibrium (LTNE) models were employed to describe the <span class="hlt">heat</span> transfer process in porous media. An analytical model based on fin theory was also employed for analyzing this problem. Exact solutions with Darcy-LTNE, Darcy-LTE, Brinkman-LTNE, Brinkman-LTE, and the fin models were obtained. Among these solutions, the Brinkman-LTNE solution can be treated as the benchmark, as it is a complete model, which covers the effect of viscous force near the solid wall and the temperature difference between the solid and fluid phases. The basic parameters that affect the velocity and temperature fields were analyzed in depth. The velocity and temperature profiles with these different models were also presented. The effects of some critical parameters on thermal <span class="hlt">performance</span> of asymmetrically <span class="hlt">heated</span> annulus fitted with a porous medium were discussed. The cited different analytical models were compared in detail with each other. The critical <span class="hlt">heat</span> <span class="hlt">flux</span> (HF) ratios for the inner and outer walls were presented in terms of a Nu- ξ curve for the five models. These solutions were developed for an asymmetrically <span class="hlt">heated</span> annular channel filled with a porous medium, which can predict the thermal <span class="hlt">performance</span> within a wide range of radii and HF ratios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100005642','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100005642"><span>Fabrication and Testing of a Thin-Film <span class="hlt">Heat</span> <span class="hlt">Flux</span> Sensor for a Stirling Convertor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, Scott D.; Fralick, Gus c.; Wrbanek, John D.; Sayir, Ali</p> <p>2010-01-01</p> <p>The NASA Glenn Research Center (GRC) has been testing high-efficiency free-piston Stirling convertors for potential use in radioisotope power systems since 1999. Stirling convertors are being operated for many years to demonstrate a radioisotope power system capable of providing reliable power for potential multiyear missions. Techniques used to monitor the convertors for change in <span class="hlt">performance</span> include measurements of temperature, pressure, energy addition, and energy rejection. Micro-porous bulk insulation is used in the Stirling convertor test setup to minimize the loss of thermal energy from the electric <span class="hlt">heat</span> source to the environment. The insulation is characterized before extended operation, enabling correlation of the net thermal energy addition to the convertor. Aging micro-porous bulk insulation changes insulation efficiency, introducing errors in the correlation for net thermal energy addition. A thin-film <span class="hlt">heat</span> <span class="hlt">flux</span> sensor was designed and fabricated to directly measure the net thermal energy addition to the Stirling convertor. The fabrication techniques include slipcasting and using Physical Vapor Deposition (PVD). One-micron-thick noble metal thermocouples measure temperature on the surface of an alumina ceramic disk and <span class="hlt">heat</span> <span class="hlt">flux</span> is calculated. Fabrication, integration, and test results of a thin-film <span class="hlt">heat</span> <span class="hlt">flux</span> sensor are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1038927','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1038927"><span><span class="hlt">Heat</span> <span class="hlt">Flux</span> Analysis of a Reacting Thermite Spray Impingent on a Substrate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Eric S. Collins; Michelle L. Pantoya; Michael A. Daniels; Daniel J. Prentice; Eric D. Steffler; Steven P. D'Arche</p> <p>2012-03-01</p> <p>Spray combustion from a thermite reaction is a new area of research relevant to localized energy generation applications, such as welding or cutting. In this study, we characterized the <span class="hlt">heat</span> <span class="hlt">flux</span> of combustion spray impinging on a target from a nozzle for three thermite mixtures. The reactions studied include aluminum (Al) with iron oxide (Fe2O3), Al with copper oxide (CuO), and Al with molybdenum oxide (MoO3). Several standoff distances (i.e., distance from the nozzle exit to the target) were analyzed. A fast response <span class="hlt">heat</span> <span class="hlt">flux</span> sensor was engineered for this purpose and is discussed in detail. Results correlated substrate damage to a threshold <span class="hlt">heat</span> <span class="hlt">flux</span> of 4550 W/cm2 for a fixed-nozzle configuration. Also, higher gas-generating thermites were shown to produce a widely dispersed spray and be less effective at imparting kinetic energy damage to a target. These results provide an understanding of the role of thermal and physical properties (i.e., such as <span class="hlt">heat</span> of combustion, gas generation, and particle size) on thermite spray combustion <span class="hlt">performance</span> measured by damaging a target substrate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120016444','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120016444"><span>Fabrication and Testing of a Thin-Film <span class="hlt">Heat</span> <span class="hlt">Flux</span> Sensor for a Stirling Convertor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, Scott D.; Fralick, Gustave; Wrbanek, John; Sayir, Ali</p> <p>2009-01-01</p> <p>The NASA Glenn Research Center (GRC) has been testing high efficiency free-piston Stirling convertors for potential use in radioisotope power systems since 1999. Stirling convertors are being operated for many years to demonstrate a radioisotope power system capable of providing reliable power for potential multi-year missions. Techniques used to monitor the convertors for change in <span class="hlt">performance</span> include measurements of temperature, pressure, energy addition, and energy rejection. Micro-porous bulk insulation is used in the Stirling convertor test set up to minimize the loss of thermal energy from the electric <span class="hlt">heat</span> source to the environment. The insulation is characterized before extended operation, enabling correlation of the net thermal energy addition to the convertor. Aging microporous bulk insulation changes insulation efficiency, introducing errors in the correlation for net thermal energy addition. A thin-mm <span class="hlt">heat</span> <span class="hlt">flux</span> sensor was designed and fabricated to directly measure the net thermal energy addition to the Stirling convertor. The fabrication techniques include slip casting and using Physical Vapor Deposition (PVD). One micron thick noble metal thermocouples measure temperature on the surface of an Alumina ceramic disc and <span class="hlt">heat</span> <span class="hlt">flux</span> is calculated. Fabrication, integration, and test results of a thin film <span class="hlt">heat</span> <span class="hlt">flux</span> sensor are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApPhL.108w3901B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApPhL.108w3901B"><span>Pool boiling with high <span class="hlt">heat</span> <span class="hlt">flux</span> enabled by a porous artery structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bai, Lizhan; Zhang, Lianpei; Lin, Guiping; Peterson, G. P.</p> <p>2016-06-01</p> <p>A porous artery structure utilizing the concept of "phase separation and modulation" is proposed to enhance the critical <span class="hlt">heat</span> <span class="hlt">flux</span> of pool boiling. A series of experiments were conducted on a range of test articles in which multiple rectangular arteries were machined directly into the top surface of a 10.0 mm diameter copper rod. The arteries were then covered by a 2.0 mm thickness microporous copper plate through silver brazing. The pool wall was fabricated from transparent Pyrex glass to allow a visualization study, and water was used as the working fluid. Experimental results confirmed that the porous artery structure provided individual flow paths for the liquid supply and vapor venting, and avoided the detrimental effects of the liquid/vapor counter flow. As a result, a maximum <span class="hlt">heat</span> <span class="hlt">flux</span> of 610 W/cm2 over a <span class="hlt">heating</span> area of 0.78 cm2 was achieved with no indication of dryout, prior to reaching the heater design temperature limit. Following the experimental tests, the mechanisms responsible for the boiling critical <span class="hlt">heat</span> <span class="hlt">flux</span> and <span class="hlt">performance</span> enhancement of the porous artery structure were analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JHyd..381..213C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JHyd..381..213C"><span>A comparison between latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> over grass using a weighing lysimeter and surface renewal analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castellví, F.; Snyder, R. L.</p> <p>2010-02-01</p> <p>SummaryAn experiment to study the <span class="hlt">performance</span> of the hourly sensible ( H) and latent <span class="hlt">heat</span> ( LE) estimates over grass using surface renewal, SR, analysis was carried out at the University of California West Side Field Station near Five Points (San Joaquin Valley, CA). Hourly eddy covariance, EC, and SR sensible <span class="hlt">heat</span> <span class="hlt">fluxes</span> were averaged from their respective half-hourly <span class="hlt">fluxes</span>. They were used to estimate hourly latent <span class="hlt">heat</span> <span class="hlt">flux</span>, LE, by calculating the residual of the energy balance equation, i.e., LE EC = R n - G - H EC and LE SR = R n - G - H SR, where R n is the net radiation; G is the soil <span class="hlt">heat</span> <span class="hlt">flux</span>; H is the buoyant sensible <span class="hlt">heat</span> <span class="hlt">flux</span> and the H subscripts denote measurements values from the EC and SR methods. Regardless of the weather conditions and time of day, H SR was comparable to H EC; especially from sunrise until the afternoon formation of a capping inversion due to regional advection of sensible <span class="hlt">heat</span> <span class="hlt">flux</span>. The main source of energy contributing to LE was ( R n - G). When ( R n - G) was positive, on average, H contributed to 9% of ( R n - G) when data were collected under unstable conditions, but it accounted for 21% under stable conditions . In general, correlation between measured LE using a weighing lysimeter, LE Lys, and LE SR was R2 = 0.97 which was substantially higher than between LE Lys and ( R n - G), R2 = 0.93. In principle, the observed <span class="hlt">performance</span> can be extrapolated to all irrigated, short, and dense-canopy vegetation that is mostly decoupled from the environment. Because for these surfaces the zero-plane displacement and the aerodynamic surface roughness length can be estimated as a portion (about 0.7 and 0.12, respectively) of the canopy height, using a two dimensional sonic anemometer capable to record high-frequency sonic temperature provides all the input to determine H SR which in conjunction with ( R n - G) is required to estimate LE.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSP...tmp...37G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSP...tmp...37G"><span><span class="hlt">Heat</span> <span class="hlt">Flux</span> for a Relativistic Dilute Bidimensional Gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>García-Perciante, A. L.; Méndez, A. R.; Escobar-Aguilar, E.</p> <p>2017-02-01</p> <p>Relativistic kinetic theory predicts substantial modifications to the dissipation mechanisms of a dilute gas. For the <span class="hlt">heat</span> <span class="hlt">flux</span>, these include (in the absence of external forces) a correction to the thermal conductivity and the appearance of a new, purely relativistic, term proportional to the density gradient. In this work we obtain such constitutive equation for the particular case of a bidimensional gas. The calculation is based on the Chapman-Enskog solution to the relativistic Boltzmann equation and yields analytical expressions for the corresponding transport coefficients, which are evaluated for the particular case of hard disks. These results will be useful for numerical simulations and may be applied to bidimensional non-dense materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023942','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023942"><span>Wedge <span class="hlt">Heat-Flux</span> Indicators for Flash Thermography</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koshti, Ajay M.</p> <p>2003-01-01</p> <p>Wedge indicators have been proposed for measuring thermal radiation that impinges on specimens illuminated by flash lamps for thermographic inspection. <span class="hlt">Heat</span> <span class="hlt">fluxes</span> measured by use of these indicators would be used, along with known thermal, radiative, and geometric properties of the specimens, to estimate peak flash temperatures on the specimen surfaces. These indicators would be inexpensive alternatives to high-speed infrared pyrometers, which would otherwise be needed for measuring peak flash surface temperatures. The wedge is made from any suitable homogenous material such as plastic. The choice of material is governed by the equation given. One side of the wedge is covered by a temperature sensitive compound that decomposes irreversibly when its temperature exceeds a rated temperature (T-rated). The uncoated side would be positioned alongside or in place of the specimen and exposed to the flash, then the wedge thickness at the boundary between the white and blackened portions measured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSP...167..123G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSP...167..123G"><span><span class="hlt">Heat</span> <span class="hlt">Flux</span> for a Relativistic Dilute Bidimensional Gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>García-Perciante, A. L.; Méndez, A. R.; Escobar-Aguilar, E.</p> <p>2017-04-01</p> <p>Relativistic kinetic theory predicts substantial modifications to the dissipation mechanisms of a dilute gas. For the <span class="hlt">heat</span> <span class="hlt">flux</span>, these include (in the absence of external forces) a correction to the thermal conductivity and the appearance of a new, purely relativistic, term proportional to the density gradient. In this work we obtain such constitutive equation for the particular case of a bidimensional gas. The calculation is based on the Chapman-Enskog solution to the relativistic Boltzmann equation and yields analytical expressions for the corresponding transport coefficients, which are evaluated for the particular case of hard disks. These results will be useful for numerical simulations and may be applied to bidimensional non-dense materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860002035','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860002035"><span>Development of <span class="hlt">heat</span> <span class="hlt">flux</span> sensors for turbine airfoils and combustor liners</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Atkinson, W. H.</p> <p>1983-01-01</p> <p>The design of durable turbine airfoils that use a minimum amount of cooling air requires knowledge of the <span class="hlt">heat</span> loads on the airfoils during engine operation. Measurement of these <span class="hlt">heat</span> loads will permit the verification or modification of the analytical models used in the design process and will improve the ability to predict and confirm the thermal <span class="hlt">performance</span> of turbine airfoil designs. <span class="hlt">Heat</span> <span class="hlt">flux</span> sensors for turbine blades and vanes must be compatible with the cast nickel-base and cobalt-base materials used in their fabrication and will need to operate in a hostile environment with regard to temperature, pressure and thermal cycling. There is also a need to miniaturize the sensors to obtain measurements without perturbing the <span class="hlt">heat</span> flows that are to be measured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983tehs.nasa...45A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983tehs.nasa...45A"><span>Development of <span class="hlt">heat</span> <span class="hlt">flux</span> sensors for turbine airfoils and combustor liners</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Atkinson, W. H.</p> <p>1983-10-01</p> <p>The design of durable turbine airfoils that use a minimum amount of cooling air requires knowledge of the <span class="hlt">heat</span> loads on the airfoils during engine operation. Measurement of these <span class="hlt">heat</span> loads will permit the verification or modification of the analytical models used in the design process and will improve the ability to predict and confirm the thermal <span class="hlt">performance</span> of turbine airfoil designs. <span class="hlt">Heat</span> <span class="hlt">flux</span> sensors for turbine blades and vanes must be compatible with the cast nickel-base and cobalt-base materials used in their fabrication and will need to operate in a hostile environment with regard to temperature, pressure and thermal cycling. There is also a need to miniaturize the sensors to obtain measurements without perturbing the <span class="hlt">heat</span> flows that are to be measured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770004397','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770004397"><span>Investigation of <span class="hlt">performance</span> limits in axial groove <span class="hlt">heat</span> pipes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Feldman, K. T.</p> <p>1976-01-01</p> <p>The entrainment-shear <span class="hlt">performance</span> limit which occurs in axial groove <span class="hlt">heat</span> pipes was investigated and explained. In the existing <span class="hlt">heat</span> pipe literature the entrainment <span class="hlt">heat</span> <span class="hlt">flux</span> limit is defined as the condition where the Weber number is greater than or equal to one. In this analysis, the critical value for the entrainment Weber number is found to be 2 pi less than or equal to 3 pi. Perhaps more important to the <span class="hlt">heat</span> pipe designer than the entrainment <span class="hlt">performance</span> limit is the prediction of the <span class="hlt">performance</span> degradation due to vapor-liquid shearing stress which is also described. Preliminary qualitative experiments were conducted to observe the shear. stress wave formation phenomena. The equations presented may be used to predict and minimize the vapor-liquid shear stress <span class="hlt">performance</span> effects that occur in axial groove and puddle flow artery <span class="hlt">heat</span> pipes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPS...285..266D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPS...285..266D"><span><span class="hlt">Heat</span> generation rate measurement in a Li-ion cell at large C-rates through temperature and <span class="hlt">heat</span> <span class="hlt">flux</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drake, S. J.; Martin, M.; Wetz, D. A.; Ostanek, J. K.; Miller, S. P.; Heinzel, J. M.; Jain, A.</p> <p>2015-07-01</p> <p>Understanding the rate of <span class="hlt">heat</span> generation in a Li-ion cell is critical for safety and <span class="hlt">performance</span> of Li-ion cells and systems. Cell <span class="hlt">performance</span>, cycle life, and system safety all depend on temperature distribution in the cell, which, in turn, depends on <span class="hlt">heat</span> generation rate within the cell and on <span class="hlt">heat</span> removal rate at the cell surface. Despite the existence of a number of theoretical models to predict <span class="hlt">heat</span> generation rate, there is not much literature on experimental measurement at high C-rates. This paper reports measurement of <span class="hlt">heat</span> generation rate from a Li-ion cell at high discharge rates, up to 9.6C, using measurements of cell temperature and surface <span class="hlt">heat</span> <span class="hlt">flux</span>. As opposed to calorimetry-based approaches, this method can be applied in situ to yield measurements of <span class="hlt">heat</span> generation rate in laboratory or field use provided that at least one a priori test is <span class="hlt">performed</span> to measure the temperature gradient within a cell in the same ambient condition. This method is based on simultaneous determination of <span class="hlt">heat</span> stored and <span class="hlt">heat</span> lost from the cell through <span class="hlt">heat</span> <span class="hlt">flux</span> and temperature measurements. A novel method is established for measurement of the internal temperature of the cell. <span class="hlt">Heat</span> generation measurements are shown to agree with well-established theoretical models. The effect of actively cooling the cell is briefly discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27967089','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27967089"><span>Local momentum and <span class="hlt">heat</span> <span class="hlt">fluxes</span> in transient transport processes and inhomogeneous systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Youping; Diaz, Adrian</p> <p>2016-11-01</p> <p>This work examines existing formalisms for the derivation of microscopic momentum and <span class="hlt">heat</span> <span class="hlt">fluxes</span>. Both analytical and simulation results are provided to show that the widely used <span class="hlt">flux</span> formulas are not applicable to transient transport processes or highly inhomogeneous systems, e.g., materials with atomically sharp interfaces. A method is formulated for formally deriving microscopic momentum and <span class="hlt">heat</span> <span class="hlt">fluxes</span> through the integral representation of conservation laws. The resulting <span class="hlt">flux</span> formulas are mathematically rigorous, fully consistent with the physical concepts of momentum and <span class="hlt">heat</span> <span class="hlt">fluxes</span>, and applicable to nonequilibrium transient processes in atomically inhomogeneous systems with general many-body forces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvE..94e3309C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvE..94e3309C"><span>Local momentum and <span class="hlt">heat</span> <span class="hlt">fluxes</span> in transient transport processes and inhomogeneous systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Youping; Diaz, Adrian</p> <p>2016-11-01</p> <p>This work examines existing formalisms for the derivation of microscopic momentum and <span class="hlt">heat</span> <span class="hlt">fluxes</span>. Both analytical and simulation results are provided to show that the widely used <span class="hlt">flux</span> formulas are not applicable to transient transport processes or highly inhomogeneous systems, e.g., materials with atomically sharp interfaces. A method is formulated for formally deriving microscopic momentum and <span class="hlt">heat</span> <span class="hlt">fluxes</span> through the integral representation of conservation laws. The resulting <span class="hlt">flux</span> formulas are mathematically rigorous, fully consistent with the physical concepts of momentum and <span class="hlt">heat</span> <span class="hlt">fluxes</span>, and applicable to nonequilibrium transient processes in atomically inhomogeneous systems with general many-body forces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1005030','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1005030"><span>Description of <span class="hlt">heat</span> <span class="hlt">flux</span> measurement methods used in hydrocarbon and propellant fuel fires at Sandia.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nakos, James Thomas</p> <p>2010-12-01</p> <p>The purpose of this report is to describe the methods commonly used to measure <span class="hlt">heat</span> <span class="hlt">flux</span> in fire applications at Sandia National Laboratories in both hydrocarbon (JP-8 jet fuel, diesel fuel, etc.) and propellant fires. Because these environments are very severe, many commercially available <span class="hlt">heat</span> <span class="hlt">flux</span> gauges do not survive the test, so alternative methods had to be developed. Specially built sensors include 'calorimeters' that use a temperature measurement to infer <span class="hlt">heat</span> <span class="hlt">flux</span> by use of a model (<span class="hlt">heat</span> balance on the sensing surface) or by using an inverse <span class="hlt">heat</span> conduction method. These specialty-built sensors are made rugged so they will survive the environment, so are not optimally designed for ease of use or accuracy. Other methods include radiometers, co-axial thermocouples, directional flame thermometers (DFTs), Sandia '<span class="hlt">heat</span> <span class="hlt">flux</span> gauges', transpiration radiometers, and transverse Seebeck coefficient <span class="hlt">heat</span> <span class="hlt">flux</span> gauges. Typical applications are described and pros and cons of each method are listed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B21A0443S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B21A0443S"><span>Eddy covariance measurement of carbon, latent and sensible <span class="hlt">heat</span> <span class="hlt">fluxes</span> from western Lake Erie</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shao, C.; Chen, J.; Stepien, C.; Bridgeman, T.; Czajkowski, K. P.; Becker, R.; Chu, H.; yang, Z.