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Sample records for rectangular heat source

  1. A study of mixed convection in large baffled rectangular chambers with and without internal heat sources

    NASA Astrophysics Data System (ADS)

    Yerkes, K. L.

    1990-03-01

    A numerical and experimental investigation to determine the thermal effects on the development of the flow structure in large baffled rectangular chambers with and without internal heat sources was completed. Two- and three-dimensional numerical models were formulated using the time dependent laminar Navier-Stokes equations assuming a Boussinesq fluid with a Prandtl number of 0.7. Experiments were conducted using a scaled down model simulated the full size chamber enabling experimental data to be obtained and subsequently compared with numerical results. Flow visualization experiments were conducted using the larger, full size chamber. Internal horizontal baffles and heat sources were located symmetrically about the vertical centerline axis. Mixed convection without internal heat sources for both aided and opposed buoyant forces showed that the development of the flow structure was sensitive to small variations in the temperature difference between the inlet and the vertical walls. Mixed convection with internal heat sources showed the flow structure to develop through a series of bifurcations from steady state, to periodic, aperiodic and finally chaotic with increasing heat source temperature. Use of the scaled down laboratory experimental model as an indicator for the flow development in the larger full size chamber showed significant 3-D effects. Flow visualization in the larger full size chamber using Silahydrocarbon aerosol droplets showed good agreement with the 2-D numerical results.

  2. Numerical simulation of three-dimensional mixed convection heat transfer from an array of discrete heat sources in a horizontal rectangular duct

    SciTech Connect

    Mahaney, H.V.; Ramadhyani, S.; Incropera, F.P. . School of Mechanical Engineering)

    1989-01-01

    Using a vectorized finite-difference marching technique, the steady-state continuity, momentum, and energy equations are solved numerically to evaluate the effects of buoyancy-induced secondary flow on forced flow in a horizontal rectangular duct with a four-row array of 12 heat sources flush mounted to the bottom wall. Secondary flows, in the form of longitudinal vortices, initially develop at spanwise positions corresponding to the edges of the heat sources. Additional plumes and vortices subsequently develop across the heater width, leading to the eventual formation of large-scale circulation patterns. For a fixed Rayleigh number and decreasing Reynolds number, the row-average Nusselt numbers decrease, reach a minimum, and subsequently increase due to bouyancy effects. Thus, due to buoyancy-induced secondary flow, conditions exist for which heat transfer may be enhanced by reducing the flow rate and hence the pump ower requiement. Heat transfer enhancement above the forced convection limit, as well as the Reynolds number range for which enhancement occurs, increases with increasing Raleigh number. Appropriate scaling parameters are introduced to characterize the strength of the buoyancy-induced secondary flow and to delineate conditions for which it is significant.

  3. Enhancement of single-phase heat transfer and critical heat flux from an ultra-high-flux simulated microelectronic heat source to a rectangular impinging jet of dielectric liquid

    SciTech Connect

    Wadsworth, D.C.; Mudawar, I. )

    1992-08-01

    Jet impingement is encountered in numerous applications demanding high heating or cooling fluxes. Examples include annealing of metal sheets and cooling of turbine blades, x-ray medical devices, laser weapons, and fusion blankets. The attractive heat transfer attributes of jet impingement have also stimulated research efforts on cooling of high-heat-flux microelectronic devices. These devices are fast approaching heat fluxes in excess of 100 W/cm[sup 2], which have to be dissipated using coolants that are both electrically and chemically compatible with electronic components. Unfortunately, fluids satisfying these requirements tend to possess poor transport properties, creating a need for significant enhancement in the heat transfer coefficient by such means as increased coolant flow rate and phase change. The cooling problem is compounded by a need to cool large arrays of heat sources in minimal volume, and to reduce the spacing between adjacent circuit boards. These requirements place severe constraints on the packaging of jet impingement cooling hardware.

  4. Natural convection heat transfer along vertical rectangular ducts

    NASA Astrophysics Data System (ADS)

    Ali, M.

    2009-12-01

    Experimental investigations have been reported on steady state natural convection from the outer surface of vertical rectangular and square ducts in air. Seven ducts have been used; three of them have a rectangular cross section and the rest have square cross section. The ducts are heated using internal constant heat flux heating elements. The temperatures along the vertical surface and the peripheral directions of the duct wall are measured. Axial (perimeter averaged) heat transfer coefficients along the side of each duct are obtained for laminar and transition to turbulent regimes of natural convection heat transfer. Axial (perimeter averaged) Nusselt numbers are evaluated and correlated using the modified Rayleigh numbers for laminar and transition regime using the vertical axial distance as a characteristic length. Critical values of the modified Rayleigh numbers are obtained for transition to turbulent. Furthermore, total overall averaged Nusselt numbers are correlated with the modified Rayleigh numbers and the area ratio for the laminar regimes. The local axial (perimeter averaged) heat transfer coefficients are observed to decrease in the laminar region and increase in the transition region. Laminar regimes are obtained at the lower half of the ducts and its chance to appear decreases as the heat flux increases.

  5. Nanofluid jet impingement heat transfer characteristics in the rectangular mini-fin heat sink

    NASA Astrophysics Data System (ADS)

    Naphon, Paisarn; Nakharintr, Lursukd

    2012-11-01

    The nanofluid jet impingement heat transfer characteristics in a rectangular mini-fin heat sink are studied. The heat sink is fabricated from aluminum by a wire electrical discharge machine. The nanofluid is a mixture of deionized water and nanoscale TiO2 particles with a volume nanoparticle concentration of 0.2%. The results obtained for nanofluid jet impingement cooling in the rectangular mini-fin heat sink are compared with those found in the water jet impingement cooling. The effects of the inlet temperature of the nanofluid, its Reynolds number, and the heat flux on the heat transfer characteristics of the rectangular mini-fin heat sink are considered. It is found that the average heat transfer rates for the nanofluid as coolant are higher than those for deionized water.

  6. Cooling of a rectangular microchannel heat sink with ammonia gas

    NASA Astrophysics Data System (ADS)

    Adham, Ahmed Mohammed; Mohd-Ghazali, Normah; Ahmad, Robiah

    2012-06-01

    The increased global demands for the minimization of integrated circuits used in electronic devices have led manufacturing companies to direct their resources towards research in that area. The minimization processes provided very powerful electronic chips but with a very large amount of heat generation. One of the methods applied to remove the heat produced is to use a microchannel heat sink. Past optimization attempts have looked at the microchannel geometry, material, and coolant types using various models to represent the heat sink. This paper reports the analytical study on the optimization of the thermal resistance and pressure drop of a rectangular microchannel heat sink using a new coolant, ammonia gas. The effect of different channel aspect ratio was investigated. Significant reduction in thermal resistance was obtained with 0.218 K/W for ammonia gas compared to that of 0.266 k/W for air under the same operating conditions. The total pressure drop achieved was 5.36 mbar and 9.52 mbar for ammonia and air respectively. The results indicate promising potential for ammonia gas as a coolant for rectangular microchannel heat sink.

  7. Corner heating in rectangular solid oxide electrochemical cell generators

    DOEpatents

    Reichner, Philip

    1989-01-01

    Disclosed is an improvement in a solid oxide electrochemical cell generator 1 having a rectangular design with four sides that meet at corners, and containing multiplicity of electrically connected fuel cells 11, where a fuel gas is passed over one side of said cells and an oxygen containing gas is passed into said cells, and said fuel is burned to form heat, electricity, and an exhaust gas. The improvement comprises passing the exhaust gases over the multiplicity of cells 11 in such a way that more of the heat in said exhaust gases flows at the corners of the generator, such as through channels 19.

  8. Boiling heat transfer in a small horizontal rectangular channel

    SciTech Connect

    Tran, T.N.; Wambsganss, M.W.; Jendrzejczyk, J.A.; France, D.M.

    1993-08-01

    Compact heat exchangers have traditionally found wide application in the transportation industry, where they are used as evaporators and condensers in vapor compression cycles for air conditioning and refrigeration. Such heat exchangers possess numerous attractive features including high thermal effectiveness, small size, low weight, design flexibility, and pure counterflow, and they can accommodate multiple streams. Today, there is a widespread interest in expanding the range of application of compact heat exchangers to include phase-change heat transfer in the process industries, among others. An overall objective of this effort is to provide the basis for establishing design technology in this area. In the present study, small channel flow boiling heat transfer was extended to a rectangular channel (4.06 {times} 1.70 mm) using refrigerant 12 (R-12). As with the circular tube studies, the flow channel wall was electrically heated providing a constant heat flux. Tests were performed over a quality range of 0.15 to 0.80, and large ranges of mass fluxes (50 to 400 kg/m{sup 2}s) and heat flux (4 to 34 kW/m{sup 2}). Heat transfer was measured and results are compared with correlation predictions.

  9. Constructal design for a rectangular body with nonuniform heat generation

    NASA Astrophysics Data System (ADS)

    Feng, Huijun; Chen, Lingen; Xie, Zhihui; Sun, Fengrui

    2016-08-01

    Nonuniform heat generation models with constant and variable cross-section high-conductivity channels (HCCs) are built in this paper. The minimum dimensionless peak temperature (DPT) is taken as the optimization objective. Different from the models with uniform heat generation and constant cross-section HCCs built by Bejan (1997) and Ledezma et al. (1997), the model with nonuniform heat generation and variable cross-section HCC is more practical and can help to improve the heat conduction performance of a thermal system. The results show that for the rectangular first-order assembly (RFOA) with nonuniform heat generation, there exist both the optimal shape of the RFOA and the optimal HCCs width ratio, which lead to the minimum DPT. They are different from those with uniform heat generation. When the heat is nonuniformly generated in the RFOA, the minimum DPT of the RFOA with variable cross-section HCC is reduced by 12.11% compared with that with constant cross-section HCC. Moreover, the numerical results are also verified by the analytical method.

  10. Improved approximate formulas for flux from cylindrical and rectangular sources

    SciTech Connect

    Wallace, O.J.; Bokharee, S.A.

    1993-03-01

    This report provides two new approximate formulas for the flux at detector points outside the radial and axial extensions of a homogeneous cylindrical source and improved approximate formulas for the flux at points opposite rectangular surface sources. These formulas extend the range of geometries for which analytic approximations may be used by shield design engineers to make rapid scoping studies and check more extensive calculations for reasonableness. These formulas can be used to support skeptical, independent evaluations and are also valuable teaching tools for introducing shield designers to complex shield analyses.

  11. Periodic orbits in tall laterally heated rectangular cavities

    NASA Astrophysics Data System (ADS)

    Net, Marta; Sánchez Umbría, Juan

    2017-02-01

    This study elucidates the origin of the multiplicity of stable oscillatory flows detected by time integration in tall rectangular cavities heated from the side. By using continuation techniques for periodic orbits, it is shown that initially unstable branches, arising at Hopf bifurcations of the basic steady flow, become stable after crossing Neimark-Sacker points. There are no saddle-node or pitchfork bifurcations of periodic orbits, which could have been alternative mechanisms of stabilization. According to the symmetries of the system, the orbits are either fixed cycles, which retain at any time the center symmetry of the steady flow, or symmetric cycles involving a time shift in the global invariance of the orbit. The bifurcation points along the branches of periodic flows are determined. By using time integrations, with unstable periodic solutions as initial conditions, we determine which of the bifurcations at the limits of the intervals of stable periodic orbits are sub- or supercritical.

  12. Heat exchange at laminar flow in rectangular channels

    NASA Astrophysics Data System (ADS)

    Valueva, E. P.; Purdin, M. S.

    2016-11-01

    Numerical modeling of heat exchange at a laminar stationary and pulsatile flow in rectangular channels with different aspect ratios of side lengths γ has been carried out by a finite difference method for two boundary conditions: a constant wall temperature and a constant heat flux density on the wall. For the boundary condition of the first kind, the similarity of distributions of the heat flux density and shear stress on the walls over the channel perimeter has been established. The reasons for a nonmonotonous dependence of the initial thermal interval length on γ are discussed. For the boundary condition of the second kind, the difference of the Nusselt number averaged over the perimeter at γ → 0 from its value for a flow in a flat channel has been explained. An increase in the Nusselt number averaged over the perimeter and the period of oscillations has been revealed for a pulsatile flow in the quasi-stationary regime at large amplitudes of the oscillations of the velocity averaged over the cross section.

  13. Acoustic source analysis of a rectangular supersonic jet

    NASA Astrophysics Data System (ADS)

    Kreitzman, Jordan; Nichols, Joseph W.

    2014-11-01

    We apply Goldstein's generalized acoustic analogy to identify acoustic sources in two high-fidelity unstructured large eddy simulation databases of a Mach 1.4 rectangular jet with and without chevrons. Two-point, two-time correlations of the acoustic source terms are evaluated at different positions in the three dimensional flow that develops downstream of the complex nozzle. Two-point statistics are compared to single-point statistics to test the quasi-normality hypothesis and other noise source models for a non-axisymmetric jet. In particular, we assess the predictive capability of a Gaussian model, a fixed-frame model and a modified-distance model. The nozzle geometries used for the simulations exactly match an experimental configuration tested at the NASA Glenn Research Center, allowing for validation in terms of both farfield noise as well as turbulence statistics. We gratefully acknowledge computational resources provided by the Argonne Leadership Computing Facility.

  14. Critical Heat Flux in Inclined Rectangular Narrow Gaps

    SciTech Connect

    Jeong J. Kim; Yong H. Kim; Seong J. Kim; Sang W. Noh; Kune Y. Suh; Joy L. Rempe; Fan-Bill Cheung; Sang B. Kim

    2004-06-01

    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 heat flux (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 heated by the thin film resistor on the back. The heater assembly was installed to the tip of the rotating arm in the heated 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.

  15. Effect of concave rectangular winglet vortex generator on convection coefficient of heat transfer

    NASA Astrophysics Data System (ADS)

    Syaiful, Sugiri, Gladys; Soetanto, Maria F.; Bae, Myung-whan

    2017-01-01

    This study shows an experimental result of effects of concave rectangular winglet vortex generator on convection heat transfer coefficient. There are two types of vortex generator those are rectangular winglet and concave rectangular winglet. The aim of this study is to observe effects of geometry and numbers of vortex generator to the increase of heat transfer coefficient. This experiment was done in a glass rectangular channel. Overall, this experiment was conducted with (rectangular and concave rectangular winglets) and without (baseline) vortex generator. Both types of vortex generator were placed at a 30° angle of attack, in an inline position, and variation numbers of vortex generator row of 1, 2 and 3 rows. Vortex generators were mounted on an aluminum plate which was mounted on a heater with 35 watts of heat, inside the rectangular channel. Airflow passed through vortex generators was varied by its inlet velocity to be 0.4 m/s to 2.0 m/s with an interval of 0.2 m/s. The experimental result shows that 3 row of concave rectangular winglet gives the highest heat transfer coefficient enhancement. Nusselt number and j-factor increase but thermal resistance decrease. Experiment results that Nusselt number and j-factor increase up to 205% while thermal resistance decreases up to 67% compared to baseline for the highest Reynolds number.

  16. Dual source heat pump

    DOEpatents

    Ecker, Amir L.; Pietsch, Joseph A.

    1982-01-01

    What is disclosed is a heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating the fluid in heat exchange relationship with a refrigerant fluid; at least two refrigerant heat exchangers, one for effecting heat exchange with the fluid and a second for effecting heat exchange between refrigerant and a heat exchange fluid and the ambient air; a compressor for efficiently compressing the refrigerant; at least one throttling valve for throttling liquid refrigerant; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circulating device and heat exchange fluid circuit for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and direction of flow of the refrigerant therethrough for selecting a particular mode of operation. The heat exchange fluid provides energy for defrosting the second heat exchanger when operating in the air source mode and also provides a alternate source of heat.

  17. Screech noise source structure of a supersonic rectangular jet

    NASA Technical Reports Server (NTRS)

    Rice, E. J.; Taghavi, R.

    1992-01-01

    The near-field of the screech noise source structure of an under-expanded supersonic rectangular jet was studied in detail. A miniature probe microphone was used along with a reference microphone to determine the amplitude and phase of the sound pressure near and in the high speed flow field. The transverse structure of the unsteady pressure field was investigated by moving the probe microphone sufficiently far into the jet so that pressure fall-off was observed. Five islands of high sound pressure level have been distinguished which may be associated with the actual local sources of sound production. These sources of screech noise are closely associated with the jet shock structure as would be expected, with the peak region of noise level being found slightly downstream of each of the five observed shocks. The third and fourth noise sources have the highest levels and are about equal in strength. All of the apparent noise sources have their peak levels in the subsonic flow region. Strong cancellations in the acoustic field are observed in the downstream and sideline directions which may account for the predominant upstream propagation of the fundamental tone noise.

  18. Natural Convection Heat Transfer in a Rectangular Water Pool with Internal Heating and Top and Bottom Cooling

    SciTech Connect

    Lee, Jong K.; Lee, Seung D.; Suh, Kune Y.