</p> <p>2013-12-01</p> <p>Long-term measurements of sensible and latent <span class="hlt">heat</span> and carbon dioxide <span class="hlt">fluxes</span> were <span class="hlt">performed</span> over a boreal lake in northern American using the direct micrometeorological eddy covariance (EC) technique. Two permanent EC <span class="hlt">flux</span> stations in western Lake Erie - Crib (41.7167N, 83.2667W, nearest distance from shore is 4.5 km) and Light (41.8314N, 83.2006W, nearest distance from shore > 12 km) sites have been operating since September, 2011. In 2012, in both sites, the sensible <span class="hlt">heat</span> <span class="hlt">flux</span> had its minimum in the afternoon (15:00-17:00) and peaked in the early morning (7:00-9:00) in August-November, varied from -4 W m-2 to +30 W m-2. The diurnal amplitude of H was largest in spring and in early fall (30 W m-2 in September) whereas it was smaller in July and August (20 W m-2). The latent <span class="hlt">heat</span> <span class="hlt">flux</span> had obvious seasonal pattern in both sites with higher values in the summer, while it did not show obvious daily courses, even did not have the day and night variation in both sites, only one trend from June to October was higher at night than during the daytime in Light site. The maximum latent <span class="hlt">heat</span> of ~180 W m-2 in summer whereas the minimum -10 W m-2 in winter were observed. The latent <span class="hlt">heat</span> <span class="hlt">flux</span> dominated clearly over the sensible <span class="hlt">heat</span> in spring and summer; that is, the Bowen ratio was less than 1 and most of the energy absorbed by the water was consumed in terms of evapotranspiration. A lookup table method was <span class="hlt">performed</span> data gap-filling in our aquatic ecosystems in order to obtain the continuously daily, monthly and yearly carbon and water budgets. In 2012, for the annual cumulative total, the evapotranspiration was 820 and 700 mm (about 2000 and 1700 MJ m-2) in Crib and Light sites, respectively, comparing with the annual rainfall of 700 mm. The annual sensible <span class="hlt">heat</span> was 480 and 300 MJ m-2 in Crib and Light sites, respectively. And there were four and five CO2 uptake months in Crib and Light sites, respectively. The maximum CO2 uptake month was in July in both sites, with -28 and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994PhDT........43L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PhDT........43L"><span>Effect of Particle Size Distribution on Wall <span class="hlt">Heat</span> <span class="hlt">Flux</span> in Pulverized-Coal Furnaces and Boilers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, Jun</p> <p></p> <p>A mathematical model of combustion and <span class="hlt">heat</span> transfer within a cylindrical enclosure firing pulverized coal has been developed and tested against two sets of measured data (one is 1993 WSU/DECO Pilot test data, the other one is the International Flame Research Foundation 1964 Test (Beer, 1964)) and one independent code FURN3D from the Argonne National Laboratory (Ahluwalia and IM, 1992). The model called PILC assumes that the system is a sequence of many well-stirred reactors. A char burnout model combining diffusion to the particle surface, pore diffusion, and surface reaction is employed for predicting the char reaction, <span class="hlt">heat</span> release, and evolution of char. The ash formation model included relates the ash particle size distribution to the particle size distribution of pulverized coal. The optical constants of char and ash particles are calculated from dispersion relations derived from reflectivity, transmissivity and extinction measurements. The Mie theory is applied to determine the extinction and scattering coefficients. The radiation <span class="hlt">heat</span> transfer is modeled using the virtual zone method, which leads to a set of simultaneous nonlinear algebraic equations for the temperature field within the furnace and on its walls. This enables the <span class="hlt">heat</span> <span class="hlt">fluxes</span> to be evaluated. In comparisons with the experimental data and one independent code, the model is successful in predicting gas temperature, wall temperature, and wall radiative <span class="hlt">flux</span>. When the coal with greater fineness is burnt, the particle size of pulverized coal has a consistent influence on combustion <span class="hlt">performance</span>: the temperature peak was higher and nearer to burner, the radiation <span class="hlt">flux</span> to combustor wall increased, and also the absorption and scattering coefficients of the combustion products increased. The effect of coal particle size distribution on absorption and scattering coefficients and wall <span class="hlt">heat</span> <span class="hlt">flux</span> is significant. But there is only a small effect on gas temperature and fuel fraction burned; it is speculated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.4569M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.4569M"><span>Mixing rates and vertical <span class="hlt">heat</span> <span class="hlt">fluxes</span> north of Svalbard from Arctic winter to spring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, Amelie; Fer, Ilker; Sundfjord, Arild; Peterson, Algot K.</p> <p>2017-06-01</p> <p>Mixing and <span class="hlt">heat</span> <span class="hlt">flux</span> rates collected in the Eurasian Basin north of Svalbard during the N-ICE2015 drift expedition are presented. The observations cover the deep Nansen Basin, the Svalbard continental slope, and the shallow Yermak Plateau from winter to summer. Mean quiescent winter <span class="hlt">heat</span> <span class="hlt">flux</span> values in the Nansen Basin are 2 W m-2 at the ice-ocean interface, 3 W m-2 in the pycnocline, and 1 W m-2 below the pycnocline. Large <span class="hlt">heat</span> <span class="hlt">fluxes</span> exceeding 300 W m-2 are observed in the late spring close to the surface over the Yermak Plateau. The data consisting of 588 microstructure profiles and 50 days of high-resolution under-ice turbulence measurements are used to quantify the impact of several forcing factors on turbulent dissipation and <span class="hlt">heat</span> <span class="hlt">flux</span> rates. Wind forcing increases turbulent dissipation seven times in the upper 50 m, and doubles <span class="hlt">heat</span> <span class="hlt">fluxes</span> at the ice-ocean interface. The presence of warm Atlantic Water close to the surface increases the temperature gradient in the water column, leading to enhanced <span class="hlt">heat</span> <span class="hlt">flux</span> rates within the pycnocline. Steep topography consistently enhances dissipation rates by a factor of four and episodically increases <span class="hlt">heat</span> <span class="hlt">flux</span> at depth. It is, however, the combination of storms and shallow Atlantic Water that leads to the highest <span class="hlt">heat</span> <span class="hlt">flux</span> rates observed: ice-ocean interface <span class="hlt">heat</span> <span class="hlt">fluxes</span> average 100 W m-2 during peak events and are associated with rapid basal sea ice melt, reaching 25 cm/d.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/868695','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/868695"><span>Quantitative method for measuring <span class="hlt">heat</span> <span class="hlt">flux</span> emitted from a cryogenic object</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Duncan, Robert V.</p> <p>1993-01-01</p> <p>The present invention is a quantitative method for measuring the total <span class="hlt">heat</span> <span class="hlt">flux</span>, and of deriving the total power dissipation, of a <span class="hlt">heat-fluxing</span> object which includes the steps of placing an electrical noise-emitting <span class="hlt">heat-fluxing</span> object in a liquid helium bath and measuring the superfluid transition temperature of the bath. The temperature of the liquid helium bath is thereafter reduced until some measurable parameter, such as the electrical noise, exhibited by the <span class="hlt">heat-fluxing</span> object or a temperature-dependent resistive thin film in intimate contact with the <span class="hlt">heat-fluxing</span> object, becomes greatly reduced. The temperature of the liquid helum bath is measured at this point. The difference between the superfluid transition temperature of the liquid helium bath surrounding the <span class="hlt">heat-fluxing</span> object, and the temperature of the liquid helium bath when the electrical noise emitted by the <span class="hlt">heat-fluxing</span> object becomes greatly reduced, is determined. The total <span class="hlt">heat</span> <span class="hlt">flux</span> from the <span class="hlt">heat-fluxing</span> object is determined as a function of this difference between these temperatures. In certain applications, the technique can be used to optimize thermal design parameters of cryogenic electronics, for example, Josephson junction and infra-red sensing devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6278578','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/6278578"><span>Quantitative method for measuring <span class="hlt">heat</span> <span class="hlt">flux</span> emitted from a cryogenic object</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Duncan, R.V.</p> <p>1993-03-16</p> <p>The present invention is a quantitative method for measuring the total <span class="hlt">heat</span> <span class="hlt">flux</span>, and of deriving the total power dissipation, of a <span class="hlt">heat-fluxing</span> object which includes the steps of placing an electrical noise-emitting <span class="hlt">heat-fluxing</span> object in a liquid helium bath and measuring the superfluid transition temperature of the bath. The temperature of the liquid helium bath is thereafter reduced until some measurable parameter, such as the electrical noise, exhibited by the <span class="hlt">heat-fluxing</span> object or a temperature-dependent resistive thin film in intimate contact with the <span class="hlt">heat-fluxing</span> object, becomes greatly reduced. The temperature of the liquid helum bath is measured at this point. The difference between the superfluid transition temperature of the liquid helium bath surrounding the <span class="hlt">heat-fluxing</span> object, and the temperature of the liquid helium bath when the electrical noise emitted by the <span class="hlt">heat-fluxing</span> object becomes greatly reduced, is determined. The total <span class="hlt">heat</span> <span class="hlt">flux</span> from the <span class="hlt">heat-fluxing</span> object is determined as a function of this difference between these temperatures. In certain applications, the technique can be used to optimize thermal design parameters of cryogenic electronics, for example, Josephson junction and infrared sensing devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H32B..01P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H32B..01P"><span>Ground <span class="hlt">Heat</span> <span class="hlt">Flux</span> Estimation: What's the Best Approach?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Purdy, A. J.; Fisher, J. B.; Famiglietti, J. S.</p> <p>2015-12-01</p> <p>Ground <span class="hlt">heat</span> <span class="hlt">flux</span> (G) is typically the smallest term of the surface energy balance (i.e., Rn=LE+H+G), but high uncertainty in G means that evaluation of the other terms remains problematic. There has been a large range of approaches to estimating G for large-scale applications, with a subsequent wide range of accuracies/errors. We provide the largest review of these approaches to date (n=10), evaluating modeled G against measured G from 78 FLUXNET sites. Empirical relationships constrained by vegetation indices and Rn better capture daily variability of instantaneous G, while a physically based <span class="hlt">heat</span> transfer model exhibits lower bias and error across all sites. Global relationships calibrated to in situ measurements also reveal low bias and error in addition to capturing the variability comparable to the other empirical relationships. We produced global decadal datasets of G for all models to illustrate regional sensitivities by model. This work has potential to improve energy balance estimates of LE and provides a new dataset to assimilate into or assess land surface models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002APS..DFD.DL007H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002APS..DFD.DL007H"><span>Critical <span class="hlt">Heat</span> <span class="hlt">Flux</span> in a Thin Annular Channel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Habtour, Ahmed; Anderson, Elgin</p> <p>2002-11-01</p> <p>The improved accuracy in predicting critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) for specific reactor core geometry would allow for increased power output. The objectives of this project were to incorporate a scale model test to determine the feasibility of generating high power density in an annular fuel arrangement in a reactor. The desired power density was 100W/cm2. This would be accomplished by using resistive <span class="hlt">heating</span> on the outer cylinder of an annular flow channel between concentric cylinders. The inner cylinder consists of a hemispherical shape in the upstream direction to condition the flow. The second objective was to study the behavior of two-phase flow through a simulated reactor core. The CHF would be measured and compared with existing correlations. Finally, the concept of a future full scale testing would be investigated. The results of this project are not only applicable to nuclear reactors, but can be used to increase the efficiency of other applications such as fuel cells, combustion engines, turbines and polymer processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/910809','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/910809"><span>Critical <span class="hlt">Heat</span> <span class="hlt">Flux</span> in Inclined Rectangular Narrow Gaps</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jeong J. Kim; Yong H. Kim; Seong J. Kim; Sang W. Noh; Kune Y. Suh; Joy L. Rempe; Fan-Bill Cheung; Sang B. Kim</p> <p>2004-06-01</p> <p>In light of the TMI-2 accident, in which the reactor vessel lower head survived the attack by molten core material, the in-vessel retention strategy was suggested to benefit from cooling the debris through a gap between the lower head and the core material. The GAMMA 1D (Gap Apparatus Mitigating Melt Attack One Dimensional) tests were conducted to investigate the critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) in narrow gaps with varying surface orientations. The CHF in an inclined gap, especially in case of the downward-facing narrow gap, is dictated by bubble behavior because the departing bubbles are squeezed. The orientation angle affects the bubble layer and escape of the bubbles from the narrow gap. The test parameters include gap sizes of 1, 2, 5 and 10 mm and the open periphery, and the orientation angles range from the fully downward-facing (180o) to the vertical (90o) position. The 15 ×35 mm copper test section was electrically <span class="hlt">heated</span> by the thin film resistor on the back. The heater assembly was installed to the tip of the rotating arm in the <span class="hlt">heated</span> water pool at the atmospheric pressure. The bubble behavior was photographed utilizing a high-speed camera through the Pyrex glass spacer. It was observed that the CHF decreased as the surface inclination angle increased and as the gap size decreased in most of the cases. However, the opposing results were obtained at certain surface orientations and gap sizes. Transition angles, at which the CHF changed in a rapid slope, were also detected, which is consistent with the existing literature. A semi-empirical CHF correlation was developed for the inclined narrow rectangular channels through dimensional analysis. The correlation provides with best-estimate CHF values for realistically assessing the thermal margin to failure of the lower head during a severe accident involving relocation of the core material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993SPIE.1997...29L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993SPIE.1997...29L"><span>Liquid jet impingement cooling with diamond substrates for extremely high <span class="hlt">heat</span> <span class="hlt">flux</span> applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lienhard V, John H.; Khounsary, Ali M.</p> <p>1993-11-01</p> <p>This paper considers the potential of jet/diamond systems for removing localized high <span class="hlt">heat</span> <span class="hlt">fluxes</span>. Diamond substrates are compared to other candidate materials. Limits on usable thermal resistances and <span class="hlt">heat</span> transfer rates are estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/911078','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/911078"><span>Correlations of Nucleate Boiling <span class="hlt">Heat</span> Transfer and Critical <span class="hlt">Heat</span> <span class="hlt">Flux</span> for External Reactor Vessel Cooling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>J. Yang; F. B. Cheung; J. L. Rempe; K. Y. Suh; S. B. Kim</p> <p>2005-07-01</p> <p>Four types of steady-state boiling experiments were conducted to investigate the efficacy of two distinctly different <span class="hlt">heat</span> transfer enhancement methods for external reactor vessel cooling under severe accident conditions. One method involved the use of a thin vessel coating and the other involved the use of an enhanced insulation structure. By comparing the results obtained in the four types of experiments, the separate and integral effect of vessel coating and insulation structure were determined. Correlation equations were obtained for the nucleate boiling <span class="hlt">heat</span> transfer and the critical <span class="hlt">heat</span> <span class="hlt">flux</span>. It was found that both enhancement methods were quite effective. Depending on the angular location, the local critical <span class="hlt">heat</span> <span class="hlt">flux</span> could be enhanced by 1.4 to 2.5 times using vessel coating alone whereas it could be enhanced by 1.8 to 3.0 times using an enhanced insulation structure alone. When both vessel coating and insulation structure were used simultaneously, the integral effect on the enhancement was found much less than the product of the two separate effects, indicating possible competing mechanisms (i.e., interference) between the two enhancement methods.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JEPT...85.1179S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JEPT...85.1179S"><span>Magnetogasdynamic shock waves in a nonideal gas with <span class="hlt">heat</span> conduction and radiation <span class="hlt">heat</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, K. K.; Nath, B.</p> <p>2012-09-01</p> <p>The purpose of this study is to obtain a self-similar solution of the problem of propagation of a magnetogasdynamic shock wave in a nonideal gas with <span class="hlt">heat</span> conduction and radiation <span class="hlt">heat</span> <span class="hlt">flux</span> in the presence of a spatially decreasing azimuthal magnetic field strength. The initial density of the medium is assumed to be constant. The <span class="hlt">heat</span> conduction is expressed in terms of Fourier's law, and the radiation is considered to be of a diffusion type for an optically thick gray gas model. The thermal conductivity and absorption coefficients are assumed to vary with temperature and density. The shock is assumed to be driven by a piston moving with a variable velocity. Similarity solutions are obtained, and the effects of variation of the gas nonidealness parameter and Alfven-Mach number on the flow field behind the shock are investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016amsf.conf..307A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016amsf.conf..307A"><span>Cold-Finger Measurement of <span class="hlt">Heat</span> Transfer Through Solidified Mold <span class="hlt">Flux</span> Layers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Assis, Karina Lara Santos; Pistorius, P. Chris</p> <p></p> <p>The thermal resistance between the cast strand and the copper mold in continuous casting is dominated by the conduction resistance through the partially solidified mold <span class="hlt">flux</span> layer and the contact resistance between the solidified mold <span class="hlt">flux</span> and the mold. In the cold-finger approach, a freeze layer of mold <span class="hlt">flux</span> is grown on a water-cooled probe immersed in molten <span class="hlt">flux</span>. In principle, the thickness of the solid layer and the steady-state <span class="hlt">heat</span> <span class="hlt">flux</span> can be used to estimate conductivity and contact resistance. Lower-basicity <span class="hlt">fluxes</span> generally give somewhat lower <span class="hlt">heat</span> <span class="hlt">fluxes</span> under these conditions and result in formation of glassy films. Glassy films are generally significantly thinner than crystalline films, because of the higher thermal conductivity of crystalline films. A potential approach to estimate thermal conductivity and contact resistance from transient changes in solid film thickness and <span class="hlt">heat</span> <span class="hlt">flux</span> is outlined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T31A0489T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T31A0489T"><span><span class="hlt">Heat</span> <span class="hlt">Flux</span> From the Endeavour Segment of the Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thompson, W. J.; McDuff, R. E.; Stahr, F. R.; Yoerger, D. R.; Jakuba, M.</p> <p>2005-12-01</p> <p>The very essence of a hydrothermal system is transfer of <span class="hlt">heat</span> by a convecting fluid, yet the <span class="hlt">flux</span> of <span class="hlt">heat</span> remains a poorly known quantity. Past studies of <span class="hlt">heat</span> <span class="hlt">flux</span> consisted primarily of point measurements of temperature and fluid flow at individual vent sites and inventories of the neutrally buoyant plume above the field. In 2000 the Flow Mow project used the Autonomous Benthic Explorer (ABE) to determine <span class="hlt">heat</span> <span class="hlt">flux</span> from Main Endeavour Field (MEF) on the Juan de Fuca Ridge by intersecting the stems of rising buoyant plumes. ABE carries instruments to measure conductivity, temperature and depth, and a MAVS current meter to determine the vertical velocity of the fluid, after correcting for vehicle motion. Complementary work on horizontal <span class="hlt">fluxes</span> suggests that the vertical <span class="hlt">flux</span> measured by ABE includes both the primary high buoyancy focused "smoker" sources and also entrained diffuse flow. In 2004, ABE was again used to determine <span class="hlt">heat</span> <span class="hlt">flux</span> not only from MEF, but also from the other four fields in the Endeavour Segment RIDGE 2000 Integrated Study Site. In this four year interval the <span class="hlt">flux</span> of <span class="hlt">heat</span> from MEF has declined by approximately a factor of two. The High Rise vent field has the greatest <span class="hlt">heat</span> <span class="hlt">flux</span>, followed by MEF, then Mothra, Salty Dawg and Sasquatch (of order 500, 300, 100, 50 MW respectively; <span class="hlt">heat</span> <span class="hlt">flux</span> at Sasquatch was below detection).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MsT..........5O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MsT..........5O"><span>Two-phase spray cooling with water/2-propanol binary mixtures for high <span class="hlt">heat</span> <span class="hlt">flux</span> focal source</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Obuladinne, Sai Sujith</p> <p></p> <p>Two-phase spray cooling has been an emerging thermal management technique offering high <span class="hlt">heat</span> transfer coefficients and critical <span class="hlt">heat</span> <span class="hlt">flux</span> levels, near-uniform surface temperatures, and efficient coolant usage that enables to design of compact and lightweight systems. Due to these capabilities, spray cooling is a promising approach for high <span class="hlt">heat</span> <span class="hlt">flux</span> applications in computing, power electronics, and optics. Two-phase spray cooling inherently depends on saturation temperature-pressure relationships of the working fluid to take advantage of high <span class="hlt">heat</span> transfer rates associated with liquid-vapor phase change. When a certain application requires strict temperature and/or pressure conditions, thermo-physical properties of the working fluid play a critical role in attaining proper efficiency, reliability, or packaging structure. However, some of the commonly used single-component working fluids have relatively poor properties and <span class="hlt">heat</span> transfer <span class="hlt">performance</span>. For example, water is the best coolant in terms of properties, yet in certain applications where the system operates at low temperature ambient, it cannot be implemented due to freezing risk. The common solution for this problem is to use the antifreeze mixtures (binary mixtures of water and alcohol) to reduce the freezing point. In such cases, utilizing binary mixtures to tune working fluid properties becomes an alternative approach. This study has two main objectives; (1) to experimentally investigate the two-phase spray cooling <span class="hlt">performance</span> of water/2-propanol binary mixture, and (2) to numerically investigate the <span class="hlt">performance</span> of an advanced <span class="hlt">heat</span> spreader featuring high and directional thermal conductivity materials for high <span class="hlt">heat</span> <span class="hlt">flux</span> focal sources. The first part of the study involves experimental characterization of <span class="hlt">heat</span> transfer <span class="hlt">performance</span>. Tests are conducted on a small-scale, closed loop spray cooling system featuring a pressure atomized spray nozzle. The test section, made of copper, measures 10 mm x 10 mm x 2 mm</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/455366','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/455366"><span>The effects of radiant barriers on ceiling <span class="hlt">heat</span> <span class="hlt">flux</span> and energy usage</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McGovern, K.T.; Beasley, D.E.</p> <p>1995-12-31</p> <p>In this study a gable ventilation system was installed in an experimental facility to determine the effects of ventilation type on radiant barrier <span class="hlt">performance</span>. The radiant barriers were installed horizontally above the ceiling insulation. The measured <span class="hlt">performance</span> was then compared to documented results for a ridge and soffit ventilation system. This study experimentally determined the effects of radiant barriers on ceiling <span class="hlt">heat</span> loss in cathedral ceiling homes during the winter <span class="hlt">heating</span> season. A normalization procedure was used to allow short term, clear sky measurements from different days of similar weather to be used to determine radiant barrier <span class="hlt">performance</span>. The procedure normalized for weather variations of ambient temperature and solar insolation under clear sky conditions to isolate the effects of radiant barriers. In these studies radiant barriers were examined for energy conservation, load shifting and demand reduction characteristics. A thermal model to predict shingle temperature in cathedral ceiling homes was also developed. The experimental results show that radiant barriers are not as effective in homes with a gable ventilation system as compared to homes with a ridge and soffit system. This result is primarily due to increased air flow rates with a ridge and soffit ventilation system. For the gable ventilation system the radiant barriers reduced the peak <span class="hlt">heat</span> <span class="hlt">flux</span> by 20% and provided an energy conservation of 4.1%. However, it was found that better load shifting characteristics were present. Radiant barriers conserved energy in a winter study of cathedral ceilings by actually reducing the total <span class="hlt">heat</span> loss from the ceiling by 40% for peak <span class="hlt">heating</span> days. The shingle temperature model was validated by comparing ceiling <span class="hlt">heat</span> <span class="hlt">flux</span> predictions using actual measured temperatures and modeled temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050210107','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050210107"><span>Spray Cooling Trajectory Angle Impact Upon <span class="hlt">Heat</span> <span class="hlt">Flux</span> Using a Straight Finned Enhanced Surface</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Silk, Eric A.; Kim, Jungho; Kiger, Ken</p> <p>2005-01-01</p> <p>Experiments were conducted to study the effects of spray trajectory angles upon <span class="hlt">heat</span> <span class="hlt">flux</span> for flat and enhanced surface spray cooling. The surface enhancement consisted of straight fins machined on the top surface of a copper heater block. Spray cooling curves were obtained with the straight fin surface aligned both parallel (axial) and perpendicular (transverse) to the spray axis. Measurements were also obtained on a flat surface heater block for comparison purposes. Each copper block had a cross-sectional area of 2.0 sq cm. A 2x2 nozzle array was used with PF-5060 as the working fluid. Thermal <span class="hlt">performance</span> data was obtained under nominally degassed (chamber pressure of 41.4 kPa) conditions. Results show that the maximum CHF in all cases was attained for a trajectory angle of 30' from the surface normal. Furthermore, trajectory angles applied to straight finned surfaces can have a critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) enhancement as much as 75% (<span class="hlt">heat</span> <span class="hlt">flux</span> value of 140 W/sq cm) relative to the vertical spray orientation for the analogous flat surface case under nominally degassed conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080006072','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080006072"><span>High-<span class="hlt">Heat-Flux</span> Cyclic Durability of Thermal and Environmental Barrier Coatings</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhu, Dongming; Ghosn, Louis L.; Miller, Robert A.