    2006-07-01

    During a severe accident, the reactor core may melt and be relocated to the lower plenum to form a hemispherical pool. If there is no effective cooling mechanism, the core debris may heat up and the molten pool run into natural convection. Natural convection heat transfer was examined in SIGMA RP (Simulant Internal Gravitated Material Apparatus Rectangular Pool). The SIGMA RP apparatus comprises a rectangular test section, heat exchanger, cartridge heaters, cooling jackets, thermocouples and a data acquisition system. The internal heater heating method was used to simulate uniform heat source which is related to the modified Rayleigh number Ra'. The test procedure started with water, the working fluid, filling in the test section. There were two boundary conditions: one dealt with both walls being cooled isothermally, while the other had to with only the upper wall being cooled isothermally. The heat exchanger was utilized to maintain the isothermal boundary condition. Four side walls were surrounded by the insulating material to minimize heat loss. Tests were carried out at 10{sup 11} < Ra' < 10{sup 13}. The SIGMA RP tests with an appropriate cartridge heater arrangement showed excellent uniform heat generation in the pool. The steady state was defined such that the temperature fluctuation stayed within {+-}0.2 K over a time period of 5,000 s. The conductive heat transfer was dominant below the critical Rayleigh number Ra'c, whereas the convective heat transfer picked up above Ra'{sub c}. In the top and bottom boundary cooling condition, the upward Nusselt number Nu{sub up} was greater than the downward Nusselt number Nu{sub dn}. In particular, the discrepancy between Nu{sub up} and Nu{sub dn} widened with Ra'. The Nu{sub up} to Nu{sub dn} ratio was varied from 7.75 to 16.77 given 1.45 x 10{sup 12} < Ra' < 9.59 x 10{sup 13}. On the other hand, Nu{sub up} was increased in absence of downward heat transfer for the case of top cooling. The current rectangular pool

  19. An approximate algorithm for the flux from a rectangular volume source

    SciTech Connect

    Wallace, O.J.

    1994-11-09

    An exact semi-analytic formula for the flux from a rectangular surface source with a slab shield has been derived and the required function table has been calculated. This formula is the basis for an algorithm which gives a good approximation for the flux from a rectangular volume source. No other hand calculation method for this source geometry is available in the literature.

  20. Acoustic source analysis of a supersonic rectangular chevron jet

    NASA Astrophysics Data System (ADS)

    Kreitzman, Jordan Richard

    Source terms corresponding to Goldstein's generalized acoustic analogy are computed from a high-fidelity simulation of a supersonic jet issuing from a rectangular nozzle with chevrons. Simulated data are validated against experimental data. We investigate the theoretical underpinning of reduced-order acoustic source models by testing the assumptions of quasi-normality and statistical axisymmetry. It is found that the flow is not quasi-normal in the axial direction but is quasi-normal in the transverse directions. Our analysis also shows that the flow is locally statistically axisymmetric close to the edges of the flow but not near the center. Fourth order correlation statistics are fit to previously used acoustic source models originally developed for axisymmetric jets. This thesis performs a detailed analysis of four different models: the Gaussian, moving-frame, fixed-frame, and modified-distance models. The latter three models are found to be similar in accuracy, while the Gaussian model is found to be a poorer fit.

  1. Thulium-170 heat source

    SciTech Connect

    Walter, C.E.; Van Konynenburg, R.; Van Sant, J.H.

    1992-01-21

    This patent describes an isotopic heat source. It comprises; at least one isotopic fuel stack, comprising alternating layers of: thulium oxide; and a low atomic weight diluent for thulium oxide; a heat block defining holes into which the fuel stacks can be placed; at least one heat pipe for heat removal, with the heat pipe being positioned in the heat block in thermal connection with the fuel stack; and a structural container surrounding the heat block.

  2. Numerical Investigation of Heat Transfer Enhancement in a Rectangular Heated Pipe for Turbulent Nanofluid

    PubMed Central

    Kazi, Salim Newaz; Sadeghinezhad, Emad

    2014-01-01

    Thermal characteristics of turbulent nanofluid flow in a rectangular pipe have been investigated numerically. The continuity, momentum, and energy equations were solved by means of a finite volume method (FVM). The symmetrical rectangular channel is heated at the top and bottom at a constant heat flux while the sides walls are insulated. Four different types of nanoparticles Al2O3, ZnO, CuO, and SiO2 at different volume fractions of nanofluids in the range of 1% to 5% are considered in the present investigation. In this paper, effect of different Reynolds numbers in the range of 5000 < Re < 25000 on heat transfer characteristics of nanofluids flowing through the channel is investigated. The numerical results indicate that SiO2-water has the highest Nusselt number compared to other nanofluids while it has the lowest heat transfer coefficient due to low thermal conductivity. The Nusselt number increases with the increase of the Reynolds number and the volume fraction of nanoparticles. The results of simulation show a good agreement with the existing experimental correlations. PMID:25254236

  3. Numerical investigation of heat transfer enhancement in a rectangular heated pipe for turbulent nanofluid.

    PubMed

    Yarmand, Hooman; Gharehkhani, Samira; Kazi, Salim Newaz; Sadeghinezhad, Emad; Safaei, Mohammad Reza

    2014-01-01

    Thermal characteristics of turbulent nanofluid flow in a rectangular pipe have been investigated numerically. The continuity, momentum, and energy equations were solved by means of a finite volume method (FVM). The symmetrical rectangular channel is heated at the top and bottom at a constant heat flux while the sides walls are insulated. Four different types of nanoparticles Al2O3, ZnO, CuO, and SiO2 at different volume fractions of nanofluids in the range of 1% to 5% are considered in the present investigation. In this paper, effect of different Reynolds numbers in the range of 5000 < Re < 25000 on heat transfer characteristics of nanofluids flowing through the channel is investigated. The numerical results indicate that SiO2-water has the highest Nusselt number compared to other nanofluids while it has the lowest heat transfer coefficient due to low thermal conductivity. The Nusselt number increases with the increase of the Reynolds number and the volume fraction of nanoparticles. The results of simulation show a good agreement with the existing experimental correlations.

  4. Natural Convection Heat Transfer in a Rectangular Liquid Metal Pool With Bottom Heating and Top Cooling

    SciTech Connect

    Lee, Il S.; Yu, Yong H.; Son, Hyoung M.; Hwang, Jin S.; Suh, Kune Y.

    2006-07-01

    An experimental study is performed to investigate the natural convection heat transfer characteristics with subcooled coolant to create engineering database for basic applications in a lead alloy cooled reactor. Tests are performed in the ALTOS (Applied Liquid-metal Thermal Operation Study) apparatus as part of MITHOS (Metal Integrated Thermo Hydrodynamic Operation System). A relationship is determined between the Nusselt number Nu and the Rayleigh number Ra in the liquid metal rectangular pool. Results are compared with correlations and experimental data in the literature. Given the similar Ra condition, the present test results for Nu of the liquid metal pool with top subcooling are found to be similar to those predicted by the existing correlations or experiments. The current test results are utilized to develop natural convection heat transfer correlations applicable to low Prandtl number Pr fluids that are heated from below and cooled by the external coolant above. Results from this study are slated to be used in designing BORIS (Battery Optimized Reactor Integral System), a small lead cooled modular fast reactor for deployment at remote sites cycled with MOBIS (Modular Optimized Brayton Integral System) for electricity generation, tied with NAVIS (Naval Application Vessel Integral System) for ship propulsion, joined with THAIS (Thermochemical Hydrogen Acquisition Integral System) for hydrogen production, and coupled with DORIS (Desalination Optimized Reactor Integral System) for seawater desalination. Tests are performed with Wood's metal (Pb-Bi-Sn-Cd) filling a rectangular pool whose lower surface is heated and upper surface cooled by forced convection of water. The test section is 20 cm long, 11.3 cm high and 15 cm wide. The simulant has a melting temperature of 78 deg. C. The constant temperature and heat flux condition was realized for the bottom heating once the steady state had been met. The test parameters include the heated bottom surface temperature

  5. Multiple source heat pump

    DOEpatents

    Ecker, Amir L.

    1983-01-01

    A heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating a fluid in heat exchange relationship with a refrigerant fluid, at least three refrigerant heat exchangers, one for effecting heat exchange with the fluid, a second for effecting heat exchange with a heat exchange fluid, and a third for effecting heat exchange with ambient air; a compressor for compressing the refrigerant; at least one throttling valve connected at the inlet side of a heat exchanger in which liquid refrigerant is vaporized; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circuit and pump for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and directional flow of refrigerant therethrough for selecting a particular mode of operation. Also disclosed are a variety of embodiments, modes of operation, and schematics therefor.

  6. Heat transfer in thin, compact heat exchangers with circular, rectangular, or pin-fin flow passages

    NASA Technical Reports Server (NTRS)

    Olson, D. A.

    1992-01-01

    Heat transfer and pressure drop have been measured of three thin, compact heat exchangers in helium gas at 3.5 MPa and higher, with Reynolds numbers of 450 to 36,000. The flow geometries for the three heat exchanger specimens were: circular tube, rectangular channel, and staggered pin fin with tapered pins. The specimens were heated radiatively at heat fluxes up to 77 W/sq cm. Correlations were developed for the isothermal friction factor as a function of Reynolds number, and for the Nusselt number as a function of Reynolds number and the ratio of wall temperature to fluid temperature. The specimen with the pin fin internal geometry had significantly better heat transfer than the other specimens, but it also had higher pressure drop. For certain conditions of helium flow and heating, the temperature more than doubled from the inlet to the outlet of the specimens, producing large changes in gas velocity, density, viscosity, and thermal conductivity. These changes in properties did not affect the correlations for friction factor and Nusselt number in turbulent flow.

  7. Boiling heat transfer during flow of distilled water in an asymmetrically heated rectangular minichannel

    NASA Astrophysics Data System (ADS)

    Strąk, Kinga; Piasecka, Magdalena

    This paper discusses test results concerning flow boiling heat transfer in a minichannel 1.7 mm in depth, 16 mm in width and 180 mm in length. The essential part of the experimental stand was a vertically oriented rectangular minichannel, which was heated asymmetrically with a plate made of Haynes-230 alloy. Distilled water was used as the cooling fluid. Changes in the temperature on the outer side of the heated plate in the central, axially symmetric part of the channel were measured using infrared thermography. Simultaneously, the other side of the heated plate in contact with the fluid was observed through a glass pane to identify the two-phase flow patterns. The one-dimensional model used for the heat transfer analysis took into account the heat flow direction, which was perpendicular to the direction of the fluid flow in the minichannel. The study involved determining local values of the heat transfer coefficient and generating boiling curves. The data for water were compared with the findings reported for the FC-72 fluid.

  8. Heat transfer in thin, compact heat exchangers with circular, rectangular, or pin-fin flow passages

    NASA Technical Reports Server (NTRS)

    Olson, D. A.

    1992-01-01

    Heat transfer and pressure drop have been measured of three thin, compact heat exchangers in helium gas at 3.5 MPa and higher, with Reynolds numbers of 450 to 36,000. The flow geometries for the three heat exchanger specimens were: circular tube, rectangular channel, and staggered pin fin with tapered pins. The specimens were heated radiatively at heat fluxes up to 77 W/sq cm. Correlations were developed for the isothermal friction factor as a function of Reynolds number, and for the Nusselt number as a function of Reynolds number and the ratio of wall temperature to fluid temperature. The specimen with the pin fin internal geometry had significantly better heat transfer than the other specimens, but it also had higher pressure drop. For certain conditions of helium flow and heating, the temperature more than doubled from the inlet to the outlet of the specimens, producing large changes in gas velocity, density, viscosity, and thermal conductivity. These changes in properties did not affect the correlations for friction factor and Nusselt number in turbulent flow.

  9. Radioisotopic heat source

    DOEpatents

    Sayell, E.H.

    1973-10-23

    A radioisotopic heat source is described which includes a core of heat productive, radioisotopic material, an impact resistant layer of graphite surrounding said core, and a shell of iridium metal intermediate the core and the impact layer. The source may also include a compliant mat of iridium between the core and the iridium shell, as well as an outer covering of iridium metal about the entire heat source. (Official Gazette)

  10. Thulium-170 heat source

    DOEpatents

    Walter, Carl E.; Van Konynenburg, Richard; VanSant, James H.

    1992-01-01

    An isotopic heat source is formed using stacks of thin individual layers of a refractory isotopic fuel, preferably thulium oxide, alternating with layers of a low atomic weight diluent, preferably graphite. The graphite serves several functions: to act as a moderator during neutron irradiation, to minimize bremsstrahlung radiation, and to facilitate heat transfer. The fuel stacks are inserted into a heat block, which is encased in a sealed, insulated and shielded structural container. Heat pipes are inserted in the heat block and contain a working fluid. The heat pipe working fluid transfers heat from the heat block to a heat exchanger for power conversion. Single phase gas pressure controls the flow of the working fluid for maximum heat exchange and to provide passive cooling.

  11. Radioisotopic heat source

    DOEpatents

    Jones, G.J.; Selle, J.E.; Teaney, P.E.

    1975-09-30

    Disclosed is a radioisotopic heat source and method for a long life electrical generator. The source includes plutonium dioxide shards and yttrium or hafnium in a container of tantalum-tungsten-hafnium alloy, all being in a nickel alloy outer container, and subjected to heat treatment of from about 1570$sup 0$F to about 1720$sup 0$F for about one h. (auth)

  12. Numerical study of heat transfer enhancement of counter nanofluids flow in rectangular microchannel heat exchanger

    NASA Astrophysics Data System (ADS)

    Mohammed, H. A.; Bhaskaran, G.; Shuaib, N. H.; Saidur, R.

    2011-09-01

    This paper reports a numerical analysis of the performance of a counter-flow rectangular shaped microchannel heat exchanger (MCHE) using nanofluids as the working fluids. Finite volume method was used to solve the three-dimensional steady, laminar developing flow and conjugate heat transfer in aluminum MCHE. The nanofluids used were Ag, Al 2O 3, CuO, SiO 2, and TiO 2 and the performance was compared with water. The thermal, flow fields and performance of the MCHE were analyzed using different nanofluids, different Reynolds numbers and different nanoparticle concentrations. Temperature profile, heat transfer coefficient, pressure profile, and wall shear stress were obtained from the simulations and the performance was discussed in terms of heat transfer rate, pumping power, effectiveness, and performance index. Results indicated enhanced performance with the usage of nanofluids, and slight penalty in pressure drop. The increase in Reynolds number caused an increase in the heat transfer rate and a decrease in the overall bulk temperature of the cold fluid. The increase in nanoparticle concentration also yielded better performance at the expense of increased pressure drop.

  13. Natural convection heat transfer for a staggered array of heated, horizontal cylinders within a rectangular enclosure

    SciTech Connect

    Triplett, C.E.

    1996-12-01

    This thesis presents the results of an experimental investigation of natural convection heat transfer in a staggered array of heated cylinders, oriented horizontally within a rectangular enclosure. The main purpose of this research was to extend the knowledge of heat transfer within enclosed bundles of spent nuclear fuel rods sealed within a shipping or storage container. This research extends Canaan`s investigation of an aligned array of heated cylinders that thermally simulated a boiling water reactor (BWR) spent fuel assembly sealed within a shipping or storage cask. The results are presented in terms of piecewise Nusselt-Rayleigh number correlations of the form Nu = C(Ra){sup n}, where C and n are constants. Correlations are presented both for individual rods within the array and for the array as a whole. The correlations are based only on the convective component of the heat transfer. The radiative component was calculated with a finite-element code that used measured surface temperatures, rod array geometry, and measured surface emissivities as inputs. The correlation results are compared to Canaan`s aligned array results and to other studies of natural convection in horizontal tube arrays.

  14. Advanced radioisotope heat source for Stirling Engines

    NASA Astrophysics Data System (ADS)

    Dobry, T. J.; Walberg, G.

    2001-02-01

    The heat exchanger on a Stirling Engine requires a thermal energy transfer from a heat source to the engine through a very limited area on the heater head circumference. Designing an effective means to assure maximum transfer efficiency is challenging. A single General Purpose Heat Source (GPHS), which has been qualified for space operations, would satisfy thermal requirements for a single Stirling Engine that would produce 55 electrical watts. However, it is not efficient to transfer its thermal energy to the engine heat exchanger from its rectangular geometry. This paper describes a conceptual design of a heat source to improve energy transfer for Stirling Engines that may be deployed to power instrumentation on space missions. .

  15. Heat transfer in a compact heat exchanger containing rectangular channels and using helium gas

    NASA Technical Reports Server (NTRS)

    Olson, D. A.

    1991-01-01

    Development of a National Aerospace Plane (NASP), which will fly at hypersonic speeds, require novel cooling techniques to manage the anticipated high heat fluxes on various components. A compact heat exchanger was constructed consisting of 12 parallel, rectangular channels in a flat piece of commercially pure nickel. The channel specimen was radiatively heated on the top side at heat fluxes of up to 77 W/sq cm, insulated on the back side, and cooled with helium gas flowing in the channels at 3.5 to 7.0 MPa and Reynolds numbers of 1400 to 28,000. The measured friction factor was lower than that of the accepted correlation for fully developed turbulent flow, although the uncertainty was high due to uncertainty in the channel height and a high ratio of dynamic pressure to pressure drop. The measured Nusselt number, when modified to account for differences in fluid properties between the wall and the cooling fluid, agreed with past correlations for fully developed turbulent flow in channels. Flow nonuniformity from channel-to-channel was as high as 12 pct above and 19 pct below the mean flow.

  16. Shear flow control of cold and heated rectangular jets by mechanical tabs. Volume 2: Tabulated data

    NASA Technical Reports Server (NTRS)

    Brown, W. H.; Ahuja, K. K.

    1989-01-01

    The effects of mechanical protrusions on the jet mixing characteristics of rectangular nozzles for heated and unheated subsonic and supersonic jet plumes were studied. The characteristics of a rectangular nozzle of aspect ratio 4 without the mechanical protrusions were first investigated. Intrusive probes were used to make the flow measurements. Possible errors introduced by intrusive probes in making shear flow measurements were also examined. Several scaled sizes of mechanical tabs were then tested, configured around the perimeter of the rectangular jet. Both the number and the location of the tabs were varied. From this, the best configuration was selected. This volume contains tabulated data for each of the data runs cited in Volume 1. Baseline characteristics, mixing modifications (subsonic and supersonic, heated and unheated) and miscellaneous charts are included.

  17. Boundary Heat Fluxes for Spectral Radiation from a Uniform Temperature Rectangular Medium

    NASA Technical Reports Server (NTRS)

    Siegel, Robert

    1992-01-01

    The effect of spectral behavior is analytically shown for radiation in a 2D rectangular geometry. The solution provides exact boundary heat flux values that can be used for comparison with values obtained from general computer programs. The spectral solution presented can be easily evaluated by numerical integration for complex variations of the spectral absorption coefficient with wavelength.

  18. Numerical study of conjugate heat transfer in rectangular microchannel heat sink with Al2O3/H2O nanofluid

    NASA Astrophysics Data System (ADS)

    Bhattacharya, P.; Samanta, A. N.; Chakraborty, S.

    2009-08-01

    In the present paper, conjugate heat transfer approach has been used to numerically study laminar forced convective heat transfer characteristics of Al2O3/H2O nanofluid flowing in a silicon microchannel heat sink (MCHS) of rectangular cross-section using thermal dispersion model. Results are presented in terms of thermal resistance that characterizes MCHS performance. It is observed that use of nanofluid improves MCHS performance by reducing fin (conductive) thermal resistance.

  19. Experimental research on heat transfer of natural convection in vertical rectangular channels with large aspect ratio

    SciTech Connect

    Lu, Qing; Qiu, Suizheng; Su, Guanghui; Tian, Wenxi; Ye, Zhonghao

    2010-01-15

    This work presents the experimental research on the steady laminar natural convection heat transfer of air in three vertical thin rectangular channels with different gap clearance. The much higher ratio of width to gap clearance (60-24) and the ratio of length to gap clearance (800-320) make the rectangular channels similar with the coolant flow passage in plate type fuel reactors. The vertical rectangular channels were composed of two stainless steal plates and were heated by electrical heating rods. The wall temperatures were detected with the K-type thermocouples which were inserted into the blind holes drilled in the steal plates. Also the air temperatures at the inlet and outlet of the channel were detected. The wall heat fluxes added to the air flow were calculated by the Fourier heat conduction law. The heat transfer characteristics were analyzed, and the average Nusselt numbers in all the three channels could be well correlated with the Rayleigh number or the modified Rayleigh number in a uniform correlation. Furthermore, the maximum wall temperatures were investigated, which is a key parameter for the fuel's integrity during some accidents. It was found that even the wall heat flux was up to 1500 W/m{sup 2}, the maximum wall temperature was lower than 350 C. All this work is valuable for the plate type reactor's design and safety analysis. (author)

  20. Milliwatt generator heat source

    NASA Astrophysics Data System (ADS)

    Mershad, E. A.

    1984-03-01

    All LANL hardware requirements were met during the reporting period as scheduled. Lot 12 of T-111 alloy sheet and Lot 8 of yttrium platelets were procured to meet future WR production needs. The GEND IP schedule requirements for 49 fueled MC2893 heat sources were met. Pressure burst surveillance activities continued to be conducted in accordance with SNLA document BB328965. Final results of evaluations of two pressure-burst capsules were normal, suggesting that the corresponding heat sources should be in good condition. The hardware production period ended with an overall hardware process yield of 98.4%.

  1. 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.

  2. Dynamic model of heat and mass transfer in rectangular adsorber of a solar adsorption machine

    NASA Astrophysics Data System (ADS)

    Chekirou, W.; Boukheit, N.; Karaali, A.

    2016-10-01

    This paper presents the study of a rectangular adsorber of solar adsorption cooling machine. The modeling and the analysis of the adsorber are the key point of such studies; because of the complex coupled heat and mass transfer phenomena that occur during the working cycle. The adsorber is heated by solar energy and contains a porous medium constituted of activated carbon AC-35 reacting by adsorption with methanol. To study the solar collector type effect on system's performances, the used model takes into account the variation of ambient temperature and solar intensity along a simulated day, corresponding to a total daily insolation of 26.12 MJ/m2 with ambient temperature average of 27.7 °C, which is useful to know the daily thermal behavior of the rectangular adsorber.

  3. Ultrasound source using a rectangular vibrating plate combined with rigid walls

    NASA Astrophysics Data System (ADS)

    Sato, Ryo; Asami, Takuya; Miura, Hikaru

    2017-07-01

    Ultrasound sources that use a stripe-mode rectangular vibrating plate radiate strong ultrasound waves in the air. In this study, we investigated the design strategy for combining the vibrating plate with rigid walls and evaluated the intense ultrasound waves radiated by the sound source. First, we examined the design method for a rectangular transverse vibrating plate with both ends fixed and the vibration amplitude distribution of the vibrating plate. Second, we measured the sound pressure distribution in the formation of the standing wave field. Finally, we clarified the relationship between the input power and sound pressure of the standing wave field antinodes.

  4. Transient natural convection heat and mass transfer in a rectangular enclosure - A numerical analysis

    NASA Technical Reports Server (NTRS)

    Han, Samuel S.; Schafer, Charles F.

    1988-01-01

    A numerical analysis of transient heat and solute transport across a rectangular cavity with combined horizontal temperature and concentration gradients is performed by a numerical method based on the SIMPLE. Numerical results show that the average Nusselt and Sherwood numbers both decrease markedly when the solutal and thermal buoyancy forces act in the opposite directions. When the solutal and thermal buoyancy forces act in the same directions, however, the average Sherwood number increases significantly and yet the average Nusselt number decreases slightly.

  5. Forced Flow Boiling Heat Transfer Properties of Liquid Hydrogen for Manganin Plate Pasted on One Side of a Rectangular Duct

    NASA Astrophysics Data System (ADS)

    Yoneda, K.; Shirai, Y.; Shiotsu, M.; Oura, Y.; Horie, Y.; Matsuzawa, T.; Shigeta, H.; Tatsumoto, H.; Hata, K.; Naruo, Y.; Kobayashi, H.; Inatani, Y.

    In this report, we show results on the forced flow boiling heat transfer experiments for manganin plate pasted on one side of a rectangular duct. Nucleate boiling heat transfer and its Departure from Nucleate Boiling (DNB) heat flux were measured for various pressures, subcooling and flow velocities. The DNB heat fluxes are higher for higher subcooling and higher flow velocity. The DNB heat fluxes were compared with the experimental data for round tube of nearly equal equivalent diameter. The DNB heat fluxes for the rectangular duct are lower than those for the round tube.

  6. Measurement of heat transfer and pressure drop in rectangular channels with turbulence promoters

    NASA Technical Reports Server (NTRS)

    Han, J. C.; Park, J. S.; Ibrahim, M. Y.

    1986-01-01

    Periodic rib turbulators were used in advanced turbine cooling designs to enhance the internal heat transfer. The objective of the present project was to investigate the combined effects of the rib angle of attack and the channel aspect ratio on the local heat transfer and pressure drop in rectangular channels with two opposite ribbed walls for Reynolds number varied from 10,000 to 60,000. The channel aspect ratio (W/H) was varied from 1 to 2 to 4. The rib angle of attack (alpha) was varied from 90 to 60 to 45 to 30 degree. The highly detailed heat transfer coefficient distribution on both the smooth side and the ribbed side walls from the channel sharp entrance to the downstream region were measured. The results showed that, in the square channel, the heat transfer for the slant ribs (alpha = 30 -45 deg) was about 30% higher that of the transverse ribs (alpha = 90 deg) for a constant pumping power. However, in the rectangular channels (W/H = 2 and 4, ribs on W side), the heat transfer at alpha = 30 -45 deg was only about 5% higher than 90 deg. The average heat transfer and friction correlations were developed to account for rib spacing, rib angle, and channel aspect ratio over the range of roughness Reynolds number.

  7. CFD Simulation Studies on the Performance of Rectangular Coil Heat Exchanger

    NASA Astrophysics Data System (ADS)

    Samsudeen, N.; Anantharaman, N.; Raviraj, Pol.

    2010-10-01

    The simulation studies are made to understand the concept of heat transfer by convection in a rectangular coiled type heat exchanger. The rectangular coil heat exchanger consists of inner and outer coil arrangements with several straight portions and bends so that the exterior flow is very similar to flow within tube-bundles. The present work focuses mainly on exploring the various flow pattern and temperature distribution through the pipe. Computer simulation studies were performed for four different angle of tube bundle inclination (0°, 30°, 60°, and 90°) with two set flow arrangements (inline and staggered arrangement) in the shell side of the heat exchanger. The simulation results show that the effect of the tube bundle inclination on the fluid velocity distribution and the heat transfer performance is observed maximum for the coil with tube bundle inclination angle between 30 degrees and 60 degrees with the staggered arrangement than with the inline arrangement due to proper mixing in the shell side and the outside flow over the tube bundle helps to create turbulence without increasing the velocity in the shell side of the heat exchanger.

  8. Low cost uniform heat source

    NASA Technical Reports Server (NTRS)

    Smith, R. B.; Prok, G. M.

    1973-01-01

    Electrically powered heat source was developed for ground simulation of isotope heat-source assembly in Brayton power system. Heat source, which operates on ordinary 110 vac power, consists of tungsten filament heating element wound onto a spirally grooved boron nitride core and inserted in a hollowed-out graphite hexahedron.

  9. Hubbell rectangular source integral calculation using a fast Chebyshev wavelets method.

    PubMed

    Manai, K; Belkadhi, K

    2016-07-01

    An integration method based on Chebyshev wavelets is presented and used to calculate the Hubbell rectangular source integral. A study of the convergence and the accuracy of the method was carried out by comparing it to previous studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. An experimental investigation of flow boiling in an asymmetrically heated rectangular microchannel

    SciTech Connect

    Huh, Cheol; Kim, Moo Hwan

    2006-08-15

    By using unique experimental techniques and carefully constructed experimental apparatus, the characteristics of flow boiling of water in microscale were investigated using a single horizontal rectangular microchannel. A polydimethylsiloxane rectangular microchannel (D{sub h}=103.5 and 133{mu}m) was fabricated by using the replica molding technique, a kind of soft lithography. A piecewise serpentine platinum microheater array on a Pyrex substrate was fabricated with the surface micromachining MEMS technique. Real time flow visualization of the phase change phenomena inside the microchannel was performed using a high speed CCD camera with microscope. The experimental local boiling heat transfer coefficients were studied, and single bubble inception, growth, and departure, as well as elongated bubble behavior were analyzed to elucidate the microscale heat transfer mechanisms. Tests were performed for mass fluxes of 77.5, 154.9, and 309.8kg/m{sup 2}s and heat fluxes of 180-500kW/m{sup 2}. The effects of mass flux, heat flux, and vapor qualities on flow boiling heat transfer in a microchannel were studied. (author)

  11. Development and applications of rectangular box-type explosively bonded structures for high-heat-load beamline components

    NASA Astrophysics Data System (ADS)

    Shu, D.; Chang, J.; Kuzay, T. M.; Brasher, D. G.

    2001-07-01

    Explosive bonding technology is a good choice to join dissimilar materials, such as 304L stainless steel and GlidCop AL-15, and is used extensively in making the advanced photon source (APS) high-heat-load beamline and front-end components. It is a bonding method in which the controlled energy of a detonating explosive is used to create a metallurgical bond between two or more similar or dissimilar materials. In recent years, special explosive bonding units with rectangular box-type joints were developed for the APS new high-heat-load beamline components. Based on this new technique, the box form of the component could be built in two halves first, then welded together. Therefore, beamline designers have more freedom to optimize the cooling surface geometry.

  12. Thermal Buckling Analysis of Rectangular Panels Subjected to Humped Temperature Profile Heating

    NASA Technical Reports Server (NTRS)

    Ko, William I.

    2004-01-01

    This research investigates thermal buckling characteristics of rectangular panels subjected to different types of humped temperature profile heating. Minimum potential energy and finite-element methods are used to calculate the panel buckling temperatures. The two methods give fairly close thermal buckling solutions. 'Buckling temperature magnification factor of the first kind, eta' is established for the fixed panel edges to scale up the buckling solution of uniform temperature loading case to give the buckling solution of the humped temperature profile loading cases. Also, 'buckling temperature magnification factor of the second kind, xi' is established for the free panel edges to scale up the buckling solution of humped temperature profile loading cases with unheated boundary heat sinks to give the buckling solutions when the boundary heat sinks are heated up.

  13. Supersonic/Hypersonic Laminar Heating Correlations for Rectangular and Impact-Induced Open and Closed Cavities

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.

    2008-01-01

    Impact and debris damage to the Space Shuttle Orbiter Thermal Protection System tiles is a random phenomenon, occurring at random locations on the vehicle surface, resulting in random geometrical shapes that are exposed to a definable range of surface flow conditions. In response to the 2003 Final Report of the Columbia Accident Investigation Board, wind tunnel aeroheating experiments approximating a wide range of possible damage scenarios covering both open and closed cavity flow conditions were systematically tested in hypersonic ground based facilities. These data were analyzed and engineering assessment tools for damage-induced fully-laminar heating were developed and exercised on orbit. These tools provide bounding approximations for the damaged-surface heating environment. This paper presents a further analysis of the baseline, zero-pressure-gradient, idealized, rectangular-geometry cavity heating data, yielding new laminar correlations for the floor-averaged heating, peak cavity endwall heating, and the downstream decay rate. Correlation parameters are derived in terms of cavity geometry and local flow conditions. Prediction Limit Uncertainty values are provided at the 95%, 99% and 99.9% levels of significance. Non-baseline conditions, including non-rectangular geometries and flows with known pressure gradients, are used to assess the range of applicability of the new correlations. All data variations fall within the 99% Prediction Limit Uncertainty bounds. Importantly, both open-flow and closed-flow cavity heating are combined into a single-curve parameterization of the heating predictions, and provide a concise mathematical model of the laminar cavity heating flow field with known uncertainty.

  14. Heat transfer performance comparisons of five different rectangular channels with parallel angled ribs

    NASA Technical Reports Server (NTRS)

    Park, J. S.; Han, J. C.; Huang, Y.; Ou, S.; Boyle, R. J.

    1992-01-01

    This paper systematically presents the results of heat transfer and friction factor data measured in five short rectangular channels with turbulence promoters. The project investigated the combined effects of the channel aspect ratio, rib angle-of-attack, and flow Reynolds number on heat transfer and pressure drop in rectangular channels with two opposite ribbed walls. The channel aspect ratio (width-to-height, W/H, ribs on side W) varied from 1/4 to 1/2, to 1, 2, and 4, while the corresponding rib angles-of-attack alpha were 90 deg, 60 deg, 45 deg, and 30 deg, respectively. The Reynolds number range was 10,000-60,000. The results suggest that the narrow aspect ratio channels (W/H less than 1) give much better heat transfer performance than the wide aspect ratio channels (W/H greater than 1). For the square channel (W/H = 1), the 60 deg/45 deg angled ribs provide the best heat transfer performance. For the narrow aspect ratio channel (W/H = 1/4 or 1/2), the 45 deg/60 deg angled ribs are recommended, while the 30 deg/45 deg angled ribs are better for wide aspect ratio channels (W/H = 4 or 2).

  15. Sloshing waves in a heated viscoelastic fluid layer in an excited rectangular tank

    NASA Astrophysics Data System (ADS)

    Sirwah, Magdy A.