</p> <p>2007-01-01</p> <p>Advanced ceramic thermal and environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect the engine components and further raise engine temperatures. For the supersonic vehicles currently envisioned in the NASA fundamental aeronautics program, advanced gas turbine engines will be used to provide high power density thrust during the extended supersonic flight of the aircraft, while meeting stringent low emission requirements. Advanced ceramic coating systems are critical to the <span class="hlt">performance</span>, life and durability of the hot-section components of the engine systems. In this work, the laser and burner rig based high-<span class="hlt">heat-flux</span> testing approaches were developed to investigate the coating cyclic response and failure mechanisms under simulated supersonic long-duration cruise mission. The accelerated coating cracking and delamination mechanism under the engine high-<span class="hlt">heat-flux</span>, and extended supersonic cruise time conditions will be addressed. A coating life prediction framework may be realized by examining the crack initiation and propagation in conjunction with environmental degradation under high-<span class="hlt">heat-flux</span> test conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DPPUP8036M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DPPUP8036M"><span>Scaling of the <span class="hlt">Heat</span> <span class="hlt">Flux</span> Width with Plasma Density in DIII-D</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Makowski, M. A.; Lasnier, C. J.; Nichols, J.; Leonard, A. W.; Osborne, T. H.; Snyder, P. B.</p> <p>2013-10-01</p> <p>The previous study of the relationship between the <span class="hlt">heat</span> <span class="hlt">flux</span> width and upstream profiles is extended with the addition of density scans. These scans range from a low-density, attached state to a high-density, detached state on both the inner and outer divertors in both L- and H-mode discharges. Under attached conditions in L-mode both the inner and outer <span class="hlt">heat</span> <span class="hlt">flux</span> profiles are well fit by Eich's fitting function and clearly indicate the transition from attached to detached states. Analysis of the density scans will be combined with previous scaling results to extend the <span class="hlt">heat</span> <span class="hlt">flux</span> width database. Comparisons to a critical gradient model will also be made to assess its validity under these new conditions. This work <span class="hlt">performed</span> under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under DE-AC52-07NA27344 and by the U.S. Department of Energy under DE-AC02-09CH11466 and DE-FC02-04ER54698.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhST..167a4020P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhST..167a4020P"><span>High <span class="hlt">heat</span> <span class="hlt">flux</span> testing of divertor plasma facing materials and components using the HHF test facility at IPR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patil, Yashashri; Khirwadkar, S. S.; Belsare, Sunil; Swamy, Rajamannar; Tripathi, Sudhir; Bhope, Kedar; Kanpara, Shailesh</p> <p>2016-02-01</p> <p>The High <span class="hlt">Heat</span> <span class="hlt">Flux</span> Test Facility (HHFTF) was designed and established recently at Institute for Plasma Research (IPR) in India for testing <span class="hlt">heat</span> removal capability and operational life time of plasma facing materials and components of the ITER-like tokamak. The HHFTF is equipped with various diagnostics such as IR cameras and IR-pyrometers for surface temperature measurements, coolant water calorimetry for absorbed power measurements and thermocouples for bulk temperature measurements. The HHFTF is capable of simulating steady state <span class="hlt">heat</span> load of several MW m-2 as well as short transient <span class="hlt">heat</span> loads of MJ m-2. This paper presents the current status of the HHFTF at IPR and high <span class="hlt">heat</span> <span class="hlt">flux</span> tests <span class="hlt">performed</span> on the curved tungsten monoblock type of test mock-ups as well as transient <span class="hlt">heat</span> <span class="hlt">flux</span> tests carried out on pure tungsten materials using the HHFTF. Curved tungsten monoblock type of test mock-ups were fabricated using hot radial pressing (HRP) technique. Two curved tungsten monoblock type test mock-ups successfully sustained absorbed <span class="hlt">heat</span> <span class="hlt">flux</span> up to 14 MW m-2 with thermal cycles of 30 s ON and 30 s OFF duration. Transient high <span class="hlt">heat</span> <span class="hlt">flux</span> tests or thermal shock tests were carried out on pure tungsten hot-rolled plate material (Make:PLANSEE) with incident power density of 0.49 GW m-2 for 20 milliseconds ON and 1000 milliseconds OFF time. A total of 6000 thermal shock cycles were completed on pure tungsten material. Experimental results were compared with mathematical simulations carried out using COMSOL Multiphysics for transient high <span class="hlt">heat</span> <span class="hlt">flux</span> tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28063826','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28063826"><span>Evaluation of <span class="hlt">Heat</span> <span class="hlt">Flux</span> Measurement as a New Process Analytical Technology Monitoring Tool in Freeze Drying.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vollrath, Ilona; Pauli, Victoria; Friess, Wolfgang; Freitag, Angelika; Hawe, Andrea; Winter, Gerhard</p> <p>2017-01-04</p> <p>This study investigates the suitability of <span class="hlt">heat</span> <span class="hlt">flux</span> measurement as a new technique for monitoring product temperature and critical end points during freeze drying. The <span class="hlt">heat</span> <span class="hlt">flux</span> sensor is tightly mounted on the shelf and measures non-invasively (no contact with the product) the <span class="hlt">heat</span> transferred from shelf to vial. <span class="hlt">Heat</span> <span class="hlt">flux</span> data were compared to comparative pressure measurement, thermocouple readings, and Karl Fischer titration as current state of the art monitoring techniques. The whole freeze drying process including freezing (both by ramp freezing and controlled nucleation) and primary and secondary drying was considered. We found that direct measurement of the transferred <span class="hlt">heat</span> enables more insights into thermodynamics of the freezing process. Furthermore, a vial <span class="hlt">heat</span> transfer coefficient can be calculated from <span class="hlt">heat</span> <span class="hlt">flux</span> data, which ultimately provides a non-invasive method to monitor product temperature throughout primary drying. The end point of primary drying determined by <span class="hlt">heat</span> <span class="hlt">flux</span> measurements was in accordance with the one defined by thermocouples. During secondary drying, <span class="hlt">heat</span> <span class="hlt">flux</span> measurements could not indicate the progress of drying as monitoring the residual moisture content. In conclusion, <span class="hlt">heat</span> <span class="hlt">flux</span> measurements are a promising new non-invasive tool for lyophilization process monitoring and development using energy transfer as a control parameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/111456','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/111456"><span>Correlation of critical <span class="hlt">heat</span> <span class="hlt">flux</span> data for uniform tubes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jafri, T.; Dougherty, T.J.; Yang, B.W.</p> <p>1995-09-01</p> <p>A data base of more than 10,000 critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) data points has been compiled and analyzed. Two regimes of CHF are observed which will be referred to as the high CHF regime and the low CHF regime. In the high CHF regime, for pressures less than 110 bar, CHF (q{sub c}) is a determined by local conditions and is adequately represented by q{sub c} = (1.2/D{sup 1/2}) exp[-{gamma}(GX{sub t}){sup 1/2}] where the parameter {gamma} is an increasing function of pressure only, X{sub t} the true mass fraction of steam, and all units are metric but the <span class="hlt">heat</span> <span class="hlt">flux</span> is in MWm{sup -2}. A simple kinetic model has been developed to estimate X{sub t} as a function of G, X, X{sub i}, and X{sub O}, where X{sub i} is the inlet quality and X{sub O} represents the quality at the Onset of Significant Vaporization (OSV) which is estimated from the Saha-Zuber (S-Z) correlation. The model is based on a rate equation for vaporization suggested by, and consistent with, the S-Z correlation and contains no adjustable parameters. When X{sub i}<X{sub O} (both negative), X{sub t} is independent of X{sub i} and is a function of local variables only. For X{sub i}>X{sub O}, X{sub t} depends on X{sub i}, a nonlocal variable, and, in this case, CHF, although determined by local conditions, obeys a nonlocal correlation. This model appears to be satisfactory for pressures less than 110 bar, where the S-Z correlation is known to be reliable. Above 110 bar the method of calculating X{sub O}, and consequently X{sub t}, appears to fail, so this approach can not be applied to high pressure CHF data. Above 35 bar, the bulk of the available data lies in the high CHF regime while, at pressures less than 35 bar, almost all of the available data lie in the low CHF regime and appear to be nonlocal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=convection&pg=3&id=EJ844005','ERIC'); return false;" href="http://eric.ed.gov/?q=convection&pg=3&id=EJ844005"><span>The Role of the Velocity Gradient in Laminar Convective <span class="hlt">Heat</span> Transfer through a Tube with a Uniform Wall <span class="hlt">Heat</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Wang, Liang-Bi; Zhang, Qiang; Li, Xiao-Xia</p> <p>2009-01-01</p> <p>This paper aims to contribute to a better understanding of convective <span class="hlt">heat</span> transfer. For this purpose, the reason why thermal diffusivity should be placed before the Laplacian operator of the <span class="hlt">heat</span> <span class="hlt">flux</span>, and the role of the velocity gradient in convective <span class="hlt">heat</span> transfer are analysed. The background to these analyses is that, when the energy…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=thermal+AND+physics&pg=5&id=EJ844005','ERIC'); return false;" href="https://eric.ed.gov/?q=thermal+AND+physics&pg=5&id=EJ844005"><span>The Role of the Velocity Gradient in Laminar Convective <span class="hlt">Heat</span> Transfer through a Tube with a Uniform Wall <span class="hlt">Heat</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Wang, Liang-Bi; Zhang, Qiang; Li, Xiao-Xia</p> <p>2009-01-01</p> <p>This paper aims to contribute to a better understanding of convective <span class="hlt">heat</span> transfer. For this purpose, the reason why thermal diffusivity should be placed before the Laplacian operator of the <span class="hlt">heat</span> <span class="hlt">flux</span>, and the role of the velocity gradient in convective <span class="hlt">heat</span> transfer are analysed. The background to these analyses is that, when the energy…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Cryo...52..505I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Cryo...52..505I"><span>Integrated computational study of ultra-high <span class="hlt">heat</span> <span class="hlt">flux</span> cooling using cryogenic micro-solid nitrogen spray</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishimoto, Jun; Oh, U.; Tan, Daisuke</p> <p>2012-10-01</p> <p>A new type of ultra-high <span class="hlt">heat</span> <span class="hlt">flux</span> cooling system using the atomized spray of cryogenic micro-solid nitrogen (SN2) particles produced by a superadiabatic two-fluid nozzle was developed and numerically investigated for application to next generation super computer processor thermal management. The fundamental characteristics of <span class="hlt">heat</span> transfer and cooling <span class="hlt">performance</span> of micro-solid nitrogen particulate spray impinging on a <span class="hlt">heated</span> substrate were numerically investigated and experimentally measured by a new type of integrated computational-experimental technique. The employed Computational Fluid Dynamics (CFD) analysis based on the Euler-Lagrange model is focused on the cryogenic spray behavior of atomized particulate micro-solid nitrogen and also on its ultra-high <span class="hlt">heat</span> <span class="hlt">flux</span> cooling characteristics. Based on the numerically predicted <span class="hlt">performance</span>, a new type of cryogenic spray cooling technique for application to a ultra-high <span class="hlt">heat</span> power density device was developed. In the present integrated computation, it is clarified that the cryogenic micro-solid spray cooling characteristics are affected by several factors of the <span class="hlt">heat</span> transfer process of micro-solid spray which impinges on <span class="hlt">heated</span> surface as well as by atomization behavior of micro-solid particles. When micro-SN2 spraying cooling was used, an ultra-high cooling <span class="hlt">heat</span> <span class="hlt">flux</span> level was achieved during operation, a better cooling <span class="hlt">performance</span> than that with liquid nitrogen (LN2) spray cooling. As micro-SN2 cooling has the advantage of direct latent <span class="hlt">heat</span> transport which avoids the film boiling state, the ultra-short time scale <span class="hlt">heat</span> transfer in a thin boundary layer is more possible than in LN2 spray. The present numerical prediction of the micro-SN2 spray cooling <span class="hlt">heat</span> <span class="hlt">flux</span> profile can reasonably reproduce the measurement results of cooling wall <span class="hlt">heat</span> <span class="hlt">flux</span> profiles. The application of micro-solid spray as a refrigerant for next generation computer processors is anticipated, and its ultra-high <span class="hlt">heat</span> <span class="hlt">flux</span> technology is expected</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title16-vol2/pdf/CFR-2011-title16-vol2-part1209-subpartA-app8.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title16-vol2/pdf/CFR-2011-title16-vol2-part1209-subpartA-app8.pdf"><span>16 CFR Figure 8 to Subpart A of... - Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile 8 Figure 8 to Subpart A of Part 1209 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER..., Subpt. A, Fig. 8 Figure 8 to Subpart A of Part 1209—Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title16-vol2/pdf/CFR-2010-title16-vol2-part1209-subpartA-app8.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title16-vol2/pdf/CFR-2010-title16-vol2-part1209-subpartA-app8.pdf"><span>16 CFR Figure 8 to Subpart A of... - Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile 8 Figure 8 to Subpart A of Part 1209 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER..., Subpt. A, Fig. 8 Figure 8 to Subpart A of Part 1209—Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/91321','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/91321"><span>Regulation of the solar wind electron <span class="hlt">heat</span> <span class="hlt">flux</span> from 1 to 5 AU: Ulysses observations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scime, E.E.; Bame, S.J.; Feldman, W.C.; Gary, S.P.; Phillips, J.L.; Balogh, A.</p> <p>1994-12-01</p> <p>In this study the authors use observations from the three-dimensional electron spectrometer and magnetometer aboard the Ulysses spacecraft to examine the solar wind electron <span class="hlt">heat</span> <span class="hlt">flux</span> from 1.2 to 5.4 AU in the ecliptic plane. Throughout Ulysses` transit to 5.4 AU, the electron <span class="hlt">heat</span> <span class="hlt">flux</span> decreases more rapidly ({approximately}R{sup {minus}3.0}) than simple collisionless expansion along the local magnetic field and is smaller than expected for a thermal gradient <span class="hlt">heat</span> <span class="hlt">flux</span>, q{sub {parallel}}e(r)={minus}k{sub {parallel}}{del}{sub {parallel}}T{sub e}(r). The radial gradients and magnitudes expected for a number of electron <span class="hlt">heat</span> <span class="hlt">flux</span> regulatory mechanisms are examined and compared to the observations. The best agreement is found for <span class="hlt">heat</span> <span class="hlt">flux</span> regulation by the whistler <span class="hlt">heat</span> <span class="hlt">flux</span> instability. The upper bound and radial scaling for the electron <span class="hlt">heat</span> <span class="hlt">flux</span> predicted for the whistler <span class="hlt">heat</span> <span class="hlt">flux</span> instability are consistent with observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title16-vol2/pdf/CFR-2014-title16-vol2-part1209-subpartA-app8.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title16-vol2/pdf/CFR-2014-title16-vol2-part1209-subpartA-app8.pdf"><span>16 CFR Figure 8 to Subpart A of... - Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile 8 Figure 8 to Subpart A of Part 1209 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER..., Subpt. A, Fig. 8 Figure 8 to Subpart A of Part 1209—Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title16-vol2/pdf/CFR-2012-title16-vol2-part1209-subpartA-app8.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title16-vol2/pdf/CFR-2012-title16-vol2-part1209-subpartA-app8.pdf"><span>16 CFR Figure 8 to Subpart A of... - Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile 8 Figure 8 to Subpart A of Part 1209 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER..., Subpt. A, Fig. 8 Figure 8 to Subpart A of Part 1209—Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ESASP.692E.147K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ESASP.692E.147K"><span>Peak <span class="hlt">Heat</span> <span class="hlt">Fluxe</span> Reduction Using Aerospikes Installed On Multimodule Launch Vehicle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kudinov, A.; Yurchenko, I.; Karakotin, I.; Vaganov, A.; Drozdov, S.; Skuratov, A.</p> <p>2011-05-01</p> <p>Based on the experimental data in the supersonic wind tunnels the flow patterns, which cause peak pressure and peak <span class="hlt">heat</span> <span class="hlt">fluxes</span> on the heavy space rocket surfaces, were researched. Physical interpretations for each flow pattern are presented. Peak areas dimensions were specified. Influence of aerospike attached to on lateral rocket module to the <span class="hlt">heat</span> <span class="hlt">fluxes</span> was investigated</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ThEng..57..232K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ThEng..57..232K"><span>Generalization of data on critical <span class="hlt">heat</span> <span class="hlt">fluxes</span> for flow swirled using a tape</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krug, A. F.; Kuzma-Kichta, Yu. A.; Komendantov, A. S.</p> <p>2010-03-01</p> <p>The available data on critical <span class="hlt">heat</span> <span class="hlt">fluxes</span> for boiling of subcooled and saturated liquid in tubes with twisted tape inserts are considered. Experimental data obtained by different researchers are generalized, and an equation for calculating critical <span class="hlt">heat</span> <span class="hlt">fluxes</span> for both smooth tubes and tubes with flow swirling by means of a tape is proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title16-vol2/pdf/CFR-2013-title16-vol2-part1209-subpartA-app8.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title16-vol2/pdf/CFR-2013-title16-vol2-part1209-subpartA-app8.pdf"><span>16 CFR Figure 8 to Subpart A of... - Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile 8 Figure 8 to Subpart A of Part 1209 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER..., Subpt. A, Fig. 8 Figure 8 to Subpart A of Part 1209—Standard Radiant <span class="hlt">Heat</span> Energy <span class="hlt">Flux</span> Profile EC03OC91...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030025342','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030025342"><span>Time and Space Resolved <span class="hlt">Heat</span> Transfer Measurements Under Nucleate Bubbles with Constant <span class="hlt">Heat</span> <span class="hlt">Flux</span> Boundary Conditions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Kim, Jungho</p> <p>2003-01-01</p> <p>Investigations into single bubble pool boiling phenomena are often complicated by the difficulties in obtaining time and space resolved information in the bubble region. This usually occurs because the heaters and diagnostics used to measure <span class="hlt">heat</span> transfer data are often on the order of, or larger than, the bubble characteristic length or region of influence. This has contributed to the development of many different and sometimes contradictory models of pool boiling phenomena and dominant <span class="hlt">heat</span> transfer mechanisms. Recent investigations by Yaddanapyddi and Kim and Demiray and Kim have obtained time and space resolved <span class="hlt">heat</span> transfer information at the bubble/heater interface under constant temperature conditions using a novel micro-heater array (10x10 array, each heater 100 microns on a side) that is semi-transparent and doubles as a measurement sensor. By using active feedback to maintain a state of constant temperature at the heater surface, they showed that the area of influence of bubbles generated in FC-72 was much smaller than predicted by standard models and that micro-conduction/micro-convection due to re-wetting dominated <span class="hlt">heat</span> transfer effects. This study seeks to expand on the previous work by making time and space resolved measurements under bubbles nucleating on a micro-heater array operated under constant <span class="hlt">heat</span> <span class="hlt">flux</span> conditions. In the planned investigation, wall temperature measurements made under a single bubble nucleation site will be synchronized with high-speed video to allow analysis of the bubble energy removal from the wall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT........92G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT........92G"><span>Pressure and <span class="hlt">heat</span> <span class="hlt">flux</span> effects on the <span class="hlt">heat</span> transfer characteristics of liquid methane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garcia, Chance P.</p> <p></p> <p>The <span class="hlt">heat</span> transfer effects on liquid methane are investigated with the use of a carbo-thermal rig at the Center for Space Exploration Technology Research (cSETR) located at the University of Texas at El Paso (UTEP). The cSETR carbo-thermal rig design approach is presented along with the design of a methane condensing mobile unit (MCMU) to supply the laboratory and rig with liquid methane. The proposed research will generate useful insight in to <span class="hlt">heat</span> transfer coefficient behavior, non-dimensional correlations, different flow conditions, varied inlet conditions, and varied <span class="hlt">heat</span> <span class="hlt">flux</span> for a subscale test article applicable to a regenerative cooled rocket engine cooling channel. The data found will also improve the knowledge base for liquid methane and non-toxic propulsion. Planned test parameters are from 1.03 to 2.07 MPa (150 to 300 psi) supply tank pressure, and 3.9 to 19 MW/m2 (2.39 to 11.6 Btu/in2-s). Presented are transient and steady state <span class="hlt">heat</span> transfer response results depicting transient and steady state <span class="hlt">heat</span> transfer effects tested at turbulent Reynolds numbers (15000 to 360000).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914314B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914314B"><span>The forgotten component of sub-glacial <span class="hlt">heat</span> flow: Upper crustal <span class="hlt">heat</span> production and resultant total <span class="hlt">heat</span> <span class="hlt">flux</span> on the Antarctic Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burton-Johnson, Alex; Halpin, Jacqueline; Whittaker, Joanne; Watson, Sally</p> <p>2017-04-01</p> <p>Seismic and magnetic geophysical methods have both been employed to produce estimates of <span class="hlt">heat</span> <span class="hlt">flux</span> beneath the Antarctic ice sheet. However, both methods use a homogeneous upper crustal model despite the variable concentration of <span class="hlt">heat</span> producing elements within its composite lithologies. Using geological and geochemical datasets from the Antarctic Peninsula we have developed a new methodology for incorporating upper crustal <span class="hlt">heat</span> production in <span class="hlt">heat</span> <span class="hlt">flux</span> models and have shown the greater variability this introduces in to estimates of crustal <span class="hlt">heat</span> <span class="hlt">flux</span>, with implications for glaciological modelling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840049031&hterms=intimate+relationships&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dintimate%2Brelationships','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840049031&hterms=intimate+relationships&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dintimate%2Brelationships"><span>Empirical models of the eddy <span class="hlt">heat</span> <span class="hlt">flux</span> and vertical shear on short time scales</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ghan, S. J.</p> <p>1984-01-01</p> <p>An intimate relation exists between the vertical shear and the horizontal eddy <span class="hlt">heat</span> <span class="hlt">flux</span> within the atmosphere. In the present investigation empirical means are employed to provide clues concerning the relationship between the shear and eddy <span class="hlt">heat</span> <span class="hlt">flux</span>. In particular, linear regression models are applied to individual and joint time series of the shear and eddy <span class="hlt">heat</span> <span class="hlt">flux</span>. These discrete models are used as a basis to infer continuous models. A description is provided of the observed relationship between the <span class="hlt">flux</span> and the shear, taking into account means, standard deviations, and lag correction functions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840049031&hterms=Intimate+relationships&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DIntimate%2Brelationships','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840049031&hterms=Intimate+relationships&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DIntimate%2Brelationships"><span>Empirical models of the eddy <span class="hlt">heat</span> <span class="hlt">flux</span> and vertical shear on short time scales</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ghan, S. J.</p> <p>1984-01-01</p> <p>An intimate relation exists between the vertical shear and the horizontal eddy <span class="hlt">heat</span> <span class="hlt">flux</span> within the atmosphere. In the present investigation empirical means are employed to provide clues concerning the relationship between the shear and eddy <span class="hlt">heat</span> <span class="hlt">flux</span>. In particular, linear regression models are applied to individual and joint time series of the shear and eddy <span class="hlt">heat</span> <span class="hlt">flux</span>. These discrete models are used as a basis to infer continuous models. A description is provided of the observed relationship between the <span class="hlt">flux</span> and the shear, taking into account means, standard deviations, and lag correction functions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090006017&hterms=pressure+model&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpressure%2Bmodel','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090006017&hterms=pressure+model&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpressure%2Bmodel"><span>Development of Solar Wind Model Driven by Empirical <span class="hlt">Heat</span> <span class="hlt">Flux</span> and Pressure Terms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sittler, Edward C., Jr.; Ofman, L.; Selwa, M.; Kramar, M.