    2014-10-01

    In this paper, we have investigated the motion of a heated viscoelastic fluid layer in a rectangular tank that is subjected to a horizontal periodic oscillation. The mathematical model of the current problem is communicated with the linearized Navier-Stokes equation of the viscoelastic fluid and heat equation together with the boundary conditions that are solved by means of Laplace transform. Time domain solutions are consequently computed by using Durbin's numerical inverse Laplace transform scheme. Various numerical results are provided and thereby illustrated graphically to show the effects of the physical parameters on the free-surface elevation time histories and heat distribution. The numerical applications revealed that increasing the Reynolds number as well as the relaxation time parameter leads to a wider range of variation of the free-surface elevation, especially for the short time history.

  16. Augmented heat transfer in rectangular channels of narrow aspect ratios with rib turbulators

    NASA Technical Reports Server (NTRS)

    Han, J. C.; Ou, S.; Park, J. S.; Lei, C. K.

    1989-01-01

    The effects of the rib angle-of-attack on the distributions of the local heat transfer coefficient and on the friction factors in short rectangular channels of narrow aspect ratios with a pair of opposite rib-roughened walls are determined for Reynolds numbers from 10,000 to 60,000. The channel width-to-height ratios are 2/4 and 1/4; the corresponding rib angles-of-attack are 90, 60, 45, and 30 deg, respectively. The results indicate that the narrow-aspect-ratio channels give better heat transfer performance than the wide-aspect-ratio channels for a constant pumping power. Semiempirical friction and heat transfer correlations are obtained. The results can be used in the design of turbine cooling channels of narrow aspect ratios.

  17. Oscillating-flow loss test results in rectangular heat exchanger passages

    NASA Technical Reports Server (NTRS)

    Wood, J. Gary

    1991-01-01

    Test results of oscillating flow losses in rectangular heat exchanger passages of various aspect ratios are given. This work was performed in support of the design of a free-piston Stirling engine (FPSE) for a dynamic space power conversion system. Oscillating flow loss testing was performed using an oscillating flow rig, which was based on a variable stroke and variable frequency linear drive motor. Tests were run over a range of oscillating flow parameters encompassing the flow regimes of the proposed engine design. Test results are presented in both tabular and graphical form and are compared against analytical predictions.

  18. Critical heat flux for free convection boiling in thin rectangular channels

    SciTech Connect

    Cheng, Lap Y.; Tichler, P.R.

    1991-01-01

    A review of the experimental data on free convection boiling critical heat flux (CHF) in vertical rectangular channels reveals three mechanisms of burnout. They are the pool boiling limit, the circulation limit, and the flooding limit associated with a transition in flow regime from churn to annular flow. The dominance of a particular mechanism depends on the dimensions of the channel. Analytical models were developed for each free convection boiling limit. Limited agreement with data is observed. A CHF correlation, which is valid for a wide range of gap sizes, was constructed from the CHFs calculated according to the three mechanisms of burnout. 17 refs., 7 figs.

  19. Two dimensional heat transfer problem in flow boiling in a rectangular minichannel

    NASA Astrophysics Data System (ADS)

    Hożejowska, Sylwia; Piasecka, Magdalena; Hożejowski, Leszek

    2015-05-01

    The paper presents mathematical modelling of flow boiling heat transfer in a rectangular minichannel asymmetrically heated by a thin and one-sided enhanced foil. Both surfaces are available for observations due to the openings covered with glass sheets. Thus, changes in the colour of the plain foil surface can be registered and then processed. Plain side of the heating foil is covered with a base coat and liquid crystal paint. Observation of the opposite, enhanced surface of the minichannel allows for identification of the gas-liquid two-phase flow patterns and vapour quality. A two-dimensional mathematical model of heat transfer in three subsequent layers (sheet glass, heating foil, liquid) was proposed. Heat transfer in all these layers was described with the respective equations: Laplace equation, Poisson equation and energy equation, subject to boundary conditions corresponding to the observed physical process. The solutions (temperature distributions) in all three layers were obtained by Trefftz method. Additionally, the temperature of the boiling liquid was obtained by homotopy perturbation method (HPM) combined with Trefftz method. The heat transfer coefficient, derived from Robin boundary condition, was estimated in both approaches. In comparison, the results by both methods show very good agreement especially when restricted to the thermal sublayer.

  20. Effect of Channel Sidewalls on Joule Heating Induced Sample Dispersion in Rectangular Ducts

    PubMed Central

    Dutta, Debashis

    2015-01-01

    In this article, we analyze the effect of channel sidewalls on the broadening of analyte bands resulting from Joule heating during their electrokinetic migration through a rectangular conduit. A method-of-moments formulation has been used to numerically evaluate the Taylor-Aris dispersivity of sample zones under these conditions for thin electrical double layers applicable to a majority of microfluidic assays. Our analysis shows that the larger surface area to volume ratio around the side regions of a rectangular channel causes these corners to stay cooler than the rest of the conduit. While such a thermal profile does not modify the electroosmotic flow in the system for a fixed temperature at the channel walls, it reduces the electrophoretic transport rate by about 10% for small temperature differentials across the channel cross-section (<10°C). The effect of these thermal gradients on the hydrodynamic dispersion of analyte bands is more significant however, increasing such band broadening by nearly an order of magnitude in large aspect ratio designs. Our analyses further show that the trends noted above are magnified when a fixed heat transfer coefficient is assumed at the channel walls, in which case, the temperature along this boundary is no longer constant. The non-isothermal channel walls combined with the temperature dependence of zeta potential and other material properties in this situation leads to a non-uniform electroosmotic slip velocity in the system modifying both fluid and analyte transport rates. Again, while the resulting solute flow profile reduces the migration velocity of sample zones only to a moderate extent, it is found to increase the hydrodynamic dispersion of analyte bands by several orders of magnitude in large aspect ratio rectangular channels. PMID:26597437

  1. Effect of Channel Sidewalls on Joule Heating Induced Sample Dispersion in Rectangular Ducts.

    PubMed

    Dutta, Debashis

    2016-02-01

    In this article, we analyze the effect of channel sidewalls on the broadening of analyte bands resulting from Joule heating during their electrokinetic migration through a rectangular conduit. A method-of-moments formulation has been used to numerically evaluate the Taylor-Aris dispersivity of sample zones under these conditions for thin electrical double layers applicable to a majority of microfluidic assays. Our analysis shows that the larger surface area to volume ratio around the side regions of a rectangular channel causes these corners to stay cooler than the rest of the conduit. While such a thermal profile does not modify the electroosmotic flow in the system for a fixed temperature at the channel walls, it reduces the electrophoretic transport rate by about 10% for small temperature differentials across the channel cross-section (<10°C). The effect of these thermal gradients on the hydrodynamic dispersion of analyte bands is more significant however, increasing such band broadening by nearly an order of magnitude in large aspect ratio designs. Our analyses further show that the trends noted above are magnified when a fixed heat transfer coefficient is assumed at the channel walls, in which case, the temperature along this boundary is no longer constant. The non-isothermal channel walls combined with the temperature dependence of zeta potential and other material properties in this situation leads to a non-uniform electroosmotic slip velocity in the system modifying both fluid and analyte transport rates. Again, while the resulting solute flow profile reduces the migration velocity of sample zones only to a moderate extent, it is found to increase the hydrodynamic dispersion of analyte bands by several orders of magnitude in large aspect ratio rectangular channels.

  2. Today's ground source heat pumps

    SciTech Connect

    Bose, J.E.

    1993-01-01

    Ground source heat pumps are one of the nation's fastest growing businesses in terms of increased sales of equipment as reported by water source heat pump manufacturers. The success can be attributed in part to these heat pump's reputation as a cost saving system and more recently as an environmentally sound concept. Engineers having an interest in ground source technology come from a large and diverse audience consisting of those who have heard about ground source systems and are contemplating entering the business and those who are experienced and looking to broaden their application base. This article discusses the water source heat pump and its benefits, the commercial Water Loop Heat Pump (WLHP), the ground source heat pump, the commercial Closed Loop/Ground Coupled WLHP, designing a ground heat exchanger, information available for design, and successful systems.

  3. Natural convection in a vertical rectangular enclosure with localized heating and cooling zones

    NASA Astrophysics Data System (ADS)

    Ishihara, I.; Matsumoto, R.; Senoo, A.

    Experimental and numerical studies of natural convection in a single phase, closed thermosyphon were carried out using a vertical, rectangular enclosure model. Only one vertical plate plays the role of heat transfer surface having 100mm height and 100mm width, and others act as the adiabatic wall made of transparent plexi-glass. The heat transfer surface is separated into three horizontal zones with an equal height; top 1/3 and bottom 1/3 of the surface are cooling and heating zones, respectively and intermediate section is an adiabatic zone. Water is used as the working fluid. Variable parameters are distance D between the heat transfer surface and an adiabatic plate opposite to the heat transfer plate, and temperature difference ΔT between heating and cooling zones. By changing both D and ΔT, three regimes of the natural convection flow; quasi-two-dimensional steady, three-dimensional steady and unsteady flows are observed by means of thermo-sensitive liquid crystal powder and numerically simulated very well by solving a set of governing equations.

  4. Analytical 1D models of the wall thermal resistance of rectangular minichannels applied in heat exchangers

    NASA Astrophysics Data System (ADS)

    Rybiński, Witold; Mikielewicz, Jarosław

    2016-09-01

    The paper presents four 1-dimensional models of thermal resistance of walls in a heat exchanger with rectangular minichannels. The first model is the simplest one, with a single wall separating two fluids. The second model of the so called equivalent wall takes into account total volume of intermediate walls between layers of minichannels and of side walls of minichannels. The next two more complicated models take separately into account thermal resistance of these walls. In these two models side walls are treated as fins. The results of models comparison are presented. It is shown that thermal resistance may be neglected for metal walls but it should be taken into account for the walls made of plastics. For the case of non-neglected wall thermal resistance the optimum wall thickness was derived. Minichannel heat exchangers made of plastic are larger than those built of metal, but are significantly cheaper. It makes possible to use of such exchangers in inexpensive microscale ORC installations.

  5. The CAV program for numerical evaluation of laminar natural convection heat transfer in vertical rectangular cavities

    NASA Astrophysics Data System (ADS)

    Novak, Milos H.; Nowak, Edwin S.

    1993-12-01

    To analyze the laminar natural convection heat transfer and fluid flow distribution in vertical rectangular cavities with or without inner partitions, the personal computer finite difference program entitled CAV is used. The CAV program was tested successfully for slender cavities with aspect ratios as high as R = H/ L = 90 and for the Grashof numbers, based on the cavity height, up to GrH = 3 x10 9. To make the CAV program useful for a number of applications, various types of boundary conditions can also be imposed on the program calculations. Presented are program applications dealing with the 2-D numerical analysis of natural convection heat transfer in very slender window cavities with and without small inner partitions and recommendations are made for window design.

  6. The study and development of the empirical correlations equation of natural convection heat transfer on vertical rectangular sub-channels

    NASA Astrophysics Data System (ADS)

    Kamajaya, Ketut; Umar, Efrizon; Sudjatmi, K. S.

    2012-06-01

    This study focused on natural convection heat transfer using a vertical rectangular sub-channel and water as the coolant fluid. To conduct this study has been made pipe heaters are equipped with thermocouples. Each heater is equipped with five thermocouples along the heating pipes. The diameter of each heater is 2.54 cm and 45 cm in length. The distance between the central heating and the pitch is 29.5 cm. Test equipment is equipped with a primary cooling system, a secondary cooling system and a heat exchanger. The purpose of this study is to obtain new empirical correlations equations of the vertical rectangular sub-channel, especially for the natural convection heat transfer within a bundle of vertical cylinders rectangular arrangement sub-channels. The empirical correlation equation can support the thermo-hydraulic analysis of research nuclear reactors that utilize cylindrical fuel rods, and also can be used in designing of baffle-free vertical shell and tube heat exchangers. The results of this study that the empirical correlation equations of natural convection heat transfer coefficients with rectangular arrangement is Nu = 6.3357 (Ra.Dh/x)0.0740.

  7. Shear flow control of cold and heated rectangular jets by mechanical tabs. Volume 1: Results and discussion

    NASA Technical Reports Server (NTRS)

    Brown, W. H.; Ahuja, K. K.

    1989-01-01

    The effects of mechanical protrusions on the jet mixing characteristics of rectangular nozzles for heated and unheated subsonic and supersonic jet plumes were studied. The characteristics of a rectangular nozzle of aspect ratio 4 without the mechanical protrusions were first investigated. Intrusive probes were used to make the flow measurements. Possible errors introduced by intrusive probes in making shear flow measurements were also examined. Several scaled sizes of mechanical tabs were then tested, configured around the perimeter of the rectangular jet. Both the number and the location of the tabs were varied. From this, the best configuration was selected. The conclusions derived were: (1) intrusive probes can produce significant errors in the measurements of the velocity of jets if they are large in diameter and penetrate beyond the jet center; (2) rectangular jets without tabs, compared to circular jets of the same exit area, provide faster jet mixing; and (3) further mixing enhancement is possible by using mechanical tabs.

  8. Flow patterns and heat convection in a rectangular water bolus for use in superficial hyperthermia.

    PubMed

    Birkelund, Yngve; Jacobsen, Svein; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R

    2009-07-07

    This paper investigates both numerically and experimentally the spatio-temporal effects of water flow in a custom-made water bolus used for superficial hyperthermia generated by a 915-MHz, 4 x 3 microwave applicator array. Similar hyperthermia models referenced in the literature use a constant water temperature and uniform heat flux to describe conduction and convection energy exchange within the heating apparatus available to cool the tissue surface. The results presented in this paper show that the spatially varying flow pattern and rate are vital factors for the overall heat control applicability of the 5 mm thick bolus under study. Regions with low flow rates and low heat convection clearly put restrictions on the maximum microwave energy possible within the limits of skin temperature rise under the bolus. Our analysis is illustrated by experimental flow front studies using a contrast liquid set-up monitored by high definition video and complemented by numerical analysis of liquid flow and heat exchange within the rectangular water bolus loaded by malignant tissue. Important factors for the improvement of future bolus designs are also discussed in terms of diameter and configuration of the water input and output tubing network.

  9. Flow patterns and heat convection in a rectangular water bolus for use in superficial hyperthermia

    NASA Astrophysics Data System (ADS)

    Birkelund, Yngve; Jacobsen, Svein; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R.

    2009-07-01

    This paper investigates both numerically and experimentally the spatio-temporal effects of water flow in a custom-made water bolus used for superficial hyperthermia generated by a 915-MHz, 4 × 3 microwave applicator array. Similar hyperthermia models referenced in the literature use a constant water temperature and uniform heat flux to describe conduction and convection energy exchange within the heating apparatus available to cool the tissue surface. The results presented in this paper show that the spatially varying flow pattern and rate are vital factors for the overall heat control applicability of the 5 mm thick bolus under study. Regions with low flow rates and low heat convection clearly put restrictions on the maximum microwave energy possible within the limits of skin temperature rise under the bolus. Our analysis is illustrated by experimental flow front studies using a contrast liquid set-up monitored by high definition video and complemented by numerical analysis of liquid flow and heat exchange within the rectangular water bolus loaded by malignant tissue. Important factors for the improvement of future bolus designs are also discussed in terms of diameter and configuration of the water input and output tubing network.

  10. New experimental results on local heat transfer inside a rectangular channel with rib-roughened surfaces

    NASA Astrophysics Data System (ADS)

    Fustinoni, D.; Gramazio, P.; Vitali, L.; Niro, A.

    2017-01-01

    In this paper we present new experimental results on local heat transfer characteristics of a forced air-flow through a 12-mm-height, rectangular channel of 1:10 aspect ratio, with square-cross-section ribs mounted onto the lower surface. Data are collected on a completely redesigned test section. Specifically, the electric heater is made of very thin copper tracks, in direct contact with the air flow and covering at 97.5% the channel lower surface to guarantee a very uniform heat flux. The copper tracks are laminated onto a 2-mm thick board of FR-4 glass epoxy to provide negligible heat conduction inside the plate and heat losses from its sides. Finally, the channel walls are in XPS and, into the upper one, a double glazing consisting of two 120 mm x 120 mm Germanium windows is mounted to allow optical access to the IR camera and to reduce local heat dispersions. Data here presented refer to convection over 4 mm x 2 mm ribs in transverse configuration for Reynolds numbers, based on the duct hydraulic diameter, ranging between 700 and 8000. Preliminary tests show how the new apparatus has significantly improved the quality, the ease and the quickness of the measurements.