</p> <p>2008-01-01</p> <p>We are developing a time stationary self-consistent 2D MHD model of the solar corona and solar wind as suggested by Sittler et al. (2003). Sittler & Guhathakurta (1999) developed a semiempirical steady state model (SG model) of the solar wind in a multipole 3-streamer structure, with the model constrained by Skylab observations. Guhathakurta et al. (2006) presented a more recent version of their initial work. Sittler et al. (2003) modified the SG model by investigating time dependent MHD, ad hoc <span class="hlt">heating</span> term with <span class="hlt">heat</span> conduction and empirical <span class="hlt">heating</span> solutions. Next step of development of 2D MHD models was <span class="hlt">performed</span> by Sittler & Ofman (2006). They derived effective temperature and effective <span class="hlt">heat</span> <span class="hlt">flux</span> from the data-driven SG model and fit smooth analytical functions to be used in MHD calculations. Improvements of the Sittler & Ofman (2006) results now show a convergence of the 3-streamer topology into a single equatorial streamer at altitudes > 2 R(sub S). This is a new result and shows we are now able to reproduce observations of an equatorially confined streamer belt. In order to allow our solutions to be applied to more general applications, we extend that model by using magnetogram data and PFSS model as a boundary condition. Initial results were presented by Selwa et al. (2008). We choose solar minimum magnetogram data since during solar maximum the boundary conditions are more complex and the coronal magnetic field may not be described correctly by PFSS model. As the first step we studied the simplest 2D MHD case with variable <span class="hlt">heat</span> conduction, and with empirical <span class="hlt">heat</span> input combined with empirical momentum addition for the fast solar wind. We use realistic magnetic field data based on NSO/GONG data, and plan to extend the study to 3D. This study represents the first attempt of fully self-consistent realistic model based on real data and including semi-empirical <span class="hlt">heat</span> <span class="hlt">flux</span> and semi-empirical effective pressure terms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.1791W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.1791W"><span>Modelling storm development and the impact when introducing waves, sea spray and <span class="hlt">heat</span> <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Lichuan; Rutgersson, Anna; Sahlée, Erik</p> <p>2015-04-01</p> <p>In high wind speed conditions, sea spray generated due to intensity breaking waves have big influence on the wind stress and <span class="hlt">heat</span> <span class="hlt">fluxes</span>. Measurements show that drag coefficient will decrease in high wind speed. Sea spray generation function (SSGF), an important term of wind stress parameterization in high wind speed, usually treated as a function of wind speed/friction velocity. In this study, we introduce a wave state depended SSGG and wave age depended Charnock number into a high wind speed wind stress parameterization (Kudryavtsev et al., 2011; 2012). The proposed wind stress parameterization and sea spray <span class="hlt">heat</span> <span class="hlt">fluxes</span> parameterization from Andreas et al., (2014) were applied to an atmosphere-wave coupled model to test on four storm cases. Compared with measurements from the FINO1 platform in the North Sea, the new wind stress parameterization can reduce the forecast errors of wind in high wind speed range, but not in low wind speed. Only sea spray impacted on wind stress, it will intensify the storms (minimum sea level pressure and maximum wind speed) and lower the air temperature (increase the errors). Only the sea spray impacted on the <span class="hlt">heat</span> <span class="hlt">fluxes</span>, it can improve the model <span class="hlt">performance</span> on storm tracks and the air temperature, but not change much in the storm intensity. If both of sea spray impacted on the wind stress and <span class="hlt">heat</span> <span class="hlt">fluxes</span> are taken into account, it has the best <span class="hlt">performance</span> in all the experiment for minimum sea level pressure and maximum wind speed and air temperature. Andreas, E. L., Mahrt, L., and Vickers, D. (2014). An improved bulk air-sea surface <span class="hlt">flux</span> algorithm, including spray-mediated transfer. Quarterly Journal of the Royal Meteorological Society. Kudryavtsev, V. and Makin, V. (2011). Impact of ocean spray on the dynamics of the marine atmospheric boundary layer. Boundary-layer meteorology, 140(3):383-410. Kudryavtsev, V., Makin, V., and S, Z. (2012). On the sea-surface drag and <span class="hlt">heat</span>/mass transfer at strong winds. Technical report, Royal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870006083','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870006083"><span>Comparison of measured and modeled radiation, <span class="hlt">heat</span> and water vapor <span class="hlt">fluxes</span>: FIFE pilot study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Blad, Blaine L.; Hubbard, Kenneth G.; Verma, Shashi B.; Starks, Patrick; Norman, John M.; Walter-Shea, Elizabeth</p> <p>1987-01-01</p> <p>The feasibility of using radio frequency receivers to collect data from automated weather stations to model <span class="hlt">fluxes</span> of latent <span class="hlt">heat</span>, sensible <span class="hlt">heat</span>, and radiation using routine weather data collected by automated weather stations was tested and the estimated <span class="hlt">fluxes</span> were compared with <span class="hlt">fluxes</span> measured over wheat. The model Cupid was used to model the <span class="hlt">fluxes</span>. Two or more automated weather stations, interrogated by radio frequency and other means, were utilized to examine some of the climatic variability of the First ISLSCP (International Satellite Land-Surface Climatology Project) Field Experiment (FIFE) site, to measure and model reflected and emitted radiation streams from various locations at the site and to compare modeled latent and sensible <span class="hlt">heat</span> <span class="hlt">fluxes</span> with measured values. Some bidirectional reflected and emitted radiation data were collected from 23 locations throughout the FIFE site. Analysis of these data along with analysis of the measured sensible and latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> is just beginning.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10103230','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10103230"><span>The validation of ocean surface <span class="hlt">heat</span> <span class="hlt">fluxes</span> in AMIP</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gleckler, P.J.; Randall, D.A.</p> <p>1993-09-01</p> <p>Recent intercomparisons of Atmospheric General Circulation Models (AGCMS) constrained with sea-surface temperatures have shown that while there are substantial differences among various models (with each other and available observations), overall the differences between them have been decreasing. The primary goal of AMIP is to enable a systematic intercomparison and validation of state-of-the- art AGCMs by supporting in-depth diagnosis of and interpretation of the model results. Official AMIP simulations are 10 years long, using monthly mean Sea-Surface Temperatures (SSTs) and sea ice conditions which are representative of the 1979--1988 decade. Some model properties are also dictated by the design of AMIP such as the solar constant, the atmospheric CO{sub 2} concentration, and the approximate horizontal resolution. In this paper, some of the preliminary results of AMIP Subproject No. 5 will be summarized. The focus will be on the intercomparison and validation of ocean surface <span class="hlt">heat</span> <span class="hlt">fluxes</span> of the AMIP simulations available thus far.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDA30008C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDA30008C"><span><span class="hlt">Heat</span> <span class="hlt">flux</span> in a penetrative convection experiment in water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Corre, Yoann; Alboussière, Thierry; Labrosse, Stéphane; Odier, Philippe; Joubaud, Sylvain</p> <p>2015-11-01</p> <p>In geophysical systems, stably stratified fluids adjacent to convective regions often experience thermal plume penetration from the latter. This penetrative convection occurs in stellar interiors between radiative and convective regions and possibly in liquid envelopes of planets, such as the Earth's core. We are interested in quantifying this process experimentally as it could play a crucial role in their dynamics. A volume of water initially at ambiant temperature is cooled from below at 0 degrees Celsius. Due to the maximum density of water near 4 degrees, a convective region develops and grows below a purely conductive region. A laser sheet crosses the experimental cell, lightening both neutrally buoyant particles and a thermosensitive fluorescent dye, which allows to monitor the velocity and temperature fields respectively (PIV-LIF technique), giving access to the local convective and conductive <span class="hlt">heat</span> <span class="hlt">flux</span>. The apparatus is placed on a rotating table to inspect the effect of the Coriolis force on the interfacial region. We find that increasing the rotation rate deepens the penetration of vortices into the conductive region, thus changing the structure of the interfacial layer and possibly eroding the stable region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930022713&hterms=Wais&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DWais','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930022713&hterms=Wais&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DWais"><span>Sensible and latent <span class="hlt">heat</span> <span class="hlt">flux</span> estimates in Antarctica</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stearns, Charles R.; Weidner, George A.</p> <p>1993-01-01</p> <p>The assumption has been made that the net annual contribution of water by the processes of deposition and sublimation to the Antarctic Ice Sheet is zero. The U.S. Antarctic Program started installing reliable automatic weather stations on the Antarctic Continent in 1980. The initial units were equipped to measure wind speed, wind direction, air pressure, and air temperature. During the 1983-1984 field season in Antarctica, three units were installed that measured a vertical air temperature difference between the nominal heights of 0.5 m and 3.0 m and relative humidity at a nominal height of 3 m. The measurements of the vertical air temperature difference and the relative humidity are the minimum required to estimate the sensible and latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> to the air, while not exceeding the available energy requirements for the weather stations. The estimates of the net annual sublimation and deposition on the Ross Ice Shelf amount to 20 to 80 percent of the annual accumulation. We conclude that the assumption that annual sublimation and deposition are zero is not valid under Antarctic conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850067082&hterms=Polar+lights&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPolar%2Blights','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850067082&hterms=Polar+lights&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPolar%2Blights"><span>Evidence for ion <span class="hlt">heat</span> <span class="hlt">flux</span> in the light ion polar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Biddle, A. P.; Moore, T. E.; Chappell, C. R.</p> <p>1985-01-01</p> <p>Cold flowing hydrogen and helium ions have been observed using the retarding ion mass spectrometer on board the Dynamics Explorer 1 spacecraft in the dayside magnetosphere at subauroral latitudes. The ions show a marked <span class="hlt">flux</span> asymmetry with respect to the relative wind direction. The observed data are fitted by a model of drifting Maxwellian distributions perturbed by a first order-Spritzer-Haerm <span class="hlt">heat</span> <span class="hlt">flux</span> distribution function. It is shown that both ion species are supersonic just equatorward of the auroral zone at L = 14, and the shape of asymmetry and direction of the asymmetry are consistent with the presence of an upward <span class="hlt">heat</span> <span class="hlt">flux</span>. At L = 6, both species evolve smoothly into warmer subsonic upward flows with downward <span class="hlt">heat</span> <span class="hlt">fluxes</span>. In the case of subsonic flows the downward <span class="hlt">heat</span> <span class="hlt">flux</span> implies a significant <span class="hlt">heat</span> source at higher altitudes. Spin curves of the spectrometer count rate versus the spin phase angle are provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810004793','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810004793"><span>High-<span class="hlt">performance</span> <span class="hlt">heat</span> pipes for <span class="hlt">heat</span> recovery applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Saaski, E. W.; Hartl, J. H.</p> <p>1980-01-01</p> <p>Methods to improve the <span class="hlt">performance</span> of reflux <span class="hlt">heat</span> pipes for <span class="hlt">heat</span> recovery applications were examined both analytically and experimentally. Various models for the estimation of reflux <span class="hlt">heat</span> pipe transport capacity were surveyed in the literature and compared with experimental data. A high transport capacity reflux <span class="hlt">heat</span> pipe was developed that provides up to a factor of 10 capacity improvement over conventional open tube designs; analytical models were developed for this device and incorporated into a computer program HPIPE. Good agreement of the model predictions with data for R-11 and benzene reflux <span class="hlt">heat</span> pipes was obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDKP1041Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDKP1041Y"><span>High fidelity simulation of nucleate boiling and transition to critical <span class="hlt">heat</span> <span class="hlt">flux</span> on enhanced structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yazdani, Miad; Alahyari, Abbas; Radcliff, Thomas; Soteriou, Marios</p> <p>2015-11-01</p> <p>Surface enhancement is often is the primary approach for improved <span class="hlt">heat</span> transfer <span class="hlt">performance</span> of two-phase thermal systems particularly when they operate in nucleate boiling regime. This paper exploits the modeling capability developed by Yazdani et al. for simulation of nucleate boiling and transition to critical <span class="hlt">heat</span> <span class="hlt">flux</span> to study the nucleation phenomenon on various enhanced structures. The multi-scale of two-phase flow associated with boiling phenomena is addressed through combination of deterministic CFD for the macro-scale transport, asymptotic based representation of micro-layer, and stochastic representation of surface roughness so as to allow a high-fidelity simulation of boiling on an arbitrary surface. In addition, given the excessive complexity of surface structures often used for enhancement of boiling <span class="hlt">heat</span> transfer, a phase-field-based method is developed to generate the structures where the numerical parameters in the phase-field model determine the topology of a given structure. The ``generated'' structure is then embedded into the two-phase flow model through virtual boundary method for the boiling simulation. The model is validated against experimental data for the boiling curve and the critical <span class="hlt">heat</span> <span class="hlt">flux</span> as well as nucleation and bubble dynamics characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApPhL.109b4102E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApPhL.109b4102E"><span>Flash boiling from carbon foams for high-<span class="hlt">heat-flux</span> transient cooling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Engerer, J. D.; Fisher, T. S.</p> <p>2016-07-01</p> <p>Flash boiling of a liquid pool results in an event characterized by rapid phase change and, as a result, high rates of expansion and cooling. Because of the potential advantages of such characteristics for convective <span class="hlt">heat</span> transfer, flash boiling is considered here for the purpose of cooling transient <span class="hlt">heat</span> loads. The event has the positive characteristics mentioned as well as rapid response (˜10 ms) and high initial rates of phase change, and then quickly decays to a steady-state regime analogous to pool boiling. The <span class="hlt">performance</span> of the cooling mechanism is evaluated using an objective function derived from the effect of temperature on the efficiency of optical transmission in a diode-pumped solid-state laser. Statistical surrogate models based on the experimental results are used to predict optimal run conditions. Experiments using these predicted parameters show that flash boiling can maintain device temperature to within ±6.1 °C through a pulsed 5 s <span class="hlt">heat</span> <span class="hlt">flux</span> of 68 W cm-2 and to within ±1.4 °C for a <span class="hlt">heat</span> <span class="hlt">flux</span> of 39 W cm-2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000056863','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000056863"><span>Critical <span class="hlt">Heat</span> <span class="hlt">Flux</span> in Pool Boiling on Metal-Graphite Composite Surfaces</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhang, Nengli; Yang, Wen-Jei; Chao, David F.; Chao, David F. (Technical Monitor)</p> <p>2000-01-01</p> <p>A study is conducted on high <span class="hlt">heat-flux</span> pool boiling of pentane on micro-configured composite surfaces. The boiling surfaces are copper-graphite (Cu-Gr) and aluminum-graphite (Al-Gr) composites with a fiber volume concentration of 50%. The micro-graphite fibers embedded in the matrix contribute to a substantial enhancement in boiling <span class="hlt">heat</span>-transfer <span class="hlt">performance</span>. Correlation equations are obtained for both the isolated and coalesced bubble regimes, utilizing a mathematical model based on a metal-graphite, two-tier configuration with the aid of experimental data. A new model to predict the critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) on the composites is proposed to explain the fundamental aspects of the boiling phenomena. Three different factors affecting the CHF are considered in the model. Two of them are expected to become the main agents driving vapor volume detachment under microgravity conditions, using the metal-graphite composite surfaces as the <span class="hlt">heating</span> surface and using liquids with an unusual Marangoni effect as the working fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPT10092P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPT10092P"><span>Time evolution of the particle and <span class="hlt">heat</span> <span class="hlt">flux</span> of the detached plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pianpanit, Theerasarn; Ishiguro, Seiji; Hasegawa, Hiroki</p> <p>2016-10-01</p> <p>The detached plasma is a regime when the particle and <span class="hlt">heat</span> <span class="hlt">flux</span> of the plasma are largely reduced before reaching the divertor target. Linear devices experiment data show that when the neutral gas pressure in front of the target increases the <span class="hlt">heat</span> <span class="hlt">flux</span> to the target largely decreases. The 1D-3V particle simulation with Monte Carlo collision and cumulative scattering angle Coulomb collision has been developed to study the kinetic effect of the detached plasma. The simulation was <span class="hlt">performed</span> with the constant temperature and pressure of neutral gas in front of the target. A large decrease in the electron temperature from 5eV to below 1 eV follows a large decrease in the ion temperature inside the neutral gas area in the case with high neutral gas pressure in front of the target. The energy <span class="hlt">flux</span> at the target decreases in the process of attaining the detached state. This work was <span class="hlt">performed</span> with the support and under the auspices of the NIFS Collaboration Research programs NIFS14KNXN279 and NIFS14KNSS059.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26347537','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26347537"><span>Arctic mass, freshwater and <span class="hlt">heat</span> <span class="hlt">fluxes</span>: methods and modelled seasonal variability.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bacon, Sheldon; Aksenov, Yevgeny; Fawcett, Stephen; Madec, Gurvan</p> <p>2015-10-13</p> <p>Considering the Arctic Ocean (including sea ice) as a defined volume, we develop equations describing the time-varying <span class="hlt">fluxes</span> of mass, <span class="hlt">heat</span> and freshwater (FW) into, and storage of those quantities within, that volume. The seasonal cycles of <span class="hlt">fluxes</span> and storage of mass, <span class="hlt">heat</span> and FW are quantified and illustrated using output from a numerical model. The meanings of 'reference values' and FW <span class="hlt">fluxes</span> are discussed, and the potential for error through the use of arbitrary reference values is examined.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990021026&hterms=Body+measurements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DBody%2Bmeasurements','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990021026&hterms=Body+measurements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DBody%2Bmeasurements"><span>Experimental Measurements of Temperature and <span class="hlt">Heat</span> <span class="hlt">Flux</span> in a High Temperature Black Body Cavity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abdelmessih, Amanie N.</p> <p>1998-01-01</p> <p>During hypersonic flight, high temperatures and high <span class="hlt">heat</span> <span class="hlt">fluxes</span> are generated. The Flight Loads Laboratory (FLL) at Dryden Flight Research Center (DFRC) is equipped to calibrate high <span class="hlt">heat</span> <span class="hlt">fluxes</span> up to 1100 kW/sq m. There are numerous uncertainties associated with these <span class="hlt">heat</span> <span class="hlt">flux</span> calibrations, as the process is transient, there are expected to be interactions between transient conduction, natural and forced convection, radiation, and possibly an insignificant degree of oxidation of the graphite cavity. Better understanding, of these mechanisms during the calibration process, will provide more reliable <span class="hlt">heat</span> transfer data during either ground testing or flight testing of hypersonic vehicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017HMT....53..439W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017HMT....53..439W"><span>Inverse estimation of near-field temperature and surface <span class="hlt">heat</span> <span class="hlt">flux</span> via single point temperature measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Chen-Wu; Shu, Yong-Hua; Xie, Ji-Jia; Jiang, Jian-Zheng; Fan, Jing</p> <p>2017-02-01</p> <p>A concept was developed to inversely estimate the near-field temperature as well as the surface <span class="hlt">heat</span> <span class="hlt">flux</span> for the transient <span class="hlt">heat</span> conduction problem with boundary condition of the unknown <span class="hlt">heat</span> <span class="hlt">flux</span>. The mathematical formula was derived for the inverse estimation of the near-field temperature and surface <span class="hlt">heat</span> <span class="hlt">flux</span> via a single point temperature measurement. The experiments were carried out in a vacuum chamber and the theoretically predicted temperatures were justified in specific positions. The inverse estimation principle was validated and the estimation deviation was evaluated for the present configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991sidr.nasa....9W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991sidr.nasa....9W"><span>Thin film <span class="hlt">heat</span> <span class="hlt">flux</span> sensor for Space Shuttle Main Engine turbine environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Will, Herbert</p> <p>1991-05-01</p> <p>The Space Shuttle Main Engine (SSME) turbine environment stresses engine components to their design limits and beyond. The extremely high temperatures and rapid temperature cycling can easily cause parts to fail if they are not properly designed. Thin film <span class="hlt">heat</span> <span class="hlt">flux</span> sensors can provide <span class="hlt">heat</span> loading information with almost no disturbance of gas flows or of the blade. These sensors can provide steady state and transient <span class="hlt">heat</span> <span class="hlt">flux</span> information. A thin film <span class="hlt">heat</span> <span class="hlt">flux</span> sensor is described which makes it easier to measure small temperature differences across very thin insulating layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990021026&hterms=Body+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DBody%2Btemperature','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990021026&hterms=Body+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DBody%2Btemperature"><span>Experimental Measurements of Temperature and <span class="hlt">Heat</span> <span class="hlt">Flux</span> in a High Temperature Black Body Cavity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abdelmessih, Amanie N.</p> <p>1998-01-01</p> <p>During hypersonic flight, high temperatures and high <span class="hlt">heat</span> <span class="hlt">fluxes</span> are generated. The Flight Loads Laboratory (FLL) at Dryden Flight Research Center (DFRC) is equipped to calibrate high <span class="hlt">heat</span> <span class="hlt">fluxes</span> up to 1100 kW/sq m. There are numerous uncertainties associated with these <span class="hlt">heat</span> <span class="hlt">flux</span> calibrations, as the process is transient, there are expected to be interactions between transient conduction, natural and forced convection, radiation, and possibly an insignificant degree of oxidation of the graphite cavity. Better understanding, of these mechanisms during the calibration process, will provide more reliable <span class="hlt">heat</span> transfer data during either ground testing or flight testing of hypersonic vehicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..152a2036M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..152a2036M"><span>Temperature and <span class="hlt">heat</span> <span class="hlt">flux</span> measurement techniques for aeroengine fire test: a review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohammed, I.; Abu Talib, A. R.; Sultan, M. T. H.; Saadon, S.</p> <p>2016-10-01</p> <p>This review is made of studies whereby some types of fire test measuring instrument were compared based on their mode of operation, sensing ability, temperature resistance and their calibration mode used for aero-engine applications. The study discusses issues affecting temperature and <span class="hlt">heat</span> <span class="hlt">flux</span> measurement, methods of measurement, calibration and uncertainties that occur in the fire test. It is found that the temperature and <span class="hlt">heat</span> <span class="hlt">flux</span> measurements of the flame from the standard burner need to be corrected and taken into account for radiation <span class="hlt">heat</span> loss. Methods for temperature and <span class="hlt">heat</span> <span class="hlt">flux</span> measurements, as well as uncertainties analysis, were also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970000389','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970000389"><span>Evaporation on/in Capillary Structures of High <span class="hlt">Heat</span> <span class="hlt">Flux</span> Two-Phase Devices</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Faghri, Amir; Khrustalev, Dmitry</p> <p>1996-01-01</p> <p>Two-phase devices (<span class="hlt">heat</span> pipes, capillary pumped loops, loop <span class="hlt">heat</span> pipes, and evaporators) have become recognized as key elements in thermal control systems of space platforms. Capillary and porous structures are necessary and widely used in these devices, especially in high <span class="hlt">heat</span> <span class="hlt">flux</span> and zero-g applications, to provide fluid transport and enhanced <span class="hlt">heat</span> transfer during vaporization and condensation. However, some unexpected critical phenomena, such as dryout in long <span class="hlt">heat</span> pipe evaporators and high thermal resistance of loop <span class="hlt">heat</span> pipe evaporators with high <span class="hlt">heat</span> <span class="hlt">fluxes</span>, are possible and have been encountered in the use of two-phase devices in the low gravity environment. Therefore, a detailed fundamental investigation is proposed to better understand the fluid behavior in capillary-porous structures during vaporization at high <span class="hlt">heat</span> <span class="hlt">fluxes</span>. The present paper addresses some theoretical aspects of this investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998HMT....33..481I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998HMT....33..481I"><span>Effect of subcooling on critical <span class="hlt">heat</span> <span class="hlt">flux</span> during pool boiling on a horizontal <span class="hlt">heated</span> wire</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inoue, T.; Kawae, N.; Monde, M.</p> <p></p> <p>Critical <span class="hlt">heat</span> <span class="hlt">flux</span>(CHF) is measured during pool boiling of water and R113 on a <span class="hlt">heated</span> horizontal wire submerged in a subcooled liquid. Experiments are conducted over a pressure range from 0.1 to 3.0MPa and subcooling up to 220K. CHF data reveal that the CHF increases in a linear fashion with an increase in subcooling, and that the increment of the CHF with increasing subcooling becomes larger with increasing pressure. The characteristics of the CHF obtained differ from those of existing correlations at high pressures, although it is a similar tendency to them in that the CHF is proportional to the subcooling. A new correlation is derived by taking into account the effect of both the density ratio, ρL/ρV, and the Peclet number, Pe, and it succeeds in predicting the CHF data up to higher pressure and higher subcooling ranges, more effectively than previous studies using existing applicable ranges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1865h0005P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1865h0005P"><span>Critical <span class="hlt">heat</span> <span class="hlt">flux</span> phenomena depending on pre-pressurization in transient <span class="hlt">heat</span> input</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Jongdoc; Fukuda, Katsuya; Liu, Qiusheng</p> <p>2017-07-01</p> <p>The critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) levels that occurred due to exponential <span class="hlt">heat</span> inputs for varying periods to a 1.0-mm diameter horizontal cylinder immersed in various liquids were measured to develop an extended database on the effect of various pressures and subcoolings by photographic study. Two main mechanisms of CHF were found. One mechanism is due to the time lag of the hydrodynamic instability (HI) which starts at steady-state CHF upon fully developed nucleate boiling, and the other mechanism is due to the explosive process of heterogeneous spontaneous nucleation (HSN) which occurs at a certain HSN superheat in originally flooded cavities on the cylinder surface. The incipience of boiling processes was completely different depending on pre-pressurization. Also, the dependence of pre-pressure in transient CHFs changed due to the wettability of boiling liquids. The objective of this work is to clarify the transient CHF phenomena due to HI or HSN by photographic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApPhL.105s1601K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApPhL.105s1601K"><span>Interfacial wicking dynamics and its impact on critical <span class="hlt">heat</span> <span class="hlt">flux</span> of boiling <span class="hlt">heat</span> transfer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Beom Seok; Lee, Hwanseong; Shin, Sangwoo; Choi, Geehong; Cho, Hyung Hee</p> <p>2014-11-01</p> <p>Morphologically driven dynamic wickability is essential for determining the hydrodynamic status of solid-liquid interface. We demonstrate that the dynamic wicking can play an integral role in supplying and propagating liquid through the interface, and govern the critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) against surface dry-out during boiling <span class="hlt">heat</span> transfer. For the quantitative control of wicking, we manipulate the characteristic lengths of hexagonally arranged nanopillars within sub-micron range through nanosphere lithography combined with top-down metal-assisted chemical etching. Strong hemi-wicking over the manipulated interface (i.e., wicking coefficients) of 1.28 mm/s0.5 leads to 164% improvement of CHF compared to no wicking. As a theoretical guideline, our wickability-CHF model can make a perfect agreement with improved CHF, which cannot be predicted by the classic models pertaining to just wettability and roughness effects, independently.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.8642G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.8642G"><span>Ground <span class="hlt">Heat</span> <span class="hlt">Flux</span> within the PMIP3/CMIP5 Last Millennium Simulations and Estimates from Geothermal Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>García-García, Almudena; José Cuesta-Valero, Francisco; Beltrami, Hugo; Mondéjar, Carlos; Finnis, Joel</p> <p>2017-04-01</p> <p>The proper simulation of the energy partitioning at the surface, both as storage within the ground and energy <span class="hlt">fluxes</span> from the surface, is crucial for the accurate representation of land-surface processes and related climate feedback mechanisms (e.g. permafrost thaw and soil carbon stability). We analyze the changes in ground <span class="hlt">heat</span> <span class="hlt">flux</span> over the last millennium as simulated by the PMIP3/CMIP5 General Circulation Models (GCMs). The following three methods were used to estimate ground <span class="hlt">heat</span> <span class="hlt">flux</span>: 1) using the surface energy balance, that is from the difference between net-radiation, latent and sensible <span class="hlt">heat</span> <span class="hlt">fluxes</span>, 2) calculations based on Surface Air Temperature (SAT), Surface Temperature (ST) and Ground Surface Temperature at 0.5m and at 1m (GST), and 3) inferences from temperature at two soil depths (GST at 0.5m and GST at 1m). Results show large regional variability among models and methods. Global estimates of ground <span class="hlt">heat</span> <span class="hlt">flux</span> from the surface energy balance differ significantly from values obtained from geothermal data over the second half of the last century. Such disagreement may be indicative of a change in the partitioning of the energy within historical simulations of the PMIP3/CMIP5 GCMs. The lack of observational data and the challenges of measuring soil <span class="hlt">fluxes</span> highlight the value of geothermal database as a potentially valuable source of information for evaluating long-term models <span class="hlt">performance</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20845819','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20845819"><span>A New Facility for Measurements of Three-Dimensional, Local Subcooled Flow Boiling <span class="hlt">Heat</span> <span class="hlt">Flux</span> and Related Critical <span class="hlt">Heat</span> <span class="hlt">Flux</span> for PFCs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Boyd, Ronald D. Sr.; Cofie, Penrose; Li Qingyuan; Ekhlassi, Ali A</p> <p>2002-01-15</p> <p>In the development of plasma-facing components for fusion reactors and high-<span class="hlt">heat-flux</span> <span class="hlt">heat</span> sinks (or components) for electronic applications, the components are usually subjected to a peripherally nonuniform <span class="hlt">heat</span> <span class="hlt">flux</span>. Even if the applied <span class="hlt">heat</span> <span class="hlt">flux</span> is uniform in the axial direction (which is unlikely), both intuition and recent investigations have clearly shown that both the local <span class="hlt">heat</span> <span class="hlt">flux</span> and the eventual critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) in this three-dimensional (3-D) case will differ significantly from similar quantities found in the voluminous body of data for uniformly <span class="hlt">heated</span> flow channels. Although this latter case has been used in the past as an estimate for the former case, more study has become necessary to examine the 3-D temperature and <span class="hlt">heat</span> <span class="hlt">flux</span> distributions and related CHF. Work thus far has shown that the nonuniform peripheral <span class="hlt">heat</span> <span class="hlt">flux</span> condition enhances CHF in some cases.To avoid the excess costs associated with using electron or ion beams to produce the nonuniform <span class="hlt">heat</span> <span class="hlt">flux</span>, a new facility was developed that will allow 3-D conjugate <span class="hlt">heat</span> transfer measurements and two-dimensional, local subcooled flow boiling <span class="hlt">heat</span> <span class="hlt">flux</span> and related CHF measurements.The configurations under study for this work consist of (a) a nonuniformly <span class="hlt">heated</span> cylinder-like test section with a circular coolant channel bored through the center and (b) a monoblock that is a square cross-section parallelepiped with a circular drilled flow channel along the channel centerline. The theoretical or ideal cylinder-like test section would be a circular cylinder with half (-90 to 90 deg) of its outside boundary subjected to a uniform <span class="hlt">heat</span> <span class="hlt">flux</span> and the remaining half insulated. For the monoblock, a uniform <span class="hlt">heat</span> <span class="hlt">flux</span> is applied to one of the outside surfaces, and the remaining surfaces are insulated. The outside diameter of the cylinder-like test section is 30.0 mm, and its length is 200.0 mm. The monoblock square is 30.0 mm long. The inside diameter of the flow channel for both types of test</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/442623','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/442623"><span>Enhancement of critical <span class="hlt">heat</span> <span class="hlt">flux</span> in subcooled flow boiling of water by use of a volatile additive</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pabisz, R.A. Jr.; Bergles, A.E.</p> <p>1996-12-31</p> <p>The present investigation considers the effect of a 1-pentanol additive in water on the critical <span class="hlt">heat</span> <span class="hlt">flux</span> (CHF) and pressure drop in forced subcooled boiling. A small quantity of 1-pentanol was added to distilled water with the objective of getting an approximate 2% by weight mixture, which had been found to give superior <span class="hlt">performance</span> in previous studies of pool and flow boiling. Experiments were <span class="hlt">performed</span> using stainless steel tubes with internal diameters of 4.4 and 6.1 mm. Tests were conducted with mass <span class="hlt">fluxes</span> of 4,400 kg/m{sup 2}s, exit pressures of 9 bar, length-to-diameter ratios of 25, and exit subcoolings from 65 to 90 C. Test sections were <span class="hlt">heated</span> directly by DC power, and critical <span class="hlt">heat</span> <span class="hlt">flux</span> data were inferred from test-section burnout. The alcohol concentration was periodically checked by draining off a sample and <span class="hlt">performing</span> a Proton Nuclear Magnetic Resonance scan on the mixture. At high subcoolings, the mixture exhibited an increase in the critical <span class="hlt">heat</span> <span class="hlt">flux</span> over that of pure water. However at low subcoolings there is a decrease in the critical <span class="hlt">heat</span> <span class="hlt">flux</span>. The increases in critical <span class="hlt">heat</span> <span class="hlt">flux</span> noted with the 1-pentanol mixture in this experiment were not as large as would be expected from saturated pool boiling results published by Van Stralen (1959). Pressure drop data for both the mixture and the pure water also were recorded. The 1-pentanol mixture, in general, exhibited larger pressure drops for the same conditions. Subcooled flow boiling has a wide array of commercial cooling applications, including blades in gas turbines, high power laser optics, plasma-facing components in fusion reactors, supercomputers, etc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA442054','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA442054"><span>Preliminary <span class="hlt">Heat</span> Transfer Characteristics of RP-2 Fuel as Tested in the High <span class="hlt">Heat</span> <span class="hlt">Flux</span> Facility (PREPRINT)</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2005-11-21</p> <p>2005. This facility, coupled with established <span class="hlt">heated</span> tube facilities, such as the NASA Glenn <span class="hlt">Heated</span> Tube Facility ( HTF ) 3 and the Wright-Patterson...operation differs from the existing facilities in both construction and <span class="hlt">heating</span> elements. Both the NASA Glenn HTF and the Wright-Patterson Phoenix Rig...ft/sec leading to <span class="hlt">heat</span> <span class="hlt">fluxes</span> of up to 100 BTU/in2 sec.1 In similarity to the HTF , the HHFF uses oxygen-free grade copper walled test sections</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NucFu..54f4011T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NucFu..54f4011T"><span>The effect of resonant magnetic perturbations on the divertor <span class="hlt">heat</span> and particle <span class="hlt">fluxes</span> in MAST</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thornton, A. J.; Kirk, A.; Cahyna, P.; Chapman, I. T.; Harrison, J. R.; Liu, Yueqiang; the MAST Team</p> <p>2014-06-01</p> <p>Edge localized modes (ELMs) are a concern for future devices, such as ITER, due to the large transient <span class="hlt">heat</span> loads they generate on the divertor surfaces which could limit the operational lifetime of the device. This paper discusses the application of resonant magnetic perturbations (RMPs) as a mechanism for ELM control on Mega Amp Spherical Tokamak (MAST). Experiments have been <span class="hlt">performed</span> using an n = 3 toroidal mode number perturbation and measurements of the strike point splitting <span class="hlt">performed</span>. The measurements have been made using both infrared and visible imaging to measure the <span class="hlt">heat</span> and particle <span class="hlt">flux</span> to the divertor. The measured profiles have shown clear splitting in L-mode which compares well with the predication of the splitting location from modelling including the effect of screening. The splitting of the strike point has also been studied as a function of time during the ELM. The splitting varies during the ELM, being the strongest at the time of the peak <span class="hlt">heat</span> <span class="hlt">flux</span> and becoming more filamentary at the end of the ELM (200 µs after the peak midplane Dα emission). Variation in the splitting profiles has also been seen, with some ELMs showing clear splitting and others no splitting. A possible explanation of this effect is proposed, and supported by modelling, which concerns the relative phase between the RMP field and the ELM filament location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990032572&hterms=thin+film+thermocouple&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dthin%2Bfilm%2Bthermocouple','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990032572&hterms=thin+film+thermocouple&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dthin%2Bfilm%2Bthermocouple"><span>Steady-State and Frequency Response of a Thin-Film <span class="hlt">Heat</span> <span class="hlt">Flux</span> Gauge</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fralick, Gustave C.; Bhatt, Hemanshu D.; Cho, Chistopher S.</p> <p>1997-01-01</p> <p>A new and simpler design of thin-film <span class="hlt">heat</span> <span class="hlt">flux</span> gauge has been developed for use In high-<span class="hlt">heat-flux</span> environments. <span class="hlt">Heat</span> <span class="hlt">flux</span> gauges of the same design were fabricated on three different substrates and tested. The <span class="hlt">heat</span> <span class="hlt">flux</span> gauge comprises a thermopile and a thermocouple junction, which measures the surface temperature. The thermopile has 40 pairs of S-type thermocouples and is covered by two thermal resistance layers. Calibration and testing of these gauges were first carried out in an arc-lamp calibration facility. Sensitivity of the gauge was discussed in terms of the relative conductivity and surface temperature. The <span class="hlt">heat</span> <span class="hlt">flux</span> calculated from the gauge output was In good agreement with the precalibrated standard sensor. The steady-state and the transient response characteristics of the <span class="hlt">heat</span> <span class="hlt">flux</span> gauge were also investigated using a carbon dioxide pulse laser as a <span class="hlt">heat</span> source. The dynamic frequency response was evaluated in terms of the nondimensional amplitude ratio with respect to the frequency spectrum of a chopped laser bcam. The frequency response of the gauge was determined to be about 3 kHz. The temperature profiles in the thin-film <span class="hlt">heat</span> <span class="hlt">flux</span> gauge were obtained numerically in steady-state conditions using FLUENT and compared with the experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JFM...547..115R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JFM...547..115R"><span><span class="hlt">Heat-flux</span> scaling for weakly forced turbulent convection in the atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rao, Kusuma G.; Narasimha, R.</p> <p></p> <p>Observational data in the atmosphere indicate that conventionally defined drag and <span class="hlt">heat</span> transfer coefficients increase rapidly as wind speed falls. It is shown here that, at sufficiently low wind speeds, the observed <span class="hlt">heat</span> <span class="hlt">flux</span> is nearly independent of wind speed but the drag increases linearly with it. These findings are not consistent with the free-convection limit of the Businger relations for Monin Obukhov theory, and lend support to the ideas of Ingersoll (1966) and Grachev (1990), till now checked only against laboratory experiments. We propose here that it is useful to define, within the regime of mixed convection, a sub-regime of ‘weakly forced convection’ in which, to a first approximation, the <span class="hlt">heat</span> <span class="hlt">flux</span> is determined by temperature differentials as in free convection and the momentum <span class="hlt">flux</span> by a perturbation, linear in wind, on free convection. It is further proposed that this regime is governed by velocity scales determined by the <span class="hlt">heat</span> <span class="hlt">flux</span> (rather than by the friction velocity as in classical turbulent boundary layer theory). Three candidates for the <span class="hlt">heat-flux</span> velocity scale are considered; novel definitions of the drag and <span class="hlt">heat</span> exchange coefficients, based on the preferred scale, are found to show very weak dependence on wind speed up to values of about 5 10 m s^{-1}; but there is some evidence that the usefulness of <span class="hlt">heat-flux</span> scaling may extend beyond the velocity limits where pure free-convection scaling for <span class="hlt">heat</span> <span class="hlt">flux</span> is valid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/19747','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/19747"><span>An inverse method to estimate stem surface <span class="hlt">heat</span> <span class="hlt">flux</span> in wildland fires</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Anthony S. Bova; Matthew B. Dickinson</p> <p>2009-01-01</p> <p>Models of wildland fire-induced stem <span class="hlt">heating</span> and tissue necrosis require accurate estimates of inward <span class="hlt">heat</span> <span class="hlt">flux</span> at the bark surface. Thermocouple probes or <span class="hlt">heat</span> <span class="hlt">flux</span> sensors placed at a stem surface do not mimic the thermal response of tree bark to flames.We show that data from thin thermocouple probes inserted just below the bark can be used, by means of a one-...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121.7290R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121.7290R"><span>Observed subseasonal variability of <span class="hlt">heat</span> <span class="hlt">flux</span> and the SST response of the tropical Indian Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raj Parampil, Sindu; Bharathraj, G. N.; Harrison, Matthew; Sengupta, Debasis</p> <p>2016-10-01</p> <p>We develop an experimental daily surface <span class="hlt">heat</span> <span class="hlt">flux</span> data set based on satellite observations to study subseasonal variability (periods shorter than 90 days) in the tropical Indian Ocean. We use incoming shortwave and longwave radiation from the International Satellite Cloud Climatology Project, and sea surface temperature (SST) from microwave sensors, to estimate net radiative <span class="hlt">flux</span>. Latent and sensible <span class="hlt">heat</span> <span class="hlt">fluxes</span> are estimated from scatterometer winds and near-surface air temperature and specific humidity from Atmospheric Infrared Sounder (AIRS) observations calibrated to buoy data. Seasonal biases in net <span class="hlt">heat</span> <span class="hlt">flux</span> are generally within 10 W m-2 of estimates from moorings, and the phases and amplitudes of subseasonal variability of <span class="hlt">heat</span> <span class="hlt">fluxes</span> are realistic. We find that the contribution of subseasonal changes in air-sea humidity gradients to latent <span class="hlt">heat</span> <span class="hlt">flux</span> equals or exceeds the contribution of subseasonal changes in wind speed in all seasons. SST responds coherently to subseasonal oscillations of net <span class="hlt">heat</span> <span class="hlt">flux</span> associated with active and suppressed phases of atmospheric convection in the summer hemisphere. Thus, subseasonal SST changes are mainly forced by <span class="hlt">heat</span> <span class="hlt">flux</span> in the northeast Indian Ocean in northern summer, and in the 15°S-5°N latitude belt in southern summer. In the winter hemisphere, subseasonal SST changes are not a one-dimensional response to <span class="hlt">heat</span> <span class="hlt">flux</span>, implying that they are mainly due to oceanic advection, entrainment, or vertical mixing. The coherent evolution of subseasonal SST variability and surface <span class="hlt">heat</span> <span class="hlt">flux</span> suggests active coupling between SST and large-scale, organized tropical convection in the summer season.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984nmsc.book.....M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984nmsc.book.....M"><span>Numerical model for swirl cooling in high-<span class="hlt">heat-flux</span> particle beam targets and the design of a swirl-flow-based plasma limiter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Milora, S. L.; Combs, S. K.; Foster, C. A.</p> <p>1984-11-01</p> <p>An unsteady, two-dimensional <span class="hlt">heat</span> conduction code was used to study the <span class="hlt">performance</span> of swirl-flow-based neutral particle beam targets. The model includes the effects of two-phase <span class="hlt">heat</span> transfer and asymmetric <span class="hlt">heating</span> of tubular elements. The calorimeter subjected to 30-s neutral beam pulses with incident <span class="hlt">heat</span> <span class="hlt">flux</span> intensities of greater than or equal to 5 kW/cu cm, is modeled. The numerical results indicate that local <span class="hlt">heat</span> <span class="hlt">fluxes</span> in excess of 7 kW/sq cm occur at the water cooled surface on the side exposed to the beam. This exceeds critical <span class="hlt">heat</span> <span class="hlt">flux</span> limits for uniformly <span class="hlt">heated</span> tubes with straight flow by approximately a factor of 5. The design of a plasma limiter based on swirl flow <span class="hlt">heat</span> transfer is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6294549','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6294549"><span>Numerical model for swirl flow cooling in high-<span class="hlt">heat-flux</span> particle beam targets and the design of a swirl-flow-based plasma limiter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Milora, S.L.; Combs, S.K.; Foster, C.A.</p> <p>1984-11-01</p> <p>An unsteady, two-dimensional <span class="hlt">heat</span> conduction code has been used to study the <span class="hlt">performance</span> of swirl-flow-based neutral particle beam targets. The model includes the effects of two-phase <span class="hlt">heat</span> transfer and asymmetric <span class="hlt">heating</span> of tubular elements. The calorimeter installed in the Medium Energy Test Facility, which has been subjected to 30-s neutral beam pulses with incident <span class="hlt">heat</span> <span class="hlt">flux</span> intensities of greater than or equal to 5 kW/cm/sup 2/, has been modeled. The numerical results indicate that local <span class="hlt">heat</span> <span class="hlt">fluxes</span> in excess of 7 kW/cm/sup 2/ occur at the water-cooled surface on the side exposed to the beam. This exceeds critical <span class="hlt">heat</span> <span class="hlt">flux</span> limits for uniformly <span class="hlt">heated</span> tubes wih straight flow by approximately a factor of 5. The design of a plasma limiter based on swirl flow <span class="hlt">heat</span> transfer is presented.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JEPT...79.1106O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JEPT...79.1106O"><span>The first critical <span class="hlt">heat-flux</span> density of kerosene in stepwise and steady-state releases of <span class="hlt">heat</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Obukhov, D. S.</p> <p>2006-11-01</p> <p>Experimental results on determination of stationary and nonstationary first critical densities of <span class="hlt">heat</span> <span class="hlt">fluxes</span> for the TS-1 hydrocarbon fuel are presented. As a consequence of the investigations carried out in a wide range of subcoolings and pressures, it has been established that for kerosene, just as for water, hydrogen, and helium, the first nonstationary critical <span class="hlt">heat-flux</span> density qcr.1n coincides with the stationary one qcr1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.9946S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.9946S"><span><span class="hlt">Heat</span> <span class="hlt">Fluxes</span> and Evaporation Measurements by Multi-Function <span class="hlt">Heat</span> Pulse Probe: a Laboratory Experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharma, V.; Ciocca, F.; Hopmans, J. W.; Kamai, T.; Lunati, I.; Parlange, M. B.