  11. Flow patterns and heat convection in a rectangular water bolus for use in superficial hyperthermia

    PubMed Central

    Birkelund, Yngve; Jacobsen, Svein; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R

    2009-01-01

    This paper investigates both numerically and experimentally the spatio-temporal effects of water flow in a custom made water bolus used for superficial hyperthermia generated by a 915-MHz, 4 × 3 microwave applicator array. Similar hyperthermia models referenced in the literature use a constant water temperature and uniform heat flux to describe conduction and convection energy exchange within the heating apparatus available to cool the tissue surface. The results presented in this paper show that the spatially varying flow pattern and rate are vital factors for the overall heat control applicability of the 5 mm thick bolus under study. Regions with low flow rates and low heat convection clearly put restrictions on the maximum microwave energy possible within the limits of skin temperature rise under the bolus. Our analysis is illustrated by experimental flow front studies using a contrast liquid setup monitored by high definition video and complemented by numerical analysis of liquid flow and heat exchange within the rectangular water bolus loaded by malignant tissue. Important factors for improvement of future bolus designs are also discussed in terms of diameter and configuration of the water input and output tubing network. PMID:19494426

  12. Numerical analysis of thermogravitational turbulent convection in a closed rectangular region with radiation source of energy

    NASA Astrophysics Data System (ADS)

    Kuznetsov, G. V.; Nee, A. E.

    2016-05-01

    The mathematical modeling of the conjugate heat transfer in a closed rectangular region has been carried out under the conditions of the radiation supply of energy. The temperature and stream function fields obtained by the modeling illustrate a substantially unsteady nature of the conjugate heat exchange process under study. An analysis of temperature distributions in typical cross sections of the solution domain has shown a considerable inhomogeneity of the temperature field. It is found that an increase in the Rayleigh number leads to substantial modifications of the temperature and stream function fields. The influence of the distribution of radiation fluxes over the internal interfaces on the temperature fields and the airflow character is shown. The influence of the turbulization on the heat transfer intensity near the interfaces between media has been estimated. Comparisons of the obtained numerical results with experimental data have shown their good agreement.

  13. Electric-field distribution near rectangular microstrip radiators for hyperthermia heating: Theory versus experiment in water

    SciTech Connect

    Underwood, H.R. ); Peterson, A.F. ); Magin, R.L. )

    1992-02-01

    A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low ([epsilon][sub r] = 10) and high ([epsilon][sub r] = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios ar 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power.

  14. Computation of the gas mass and heat fluxes in a rectangular channel in the free molecular regime

    NASA Astrophysics Data System (ADS)

    Germider, O. V.; Popov, V. N.; Yushkanov, A. A.

    2016-06-01

    The problem of heat- and mass transfer in a long rectangular channel of a constant cross section is solved in the free molecular regime. The distributions of the mass flow rate and the heat flux vector over the channel cross section are calculated. The specific gas mass flux and heat flux are calculated. The results are compared with those obtained for nearly free molecular flows.

  15. Analytical solutions of heat transfer for laminar flow in rectangular channels

    NASA Astrophysics Data System (ADS)

    Rybiński, Witold; Mikielewicz, Jarosław

    2014-12-01

    The paper presents two analytical solutions namely for Fanning friction factor and for Nusselt number of fully developed laminar fluid flow in straight mini channels with rectangular cross-section. This type of channels is common in mini- and microchannel heat exchangers. Analytical formulae, both for velocity and temperature profiles, were obtained in the explicit form of two terms. The first term is an asymptotic solution of laminar flow between parallel plates. The second one is a rapidly convergent series. This series becomes zero as the cross-section aspect ratio goes to infinity. This clear mathematical form is also inherited by the formulae for friction factor and Nusselt number. As the boundary conditions for velocity and temperature profiles no-slip and peripherally constant temperature with axially constant heat flux were assumed (H1 type). The velocity profile is assumed to be independent of the temperature profile. The assumption of constant temperature at the channel's perimeter is related to the asymptotic case of channel's wall thermal resistance: infinite in the axial direction and zero in the peripheral one. It represents typical conditions in a minichannel heat exchanger made of metal.

  16. Numerical investigation on the performance of fin and tube heat exchangers using rectangular vortex generators

    NASA Astrophysics Data System (ADS)

    Zeeshan, Mohd; Hazarika, Saheera Azmi; Nath, Sujit; Bhanja, Dipankar

    2017-07-01

    In the present work, a 3-D numerical investigation has been performed to explore the effect of attack angles on the thermal-hydraulic performance of fin and tube heat exchanger (FTHE) using rectangular winglet pairs (RWPs). RWPs are placed adjacent to the tubes and three attack angels are considered for the study i.e. 5°, 15° and 25°. The effect of attack angles are examined on the heat transfer characteristics as well as in pressure drop penalty with airside Reynolds number Rea ranges from 500 to 900. Two performance evaluation criteria namely PEC1 i.e. area goodness factor (j/f) and PEC2 i.e. heat transfer rate per unit fan power consumption (Q/Pf) are considered for the performance evaluation. Furthermore, MOORA method is applied to obtain the performance order of FTHE configurations by taking PEC1 and PEC2 as beneficial attributes and fan power Pf as a non-beneficial attribute, keeping equal importance to each attribute. The results show that 5° attack angle provides the better performance in terms of PEC1 as heat transfer coefficient is increased by 27.70% at Rea=500 and 32.73% at Rea=900 respectively with 13.01% increased pressure drop penalty at Rea=500 and 14.26% at Rea=900 respectively. In terms of PEC2, though the 5° attack angle provides the high values of Q/Pf factor among the 15° and 25° attack angles, but it is found insignificant to replace the baseline configuration i.e. plain fin and tube heat exchanger configuration without vortex generators. Moreover, in MOORA optimization analysis also, it is found that 5° attack angle provides the better thermal-hydraulic performance.

  17. Numerical Investigation of Laminar Heat Transfer of Nanofluid-Cooled Mini-Rectangular Fin Heat Sinks

    NASA Astrophysics Data System (ADS)

    Naphon, Paisarn; Nakharintr, Lursukd

    2015-05-01

    The single- and two-phase models in three-dimensional analysis are applied to study laminar convective heat transfer of nanofluids in a minichannel heat sink. The nanofluids with suspending TiO 2 nanoparticles of average diameter 21 nm are prepared by ultrasound with a constant nanoparticle concentration of 0.4 vol.% without using surfactants. Experiments are carried out to verify the predicted results. It is shown that the results obtained from the two-phase model are more precise in comparison with the experimental results than those from the single-phase model. The predicted heat transfer coefficients for nanofluids are higher than those for water.

  18. Increasing heat transfer of non-Newtonian nanofluid in rectangular microchannel with triangular ribs

    NASA Astrophysics Data System (ADS)

    Shamsi, Mohammad Reza; Akbari, Omid Ali; Marzban, Ali; Toghraie, Davood; Mashayekhi, Ramin

    2017-09-01

    In this study, computational fluid dynamics and the laminar flow of the non-Newtonian fluid have been numerically studied. The cooling fluid includes water and 0.5 wt% Carboxy methyl cellulose (CMC) making the non-Newtonian fluid. In order to make the best of non-Newtonian nanofluid in this simulation, solid nanoparticles of Aluminum Oxide have been added to the non-Newtonian fluid in volume fractions of 0-2% with diameters of 25, 45 and 100 nm. The supposed microchannel is rectangular and two-dimensional in Cartesian coordination. The power law has been used to speculate the dynamic viscosity of the cooling nanofluid. The field of numerical solution is simulated in the Reynolds number range of 5 < Re < 300. A constant heat flux of 10,000 W/m2 is exercised on the lower walls of the studied geometry. Further, the effect of triangular ribs with angle of attacks of 30°, 45° and 60° is studied on flow parameters and heat transfer due to the fluid flow. The results show that an increase in the volume fraction of nanoparticles as well as the use for nanoparticles with smaller diameters lead to greater heat transfer. Among all the studied forms, the triangular rib from with an angle of attack 30° has the biggest Nusselt number and the smallest pressure drop along the microchannel. Also, an increase in the angle of attack and as a result of a sudden contact between the fluid and the ribs and also a reduction in the coflowing length (length of the rib) cause a cut in heat transfer by the fluid in farther parts from the solid wall (tip of the rib).

  19. Direct Numerical Simulation of Turbulent Heat Transfer Behind a Rectangular Orifice

    NASA Astrophysics Data System (ADS)

    Makino, Soihiro; Iwamoto, Kaoru; Kawamura, Hiroshi

    Direct numerical simulation of turbulent heat transfer with a rectangular orifice has been performed for Reτ0(=uτ0δ⁄ν) = 300, where uτ0 is the friction velocity calculated from the mean pressure gradient imposed to drive the flow, δ the channel half width and ν the kinematic viscosity. The Prandtl number is 0.71. The ratio of slit height to channel height is assumed to be β=0.3,0.4,0.5,0.6 and 0.7. For β=0.3-0.6, the mean flow becomes asymmetric in the wall-normal direction by the Coanda effect behind the orifice. In the case of β=0.7, however, the mean flow is symmetry. The Nusselt number profiles over the bottom and top walls are different significantly for the asymmetric cases. Large-scale Kelvin-Helmholtz(K-H) vortices are generated at the orifice edges. An entrainment process is observed in the temperature field around these vortices. Subsequently, these K-H vortices become deformed and break up into disordered small-scale structures in the shear layers behind the orifice. In this scenario, the turbulent transport is promoted in the temperature field. In addition, the separation, the reattachment and also the contraction effects are discussed on the profiles of the mean temperature, the temperature variance and the turbulent heat fluxes.

  20. Developing flow and heat transfer in a rectangular duct with a moving wall

    SciTech Connect

    Payvar, P.; Majumdar, P. . Dept. of Mechanical Engineering)

    1994-07-01

    Flow and heat transfer are studied numerically in a duct of rectangular cross section with a moving wall. The temperature of the moving wall is assumed to be constant while the other three walls are insulated. This boundary condition has important applications in the design of oil-cooled friction pairs. Results are presented for wall Reynolds numbers of 0, 100, 500, and 2500; Prandtl numbers of 0.7, 10, 50, and 100; and cross-sectional aspect ratios of 0.5 and 1. It is found that flow and heat transfer are strongly affected by an interaction between the boundary layer on the moving wall and a recirculation zone set up by that wall. In particular, the Nusselt number shows an interesting maximum before fully developed conditions are established. This maximum is believed to result from the enhancing effect of the widening recirculation zone as fully developed conditions are approached. Hydrodynamic and thermal entrance lengths are drastically reduced with increasing wall Reynolds number. This behavior can be used to advantage in the optimal design of grooved, oil-cooled friction pairs such as wet clutches.

  1. Design and fabrication of circular and rectangular components for electron-cyclotron-resonant heating of tandem mirror experiment-upgrade

    SciTech Connect

    Felker, B.; Calderon, M.O.; Chargin, A.K.; Coffield, F.E.; Lang, D.D.; Rubert, R.R.; Pedrotti, L.R.; Stallard, B.W.; Gallagher, N.C. Jr.; Sweeney, D.W.

    1983-11-18

    The electron-cyclotron-resonant heating (ECRH) systems of rectangular waveguides on Tandem Mirror Experiment-Upgrade (TMX-U) operated with a overall efficiency of 50%, each system using a 28-GHz, 200-kW pulsed gyrotron. We designed and built four circular-waveguide systems with greater efficiency and greater power-handling capabilities to replace the rectangular waveguides. Two of these circular systems, at the 5-kG second-harmonic heating locations, have a total transmission efficiency of >90%. The two systems at the 10-kG fundamental heating locations have a total transmission efficiency of 80%. The difference in efficiency is due to the additional components required to launch the microwaves in the desired orientation and polarization with respect to magnetic-field lines at the 10-kG points. These systems handle the total power available from each gyrotron but do not have the arcing limitation problem of the rectangular waveguide. Each system requires several complex components. The overall physical layout and the design considerations for the rectangular and circular waveguide components are described here.

  2. Analysis of heat transfer and nanofluid fluid flow in microchannels with trapezoidal, rectangular and triangular shaped ribs

    NASA Astrophysics Data System (ADS)

    Behnampour, Ali; Akbari, Omid Ali; Safaei, Mohammad Reza; Ghavami, Mohammad; Marzban, Ali; Sheikh Shabani, Gholamreza Ahmadi; zarringhalam, Majid; Mashayekhi, Ramin

    2017-07-01

    In the present study, the effect of triangular, rectangular and trapezoidal ribs on the laminar heat transfer of water-Ag nanofluid in a ribbed triangular channel under a constant heat flux was numerically studied using finite volume method. Height and width of ribs have been assumed to be fixed in order to study the effect of different rib forms. Modeling were performed for laminar flow (Re=1, 50 and 100) and nanofluid volume fractions of 0, 2% and 4%. The results indicated that an increase in volume fraction of solid nanoparticle leads to convectional heat transfer coefficient enhancement of the cooling fluid, whereas increasing the Nusselt number results in a loss of friction coefficient and pressure. Also, along with the fluid velocity increment, there will be an optimal proportion between heat and hydrodynamic transfer behavior which optimizes performance evaluation criteria (PEC) behavior. Among all of the investigated rib forms, the rectangular one made the most changes in the streamlines and the triangular form has the best thermal performance evaluation criteria values. For all studied Reynold numbers, heat transfer values are least for rectangular rib from. Therefore, trapezoidal ribs are recommended in high Reynold numbers.

  3. Transition to Turbulence in Rectangular Channels with Eddy Promoters: Implications to Heat Transfer Augmentation.

    NASA Astrophysics Data System (ADS)

    Kapat, Jayanta Sankar

    1991-02-01

    The work deals with experimental investigation of laminar-to-turbulent transition in a rectangular channel of aspect ratio 0.116 in the presence of periodic eddy promoters. The study is motivated by the role of transition in heat transfer enhancement schemes that employ flow destabilization strategies: specifically, for this type of augmentation systems, the most efficient performance (minimum pumping power per unit of heat removal) occurs in the transition region. Seven different geometries are tested: plain channel and six different arrangements of cylindrical eddy promoters. Placement of the eddy promoters in the channel, depending on the pattern, can significantly reduce Reynolds number values at transition: the critical Reynolds number (based on the average velocity and the channel height) ranges from 1500 (for a plain channel) to about 400 (for the most unstable configuration deployed). For all the cases tested, demarcation of transition can be correlated with the following expression, Re_tau = sqrt{ {| tau_{w,avoverrho }}} {H/2overnu} = 40 ~ 60,where | tau_{w,av} is the spatially averaged value of mean wall shear stress and H is the channel height. The above correlation extends to other geometries. The approximate invariance of Re_ tau at transition allows evaluation of heat transfer at transition point by using only the critical Reynolds number (Recrit). Based on Colburn analogy, Nu at transition for fluids with Pr > 0.6 can be calculated as Nu~ {10,000over Recrit} Pr^{1/3}.(Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253 -1690.).

  4. High Rayleigh number convection in rectangular enclosures with differentially heated vertical walls and aspect ratios between zero and unity

    SciTech Connect

    Kassemi, S.A.

    1988-04-01

    High Rayleigh number convection in a rectangular cavity with insulated horizontal surfaces and differentially heated vertical walls was analyzed for an arbitrary aspect ratio smaller than or equal to unity. Unlike previous analytical studies, a systematic method of solution based on linearization technique and analytical iteration procedure was developed to obtain approximate closed-form solutions for a wide range of aspect ratios. The predicted velocity and temperature fields are shown to be in excellent agreement with available experimental and numerical data.

  5. High Rayleigh number convection in rectangular enclosures with differentially heated vertical walls and aspect ratios between zero and unity

    NASA Technical Reports Server (NTRS)

    Kassemi, Siavash A.

    1988-01-01

    High Rayleigh number convection in a rectangular cavity with insulated horizontal surfaces and differentially heated vertical walls was analyzed for an arbitrary aspect ratio smaller than or equal to unity. Unlike previous analytical studies, a systematic method of solution based on linearization technique and analytical iteration procedure was developed to obtain approximate closed-form solutions for a wide range of aspect ratios. The predicted velocity and temperature fields are shown to be in excellent agreement with available experimental and numerical data.

  6. Non-intrusive measurements of transitional and turbulent convective heat transfer in a rectangular microchannel

    NASA Astrophysics Data System (ADS)

    Natrajan, V. K.; Christensen, K. T.

    2011-08-01

    The thermal-transport characteristics of transitional and turbulent flow through smooth- and rough-wall rectangular microchannels (Dh = 600 μm) under constant-heat-flux conditions at three of the four walls were investigated by performing non-intrusive and spatially resolved measurements of fluid temperature via two-color fluorescent thermometry. These measurements, along with bulk pressure-drop measurements, were performed over the Reynolds-number range 1300\\le {\\emph {Re}} \\le 5200. The pressure-drop results revealed the onset of transition above {\\emph {Re}_{cr}}\\cong 1800 for the smooth-wall case, consistent with the onset of transition at the macroscale. However, with increasing surface roughness, deviation from laminar behavior was noted at progressively lower Re which indicates that {\\emph {Re}_{cr}} is a function of roughness. Mean temperature profiles calculated from data sets acquired in the transitional regime for the smooth- and rough-wall cases illustrated deviation from fully developed laminar behavior for {\\emph {Re} \\gt \\emph {Re}_{cr}}. Nevertheless, these profiles still suggest similarities in the transitional pathway of the thermal-transport behavior for the smooth and rough cases save for a relative shift due to the onset of transition at lower Re with increasing surface roughness. Estimates of the bulk Nusselt number indicated enhancement in thermal transport over the smooth-wall case with increasing surface roughness in both the transitional and turbulent regimes, though the smooth-wall data agreed well with macroscale predictions over the range of turbulent Re considered. While the shift in the transitional pathway of the thermal transport behavior toward lower Re accounts for a portion of this enhancement, an increase in turbulent convection with increasing surface roughness might also contribute in this regard.

  7. General Purpose Heat Source Simulator

    NASA Technical Reports Server (NTRS)

    Emrich, William J., Jr.

    2008-01-01

    The General Purpose Heat Source (GPHS) project seeks to combine the development of an electrically heated, single GPHS module simulator with the evaluation of potential nuclear surface power systems. The simulator is designed to match the form, fit, and function of actual GPHS modules which normally generate heat through the radioactive decay of Pu238. The use of electrically heated modules rather than modules containing Pu238 facilitates the testing of the subsystems and systems without sacrificing the quantity and quality of the test data gathered. Current GPHS activities are centered on developing robust heater designs with sizes and weights which closely match those of actual Pu238 fueled GPHS blocks. Designs are being pursued which will allow operation up to 1100 C.

  8. Variation of forced convective heat transfer in rectangular duct flow of a magnetic fluid under magnetic field

    NASA Astrophysics Data System (ADS)

    Motozawa, M.; Sekine, T.; Sawada, T.; Kawaguchi, Y.

    2013-02-01

    Variation of forced convective heat transfer in a rectangular duct flow of a magnetic fluid under a magnetic field was investigated experimentally. Experiments were performed changing the magnetic field intensity, and this magnetic field could be varied from 0 mT to 600 mT. The Reynolds number based on the hydraulic diameter was set to 960, 1900 (laminar flow), and 2830 (turbulent flow). The results of the experiments show that in the case of laminar flow of the magnetic fluid, when a magnetic field is applied to a magnetic fluid flow, heat transfer locally increases in the region where the magnetic field exists. In contrast, in the turbulent flow of the magnetic fluid, heat transfer is not enhanced but reduced. In order to better understand this heat transfer phenomenon, we measured the velocity distribution of magnetic fluid flow by the Ultrasonic Velocity Profile (UVP) method. In the case of laminar flow, the result shows that the flow velocity at the center of the rectangular duct decreases and the velocity gradient in the near-wall region increases. Moreover, we calculated the flow resistance under a magnetic field by measurement of the pressure gradient, and the relationship between heat transfer and flow resistance was discussed.

  9. Numerical simulation of FENE-P viscoelastic fluids flow and heat transfer in grooved channel with rectangular cavities

    NASA Astrophysics Data System (ADS)

    Filali, Abdelkader; Khezzar, Lyes; Alshehhi, Mohamed Saeed

    2017-08-01

    The forced convection heat transfer for non-Newtonian viscoelastic fluids obeying the FENE-P model in a parallel-plate channel with transverse rectangular cavities is carried out numerically using ANSYS-POLYFLOW code. The flow investigated is assumed to be two-dimensional, incompressible, laminar and steady. The flow behavior and temperature distribution influenced by the re-circulation caused by the variation of cross-section area along the stream wise direction have been studied. The constant heat flux condition has been applied and the effects of the different parameters, such as the aspect ratio of channel cavities (AR = 0.25, 0.5), the Reynolds number ( Re = 25, 250, and 500), the fluid elasticity defined by the Weissenberg number ( We), and the extensibility parameter of the model ( L 2), on heat transfer characteristics have been explored for channels of three successive cavities configuration. Different levels of heat transfer enhancement were obtained and discussed.

  10. Heat-transfer coefficients for air flowing in round tubes, in rectangular ducts, and around finned cylinders

    NASA Technical Reports Server (NTRS)

    Drexel, Rober E; Mcadams, William H

    1945-01-01

    Report reviews published data and presents some new data on heat transfer to air flowing in round tubes, in rectangular ducts, and around finned cylinders. The available data for heat transfer to air in straight ducts of rectangular and circular cross section have been correlated in plots of Stanton number versus Reynolds number to provide a background for the study of the data for finned cylinders. Equations are recommended for both the streamlined and turbulent regions, and data are presented for the transition region between turbulent and laminar flow. Use of hexagonal ends on round tubes causes the characteristics of laminar flow to extend to high Reynolds numbers. Average coefficients for the entire finned cylinder have been calculated from the average temperature at the base of the fins and an equation which was derived to allow for the effectiveness of the fins. The available results for each finned cylinder are correlated herein in terms of graphs of Stanton number versus Reynolds number. In general, for a given Reynolds number, the Stanton number increases with increases in both spacing and width of the fins, and is apparently independent of cylinder diameter and temperature difference. For a given coefficient of heat transfer improved baffles and rough or wavy surfaces give a substantial reduction in pumping power per unit of heat transfer surface and a somewhat smaller decrease in pressure drop. (author)

  11. General Purpose Heat Source Simulator

    NASA Technical Reports Server (NTRS)

    Emrich, Bill

    2008-01-01

    The General Purpose Heat Source (GPHS) simulator project is designed to replicate through the use of electrical heaters, the form, fit, and function of actual GPHS modules which generate heat through the radioactive decay of Pu238. The use of electrically heated modules rather than modules containing Pu238 facilitates the testing of spacecraft subsystems and systems without sacrificing the quantity and quality of the test data gathered. Previous GPHS activities are centered around developing robust heater designs with sizes and weights that closely matched those of actual Pu238 fueled GPHS blocks. These efforts were successful, although their maximum temperature capabilities were limited to around 850 C. New designs are being pursued which also replicate the sizes and weights of actual Pu238 fueled GPHS blocks but will allow operation up to 1100 C.

  12. General Purpose Heat Source Simulator

    NASA Technical Reports Server (NTRS)

    Emrich, Bill

    2008-01-01

    The General Purpose Heat Source (GPHS) simulator project is designed to replicate through the use of electrical heaters, the form, fit, and function of actual GPHS modules which generate heat through the radioactive decay of Pu238. The use of electrically heated modules rather than modules containing Pu238 facilitates the testing of spacecraft subsystems and systems without sacrificing the quantity and quality of the test data gathered. Previous GPHS activities are centered around developing robust heater designs with sizes and weights that closely matched those of actual Pu238 fueled GPHS blocks. These efforts were successful, although their maximum temperature capabilities were limited to around 850 C. New designs are being pursued which also replicate the sizes and weights of actual Pu238 fueled GPHS blocks but will allow operation up to 1100 C.

  13. Analytical and experimental heat transfer and flow-field prediction on a rectangular reentry module

    SciTech Connect

    Laganelli, A.L.

    1980-02-05

    A General Purpose Heat Source (GPHS) has been designed for the purpose of supplying power to a radioisotope thermal generator intended for interplanetary missions. The baseline configuration, nominally 2 in. x 4 in. x 4 in. with sharp edges and corners, is required to survive accidental earth reentry as well as terminal impact velocities. Several problems have been identified relative to survival criteria during reentry. This paper is concerned with the flow field and reentry heating for a broad face-on or side-on reentry orientation. Moreover, the analysis considers convective heat transfer in the absence of roughness or ablation effects during the supersonic/hypersonic regime of reentry. The anaytical results are compared with wind tunnel data. From these studies it was concluded that heat transfer distributions for non-circular shapes ca be obtained for reentry conditions using wind tunnel data for the surface distributions and a stagnation value based on a reference sphere condition. The distributions obtained at a fixed Mach number (M > 1) appear valid over an extended range of Mach numbers. The above required definition of a proper velocity gradient, and definition of an area aspect ratio. Flowfield predictions (inviscid) using the CM2DT program provide a proper definition of pressure and shock characteristics for non-similar (viscous) solutions. (LCL)

  14. The influence of tip clearance and Prandtl number on turbulent forced convection heat transfer of rectangular fins

    NASA Astrophysics Data System (ADS)

    Park, Hae-Kyun; Chung, Bum-Jin

    2016-12-01

    The turbulent forced convection heat transfer of rectangular fins in a duct was investigated by varying the tip clearance and Pr. Mass transfer experiments using a H2SO4-CuSO4 electroplating system were performed based on the analogy between heat and mass transfers. FLUENT 6.3 was used for calculations. Turbulent models were tested and the Reynolds Stress Model was chosen, which showed a 1.15 % discrepancy with the existing correlation for a simple tube flow when Pr = 2, but 13 % when Pr = 2014. For a more complex fin channel, the discrepancy increased up to 30 %. The optimal tip clearances, corresponding to maximum heat transfer rates, did not vary with Pr, which is explained using the temperature contours. The results were also compared with the laminar case where Pr influenced the optimal tip clearance.

  15. A numerical simulation of the flow field and heat transfer in a rectangular passage with a turbulence promoter

    NASA Astrophysics Data System (ADS)

    Becker, Brian R.; Rivir, Richard B.

    1988-06-01

    A numerical study of the flow field and heat transfer in a turbine blade control cooling passage is described. Attention is focused on a short straight section of the rectangular passage which includes a single turbulator protruding from its floor. The two-dimensional, transient, Reynolds averaged Navier Stokes, continuity and energy equations are iterated to a steady state solution using the MacCormick explicit predictor-corrector algorithm. Turbulence closure is achieved through the use of the Baldwin-Lomax form of the Cebeci-Smith algebraic two layer eddy viscosity model. Plots of skin friction, local heat transfer rate, streamlines, velocity profiles and temperature profiles are given. It was found that the widely used Reynolds Analogy greatly underpredicts the heat transfer rate as given by a direct calculation using Fourier's law.

  16. Effect of oscillation frequency on wall shear stress and pressure drop in a rectangular channel for heat transfer applications

    NASA Astrophysics Data System (ADS)

    Blythman, R.; Persoons, T.; Jeffers, N.; Murray, DB

    2016-09-01

    The exploitation of flow unsteadiness in microchannels is a potentially useful technique for enhancing cooling of future photonics systems. Pulsation is thought to alter the thickness of the hydrodynamic and thermal boundary layers, and hence affect the overall thermal resistance of the heat sink. While the mechanical and thermal problems are inextricably linked, it is useful to decouple the parameters to better understand the mechanisms underlying any heat transfer enhancement. The current work characterises the behaviour of the wall shear stress and pressure gradient with frequency, using experimental particle image velocimetry (PIV) measurements and the analytical solution for oscillatory flow in a two-dimensional rectangular channel. Both wall shear stress and pressure gradient are augmented with frequency compared to steady flow, though the pressure gradient increases more significantly as a result of growing inertial losses. The three distinct regimes of unsteadiness are shown to display unique relationships between the parameters pertinent to heat transfer and should therefore be considered independently with respect to thermal enhancement capability. To this end, the regime boundaries are estimated at Womersley number Wo = 1.6 and 28.4 in a rectangular channel, based on the contribution of viscous and inertial losses.

  17. Heat sources for mantle plumes

    NASA Astrophysics Data System (ADS)

    Beier, C.; Rushmer, T.; Turner, S. P.

    2008-06-01

    Melting anomalies in the Earth's upper mantle have often been attributed to the presence of mantle plumes that may originate in the lower mantle, possibly from the core-mantle boundary. Globally, mantle plumes exhibit a large range in buoyancy flux that is proportional to their temperature and volume. Plumes with higher buoyancy fluxes should have higher temperatures and experience higher degrees of partial melting. This excess heat in mantle plumes could reflect either (1) an enrichment of the heat-producing elements (HPE: U, Th, K) in their mantle source leading to an increase of heat production by radioactive decay, (2) material transport from core to mantle (either advective or diffusive), or (3) conductive heat transport across the core-mantle boundary. The advective/diffusive transport of heat may result in a physical contribution of material from the core to the lower mantle. If core material is incorporated into the lower mantle, mantle plumes with a higher buoyancy flux should have higher core tracers, e.g., increased 186Os, 187Os, and Fe concentrations. Geophysical and dynamic modeling indicate that at least Afar, Easter, Hawaii, Louisville, and Samoa may all originate at the core-mantle boundary. These plumes encompass the whole range of known buoyancy fluxes from 0.9 Mg s-1 (Afar) to 8.7 Mg s-1 (Hawaii), providing evidence that the buoyancy flux is largely independent of other geophysical parameters. In an effort to explore whether the heat-producing elements are the cause of excess heat we looked for correlations between fractionation-corrected concentrations of the HPE and buoyancy flux. Our results suggest that there is no correlation between HPE concentrations and buoyancy flux (with and without an additional correction for variable degrees of partial melting). As anticipated, K, Th, and U are positively correlated with each other (e.g., Hawaii, Iceland, and Galapagos have significantly lower concentrations than, e.g., Tristan da Cunha, the Canary

  18. Heat-Transfer Coefficients for Air Flowing in Round Tubes, in Rectangular Ducts, and around Finned Cylinders

    DTIC Science & Technology

    1945-02-01

    985, 1945. M@ria, R. H., rnd Streid , D. D.: Laminar-Flow Heat Trsns- fer Coefffoimts for Duets. Trans. A.S.M.E., vol. 62, 1940, pp. 625-533. ● F...AIR /Af RECTANGULAR DUCTS NORRIS 1 AND A STREID / ./D.a=10 o 0 1000 YEATINC OR :OOLING h h h c h : h h h De (iNCHES; 0.533 0.463 0.233 0.463 “0.238 F

  19. Multiple source ground heat storage

    NASA Astrophysics Data System (ADS)

    Belzile, P.; Lamarche, L.; Rousse, D. R.

    2016-09-01

    Sharing geothermal borefields is usually done with each borehole having the same inlet conditions (flow rate, temperature and fluid). The objective of this research is to improve the energy efficiency of shared and hybrid geothermal borefields by segregating heat transfer sources. Two models are briefly presented: The first model allows the segregation of the inlet conditions for each borefields; the second model allows circuits to be defined independently for each leg of double U-tubes in a borehole. An application couples residential heat pumps and arrays of solar collectors. Independent circuits configuration gave the best energy savings in a symmetric configuration, the largest shank spacing and with solar collectors functioning all year long. The boreholes have been shortened from 300 m to 150 m in this configuration.

  20. Boiling Visualization and Critical Heat Flux Phenomena In Narrow Rectangular Gap

    SciTech Connect

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

    2004-12-01

    An experimental study was performed to investifate the pool boling critical hear flux (CHF) on one-dimensional inclined rectangular channels with narrow gaps by changing the orientation of a copper test heater assembly. In a pool of saturated water at atmospheric pressure, the test parameters include the gap sizes of 1,2,5, and 10 mm, andthe surface orientation angles from the downward facing position (180 degrees) to the vertical position (90 degress) respectively.

  1. 30 CFR 56.4500 - Heat sources.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Heat sources. 56.4500 Section 56.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 56.4500 Heat sources. Heat sources capable of producing combustion...

  2. 30 CFR 57.4500 - Heat sources.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Heat sources. 57.4500 Section 57.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 57.4500 Heat sources. Heat sources capable of producing combustion...

  3. 30 CFR 56.4500 - Heat sources.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Heat sources. 56.4500 Section 56.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 56.4500 Heat sources. Heat sources capable of producing combustion...

  4. 30 CFR 57.4500 - Heat sources.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Heat sources. 57.4500 Section 57.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 57.4500 Heat sources. Heat sources capable of producing combustion...

  5. 30 CFR 57.4500 - Heat sources.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Heat sources. 57.4500 Section 57.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 57.4500 Heat sources. Heat sources capable of producing combustion...

  6. 30 CFR 57.4500 - Heat sources.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Heat sources. 57.4500 Section 57.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 57.4500 Heat sources. Heat sources capable of producing combustion...

  7. 30 CFR 56.4500 - Heat sources.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Heat sources. 56.4500 Section 56.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 56.4500 Heat sources. Heat sources capable of producing combustion...

  8. 30 CFR 56.4500 - Heat sources.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Heat sources. 56.4500 Section 56.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 56.4500 Heat sources. Heat sources capable of producing combustion...

  9. 30 CFR 56.4500 - Heat sources.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Heat sources. 56.4500 Section 56.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 56.4500 Heat sources. Heat sources capable of producing combustion...

  10. 30 CFR 57.4500 - Heat sources.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Heat sources. 57.4500 Section 57.4500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Installation/construction/maintenance § 57.4500 Heat sources. Heat sources capable of producing combustion...

  11. Natural convection flow and heat transfer between a fluid layer and a porous layer inside a rectangular enclosure

    SciTech Connect

    Beckermann, C.; Ramadhyani, S.; Viskanta, R. )

    1987-05-01

    A numerical and experimental study is performed to analyze the steady-state natural convection fluid flow and heat transfer in a vertical rectangular enclosure that is partially filled with a vertical layer of a fluid-saturated porous medium. The flow in the porous layer is modeled utilizing the Brinkman-Forchheimer-extended Darcy equations. The numerical model is verified by conducting a number of experiments, with spherical glass beads as the porous medium and water and glycerin as the fluids, in rectangular test cells. The agreement between the flow visualization results and temperature measurements and the numerical model is, in general, good. It is found that the amount of fluid penetrating from the fluid region into the porous layer depends strongly on the Darcy (Da) and Rayleigh (Ra) numbers. For a relatively low product of Ra {times} Da, the flow takes place primarily in the fluid layers, and heat transfer in the porous layer is by conduction only. On other hand, fluid penetrating into a relatively highly permeable porous layer has a significant impact on the natural convection flow patterns in the entire enclosure.