</p> <p>2012-04-01</p> <p>Multi Functional <span class="hlt">Heat</span> Pulse Probes (MFHPP) are multi-needles probes developed in the last years able to measure temperature, thermal properties such as thermal diffusivity and volumetric <span class="hlt">heat</span> capacity, from which soil moisture is directly retrieved, and electric conductivity (through a Wenner array). They allow the simultaneous measurement of coupled <span class="hlt">heat</span>, water and solute transport in porous media, then. The use of only one instrument to estimate different quantities in the same volume and almost at the same time significantly reduces the need to interpolate different measurement types in space and time, increasing the ability to study the interdependencies characterizing the coupled transports, especially of water and <span class="hlt">heat</span>, and water and solute. A three steps laboratory experiment is realized at EPFL to investigate the effectiveness and reliability of the MFHPP responses in a loamy soil from Conthey, Switzerland. In the first step specific calibration curves of volumetric <span class="hlt">heat</span> capacity and thermal conductivity as function of known volumetric water content are obtained placing the MFHPP in small samplers filled with the soil homogeneously packed at different saturation degrees. The results are compared with literature values. In the second stage the ability of the MFHPP to measure <span class="hlt">heat</span> <span class="hlt">fluxes</span> is tested within a homemade thermally insulated calibration box and results are matched with those by two self-calibrating Heatflux plates (from Huxseflux), placed in the same box. In the last step the MFHPP are used to estimate the cumulative subsurface evaporation inside a small column (30 centimeters height per 8 centimeters inner diameter), placed on a scale, filled with the same loamy soil (homogeneously packed and then saturated) and equipped with a vertical array of four MFHPP inserted close to the surface. The subsurface evaporation is calculated from the difference between the net sensible <span class="hlt">heat</span> and the net <span class="hlt">heat</span> storage in the volume scanned by the probes, and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10185286','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10185286"><span>Liquid jet impingement cooling with diamond substrates for extremely high <span class="hlt">heat</span> <span class="hlt">flux</span> applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lienhard, J.H. V; Khounsary, A.M.</p> <p>1993-09-01</p> <p>The combination of impinging jets and diamond substrates may provide an effective solution to a class of extremely high <span class="hlt">heat</span> <span class="hlt">flux</span> problems in which very localized <span class="hlt">heat</span> loads must be removed. Some potential applications include the cooling of high-<span class="hlt">heat</span>-load components in synchrotron x-ray, fusion, and semiconductor laser systems. Impinging liquid jets are a very effective vehicle for removing high <span class="hlt">heat</span> <span class="hlt">fluxes</span>. The liquid supply arrangement is relatively simple, and low thermal resistances can be routinely achieved. A jet`s cooling ability is a strong function of the size of the cooled area relative to the jet diameter. For relatively large area targets, the critical <span class="hlt">heat</span> <span class="hlt">fluxes</span> can approach 20 W/mm{sup 2}. In this situation, burnout usually originates at the outer edge of the cooled region as increasing <span class="hlt">heat</span> <span class="hlt">flux</span> inhibits the liquid supply. Limitations from liquid supply are minimized when <span class="hlt">heating</span> is restricted to the jet stagnation zone. The high stagnation pressure and high velocity gradients appear to suppress critical <span class="hlt">flux</span> phenomena, and <span class="hlt">fluxes</span> of up to 400 W/mm{sup 2} have been reached without evidence of burnout. Instead, the restrictions on <span class="hlt">heat</span> <span class="hlt">flux</span> are closely related to properties of the cooled target. Target properties become an issue owing to the large temperatures and large temperature gradients that accompany <span class="hlt">heat</span> <span class="hlt">fluxes</span> over 100 W/mm{sup 2}. These conditions necessitate a target with both high thermal conductivity to prevent excessive temperatures and good mechanical properties to prevent mechanical failures. Recent developments in synthetic diamond technology present a possible solution to some of the solid-side constraints on <span class="hlt">heat</span> <span class="hlt">flux</span>. Polycrystalline diamond foils can now be produced by chemical vapor deposition in reasonable quantity and at reasonable cost. Synthetic single crystal diamonds as large as 1 cm{sup 2} are also available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.2819C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2819C"><span>Anthropogenic <span class="hlt">Heat</span> <span class="hlt">Flux</span> Estimation from Space: Results of the second phase of the URBANFLUXES Project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chrysoulakis, Nektarios; Marconcini, Mattia; Gastellu-Etchegorry, Jean-Philippe; Grimmond, Sue; Feigenwinter, Christian; Lindberg, Fredrik; Del Frate, Fabio; Klostermann, Judith; Mitraka, Zina; Esch, Thomas; Landier, Lucas; Gabey, Andy; Parlow, Eberhard; Olofson, Frans</p> <p>2017-04-01</p> <p>The H2020-Space project URBANFLUXES (URBan ANthrpogenic <span class="hlt">heat</span> <span class="hlt">FLUX</span> from Earth observation Satellites) investigates the potential of Copernicus Sentinels to retrieve anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span>, as a key component of the Urban Energy Budget (UEB). URBANFLUXES advances the current knowledge of the impacts of UEB <span class="hlt">fluxes</span> on urban <span class="hlt">heat</span> island and consequently on energy consumption in cities. In URBANFLUXES, the anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span> is estimated as a residual of UEB. Therefore, the rest UEB components, namely, the net all-wave radiation, the net change in <span class="hlt">heat</span> storage and the turbulent sensible and latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> are independently estimated from Earth Observation (EO), whereas the advection term is included in the error of the anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span> estimation from the UEB closure. The Discrete Anisotropic Radiative Transfer (DART) model is employed to improve the estimation of the net all-wave radiation balance, whereas the Element Surface Temperature Method (ESTM), adjusted to satellite observations is used to improve the estimation the estimation of the net change in <span class="hlt">heat</span> storage. Furthermore the estimation of the turbulent sensible and latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> is based on the Aerodynamic Resistance Method (ARM). Based on these outcomes, QF is estimated by regressing the sum of the turbulent <span class="hlt">heat</span> <span class="hlt">fluxes</span> versus the available energy. In-situ <span class="hlt">flux</span> measurements are used to evaluate URBANFLUXES outcomes, whereas uncertainties are specified and analyzed. URBANFLUXES is expected to prepare the ground for further innovative exploitation of EO in scientific activities (climate variability studies at local and regional scales) and future and emerging applications (sustainable urban planning, mitigation technologies) to benefit climate change mitigation/adaptation. This study presents the results of the second phase of the project and detailed information on URBANFLUXES is available at: http://urbanfluxes.eu</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B42B..05C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B42B..05C"><span>Anthropogenic <span class="hlt">Heat</span> <span class="hlt">Flux</span> Estimation from Space: Results of the first phase of the URBANFLUXES Project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chrysoulakis, N.; Marconcini, M.; Gastellu-Etchegorry, J. P.; Grimmond, S. B.; Feigenwinter, C.; Lindberg, F.; Del Frate, F.; Klostermann, J.; Mitraka, Z.; Esch, T.; Landier, L.; Gabey, A. M.; Parlow, E.; Olofson, F.</p> <p>2016-12-01</p> <p>The H2020-Space project URBANFLUXES (URBan ANthrpogenic <span class="hlt">heat</span> <span class="hlt">FLUX</span> from Earth observation Satellites) investigates the potential of Copernicus Sentinels to retrieve anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span>, as a key component of the Urban Energy Budget (UEB). URBANFLUXES advances the current knowledge of the impacts of UEB <span class="hlt">fluxes</span> on urban <span class="hlt">heat</span> island and consequently on energy consumption in cities. In URBANFLUXES, the anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span> is estimated as a residual of UEB. Therefore, the rest UEB components, namely, the net all-wave radiation, the net change in <span class="hlt">heat</span> storage and the turbulent sensible and latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> are independently estimated from Earth Observation (EO), whereas the advection term is included in the error of the anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span> estimation from the UEB closure. The Discrete Anisotropic Radiative Transfer (DART) model is employed to improve the estimation of the net all-wave radiation balance, whereas the Element Surface Temperature Method (ESTM), adjusted to satellite observations is used to improve the estimation the estimation of the net change in <span class="hlt">heat</span> storage. Furthermore the estimation of the turbulent sensible and latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> is based on the Aerodynamic Resistance Method (ARM). Based on these outcomes, QF is estimated by regressing the sum of the turbulent <span class="hlt">heat</span> <span class="hlt">fluxes</span> versus the available energy. In-situ <span class="hlt">flux</span> measurements are used to evaluate URBANFLUXES outcomes, whereas uncertainties are specified and analyzed. URBANFLUXES is expected to prepare the ground for further innovative exploitation of EO in scientific activities (climate variability studies at local and regional scales) and future and emerging applications (sustainable urban planning, mitigation technologies) to benefit climate change mitigation/adaptation. This study presents the results of the first phase of the project and detailed information on URBANFLUXES is available at: http://urbanfluxes.eu</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/948969','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/948969"><span>Innovative Divertor Development to Solve the Plasma <span class="hlt">Heat-Flux</span> Problem</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rognlien, T; Ryutov, D; Makowski, M; Soukhanovskii, V; Umansky, M; Cohen, R; HIll, D; Joseph, I</p> <p>2009-02-26</p> <p>Large, localized plasma <span class="hlt">heat</span> exhaust continues to be one of the critical problems for the development of tokamak fusion reactors. Excessive <span class="hlt">heat</span> <span class="hlt">flux</span> erodes and possibly melts plasma-facing materials, thereby dramatically shortening their lifetime and increasing the impurity contamination of the core plasma. A detailed assessment by the ITER team for their divertor has revealed substantial limitations on the operational space imposed by the divertor <span class="hlt">performance</span>. For a fusion reactor, the problem becomes worse in that the divertor must accommodate 20% of the total fusion power (less any broadly radiated loss), while not allowing excess buildup of tritium in the walls nor excessive impurity production. This is an extremely challenging set of problems that must be solved for fusion to succeed as a power source; it deserves a substantial research investment. Material <span class="hlt">heat-flux</span> constraints: Results from present-day tokamaks show that there are two major limitations of peak plasma <span class="hlt">heat</span> exhaust. The first is the continuous flow of power to the divertor plates and nearby surfaces that, for present technology, is limited to 10-20 MW/m{sup 2}. The second is the transient peak <span class="hlt">heat-flux</span> that can be tolerated in a short time, {tau}{sub m}, before substantial ablation and melting of the surface occurs; such common large transient events are Edge Localized Mode (ELMs) and disruptions. The material limits imposed by these events give a peak energy/{tau}{sub m}{sup 1/2} parameter of {approx} 40 MJ/m{sup 2}s{sup 1/2} [1]. Both the continuous and transient limits can be approached by input powers in the largest present-day devices, and future devices are expected to substantially exceed the limits unless a solution can be found. Since the early 90's LLNL has developed the analytic and computational foundation for analyzing divertor plasmas, and also suggested and studied a number of solid and liquid material concepts for improving divertor/wall <span class="hlt">performance</span>, with the most recent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5894525','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5894525"><span>Measurement of <span class="hlt">performance</span> limits in cryogenic <span class="hlt">heat</span> pipes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Haug, F.; Prenger, F.C.; Chrisman, R.H.</p> <p>1986-01-01</p> <p>This paper describes the results of an experimental study designed to investigate the fabrication and operation of gravity-assist cryogenic <span class="hlt">heat</span> pipes. Two <span class="hlt">heat</span> pipes were built, the first having no formal wick but a roughened internal surface, the second having spiral grooves machined with a specially developed tool. The wall material of the <span class="hlt">heat</span> pipes was brass and hydrogen was used as the working fluid. The wicked <span class="hlt">heat</span> pipe became operational over the entire temperature range from the triple-point to the critical point. The <span class="hlt">performance</span> limitation depended on the operating temperature and the tilt angle. Axial <span class="hlt">heat</span> <span class="hlt">flux</span> densities of up to 50W/cm/sup 2/ were obtained. 15 refs., 9 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JMEP...22.1848P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JMEP...22.1848P"><span>Influence of Steel Grade on Surface Cooling Rates and <span class="hlt">Heat</span> <span class="hlt">Flux</span> during Quenching</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Prasanna Kumar, T. S.</p> <p>2013-07-01</p> <p>Immersion quenching is one of the most widely used processes for achieving martensitic and bainitic steels. The efficiency and quality of quenching are generally tested using standard quench probes for obtaining the cooling curves. A host of parameters like quenchant type, steel grade, bath agitation, section thickness, etc., affect the cooling curves. Cooling curve analyses covered under ASTM standards cannot be used to assess the <span class="hlt">performance</span> of a quenchant for different grades of steel, as they use a common material for the probe. This article reports the development of equipment, which, in conjunction with mathematical models, can be used for obtaining cooling curves for a specific steel/quenchant combination. The mathematical models couple nonlinear transient inverse <span class="hlt">heat</span> transfer with phase transformation, resulting in cooling curves specific to the steel grade-quenchant combination. The austenite decomposition models were based on an approach consistent with both the TTT diagram of the steel and Fe-C equilibrium phase diagrams. The TTT diagrams for the specific chemistry of the specimens and the thermophysical properties of the individual phases as functions of temperature were obtained using JMatPro software. Experiments were conducted in the laboratory for computing surface temperature and <span class="hlt">heat</span> <span class="hlt">flux</span> at the mid-section of a 25-mm diameter by 100-mm-long cylindrical specimen of two types of steels in two different quenchants. A low alloy steel (EN19) and a plain carbon steel (C45) were used for bringing out the influence of austenite transformation on surface cooling rates and <span class="hlt">heat</span> <span class="hlt">flux</span>. Two types of industrial quenchants (i) a mineral oil, and (ii) an aqueous solution of polymer were used. The results showed that the cooling curves, cooling rate curves, and the surface <span class="hlt">heat</span> <span class="hlt">flux</span> depended on the steel grade with the quenchant remaining the same.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/784115','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/784115"><span>Experimental Study of Thermal Crisis in Connection with Tokamak Reactor High <span class="hlt">Heat</span> <span class="hlt">Flux</span> Components</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gallo, D.; Giardina, M.; Castiglia, F.; Celata, G.P.; Mariani, A.; Zummo, G.; Cumo, M.</p> <p>2000-12-31</p> <p>The results of an experimental research on high <span class="hlt">heat</span> <span class="hlt">flux</span> thermal crisis in forced convective subcooled water flow, under operative conditions of interest to the thermal-hydraulic design of TOKAMAK fusion reactors, are here reported. These experiments, carried out in the framework of a collaboration between the Nuclear Engineering Department of Palermo University and the National Institute of Thermal - Fluid Dynamics of the ENEA - Casaccia (Rome), were <span class="hlt">performed</span> on the STAF (Scambio Termico Alti Flussi) water loop and consisted, essentially, in a high speed photographic study which enabled focusing several information on bubble characteristics and flow patterns taking place during the burnout phenomenology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ResPh...7..126H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ResPh...7..126H"><span>Flow between two stretchable rotating disks with Cattaneo-Christov <span class="hlt">heat</span> <span class="hlt">flux</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hayat, Tasawar; Qayyum, Sumaira; Imtiaz, Maria; Alsaedi, Ahmed</p> <p></p> <p>An analysis is <span class="hlt">performed</span> to investigate flow between two stretchable rotating disks. Thermal equation is constructed by Cattaneo-Christov <span class="hlt">heat</span> <span class="hlt">flux</span> theory. Porous medium is also taken into account. The nonlinear partial differential equations are first converted to ordinary differential equations and then computed for the convergent series solutions. Discussion about impact of dimensionless parameters on velocities, temperature and skin friction coefficient is given. It is observed that the radial velocity at upper disk enhances for larger values of ratio of corresponding stretching rate to angular velocity. Velocity in y-direction decays with an increase in rotational parameter. Magnitude of temperature profile decays for larger Prandtl number and thermal relaxation parameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10115375','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10115375"><span>A field study of the effects of inhomogeneities of surface sensible and latent <span class="hlt">heat</span> <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Doran, J.C.; Barnes, F.J.; Coulter, R.L.; Crawford, T.L.</p> <p>1992-01-01</p> <p>In recent years, the problem of characterizing turbulent <span class="hlt">fluxes</span> of <span class="hlt">heat</span>, momentum, and moisture over inhomogeneous surfaces has received increasing attention. This issue is relevant to the <span class="hlt">performance</span> of general circulation models (GCMs), in which a single grid element can encompass a variety of surface and topographical features. Although considerable progress has been made in describing the energy balance at a surface partially covered by vegetation, less is known about how to treat adjacent regions of sharply contrasting surface characteristics. One difficulty is the scarcity of suitable data sets with which to study the problem, particularly on scales of tens to hundreds of kilometers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996SoPh..166...17F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996SoPh..166...17F"><span>Radiative <span class="hlt">Heating</span> and the Buoyant Rise of Magnetic <span class="hlt">Flux</span> Tubes in the Solar interior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fan, Y.; Fisher, G. H.</p> <p>1996-06-01</p> <p>We study the effect of radiative <span class="hlt">heating</span> on the evolution of thin magnetic <span class="hlt">flux</span> tubes in the solar interior and on the eruption of magnetic <span class="hlt">flux</span> loops to the surface. Magnetic <span class="hlt">flux</span> tubes experience radiative <span class="hlt">heating</span> because (1) the mean temperature gradient in the lower convection zone and the overshoot region deviates substantially from that of radiative equilibrium, and hence there is a non-zero divergence of radiative <span class="hlt">heat</span> <span class="hlt">flux</span>; and (2) the magnetic pressure of the <span class="hlt">flux</span> tube causes a small change of the thermodynamic properties within the tube relative to the surrounding field-free fluid, resulting in an additional divergence of radiative <span class="hlt">heat</span> <span class="hlt">flux</span>. Our calculations show that the former constitutes the dominant source of radiative <span class="hlt">heating</span> experienced by the <span class="hlt">flux</span> tube. In the overshoot region, the radiative <span class="hlt">heating</span> is found to cause a quasi-static rising of the toroidal <span class="hlt">flux</span> tubes with an upward drift velocity ˜ 10-3|δ| cm s-1, where δ ≡ ∇e - ∇ad < 0 describes the subadiabaticity in the overshoot layer. The upward drift velocity does not depend sensitively on the field strength of the <span class="hlt">flux</span> tubes. Thus in order to store toroidal <span class="hlt">flux</span> tubes in the overshoot region for a period comparable to the length of the solar cycle, the magnitude of the subadiabaticity δ(< 0) in the overshoot region must be as large as ˜ 3 × 10-4. We discuss the possibilities for increasing the magnitude of δ and for reducing the rate of radiative <span class="hlt">heating</span> of the <span class="hlt">flux</span> tubes in the overshoot region. Using numerical simulations we study the formation of ‘Ω’-shaped emerging loops from toroidal <span class="hlt">flux</span> tubes in the overshoot region as a result of radiative <span class="hlt">heating</span>. The initial toroidal tube is assumed to be non-uniform in its thermodynamic properties along the tube and lies at varying depths beneath the base of the convection zone. The tube is initially in a state of neutral buoyancy with the internal density of the tube plasma equal to the local external density. We find from our</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Icar..250..116P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Icar..250..116P"><span>Elastic thickness and <span class="hlt">heat</span> <span class="hlt">flux</span> estimates for the uranian satellite Ariel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peterson, G.; Nimmo, F.; Schenk, P.</p> <p>2015-04-01</p> <p>The surface of Ariel, an icy satellite orbiting Uranus, shows extensional tectonic features suggesting an episode of endogenic <span class="hlt">heating</span> in the satellite's past. Using topography derived from stereo-photoclinometry, we identified flexural uplift at a rift zone suggesting elastic thickness values in the range 3.8-4.4 km. We estimate the temperature at the base of the lithosphere to be in the range 99-146 K, depending on the strain rate assumed, with corresponding <span class="hlt">heat</span> <span class="hlt">fluxes</span> of 28-92 mW/m2. Neither tidal <span class="hlt">heating</span>, assuming Ariel's current eccentricity, nor radiogenic <span class="hlt">heat</span> production from the silicate core are enough to cause the inferred <span class="hlt">heat</span> <span class="hlt">fluxes</span>. None of three proposed ancient mean-motion resonances produce equilibrium tidal <span class="hlt">heating</span> values in excess of 4.3 mW/m2. Thus, the origin of the inferred high <span class="hlt">heat</span> <span class="hlt">fluxes</span> is currently mysterious.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3995107','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3995107"><span>Estimation of Surface <span class="hlt">Heat</span> <span class="hlt">Flux</span> and Surface Temperature during Inverse <span class="hlt">Heat</span> Conduction under Varying Spray Parameters and Sample Initial Temperature</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Aamir, Muhammad; Liao, Qiang; Zhu, Xun; Aqeel-ur-Rehman; Wang, Hong</p> <p>2014-01-01</p> <p>An experimental study was carried out to investigate the effects of inlet pressure, sample thickness, initial sample temperature, and temperature sensor location on the surface <span class="hlt">heat</span> <span class="hlt">flux</span>, surface temperature, and surface ultrafast cooling rate using stainless steel samples of diameter 27 mm and thickness (mm) 8.5, 13, 17.5, and 22, respectively. Inlet pressure was varied from 0.2 MPa to 1.8 MPa, while sample initial temperature varied from 600°C to 900°C. Beck's sequential function specification method was utilized to estimate surface <span class="hlt">heat</span> <span class="hlt">flux</span> and surface temperature. Inlet pressure has a positive effect on surface <span class="hlt">heat</span> <span class="hlt">flux</span> (SHF) within a critical value of pressure. Thickness of the sample affects the maximum achieved SHF negatively. Surface <span class="hlt">heat</span> <span class="hlt">flux</span> as high as 0.4024 MW/m2 was estimated for a thickness of 8.5 mm. Insulation effects of vapor film become apparent in the sample initial temperature range of 900°C causing reduction in surface <span class="hlt">heat</span> <span class="hlt">flux</span> and cooling rate of the sample. A sensor location near to quenched surface is found to be a better choice to visualize the effects of spray parameters on surface <span class="hlt">heat</span> <span class="hlt">flux</span> and surface temperature. Cooling rate showed a profound increase for an inlet pressure of 0.8 MPa. PMID:24977219</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24977219','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24977219"><span>Estimation of surface <span class="hlt">heat</span> <span class="hlt">flux</span> and surface temperature during inverse <span class="hlt">heat</span> conduction under varying spray parameters and sample initial temperature.