  12. Vibration effect on the Soret-induced convection of ternary mixture in a rectangular cavity heated from below

    NASA Astrophysics Data System (ADS)

    Lyubimova, T. P.; Zubova, N. A.

    2017-06-01

    This paper presents the results of numerical simulation of the Soret-induced convection of ternary mixture in the rectangular cavity elongated in horizontal direction in gravity field. The cavity has rigid impermeable boundaries. It is heated from the bellow and undergoes translational linearly polarized vibrations of finite amplitude and frequency in the horizontal direction. The problem is solved by finite difference method in the framework of full unsteady non-linear approach. The procedure of diagonalization of the molecular diffusion coefficient matrix is applied, allowing to eliminate cross-diffusion components in the equations and to reduce the number of the governing parameters. The calculations are performed for model ternary mixture with positive separation ratios of the components. The data on the vibration effect on temporal evolution of instantaneous and average fields and integral characteristics of the flow and heat and mass transfer at different levels of gravity are obtained.

  13. The use of holographic interferometry for measurements of temperature in a rectangular heat pipe. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Marn, Jure

    1989-01-01

    Holographic interferometry is a nonintrusive method and as such possesses considerable advantages such as not disturbing the velocity and temperature field by creating obstacles which would alter the flow field. These optical methods have disadvantages as well. Holography, as one of the interferometry methods, retains the accuracy of older methods, and at the same time eliminates the system error of participating components. The holographic interferometry consists of comparing the objective beam with the reference beam and observing the difference in lengths of optical paths, which can be observed during the propagation of the light through a medium with locally varying refractive index. Thus, change in refractive index can be observed as a family of nonintersecting surfaces in space (wave fronts). The object of the investigation was a rectangular heat pipe. The goal was to measure temperatures in the heat pipe, which yields data for computer code or model assessment. The results were obtained by calculating the temperatures by means of finite fringes.

  14. Analytical solution for boundary heat fluxes from a radiating rectangular medium

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1991-01-01

    Reference is made to the work of Shah (1979) which demonstrated the possibility of partially integrating the radiative equations analytically to obtain an 'exact' solution. Shah's solution was given as a double integration of the modified Bessel function of order zero. Here, it is shown that the 'exact' solution for a rectangular region radiating to cold black walls can be conveniently derived, and expressed in simple form, by using an integral function, Sn, analogous to the exponential integral function appearing in plane-layer solutions.

  15. Analytical solution for boundary heat fluxes from a radiating rectangular medium

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1991-01-01

    Reference is made to the work of Shah (1979) which demonstrated the possibility of partially integrating the radiative equations analytically to obtain an 'exact' solution. Shah's solution was given as a double integration of the modified Bessel function of order zero. Here, it is shown that the 'exact' solution for a rectangular region radiating to cold black walls can be conveniently derived, and expressed in simple form, by using an integral function, Sn, analogous to the exponential integral function appearing in plane-layer solutions.

  16. Carbothermic reduction with parallel heat sources

    DOEpatents

    Troup, Robert L.; Stevenson, David T.

    1984-12-04

    Disclosed are apparatus and method of carbothermic direct reduction for producing an aluminum alloy from a raw material mix including aluminum oxide, silicon oxide, and carbon wherein parallel heat sources are provided by a combustion heat source and by an electrical heat source at essentially the same position in the reactor, e.g., such as at the same horizontal level in the path of a gravity-fed moving bed in a vertical reactor. The present invention includes providing at least 79% of the heat energy required in the process by the electrical heat source.

  17. Control of heat source in a heat conduction problem

    NASA Astrophysics Data System (ADS)

    Lyashenko, V.; Kobilskaya, E.

    2014-11-01

    The mathematical model of thermal processes during the heat treatment of a moving axisymmetric environment, for example wire. is considered. The wire is heated by internal constantly or periodically operating heat source. It is presented in the form of initial-boundary value problem for the unsteady heat equation with internal constantly or periodically operating heat source. The purpose of the work is the definition of control parameter of temperature field of a moving area, which is heated by internal heat source. The control parameters are determined by solving a nonlocal problem for the heat equation. The problem of getting an adequate temperature distribution throughout the heating area is considered. Therefore, a problem of heat source control is solved, in particular, control by electric current. Control of the heat source allows to maintain the necessary, from a technological point of view, temperature in the heating area. In this paper, to find additional information about the source of heat. The integral condition is used in the control problem. Integral condition, which is considered in the work, determines the energy balance of the heating zone and connects the desired temperature distribution in the internal points of area with temperatures at the boundaries. Control quality in an extremum formulation of the problem is assessed using the quadratic functional. In function space, from a physical point of view, proposed functional is the absolute difference between the actual emission of energy and absorbed energy in the heating zone. The absorbed energy is calculated by solving of the boundary value problem. Methods of determining the control parameters of temperature field are proposed. The resulting problem is solved by iterative methods. At different physical conditions, numerical calculations are carried out, control parameters of the heat treatment process are obtained.

  18. Interaction of a turbulent-jet noise source with transverse modes in a rectangular duct

    NASA Technical Reports Server (NTRS)

    Succi, G. P.; Baumeister, K. J.; Ingard, K. U.

    1978-01-01

    A turbulent jet was used to excite transverse acoustic modes in a rectangular duct. The pressure spectrum showed asymmetric singularities (pressure spikes) at the resonant frequencies of the duct modes. This validates previously published theoretical results. These pressure spikes occurred over a range of jet velocities, orientations, and inlet turbulence levels. At the frequency of the spike, the measured transverse pressure shape matched the resonant mode shape.

  19. Unsteady flow and heat transfer in a channel with a built-in tandem of rectangular cylinders

    SciTech Connect

    Valencia, A.

    1996-05-10

    The incompressible unsteady flow past a channel with a pair of cylinders of rectangular cross section, placed in tandem normal to the flow, is investigated by numerical simulation. The objective is to evaluate the effect of cylinder separation distance, S/H, on the flow behavior and heat transfer on the channel walls, over a range of Reynolds numbers. Above a critical Reynolds number, these flows bifurcate to a time-periodic self-sustained oscillatory state. The results reveal for S/H = 2.0 three distinct flow patterns: steady flow (Re = 200), time-periodic oscillatory state (400 {le} Re {le} 800), and quasi-periodic oscillatory flow (Re = 1,000). For S/H < 2.0 the intercylinder flow consists of a pair of steady counterrotating eddies that do not exchange fluid with the surrounding and unsteady eddies. Eddy shedding is observed only for the downstream cylinder for Re > 600.

  20. Thulium heat sources for space power applications

    SciTech Connect

    Alderman, C.J.

    1992-05-01

    Reliable power supplies for use in transportation and remote systems will be an important part of space exploration terrestrial activities. A potential power source is available in the rare earth metal, thulium. Fuel sources can be produced by activating Tm-169 targets in the space station reactor. The resulting Tm-170 heat sources can be used in thermoelectric generators to power instrumentation and telecommunications located at remote sites such as weather stations. As the heat source in a dynamic Sterling or Brayton cycle system, the heat source can provide a lightweight power source for rovers or other terrestrial transportation systems.

  1. The effect of different inlet conditions of air in a rectangular channel on convection heat transfer: Turbulence flow

    SciTech Connect

    Kurtbas, Irfan

    2008-10-15

    Theoretical and empirical correlations for duct flow are given for hydrodynamically and thermally developed flow in most of previous studies. However, this is commonly not a realistic inlet configuration for heat exchanger, in which coolant flow generally turns through a serpentine shaped passage before entering heat sinks. Accordingly, an experimental investigation was carried out to determine average heat transfer coefficients in uniformly heated rectangular channel with 45 and 90 turned flow, and with wall mounted a baffle. The channel was heated through bottom side with the baffle. In present work, a detailed study was conducted for three different height of entry channel (named as the ratio of the height of entry channel to the height of test section (anti H{sub c}=h{sub c}/H)) by varying Reynolds number (Re{sub Dh}). Another variable parameter was the ratio of the baffle height to the channel height (anti H{sub b}=h{sub b}/H). Only one baffle was attached on the bottom (heating) surface. The experimental procedure was validated by comparing the data for the straight channel with no baffle. Reynolds number (Re{sub Dh}) was varied from 2800 to 30,000, so the flow was considered as only turbulent regime. All experiments were conduced with air accordingly; Prandtl number (Pr) was approximately fixed at 0.71. The results showed that average Nusselt number for {theta}=45 and {theta}=90 were 9% and 30% higher, respectively, than that of the straight channel without baffle. Likewise, the pressure drop increased up to 4.4 to 5.3 times compare to the straight channel. (author)

  2. Heating times for round and rectangular cross sections of wood in steam

    Treesearch

    William T. Simpson

    2001-01-01

    Heat sterilization of wood in various forms is currently receiving attention as a means of killing insects or pathogens to prevent their transfer from one region of the world to another in trade. One concern is the amount of time required to heat wood of various cross-sectional sizes and configurations to a temperature that will kill the insects or pathogens....

  3. Lattice Boltzmann simulation of fluid flow and heat transfer in a parallel-plate channel with transverse rectangular cavities

    NASA Astrophysics Data System (ADS)

    Mohebbi, Rasul; Heidari, Hanif

    The aim of this paper is investigating the forced convection heat transfer in a channel with transverse rectangular cavities using the lattice Boltzmann method (LBM) which is not available in the literature yet. The effects of the Reynolds number (100-400), cavity aspect ratio (AR=0.25, 0.5, 1.0), distance of cavities from each other (S‧=0,2,4,6) in fixed depth of cavity (A‧=0.5) on the velocity and temperature profiles are studied. Moreover, the flow patterns such as deflection and re-circulation zone inside the cavities are obtained. The local and averaged Nusselt numbers on the channel walls are achieved. The results show that the channel with cavities achieves heat transfer enhancements relative to the smooth channel. For the constant cavity aspect ratio, the maximum value of averaged Nusselt number in the channel is obtained in the case of S‧=2. Heat transfer to the working fluids increases significantly by increasing the aspect ratio. The existed results are used to ascertain the validity of the numerical code and excellent agreement between results was found.

  4. An experimental investigation of heat transfer characteristics for steam cooling in a rectangular channel with parallel ribs

    NASA Astrophysics Data System (ADS)

    Ma, Chao; Chen, Xiaoling; Wang, Jianfei; Zang, Shusheng; Ji, Yongbin

    2014-10-01

    An experimental study of heat transfer characteristics in superheated steam cooled rectangular channels with parallel ribs was conducted. The distribution of the heat transfer coefficient on the rib-roughed channel was measured by IR camera. The blockage ratio (e/Dh) of the tested channel is 0.078 and the aspect ratio (W/H) is fixed at 3.0. Influences of the rib pitch-to-height ratio (P/e) and the rib angle on heat transfer for steam cooling were investigated. In this paper, the Reynolds number (Re) for steam ranges from 3070 to 14800, the rib pitch-to-height ratios were 8, 10 and 12, and rib angles were 90°, 75°, 60°, and 45°. Based on results above, we have concluded that: In case of channels with 90° tranverse ribs, for larger rib pitch models (the rib pitch-to-height ratio=10 and 12), areas with low heat transfer coefficient in front of rib is larger and its minimum is lower, while the position of the region with high heat transfer coefficient nearly remains the same, but its maximun of heat transfer coefficient becomes higher. In case of channels with inclined ribs, heat transfer coefficients on the surface decrease along the direction of each rib and show an apparent nonuniformity, consequently the regions with low Nusselt number values closely following each rib expand along the aforementioned direction and that of relative high Nusselt number values vary inversely. For a square channel with 90° ribs at Re=14800, wider spacing rib configurations (the rib pitch-to-height ratio=10 and 12) give an area-averaged heat transfer on the rib-roughened surface about 8.4% and 11.4% more than P/e=8 model, respectively; for inclined parallel ribs with different rib angles at Re= 14800, the area-averaged heat transfer coefficients of 75°, 60° and 45° ribbed surfaces increase by 20.1%, 42.0% and 44.4% in comparison with 90° rib angle model. 45° angle rib-roughened channel leads to a maximal augmentation of the area-averaged heat transfer coefficient in all

  5. Mixed convection flow and heat transfer in entrance region of rectangular ducts rotating about a parallel axis

    SciTech Connect

    Soong, C.Y.; Yan, W.M.

    1995-12-31

    The objective of the present work is to investigate the laminar mixed convection flow and heat transfer in the entrance region of heated rectangular ducts rotating about a parallel axis. Heating conditions of isothermal and iso-flux are both considered. Boussinesq approximation is invoked to take into account buoyancy effect induced by centrifugal force. Navier-Stokes/Boussinesq system can be cast into a dimensionless form, in which five governing parameters, the Prandtl number Pr, rotational Reynolds number J, rotational Grashof number Gr{sub {Omega}}, aspect ratio {gamma} and the eccentricity E, are involved. Mechanisms of secondary vortex development in the ducts are explored by a theoretical analysis on vorticity transport equation. The values of Pr and E are fixed as 0.7 and 10, respectively. For various combinations of the other thee parameters, a vorticity-velocity method implemented with a marching technique is employed to solve the resultant three-dimensional system for simultaneously developing flow and temperature fields. The emphasis is placed on the rotational effects, including both coriolis force and centrifugal buoyancy; on the non-isothermal flow and the related heat transfer. The results reveal that the friction factors and heat transfer rates can be enhanced by Coriolis and rotation-induced buoyancy effects; and the variations of the local values are closely related to the evolution of the secondary vortices in ducts. The differences in flow behaviors and thermal characteristics for UWT and UHF are also investigated by the present theoretical analysis on secondary flow mechanism as well as the computational results.

  6. Thulium heat sources for space power application

    NASA Astrophysics Data System (ADS)

    Alderman, C. J.

    1992-10-01

    Reliable electrical power supplies for use in transportation and remote systems will be an important part of space exploration activities on planet surfaces. A potential power source is available through the use of thulium, a rare earth metal. Heat sources can be produced by neutron activation of naturally occurring thulium (Tm-169) targets in the base station nuclear power reactor. The resulting Tm-170 heat sources can be used in thermoelectric generators to power instrumentation and telecommunications systems located at remote sites. Combined with a dynamic Sterling or Brayton cycle conversion system, the heat source can power a lightweight electrical source for rovers or other surface transportation systems.

  7. Heat source reentry vehicle design study

    NASA Technical Reports Server (NTRS)

    Ryan, R. L.

    1971-01-01

    The design details are presented of a flight-type heat source reentry vehicle and heat exchanger compatible with the isotope Brayton power conversion system. The reference reentry vehicle and heat exchanger were modified, orbital and superorbital capability was assessed, and a complete set of detail design layout drawings were provided.

  8. Fuel change possibilities in small heat source

    NASA Astrophysics Data System (ADS)

    Durčanský, Peter; Kapjor, Andrej; Jandačka, Jozef

    2017-09-01

    Rural areas are characterized by a larger number of older family houses with higher fuel consumption for heating. Some areas are not gasified, which means that the fuel base for heating the buildings is very limited. Heating is mainly covered by solid fuels with high emissions and low efficiency. But at the same time, the amount of energy in the form of biowaste can be evaluated and used further. We will explore the possibilities to convert biogas to heat of using a gas burner in a small heat source. However, the heat produced can be used other than for heating or hot water production. The added value for heat generation can be the production of electricity, in the use of heat energy through cogeneration unit with unconventional heat engine. The proposed solution could economically benefit the entire system, because electricity is a noble form of energy and its use is versatile.

  9. Mini-Brayton heat source assembly development

    NASA Technical Reports Server (NTRS)

    Wein, D.; Zimmerman, W. F.

    1978-01-01

    The work accomplished on the Mini-Brayton Heat Source Assembly program is summarized. Required technologies to design, fabricate and assemble components for a high temperature Heat Source Assembly (HSA) which would generate and transfer the thermal energy for a spaceborne Brayton Isotope Power System (BIPS) were developed.

  10. Investigation of hydrodynamics and heat transfer at liquid metal downflow in a rectangular duct in a coplanar magnetic field

    NASA Astrophysics Data System (ADS)

    Poddubnyi, I. I.; Razuvanov, N. G.