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Aamir, Muhammad; Liao, Qiang; Zhu, Xun; Aqeel-ur-Rehman; Wang, Hong; Zubair, Muhammad</p> <p>2014-01-01</p> <p>An experimental study was carried out to investigate the effects of inlet pressure, sample thickness, initial sample temperature, and temperature sensor location on the surface <span class="hlt">heat</span> <span class="hlt">flux</span>, surface temperature, and surface ultrafast cooling rate using stainless steel samples of diameter 27 mm and thickness (mm) 8.5, 13, 17.5, and 22, respectively. Inlet pressure was varied from 0.2 MPa to 1.8 MPa, while sample initial temperature varied from 600°C to 900°C. Beck's sequential function specification method was utilized to estimate surface <span class="hlt">heat</span> <span class="hlt">flux</span> and surface temperature. Inlet pressure has a positive effect on surface <span class="hlt">heat</span> <span class="hlt">flux</span> (SHF) within a critical value of pressure. Thickness of the sample affects the maximum achieved SHF negatively. Surface <span class="hlt">heat</span> <span class="hlt">flux</span> as high as 0.4024 MW/m(2) was estimated for a thickness of 8.5 mm. Insulation effects of vapor film become apparent in the sample initial temperature range of 900°C causing reduction in surface <span class="hlt">heat</span> <span class="hlt">flux</span> and cooling rate of the sample. A sensor location near to quenched surface is found to be a better choice to visualize the effects of spray parameters on surface <span class="hlt">heat</span> <span class="hlt">flux</span> and surface temperature. Cooling rate showed a profound increase for an inlet pressure of 0.8 MPa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011HMT....47.1341B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011HMT....47.1341B"><span>Modelling of <span class="hlt">heat</span> <span class="hlt">flux</span> received by a bubble pump of absorption-diffusion refrigeration cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benhmidene, Ali; Chaouachi, Béchir; Gabsi, Slimane; Bourouis, Mahmoud</p> <p>2011-11-01</p> <p>In the present study, the <span class="hlt">heat</span> <span class="hlt">flux</span> received by a bubble pump, which was simulated to a vertical tube 1 m long and with a variable diameter, was optimized. A numerical study was carried out in order to solve balance equations concerning the water-ammonia mixture in the up flow. The two-fluid model was used to derive the equations. A numerical study was carried out on a <span class="hlt">heat</span> <span class="hlt">flux</span> between 1 and 70 kW m-2 and the liquid velocity was determined. The optimum <span class="hlt">flux</span> was determined for a tube diameter equal to 4, 6, 8 and 10 mm and a mass flow rate ranging from 10 to 90 kg m-2 s-1. The optimum <span class="hlt">heat</span> <span class="hlt">flux</span> was correlated as a function of the tube diameter and mass flow rate, while the minimum <span class="hlt">heat</span> <span class="hlt">flux</span> required for pumping was correlated as a function of the tube diameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850046194&hterms=magnetic+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmagnetic%2Bcooling','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850046194&hterms=magnetic+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmagnetic%2Bcooling"><span>On the <span class="hlt">heating</span> mechanism of magnetic <span class="hlt">flux</span> loops in the solar atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Song, M. T.; Wu, S. T.</p> <p>1984-01-01</p> <p>An investigation is conducted of physical <span class="hlt">heating</span> mechanisms due to the ponderomotive forces exerted by turbulent waves along the solar atmosphere's curved magnetic <span class="hlt">flux</span> loops. Results indicate that the temperature difference between the inside and outside of the <span class="hlt">flux</span> loop can be classified into three parts, two of which represent the cooling or <span class="hlt">heating</span> effect exerted by the ponderomotive force, while the third is the <span class="hlt">heating</span> effect due to turbulent energy conversion from the localized plasma. This <span class="hlt">heating</span> mechanism is used to illustrate solar atmospheric <span class="hlt">heating</span> by means of an example that leads to the formulation of plages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981STIN...8130405M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981STIN...8130405M"><span>Ceramic <span class="hlt">heat</span> exchangers: Manufacturing techniques and <span class="hlt">performance</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merrigan, M. A.; Sandstrom, D. J.</p> <p>1981-05-01</p> <p>The objective of the ceramic <span class="hlt">heat</span> pipe program being conducted at Los Alamos is demonstration of the practical feasibility of this technology for the solution of severe high temperature recuperation functions. Ceramic <span class="hlt">heat</span> pipe recuperators were theoretically shown to offer distinct advantages over conventional ceramic <span class="hlt">heat</span> exchangers from the standpoint of efficiency of <span class="hlt">heat</span> recuperation and economics. The main stumbling block to their widespread utilization is related to the problems of materials for construction and the details of fabrication and assembly. The <span class="hlt">performance</span> objectives of ceramic <span class="hlt">heat</span> pipes and some aspects of the materials technology program aimed at solving the problem of economic ceramic <span class="hlt">heat</span> pipe fabrication are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24946013','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24946013"><span>Estimation of surface <span class="hlt">heat</span> <span class="hlt">flux</span> and temperature distributions in a multilayer tissue based on the hyperbolic model of <span class="hlt">heat</span> conduction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Haw-Long; Chen, Wen-Lih; Chang, Win-Jin; Yang, Yu-Ching</p> <p>2015-01-01</p> <p>In this study, an inverse algorithm based on the conjugate gradient method and the discrepancy principle is applied to solve the inverse hyperbolic <span class="hlt">heat</span> conduction problem in estimating the unknown time-dependent surface <span class="hlt">heat</span> <span class="hlt">flux</span> in a skin tissue, which is stratified into epidermis, dermis, and subcutaneous layers, from the temperature measurements taken within the medium. Subsequently, the temperature distributions in the tissue can be calculated as well. The concept of finite <span class="hlt">heat</span> propagation velocity is applied to the modeling of the bioheat transfer problem. The inverse solutions will be justified based on the numerical experiments in which two different <span class="hlt">heat</span> <span class="hlt">flux</span> distributions are to be determined. The temperature data obtained from the direct problem are used to simulate the temperature measurements. The influence of measurement errors on the precision of the estimated results is also investigated. Results show that an excellent estimation on the time-dependent surface <span class="hlt">heat</span> <span class="hlt">flux</span> can be obtained for the test cases considered in this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhST..128..182M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhST..128..182M"><span>Qualification of high <span class="hlt">heat</span> <span class="hlt">flux</span> components: application to target elements of W7-X divertor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Missirlian, M.; Durocher, A.; Grosman, A.; Schlosser, J.; Boscary, J.; Escourbiac, F.; Cismondi, F.</p> <p>2007-03-01</p> <p>The development of actively cooled plasma-facing components (PFC) represents one of fusion's most challenging engineering efforts. In this frame, a high-quality bonding between the refractory armour and the <span class="hlt">heat</span> sink is essential to ensure the <span class="hlt">heat</span> removal capability and the thermal <span class="hlt">performances</span> of PFC. Experience gained during manufacturing of Tore Supra actively cooled PFC led to the establishment of a qualification methodology and provided a large experience of acceptance criteria using an active infrared thermography (système d'acquisition de traitement infra-rouge, SATIR). This paper presents the application of this qualification process to the W7-X pre-series components, with the objective of assessing and defining workable acceptance criteria that enable reliable predictions of <span class="hlt">performance</span> at the nominal <span class="hlt">heat</span> <span class="hlt">flux</span> requirements in W7-X. Finally, to check the reliability of the non-destructive examination (NDE) method by transient infrared thermography, the newly defined acceptance criteria were applied to W7-X pre-series target elements (batch #3). The SATIR results, benchmarked with HHF tests <span class="hlt">performed</span> on the GLADIS ion beam facility were discussed to assess the ability to detect critical defects at the interface between tiles and <span class="hlt">heat</span> sink.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122..726R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122..726R"><span>Surface <span class="hlt">flux</span> and ocean <span class="hlt">heat</span> transport convergence contributions to seasonal and interannual variations of ocean <span class="hlt">heat</span> content</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roberts, C. D.; Palmer, M. D.; Allan, R. P.; Desbruyeres, D. G.; Hyder, P.; Liu, C.; Smith, D.</p> <p>2017-01-01</p> <p>We present an observation-based <span class="hlt">heat</span> budget analysis for seasonal and interannual variations of ocean <span class="hlt">heat</span> content (H) in the mixed layer (Hmld) and full-depth ocean (Htot). Surface <span class="hlt">heat</span> <span class="hlt">flux</span> and ocean <span class="hlt">heat</span> content estimates are combined using a novel Kalman smoother-based method. Regional contributions from ocean <span class="hlt">heat</span> transport convergences are inferred as a residual and the dominant drivers of Hmld and Htot are quantified for seasonal and interannual time scales. We find that non-Ekman ocean <span class="hlt">heat</span> transport processes dominate Hmld variations in the equatorial oceans and regions of strong ocean currents and substantial eddy activity. In these locations, surface temperature anomalies generated by ocean dynamics result in turbulent <span class="hlt">flux</span> anomalies that drive the overlying atmosphere. In addition, we find large regions of the Atlantic and Pacific oceans where <span class="hlt">heat</span> transports combine with local air-sea <span class="hlt">fluxes</span> to generate mixed layer temperature anomalies. In all locations, except regions of deep convection and water mass transformation, interannual variations in Htot are dominated by the internal rearrangement of <span class="hlt">heat</span> by ocean dynamics rather than the loss or addition of <span class="hlt">heat</span> at the surface. Our analysis suggests that, even in extratropical latitudes, initialization of ocean dynamical processes could be an important source of skill for interannual predictability of Hmld and Htot. Furthermore, we expect variations in Htot (and thus thermosteric sea level) to be more predictable than near surface temperature anomalies due to the increased importance of ocean <span class="hlt">heat</span> transport processes for full-depth <span class="hlt">heat</span> budgets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.1551S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.1551S"><span>Modelling the mechanical response of an idealized ice stream to variations in geothermal <span class="hlt">heat</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith-Johnsen, Silje; de Fleurian, Basile; Hestnes Nisancioglu, Kerim</p> <p>2017-04-01</p> <p>The spatial distribution of geothermal <span class="hlt">heat</span> <span class="hlt">flux</span> beneath the Greenland Ice Sheet is largely unknown partly due to difficulties in accessing the bed, and bore hole data providing point measurements only. Studies using tectonic, seismic and magnetic models to retrieve the geothermal <span class="hlt">heat</span> <span class="hlt">flux</span> show very different results indicating large uncertainties. However, modelling studies point to a geothermal <span class="hlt">heat</span> <span class="hlt">flux</span> anomaly that may influence the Northeast Greenland Ice Stream (NEGIS). Previous studies have investigated the impact of the uncertainty in geothermal heatflux on ice dynamics. These studies are mainly focusing on the impact on the ice rheology as the basal condition are derived from inverse modelling methods (including the geothermal <span class="hlt">heat</span> <span class="hlt">flux</span> variability in the variability of the friction coefficient). Another important feedback is the increase in subglacial meltwater production which may affect the sliding velocities of an ice stream, and has not been taken into account in preceding studies. In this study we investigate the impact of variations in geothermal <span class="hlt">heat</span> <span class="hlt">flux</span> on ice dynamics by analysing the mechanical response of a synthetic ice stream simulating NEGIS using the Ice Sheet System Model (Larour et al. 2012). We present results from model experiments using different <span class="hlt">heat</span> <span class="hlt">flux</span> configurations, friction laws and a hydrology model, showing the importance of geothermal <span class="hlt">heat</span> <span class="hlt">flux</span> on basal conditions of fast flowing ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917050Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917050Z"><span>Mesoscale eddies control meridional <span class="hlt">heat</span> <span class="hlt">flux</span> variability in the subpolar North Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Jian; Bower, Amy; Yang, Jiayan; Lin, Xiaopei; Zhou, Chun</p> <p>2017-04-01</p> <p>The meridional <span class="hlt">heat</span> <span class="hlt">flux</span> in the subpolar North Atlantic is vital to the climate of the high-latitude North Atlantic. For the basinwide <span class="hlt">heat</span> <span class="hlt">flux</span> across a section between Greenland and Scotland, much of the variability occurs in the Iceland basin, where the North Atlantic Current (NAC) carries relatively warm and salty water northward. As a component of the Overturning in the Subpolar North Atlantic Program (OSNAP), WHOI and OUC are jointly operating gliders in the Iceland Basin to continuously monitor the circulation and corresponding <span class="hlt">heat</span> <span class="hlt">flux</span> in this eddy-rich region. Based on one year of observations, two circulation regimes in the Iceland basin have been identified: a mesoscale eddy like circulation pattern and northward NAC circulation pattern. When a mesoscale eddy is generated, the rotational currents associated with the eddy lead to both northward and southward flow in the Iceland basin. This is quite different from the broad northward flow associated with the NAC when there is no eddy. The transition between the two regimes coupled with the strong temperature front in the Iceland basin can modify the meridional <span class="hlt">heat</span> <span class="hlt">flux</span> on the order of 0.3PW, which is the dominant source for the <span class="hlt">heat</span> <span class="hlt">flux</span> change the Iceland Basin. According to high-resolution numerical model results, the Iceland Basin has the largest contribution to the meridional <span class="hlt">heat</span> <span class="hlt">flux</span> variability along the section between Greenland and Scotland. Therefore, mesoscale eddies in the Iceland Basin provide important dynamics to control the meridional <span class="hlt">heat</span> <span class="hlt">flux</span> variability in the subpolar North Atlantic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE10008E..0CC','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE10008E..0CC"><span>Anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span> estimation from space: results of the first phase of the URBANFLUXES project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chrysoulakis, Nektarios; Marconcini, Mattia; Gastellu-Etchegorry, Jean-Philippe; Grimmond, C. S. B.; Feigenwinter, Christian; Lindberg, Fredrik; Del Frate, Fabio; Klostermann, Judith; Mitraka, Zina; Esch, Thomas; Landier, Lucas; Gabey, Andy; Parlow, Eberhard; Olofson, Frans</p> <p>2016-10-01</p> <p>H2020-Space project URBANFLUXES (URBan ANthrpogenic <span class="hlt">heat</span> <span class="hlt">FLUX</span> from Earth observation Satellites) investigates the potential of Copernicus Sentinels to retrieve anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span>, as a key component of the Urban Energy Budget (UEB). URBANFLUXES advances the current knowledge of the impacts of UEB <span class="hlt">fluxes</span> on urban <span class="hlt">heat</span> island and consequently on energy consumption in cities. This will lead to the development of tools and strategies to mitigate these effects, improving thermal comfort and energy efficiency. In URBANFLUXES, the anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span> is estimated as a residual of UEB. Therefore, the rest UEB components, namely, the net all-wave radiation, the net change in <span class="hlt">heat</span> storage and the turbulent sensible and latent <span class="hlt">heat</span> <span class="hlt">fluxes</span> are independently estimated from Earth Observation (EO), whereas the advection term is included in the error of the anthropogenic <span class="hlt">heat</span> <span class="hlt">flux</span> estimation from the UEB closure. The project exploits Sentinels observations, which provide improved data quality, coverage and revisit times and increase the value of EO data for scientific work and future emerging applications. These observations can reveal novel scientific insights for the detection and monitoring of the spatial distribution of the urban energy budget <span class="hlt">fluxes</span> in cities, thereby generating new EO opportunities. URBANFLUXES thus exploits the European capacity for space-borne observations to enable the development of operational services in the field of urban environmental monitoring and energy efficiency in cities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ClDy...49..983V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ClDy...49..983V"><span>An assessment of air-sea <span class="hlt">heat</span> <span class="hlt">fluxes</span> from ocean and coupled reanalyses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valdivieso, Maria; Haines, Keith; Balmaseda, Magdalena; Chang, You-Soon; Drevillon, Marie; Ferry, Nicolas; Fujii, Yosuke; Köhl, Armin; Storto, Andrea; Toyoda, Takahiro; Wang, Xiaochun; Waters, Jennifer; Xue, Yan; Yin, Yonghong; Barnier, Bernard; Hernandez, Fabrice; Kumar, Arun; Lee, Tong; Masina, Simona; Andrew Peterson, K.</p> <p>2017-08-01</p> <p>Sixteen monthly air-sea <span class="hlt">heat</span> <span class="hlt">flux</span> products from global ocean/coupled reanalyses are compared over 1993-2009 as part of the Ocean Reanalysis Intercomparison Project (ORA-IP). Objectives include assessing the global <span class="hlt">heat</span> closure, the consistency of temporal variability, comparison with other <span class="hlt">flux</span> products, and documenting errors against in situ <span class="hlt">flux</span> measurements at a number of OceanSITES moorings. The ensemble of 16 ORA-IP <span class="hlt">flux</span> estimates has a global positive bias over 1993-2009 of 4.2 ± 1.1 W m-2. Residual <span class="hlt">heat</span> gain (i.e., surface <span class="hlt">flux</span> + assimilation increments) is reduced to a small positive imbalance (typically, +1-2 W m-2). This compensation between surface <span class="hlt">fluxes</span> and assimilation increments is concentrated in the upper 100 m. Implied steady meridional <span class="hlt">heat</span> transports also improve by including assimilation sources, except near the equator. The ensemble spread in surface <span class="hlt">heat</span> <span class="hlt">fluxes</span> is dominated by turbulent <span class="hlt">fluxes</span> (>40 W m-2 over the western boundary currents). The mean seasonal cycle is highly consistent, with variability between products mostly <10 W m-2. The interannual variability has consistent signal-to-noise ratio ( 2) throughout the equatorial Pacific, reflecting ENSO variability. Comparisons at tropical buoy sites (10°S-15°N) over 2007-2009 showed too little ocean <span class="hlt">heat</span> gain (i.e., <span class="hlt">flux</span> into the ocean) in ORA-IP (up to 1/3 smaller than buoy measurements) primarily due to latent <span class="hlt">heat</span> <span class="hlt">flux</span> errors in ORA-IP. Comparisons with the Stratus buoy (20°S, 85°W) over a longer period, 2001-2009, also show the ORA-IP ensemble has 16 W m-2 smaller net <span class="hlt">heat</span> gain, nearly all of which is due to too much latent cooling caused by differences in surface winds imposed in ORA-IP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ClDy..tmp..392V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ClDy..tmp..392V"><span>An assessment of air-sea <span class="hlt">heat</span> <span class="hlt">fluxes</span> from ocean and coupled reanalyses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valdivieso, Maria; Haines, Keith; Balmaseda, Magdalena; Chang, You-Soon; Drevillon, Marie; Ferry, Nicolas; Fujii, Yosuke; Köhl, Armin; Storto, Andrea; Toyoda, Takahiro; Wang, Xiaochun; Waters, Jennifer; Xue, Yan; Yin, Yonghong; Barnier, Bernard; Hernandez, Fabrice; Kumar, Arun; Lee, Tong; Masina, Simona; Andrew Peterson, K.</p> <p>2015-10-01</p> <p>Sixteen monthly air-sea <span class="hlt">heat</span> <span class="hlt">flux</span> products from global ocean/coupled reanalyses are compared over 1993-2009 as part of the Ocean Reanalysis Intercomparison Project (ORA-IP). Objectives include assessing the global <span class="hlt">heat</span> closure, the consistency of temporal variability, comparison with other <span class="hlt">flux</span> products, and documenting errors against in situ <span class="hlt">flux</span> measurements at a number of OceanSITES moorings. The ensemble of 16 ORA-IP <span class="hlt">flux</span> estimates has a global positive bias over 1993-2009 of 4.2 ± 1.1 W m-2. Residual <span class="hlt">heat</span> gain (i.e., surface <span class="hlt">flux</span> + assimilation increments) is reduced to a small positive imbalance (typically, +1-2 W m-2). This compensation between surface <span class="hlt">fluxes</span> and assimilation increments is concentrated in the upper 100 m. Implied steady meridional <span class="hlt">heat</span> transports also improve by including assimilation sources, except near the equator. The ensemble spread in surface <span class="hlt">heat</span> <span class="hlt">fluxes</span> is dominated by turbulent <span class="hlt">fluxes</span> (>40 W m-2 over the western boundary currents). The mean seasonal cycle is highly consistent, with variability between products mostly <10 W m-2. The interannual variability has consistent signal-to-noise ratio (~2) throughout the equatorial Pacific, reflecting ENSO variability. Comparisons at tropical buoy sites (10°S-15°N) over 2007-2009 showed too little ocean <span class="hlt">heat</span> gain (i.e., <span class="hlt">flux</span> into the ocean) in ORA-IP (up to 1/3 smaller than buoy measurements) primarily due to latent <span class="hlt">heat</span> <span class="hlt">flux</span> errors in ORA-IP. Comparisons with the Stratus buoy (20°S, 85°W) over a longer period, 2001-2009, also show the ORA-IP ensemble has 16 W m-2 smaller net <span class="hlt">heat</span> gain, nearly all of which is due to too much latent cooling caused by differences in surface winds imposed in ORA-IP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MeScT..26b5303C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MeScT..26b5303C"><span>New technique for the fabrication of miniature thin film <span class="hlt">heat</span> <span class="hlt">flux</span> gauges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Collins, Matthew; Chana, Kam; Povey, Thomas</p> <p>2015-02-01</p> <p>This paper details the improvements made to the design and fabrication of thin-film <span class="hlt">heat</span> <span class="hlt">flux</span> gauges at Oxford. These improvements have been driven by the desire to improve measurement accuracy and resolution in short duration wind-tunnel experiments. A thin-film <span class="hlt">heat</span> <span class="hlt">flux</span> gauge (TFHFG) measures <span class="hlt">heat</span> <span class="hlt">flux</span> by recording the temperature history of thin film resistive temperature sensors sputtered onto an insulating substrate. The <span class="hlt">heat</span> <span class="hlt">flux</span> can then be calculated using Fourier’s law of <span class="hlt">heat</span> conduction. A new fabrication process utilising technology from the manufacture of flexible printed circuit boards is outlined, which enables the production of significantly smaller and more robust gauges than those previously used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890052278&hterms=Norwegian+Sea&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DNorwegian%2BSea','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890052278&hterms=Norwegian+Sea&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DNorwegian%2BSea"><span>A study of oceanic surface <span class="hlt">heat</span> <span class="hlt">fluxes</span> in the Greenland, Norwegian, and Barents Seas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hakkinen, Sirpa; Cavalieri, Donald J.</p> <p>1989-01-01</p> <p>This study examines oceanic surface <span class="hlt">heat</span> <span class="hlt">fluxes</span> in the Norwegian, Greenland, and Barents seas using the gridded Navy Fleet Numerical Oceanography Central surface analysis and the First GARP Global Experiment (FGGE) IIc cloudiness data bases. Monthly and annual means of net and turbulent <span class="hlt">heat</span> <span class="hlt">fluxes</span> are computed for the FGGE year 1979. The FGGE IIb data base consisting of individual observations provides particularly good data coverage in this region for a comparison with the gridded Navy winds and air temperatures. The standard errors of estimate between the Navy and FGGE IIb winds and air temperatures are 3.6 m/s and 2.5 C, respectively. The computations for the latent and sensible <span class="hlt">heat</span> <span class="hlt">fluxes</span> are based on bulk formulas with the same constant <span class="hlt">heat</span> exchange coefficient of 0.0015. The results show extremely strong wintertime <span class="hlt">heat</span> <span class="hlt">fluxes</span> in the northern Greenland Sea and especially in the Barents Sea in contrast to previous studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22253075','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22253075"><span>E × B shear pattern formation by radial propagation of <span class="hlt">heat</span> <span class="hlt">flux</span> waves</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kosuga, Y.; Diamond, P. H.; Dif-Pradalier, G.; Gürcan, Ö. D.</p> <p>2014-05-15</p> <p>A novel theory to describe the formation of E×B flow patterns by radially propagating <span class="hlt">heat</span> <span class="hlt">flux</span> waves is presented. A model for <span class="hlt">heat</span> avalanche dynamics is extended to include a finite delay time between the instantaneous <span class="hlt">heat</span> <span class="hlt">flux</span> and the mean <span class="hlt">flux</span>, based on an analogy between <span class="hlt">heat</span> avalanche dynamics and traffic flow dynamics. The response time introduced here is an analogue of the drivers' response time in traffic dynamics. The microscopic foundation for the time delay is the time for mixing of the phase space density. The inclusion of the finite response time changes the model equation for avalanche dynamics from Burgers equation to a nonlinear telegraph equation. Based on the telegraph equation, the formation of <span class="hlt">heat</span> <span class="hlt">flux</span> jams is predicted. The growth rate and typical interval of jams are calculated. The connection of the jam interval to the typical step size of the E×B staircase is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130000651','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130000651"><span>Surface Catalysis and Oxidation on Stagnation Point <span class="hlt">Heat</span> <span class="hlt">Flux</span> Measurements in High Enthalpy Arc Jets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nawaz, Anuscheh; Driver, David M.; Terrazas-Salinas</p> <p>2013-01-01</p> <p><span class="hlt">Heat</span> <span class="hlt">flux</span> sensors are routinely used in arc jet facilities to determine <span class="hlt">heat</span> transfer rates from plasma plume. The goal of this study is to assess the impact of surface composition changes on these <span class="hlt">heat</span> <span class="hlt">flux</span> sensors. Surface compositions can change due to oxidation and material deposition from the arc jet. Systematic surface analyses of the sensors were conducted before and after exposure to plasma. Currently copper is commonly used as surface material. Other surface materials were studied including nickel, constantan gold, platinum and silicon dioxide. The surfaces were exposed to plasma between 0.3 seconds and 3 seconds. Surface changes due to oxidation as well as copper deposition from the arc jets were observed. Results from changes in measured <span class="hlt">heat</span> <span class="hlt">flux</span> as a function of surface catalycity is given, along with a first assessment of enthalpy for these measurements. The use of cupric oxide is recommended for future <span class="hlt">heat</span> <span class="hlt">flux</span> measurements, due to its consistent surface composition arc jets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhPl...21e5701K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhPl...21e5701K"><span>E × B shear pattern formation by radial propagation of <span class="hlt">heat</span> <span class="hlt">flux</span> wavesa)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kosuga, Y.; Diamond, P. H.; Dif-Pradalier, G.; Gürcan, Ã.-. D.</p> <p>2014-05-01</p> <p>A novel theory to describe the formation of E ×B flow patterns by radially propagating <span class="hlt">heat</span> <span class="hlt">flux</span> waves is presented. A model for <span class="hlt">heat</span> avalanche dynamics is extended to include a finite delay time between the instantaneous <span class="hlt">heat</span> <span class="hlt">flux</span> and the mean <span class="hlt">flux</span>, based on an analogy between <span class="hlt">heat</span> avalanche dynamics and traffic flow dynamics. The response time introduced here is an analogue of the drivers' response time in traffic dynamics. The microscopic foundation for the time delay is the time for mixing of the phase space density. The inclusion of the finite response time changes the model equation for avalanche dynamics from Burgers equation to a nonlinear telegraph equation. Based on the telegraph equation, the formation of <span class="hlt">heat</span> <span class="hlt">flux</span> jams is predicted. The growth rate and typical interval of jams are calculated. The connection of the jam interval to the typical step size of the E ×B staircase is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27..670T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27..670T"><span>On-board Direct Eddy <span class="hlt">Flux</span> Measurements of <span class="hlt">Heat</span>, Water Vapor and Co2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsukamoto, O.; Takahashi, S.; Kono, T.; Yamashita, E.; Ishida, H.</p> <p></p> <p>Direct eddy <span class="hlt">fluxes</span> of <span class="hlt">heat</span>(sensible and latent), water vapor and CO2 were measuted with on-board eddy <span class="hlt">flux</span> system over the Pacific. Present authors are continueing direct eddy <span class="hlt">flux</span> measurement on R/V MIRAI(JAMSTEC) cruising the Pacific. I addition to these routine <span class="hlt">heat</span> <span class="hlt">flux</span> evaluation, direct CO2 <span class="hlt">flux</span> measurements were applied with LI- 7500 (Licor) and Kaijo sonic anemometer. The eddy <span class="hlt">flux</span> system including CO2 sensor worked very well even in the moving ship. Small amplitude of turbulent fluctuations of CO2 were measured and it is found that CO2 was transported downward to sea surface during a month(Nov-Dec 2001) around 2N,138E. CO2 concentrations in the air and sea water were also measured and they also confirmed the CO2 sink. The automated real-time eddy <span class="hlt">flux</span> system including ship motion correction has started and this can be applied to other cruising ships.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170002665&hterms=challenge+value&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dchallenge%2Bvalue','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170002665&hterms=challenge+value&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dchallenge%2Bvalue"><span>GEM-CEDAR Challenge: Poynting <span class="hlt">Flux</span> at DMSP and Modeled Joule <span class="hlt">Heat</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rastaetter, Lutz; Shim, Ja Soon; Kuznetsova, Maria M.; Kilcommons, Liam M.; Knipp, Delores J.; Codrescu, Mihail; Fuller-Rowell, Tim; Emery, Barbara; Weimer, Daniel R.; Cosgrove, Russell; Wiltberger, Michael; Raeder, Joachim; Li, Wenhui; Toth, Gabor; Welling, Daniel</p> <p>2016-01-01</p> <p>Poynting <span class="hlt">flux</span> into the ionosphere measures the electromagnetic energy coming from the magnetosphere. This energy <span class="hlt">flux</span> can vary greatly between quiet times and geomagnetic active times. As part of the Geospace Environment Modeling-coupling energetics and dynamics of atmospheric regions modeling challenge, physics-based models of the 3-D ionosphere and ionospheric electrodynamics solvers of magnetosphere models that specify Joule <span class="hlt">heat</span> and empirical models specifying Poynting <span class="hlt">flux</span> were run for six geomagnetic storm events of varying intensity. We compared model results with Poynting <span class="hlt">flux</span> values along the DMSP-15 satellite track computed from ion drift meter and magnetic field observations. Although being a different quantity, Joule <span class="hlt">heat</span> can in practice be correlated to incoming Poynting <span class="hlt">flux</span> because the energy is dissipated primarily in high latitudes where Poynting <span class="hlt">flux</span> is being deposited. Within the physics-based model group, we find mixed results with some models overestimating Joule <span class="hlt">heat</span> and some models agreeing better with observed Poynting <span class="hlt">flux</span> rates as integrated over auroral passes. In contrast, empirical models tend to underestimate integrated Poynting <span class="hlt">flux</span> values. Modeled Joule <span class="hlt">heat</span> or Poynting <span class="hlt">flux</span> patterns often resemble the observed Poynting <span class="hlt">flux</span> patterns on a large scale, but amplitudes can differ by a factor of 2 or larger due to the highly localized nature of observed Poynting <span class="hlt">flux</span> deposition that is not captured by the models. In addition, the positioning of modeled patterns appear to be randomly shifted against the observed Poynting <span class="hlt">flux</span> energy input. This study is the first to compare Poynting <span class="hlt">flux</span> and Joule <span class="hlt">heat</span> in a large variety of models of the ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170002665&hterms=heat&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dheat','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170002665&hterms=heat&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dheat"><span>GEM-CEDAR Challenge: Poynting <span class="hlt">Flux</span> at DMSP and Modeled Joule <span class="hlt">Heat</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rastaetter, Lutz; Shim, Ja Soon; Kuznetsova, Maria M.; Kilcommons, Liam M.; Knipp, Delores J.; Codrescu, Mihail; Fuller-Rowell, Tim; Emery, Barbara; Weimer, Daniel R.; Cosgrove, Russell; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170002665'); toggleEditAbsImage('author_20170002665_show'); toggleEditAbsImage('author_20170002665_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170002665_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170002665_hide"></p> <p>2016-01-01</p> <p>Poynting <span class="hlt">flux</span> into the ionosphere measures the electromagnetic energy coming from the magnetosphere. This energy <span class="hlt">flux</span> can vary greatly between quiet times and geomagnetic active times. As part of the Geospace Environment Modeling-coupling energetics and dynamics of atmospheric regions modeling challenge, physics-based models of the 3-D ionosphere and ionospheric electrodynamics solvers of magnetosphere models that specify Joule <span class="hlt">heat</span> and empirical models specifying Poynting <span class="hlt">flux</span> were run for six geomagnetic storm events of varying intensity. We compared model results with Poynting <span class="hlt">flux</span> values along the DMSP-15 satellite track computed from ion drift meter and magnetic field observations. Although being a different quantity, Joule <span class="hlt">heat</span> can in practice be correlated to incoming Poynting <span class="hlt">flux</span> because the energy is dissipated primarily in high latitudes where Poynting <span class="hlt">flux</span> is being deposited. Within the physics-based model group, we find mixed results with some models overestimating Joule <span class="hlt">heat</span> and some models agreeing better with observed Poynting <span class="hlt">flux</span> rates as integrated over auroral passes. In contrast, empirical models tend to underestimate integrated Poynting <span class="hlt">flux</span> values. Modeled Joule <span class="hlt">heat</span> or Poynting <span class="hlt">flux</span> patterns often resemble the observed Poynting <span class="hlt">flux</span> patterns on a large scale, but amplitudes can differ by a factor of 2 or larger due to the highly localized nature of observed Poynting <span class="hlt">flux</span> deposition that is not captured by the models. In addition, the positioning of modeled patterns appear to be randomly shifted against the observed Poynting <span class="hlt">flux</span> energy input. This study is the first to compare Poynting <span class="hlt">flux</span> and Joule <span class="hlt">heat</span> in a large variety of models of the ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SpWea..14..113R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SpWea..14..113R"><span>GEM-CEDAR challenge: Poynting <span class="hlt">flux</span> at DMSP and modeled Joule <span class="hlt">heat</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rastätter, Lutz; Shim, Ja Soon; Kuznetsova, Maria M.; Kilcommons, Liam M.; Knipp, Delores J.; Codrescu, Mihail; Fuller-Rowell, Tim; Emery, Barbara; Weimer, Daniel R.; Cosgrove, Russell; Wiltberger, Michael; Raeder, Joachim; Li, Wenhui; Tóth, Gábor; Welling, Daniel</p> <p>2016-02-01</p> <p>Poynting <span class="hlt">flux</span> into the ionosphere measures the electromagnetic energy coming from the magnetosphere. This energy <span class="hlt">flux</span> can vary greatly between quiet times and geomagnetic active times. As part of the Geospace Environment Modeling-coupling energetics and dynamics of atmospheric regions modeling challenge, physics-based models of the 3-D ionosphere and ionospheric electrodynamics solvers of magnetosphere models that specify Joule <span class="hlt">heat</span> and empirical models specifying Poynting <span class="hlt">flux</span> were run for six geomagnetic storm events of varying intensity. We compared model results with Poynting <span class="hlt">flux</span> values along the DMSP-15 satellite track computed from ion drift meter and magnetic field observations. Although being a different quantity, Joule <span class="hlt">heat</span> can in practice be correlated to incoming Poynting <span class="hlt">flux</span> because the energy is dissipated primarily in high latitudes where Poynting <span class="hlt">flux</span> is being deposited. Within the physics-based model group, we find mixed results with some models overestimating Joule <span class="hlt">heat</span> and some models agreeing better with observed Poynting <span class="hlt">flux</span> rates as integrated over auroral passes. In contrast, empirical models tend to underestimate integrated Poynting <span class="hlt">flux</span> values. Modeled Joule <span class="hlt">heat</span> or Poynting <span class="hlt">flux</span> patterns often resemble the observed Poynting <span class="hlt">flux</span> patterns on a large scale, but amplitudes can differ by a factor of 2 or larger due to the highly localized nature of observed Poynting <span class="hlt">flux</span> deposition that is not captured by the models. In addition, the positioning of modeled patterns appear to be randomly shifted against the observed Poynting <span class="hlt">flux</span> energy input. This study is the first to compare Poynting <span class="hlt">flux</span> and Joule <span class="hlt">heat</span> in a large variety of models of the ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ThApC.129..913A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ThApC.129..913A"><span>Estimation of ground <span class="hlt">heat</span> <span class="hlt">flux</span> from soil temperature over a bare soil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>An, Kedong; Wang, Wenke; Wang, Zhoufeng; Zhao, Yaqian; Yang, Zeyuan; Chen, Li; Zhang, Zaiyong; Duan, Lei</p> <p>2017-08-01</p> <p>Ground soil <span class="hlt">heat</span> <span class="hlt">flux</span>, G 0, is a difficult-to-measure but important component of the surface energy budget. Over the past years, many methods were proposed to estimate G 0; however, the application of these methods was seldom validated and assessed under different weather conditions. In this study, three popular models (force-restore, conduction-convection, and harmonic) and one widely used method (plate calorimetric), which had well <span class="hlt">performance</span> in publications, were investigated using field data to estimate daily G 0 on clear, cloudy, and rainy days, while the gradient calorimetric method was regarded as the reference for assessing the accuracy. The results showed that harmonic model was well reproducing the G 0 curve for clear days, but it yielded large errors on cloudy and rainy days. The force-restore model worked well only under rainfall condition, but it was poor to estimate G 0 under rain-free conditions. On the contrary, the conduction-convection model was acceptable to determine G 0 under rain-free conditions, but it generated large errors on rainfall days. More importantly, the plate calorimetric method was the best to estimate G 0 under different weather conditions compared with the three models, but the <span class="hlt">performance</span> of this method is affected by the placement depth of the <span class="hlt">heat</span> <span class="hlt">flux</span> plate. As a result, the <span class="hlt">heat</span> <span class="hlt">flux</span> plate was recommended to be buried as close as possible to the surface under clear condition. But under cloudy and rainy conditions, the plate placed at depth of around 0.075 m yielded G 0 well. Overall, the findings of this paper provide guidelines to acquire more accurate estimation of G 0 under different weather conditions, which could improve the surface energy balance in field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11874138','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11874138"><span>Methodology for estimation of time-dependent surface <span class="hlt">heat</span> <span class="hlt">flux</span> due to cryogen spray cooling.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tunnell, James W; Torres, Jorge H; Anvari, Bahman</p> <p>2002-01-01</p> <p>Cryogen spray cooling (CSC) is an effective technique to protect the epidermis during cutaneous laser therapies. Spraying a cryogen onto the skin surface creates a time-varying <span class="hlt">heat</span> <span class="hlt">flux</span>, effectively cooling the skin during and following the cryogen spurt. In previous studies mathematical models were developed to predict the human skin temperature profiles during the cryogen spraying time. However, no studies have accounted for the additional cooling due to residual cryogen left on the skin surface following the spurt termination. We formulate and solve an inverse <span class="hlt">heat</span> conduction (IHC) problem to predict the time-varying surface <span class="hlt">heat</span> <span class="hlt">flux</span> both during and following a cryogen spurt. The IHC formulation uses measured temperature profiles from within a medium to estimate the surface <span class="hlt">heat</span> <span class="hlt">flux</span>. We implement a one-dimensional sequential function specification method (SFSM) to estimate the surface <span class="hlt">heat</span> <span class="hlt">flux</span> from internal temperatures measured within an in vitro model in response to a cryogen spurt. Solution accuracy and experimental errors are examined using simulated temperature data. <span class="hlt">Heat</span> <span class="hlt">flux</span> following spurt termination appears substantial; however, it is less than that during the spraying time. The estimated time-varying <span class="hlt">heat</span> <span class="hlt">flux</span> can subsequently be used in forward <span class="hlt">heat</span> conduction models to estimate temperature profiles in skin during and following a cryogen spurt and predict appropriate timing for onset of the laser pulse.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPCO6014B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPCO6014B"><span>Reduction in resonant magnetic field induced <span class="hlt">heat</span> <span class="hlt">flux</span> splitting caused by detachment of the divertor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Briesemeister, A. R.; Ahn, J.-W.; Hillis, D. L.; Lore, J. D.; Shafer, M. W.; Unterberg, E. A.; Wingen, A.; Schmitz, O.; Frerichs, H.; Makowski, M. A.; McLean, A. G.; Ferraro, N. M.</p> <p>2015-11-01</p> <p>Measurements in DIII-D show that in high-density detached divertor conditions, the inter-ELM non-axisymmetric <span class="hlt">heat</span> <span class="hlt">flux</span> striations generated by resonant magnetic perturbations (RMPs) are eliminated. Non-axisymmetric <span class="hlt">heat</span> loads caused by the RMP fields used to mitigate ELMs could reduce the lifetime of divertor components in ITER and future devices. It is shown that for RMPs with an n=3 toroidal mode number low levels of gas puffing can cause an increase in the <span class="hlt">heat</span> <span class="hlt">flux</span> splitting, but at high densities where the divertor becomes detached this splitting is eliminated. VUV imaging and 2D divertor Thomson scattering are used to measure RMP induced perturbations to the plasma conditions above the target plates. Modeling <span class="hlt">performed</span> with the 3D fluid transport code EMC3-EIRENE both with and without the plasma response calculated by M3D-C1 is compared to the measured divertor conditions. Work supported by the US DOE under DE-AC05-00OR22725, DE-FC02-04ER54698, DE-AC52-07NA27344 & DE-FG02-92ER54139.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050051730','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050051730"><span>Time and Space Resolved Wall Temperature Measurements during Nucleate Boiling with Constant <span class="hlt">Heat</span> <span class="hlt">Flux</span> Boundary Conditions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Yerramilli, Vamsee K.; Kim, Jungho</p> <p>2005-01-01</p> <p>The lack of temporally and spatially resolved measurements under nucleate bubbles has complicated efforts to fully explain pool-boiling phenomena. The objective of this current work is to acquire time and space resolved temperature distributions under nucleate bubbles on a constant <span class="hlt">heat</span> <span class="hlt">flux</span> surface. This was <span class="hlt">performed</span> using a microheater array with 100 micron resolution that allowed effectively simultaneous measurements of surface temperature while supplying a constant dissipative <span class="hlt">heat</span> <span class="hlt">flux</span>. This data is then correlated with high speed (> 1000Hz) visual recordings of the bubble growth and departure from the heater surface acquired from below and from the side of the heater. The data indicate that a significant source of energy during bubble nucleation and initial growth is the superheated layer around the bubble. Bubble coalescence was not observed to decrease surface temperature as significantly as bubble departure from the surface. Since bubble departure is typically followed by a sharp increase in the heater surface temperature, it is surmised that the departing bubble effectively removes the superheated layer, allowing a high local <span class="hlt">heat</span> transfer rate with the bulk fluid through transient conduction/micro-convection during rewetting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870049077&hterms=albrecht&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dalbrecht','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870049077&hterms=albrecht&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dalbrecht"><span>Parametric representation of <span class="hlt">heat</span> and moisture <span class="hlt">fluxes</span> in cloud-topped mixed layers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Penc, Richard S.; Albrecht, Bruce A.</p> <p>1987-01-01</p> <p>The Betts (1973, 1978) parametrization of <span class="hlt">heat</span> and moisture <span class="hlt">fluxes</span> is tested using measurements made in thin, broken, and solid stratocumulus clouds by the NCAR Electra off the California coast in June 1976. The turbulence data are used to determine updraft-downdraft properties, <span class="hlt">heat</span> and moisture <span class="hlt">fluxes</span>, spectra, and cospectra. From the convective properties, vertical mass <span class="hlt">flux</span> profiles are obtained and examined for consistency. A convective scaling which is appropriate for cloud-topped mixed layers is discussed. The results demonstrate the usefulness of a mass <span class="hlt">flux</span> formulation in modeling applications for cloud conditions varying between solid and broken.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720011318','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720011318"><span>Pyrotechnic hazards classification and evaluation program test report. <span class="hlt">Heat</span> <span class="hlt">flux</span> study of deflagrating pyrotechnic munitions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fassnacht, P. O.</p> <p>1971-01-01</p> <p>A <span class="hlt">heat</span> <span class="hlt">flux</span> study of deflagrating pyrotechnic munitions is presented. Three tests were authorized to investigate whether <span class="hlt">heat</span> <span class="hlt">flux</span> measurements may be used as effective hazards evaluation criteria to determine safe quantity distances for pyrotechnics. A passive sensor study was conducted simultaneously to investigate their usefulness in recording events and conditions. It was concluded that <span class="hlt">heat</span> <span class="hlt">flux</span> measurements can effectively be used to evaluate hazards criteria and that passive sensors are an inexpensive tool to record certain events in the vicinity of deflagrating pyrotechnic stacks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12564506','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12564506"><span>Effects of mass flow rate and droplet velocity on surface <span class="hlt">heat</span> <span class="hlt">flux</span> during cryogen spray cooling.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Karapetian, Emil; Aguilar, Guillermo; Kimel, Sol; Lavernia, Enrique J; Nelson, J Stuart</p> <p>2003-01-07</p> <p>Cryogen spray cooling (CSC) is used to protect the epidermis during dermatologic laser surgery. To date, the relative influence of the fundamental spray parameters on surface cooling remains incompletely understood. This study explores the effects of mass flow rate and average droplet velocity on the surface <span class="hlt">heat</span> <span class="hlt">flux</span> during CSC. It is shown that the effect of mass flow rate on the surface <span class="hlt">heat</span> <span class="hlt">flux</span> is much more important compared to that of droplet velocity. However, for fully atomized sprays with small flow rates, droplet velocity can make a substantial difference in the surface <span class="hlt">heat</span> <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890056315&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddropout','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890056315&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddropout"><span>Electron <span class="hlt">heat</span> <span class="hlt">flux</span> dropouts in the solar wind - Evidence for interplanetary magnetic field reconnection?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mccomas, D. J.; Gosling, J. T.; Phillips, J. L.; Bame, S. J.; Luhmann, J. G.; Smith, E. J.</p> <p>1989-01-01</p> <p>An examination of ISEE-3 data from 1978 reveal 25 electron <span class="hlt">heat</span> <span class="hlt">flux</span> dropout events ranging in duration from 20 min to over 11 hours. The <span class="hlt">heat</span> <span class="hlt">flux</span> dropouts are found to occur in association with high plasma densities, low plasma velocities, low ion and electron temperatures, and low magnetic field magnitudes. It is suggested that the <span class="hlt">heat</span> <span class="hlt">flux</span> dropout intervals may indicate that the spacecraft is sampling plasma regimes which are magnetically disconnected from the sun and instead are connected to the outer heliosphere at both ends.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730019076','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730019076"><span>Extended hydrodynamic theory of the peak and minimum pool boiling <span class="hlt">heat</span> <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Linehard, J. H.; Dhir, V. K.</p> <p>1973-01-01</p> <p>The hydrodynamic theory of the extreme pool boiling <span class="hlt">heat</span> <span class="hlt">fluxes</span> is expanded to embrace a variety of problems that have not previously been analyzed. These problems include the prediction of the peak <span class="hlt">heat</span> <span class="hlt">flux</span> on a variety of finite heaters, the influence of viscosity on the Taylor and Helmoltz instability mechanisms with application to film boiling and to the peak <span class="hlt">heat</span> <span class="hlt">flux</span> in viscous liquids, the formalization of the analogy between high-current-density electrolysis and boiling, and the description of boiling in the low-gravity limit. The predictions are verified with a large number of new data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910015010','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910015010"><span>Analysis of the transient calibration of <span class="hlt">heat</span> <span class="hlt">flux</span> sensors: One dimensional case</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dybbs, A.; Ling, J. X.</p> <p>1989-01-01</p> <p>The effect of transient <span class="hlt">heat</span> <span class="hlt">flux</span> on <span class="hlt">heat</span> <span class="hlt">flux</span> sensor response and calibration is analyzed. A one dimensional case was studied in order to elucidate the key parameters and trends for the problem. It has the added advantage that the solutions to the governing equations can be obtained by analytic means. The analytical results obtained to date indicate that the transient response of a <span class="hlt">heat</span> <span class="hlt">flux</span> sensor depends on the thermal boundary conditions, the geometry and the thermal properties of the sensor. In particular it was shown that if the thermal diffusivity of the sensor is small, then the transient behavior must be taken into account.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6432052','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6432052"><span>Experimental <span class="hlt">performance</span> of a <span class="hlt">heat</span> pipe</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Said, S.A.; Akash, B.A. . Dept. of Mechanical and Industrial Engineering)</p> <p>1999-07-01</p> <p><span class="hlt">Heat</span> pipes can be used to enhance the amount of <span class="hlt">heat</span> transfer. Since <span class="hlt">heat</span> transmitted through a <span class="hlt">heat</span> pipe is based on phase change, it can be pointed out that using a <span class="hlt">heat</span> pipe with similar dimensions of a solid metal pipe, larger amounts of <span class="hlt">heat</span> transfer will be obtained. Their application is wide and can be used, for example, in energy conservation, such as <span class="hlt">heat</span> recovery in hot exhaust gas system, and for use in domestic and industrial applications. Solar <span class="hlt">heating</span> is also another example