    2016-02-01

    Hydrodynamics and heat transfer in a liquid metal downflow in a rectangular duct with an aspect ratio of approximately 3/1 in a coplanar magnetic field (MF) are studied upon inhomogeneous (one-sided) heating of the duct. The flow in the heat-transfer duct of the cooling system of a liquid-metal blanket module of the tokamak-type thermonuclear reactor is modeled. Experiments were carried out at the mercury magnetohydrodynamic (MHD) test facility, which is a part of the MHD-complex of Moscow Power Engineering Institute-Joint Institute for High Temperatures of the Russian Academy of Sciences. A probe technique is used for measurements in the flow. The studies are performed within the following ranges of regime parameters: Reynolds numbers Re = 10000-55000, Hartmann numbers Ha = 0-800, and Grashof numbers Grq = 0-6 × 108. Averaged profiles of velocity, temperature, temperature fluctuations of the flow, and duct wall temperature are presented for two typical flow regimes. Detailed measurements are performed in the duct cross-section distant from the heating beginning in the region of homogeneous MF. MF leads to the turbulent transport suppression, owing to which the temperature on the heated wall increases. A considerable influence of the heat-gravitational counter-convection, the interaction of which with the external MF leads in some regimes to the appearance and development of instabilities in the laminarized flow, is revealed under the downflow conditions. Generation of large-scale secondary vortices with the axis parallel to the MF induction causes temperature fluctuations of the abnormal intensity that considerably exceeds the level of turbulent fluctuations. Such temperature fluctuations easily penetrate into the duct wall and can lead to the fatigue breakdown of thermonuclear reactor cooling paths. Ranges of unallowable regime parameters are determined and the boundary in coordinates Gr-Re is presented, where this effect is revealed or vanishes. The numerical

  11. Experimental Investigation of Turbulent Heat Transfer in Straight and Curved Rectangular Ducts.

    DTIC Science & Technology

    1983-09-01

    1473 COITION OF INOV 49IS OSSOLETE Unclassified S,’N 0102. LX. 014- 6601 SECURITY CLASSIFICATION Of THIS PAGE (When Does BRtewev Unclassified "umvTY C3...C. POWER CALCULATIONS --------------------- 63 D. MASS FLOW RATE CALCULATIONS ------------ 64 E. REYNOLDS NUMBER CALCULATIONS ----------- 66 F. HEAT...measure power supplied to the Temsheet. --------------------------------------- 38 12. Straight vs. curved section results, present study

  12. Rewet Performance of a Rectangular Grooved Heat Pipe Wick After Gravitationally Induced Dryout

    DTIC Science & Technology

    1992-12-01

    Ad Astral Lowell S. Hawthorne ii TABLE OF CONTENTS Page Acknowledgements ............ ..................... ii List of Figures...research projects and actual applications. Secondly, because it performs well in moderate-heat applications, it was well-suited for an AFIT laboratory...position he oversaw several multimillion dollar security construction projects as well as assisting Sandia National Laboratories in the design, installation

  13. Experimental study of flow boiling heat transfer in a rectangular minichannel by using various enhanced heating surface

    NASA Astrophysics Data System (ADS)

    Piasecka, Magdalena

    2012-11-01

    The paper presents the results of flow boiling heat transfer in a horizontal minichannel, 1 mm deep, 40 mm wide and 360 mm long. The heating element for FC-72 which flows along the minichannel is a thin enhanced alloy. It is possible to observe both surfaces of the minichannel through an opening covered with two glass panes. The first one allows observing changes in the temperature of the foil surface due to liquid crystal thermography. The second allows the identification of the two-phase flow patterns. The experiments employed the enhanced heating foil with various depressions, distributed diversely on the surface. Two types of enhanced heating surfaces: with micro re-entrant cavities evenly distributed, and with mini re-entrant cavities unevenly distributed, were used for the purpose of the investigation. The main objective of the paper is to determine the void fraction for cross-sections of selected images for increasing heat fluxes supplied to the heating surface. The results are presented as the void fraction dependence along the minichannel length for the selected cross-sections. Exemplary boiling curves derived from data obtained from initial increasing and subsequent decreasing the heat flux supplied to the foil are also presented. The investigation has been intended to determine the correlation for the calculations of the Nusselt number as a function of variable parameters.

  14. The heat treating source book

    SciTech Connect

    Gupton, P.S.

    1986-01-01

    The first section of this book reviews current trends and is followed by an article describing how to design for lower cost and high-quality heat treatment. Two separate sections deal with ferrous materials and non-ferrous metals. Coverage includes stress-relief heat treating, normalizing and cold treating of steel; ultrahigh-strength steels; tool steels; maraging steels; austenitic stainless steels and cast irons, as well as aluminum alloys, titanium and its alloys, nickel-base superalloys, special purpose alloys and lead and its alloys. Other topics discussed are carburizing, carbonitriding and nitriding; vacuum methods; salt bath processing; methods of measuring case depth; and atmosphere control and nitrogen as all-purpose atmosphere. Also, information is provided on energy-efficient operations, production systems, selecting and handling quenching fluids, furnace control instrumentation, and guidelines for heat treating powdered metal parts.

  15. Heat transfer and pressure drop in rectangular channels with crossing fins (a Review)

    NASA Astrophysics Data System (ADS)

    Sokolov, N. P.; Polishchuk, V. G.; Andreev, K. D.; Rassokhin, V. A.; Zabelin, N. A.

    2015-06-01

    Channels with crossing finning find wide use in the cooling paths of high-temperature gas turbine blade systems. At different times, different institutions carried out experimental investigations of heat transfer and pressure drop in channels with coplanar finning of opposite walls for obtaining semiempirical dependences of Nusselt criteria (dimensionless heat-transfer coefficients) and pressure drop coefficients on the operating Reynolds number and relative geometrical parameters (or their complexes). The shape of experimental channels, the conditions of experiments, and the used variables were selected so that they would be most suited for solving particular practical tasks. Therefore, the results obtained in processing the experimental data have large scatter and limited use. This article considers the results from experimental investigations of different authors. In comparing the results, additional calculations were carried out for bringing the mathematical correlations to the form of dependences from the same variables. Generalization of the results is carried out. In the final analysis, universal correlations are obtained for determining the pressure drop coefficients and Nusselt number values for the flow of working medium in channels with coplanar finning.

  16. EXPERIMENTAL INVESTIGATION OF NATURAL CONVECTION HEAT TRANSFER OF IONIC LIQUID IN A RECTANGULAR ENCLOSURE HEATED FROM BELOW

    SciTech Connect

    Fox, E.; Visser, A.; Bridges, N.

    2011-07-18

    This paper presents an experimental study of natural convection heat transfer for an Ionic Liquid. The experiments were performed for 1-butyl-2, 3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, ([C{sub 4}mmim][NTf{sub 2}]) at a Raleigh number range of 1.26 x 10{sup 7} to 8.3 x 10{sup 7}. In addition to determining the convective heat transfer coefficients, this study also included experimental determination of thermophysical properties of [C{sub 4}mmim][NTf{sub 2}] such as, density, viscosity, heat capacity, and thermal conductivity. The results show that the density of [C{sub 4}mmim][NTf{sub 2}] varies from 1.437-1.396 g/cm{sup 3} within the temperature range of 10-50 C, the thermal conductivity varies from 0.105-0.116 W/m.K between a temperature of 10 to 60 C, the heat capacity varies from 1.015 J/g.K - 1.760 J/g.K within temperature range of 25-340 C and the viscosity varies from 18cp-243cp within temperature range 10-75 C. The results for density, thermal conductivity, heat capacity, and viscosity were in close agreement with the values in the literature. Measured dimensionless Nusselt number was observed to be higher for the ionic liquid than that of DI water. This is expected as Nusselt number is the ratio of heat transfer by convection to conduction and the ionic liquid has lower thermal conductivity (approximately 18%) than DI water.

  17. Simulation analysis of rectangular dielectric-loaded traveling wave amplifiers for THz sources

    NASA Astrophysics Data System (ADS)

    Wang, Changbiao

    2007-12-01

    Nonlinear simulation results for a 220-GHz rectangular dielectric-loaded traveling-wave amplifier are presented. Simulations are used to check a linear theory that is developed by phenomenological introduction of an effective dielectric parameter for electron beam channel, and it is found that the rf power gains from Pierce three-wave theory and particle simulations are in reasonable agreement. It is shown that the rf power gain during initial beam-wave interaction is positive; the falling on the initial rf power profile, which has been thought to be the rf power transferred to the beam for bunching buildup (negative gain effect), is probably resulting from numerical errors. Beam-wave interaction mechanism is analyzed by examining the evolution of beam bunching centers. Influences of various parameters on amplifier performance are examined, and transverse space-charge effect is analyzed. A symmetric excitation scheme for rf couplers is proposed, and rf field jumps on the common intersection line of vacuum, dielectric, and metal wall, which were found in rf simulations, are explained theoretically.

  18. Effects of the aspect ratio on the optimal tilting angle for maximum convection heat transfer across air-filled rectangular enclosures differentially heated at sides

    NASA Astrophysics Data System (ADS)

    Cianfrini, C.; Corcione, M.; Habib, E.; Quintino, A.

    2017-06-01

    Natural convection in air-filled rectangular cavities inclined with respect to gravity, so that the heated wall is facing upwards, is studied numerically under the assumption of two-dimensional laminar flow. A computational code based on the SIMPLE-C algorithm is used for the solution of the system of the mass, momentum and energy transfer governing equations. Simulations are performed for height-to-width aspect ratios of the enclosure from 0.25 to 8, Rayleigh numbers based on the length of the heated and cooled walls from 102 to 107, and tilting angles of the enclosure from 0° to 75°. The existence of an optimal tilting angle is confirmed for any investigated configuration, at a location that increases as the Rayleigh number is decreased, and the height-to-width aspect ratio of the cavity are increased, unless the value of the Rayleigh number is that corresponding to the onset of convection or just higher. Dimensionless correlating equations are developed to predict the optimal tilting angle and the heat transfer performance of the enclosure.

  19. Computationally Efficient Direction Finding for a Mixture of Circular and Strictly Noncircular Sources with Uniform Rectangular Arrays.

    PubMed

    Wang, Qing; Zhu, Xiaotian; Chen, Hua; Wang, Laihua; Yan, Weiqing; Fang, Haoyu

    2017-06-02

    In this paper, a novel two-dimensional (2D) direction-of-arrival (DOA) estimation algorithm for the mixed circular and strictly noncircular sources is proposed. A general array model with a mixture of signals is firstly built based on uniform rectangular arrays (URAs), and then, the approach, which uses the rank-reduction-based ROOT-MUSIC, can solve 2D DOA estimation problem. Besides, the theoretical error of the proposed algorithm, a criterion of the performance for evaluation, is analyzed by the first-order Taylor expression using second-order statistics. As verified by the simulation results, a better DOA estimation performance and a lower computational complexity are achieved by the proposed algorithm than the existing methods resorting to the noncircularity of the incoming signals.

  20. Computationally Efficient Direction Finding for a Mixture of Circular and Strictly Noncircular Sources with Uniform Rectangular Arrays

    PubMed Central

    Wang, Qing; Zhu, Xiaotian; Chen, Hua; Wang, Laihua; Yan, Weiqing; Fang, Haoyu

    2017-01-01

    In this paper, a novel two-dimensional (2D) direction-of-arrival (DOA) estimation algorithm for the mixed circular and strictly noncircular sources is proposed. A general array model with a mixture of signals is firstly built based on uniform rectangular arrays (URAs), and then, the approach, which uses the rank-reduction-based ROOT-MUSIC, can solve 2D DOA estimation problem. Besides, the theoretical error of the proposed algorithm, a criterion of the performance for evaluation, is analyzed by the first-order Taylor expression using second-order statistics. As verified by the simulation results, a better DOA estimation performance and a lower computational complexity are achieved by the proposed algorithm than the existing methods resorting to the noncircularity of the incoming signals. PMID:28574458

  1. Transient natural convection in rectangular enclosures heated from one side and cooled from above

    SciTech Connect

    Aydin, O.

    1999-01-01

    Buoyancy-induced flows in enclosures play an important role in many engineering applications, such as heating and cooling of buildings, electronics cooling, solar energy collection systems, materials processing, energy storage systems, etc. Here, a numerical investigation into two-dimensional transient natural convection of single-phase fluids inside a completely filled square enclosure has been conducted for the Prandtl numbers of 0.71 and 7.1, and the Rayleigh number range 10{sup 3}--10{sup 7}. The fluid is assumed to be initially at a uniform temperature and motionless. Then, at time zero, the flow is driven by instantaneously raising and lowering the temperatures at the left side and the top wall, respectively. Adiabatic boundary conditions are used at the remaining walls. The unsteady Navier-Stokes equations, governing the flow under Boussinesq approximation, are solved with the vorticity-stream function formulation using the finite difference method. The development of the flow and temperature fields following these temperature changes are determined numerically. The transient behavior of the average Nusselt number at the hot wall is traced.

  2. Active control of sound radiation from a vibrating rectangular panel by sound sources and vibration inputs - An experimental comparison

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.; Hansen, C. H.; Snyder, S. D.

    1991-01-01

    Active control of sound radiation from a rectangular panel by two different methods has been experimentally studied and compared. In the first method a single control force applied directly to the structure is used with a single error microphone located in the radiated acoustic field. Global attenuation of radiated sound was observed to occur by two main mechanisms. For 'on-resonance' excitation, the control force had the effect of increasing the total panel input impedance presented to the nosie source, thus reducing all radiated sound. For 'off-resonance' excitation, the control force tends not significantly to modify the panel total response amplitude but rather to restructure the relative phases of the modes leading to a more complex vibration pattern and a decrease in radiation efficiency. For acoustic control, the second method, the number of acoustic sources required for global reduction was seen to increase with panel modal order. The mechanism in this case was that the acoustic sources tended to create an inverse pressure distribution at the panel surface and thus 'unload' the panel by reducing the panel radiation impedance. In general, control by structural inputs appears more effective than control by acoustic sources for structurally radiated noise.

  3. Characterization and modeling of the heat source

    SciTech Connect

    Glickstein, S.S.; Friedman, E.

    1993-10-01

    A description of the input energy source is basic to any numerical modeling formulation designed to predict the outcome of the welding process. The source is fundamental and unique to each joining process. The resultant output of any numerical model will be affected by the initial description of both the magnitude and distribution of the input energy of the heat source. Thus, calculated weld shape, residual stresses, weld distortion, cooling rates, metallurgical structure, material changes due to excessive temperatures and potential weld defects are all influenced by the initial characterization of the heat source. Understandings of both the physics and the mathematical formulation of these sources are essential for describing the input energy distribution. This section provides a brief review of the physical phenomena that influence the input energy distributions and discusses several different models of heat sources that have been used in simulating arc welding, high energy density welding and resistance welding processes. Both simplified and detailed models of the heat source are discussed.

  4. Optimization of an ammonia-cooled rectangular microchannel heat sink using multi-objective non-dominated sorting genetic algorithm (NSGA2)

    NASA Astrophysics Data System (ADS)

    Adham, Ahmed Mohammed; Mohd-Ghazali, Normah; Ahmad, Robiah

    2012-10-01

    The ever decreasing size of modern electronic packaging has induced researchers to search for an effective and efficient heat removal system to handle the continuously increasing power density. Investigations have involved different geometry, material and coolant to address the thermal management issues. This paper reports the potential improvement in the overall performance of a rectangular microchannel heat sink using a new gaseous coolant namely ammonia gas. Using a multi-objective general optimization scheme with the thermal resistance model as an analysis method in combination with a non-dominated sorting genetic algorithm as an optimization technique, it was found that significant reduction in the total thermal resistance up to 34 % for ammonia-cooled compared to air-cooled microchannel heat sink under the same operating conditions is achievable. In addition, a considerable decrease in the microchannel heat sink's mass up to 30 % was achieved due to the different heat sink's material used.

  5. The Radiated Field Generated by a Monopole Source in a Short, Rigid, Rectangular Duct. Degree awarded by George Washington Univ.

    NASA Technical Reports Server (NTRS)

    Lakota, Barbara Anne

    1998-01-01

    This thesis develops a method to model the acoustic field generated by a monopole source placed in a moving rectangular duct. The walls of the duct are assumed to be infinitesimally thin and the source is placed at the center of the duct. The total acoustic pressure is written in terms of the free-space pressure, or incident pressure, and the scattered pressure. The scattered pressure is the augmentation to the incident pressure due to the presence of the duct. It satisfies a homogeneous wave equation and is discontinuous across the duct walls. Utilizing an integral representation of the scattered pressure, a set of singular boundary integral equations governing the unknown jump in scattered pressure is derived. This equation is solved by the method of collocation after representing the jump in pressure as a double series of shape functions. The solution obtained is then substituted back into the integral representation to determine the scattered pressure, and the total acoustic pressure at any point in the field. A few examples are included to illustrate the influence of various geometric and kinematic parameters on the radiated sound field.

  6. Heat Deposition in Positron Sources for ILC

    SciTech Connect

    Bharadwaj, V.; Pitthan, R.; Sheppard, J.; Vincke, H.; Wang, J.W.; /SLAC

    2006-03-15

    In the International Linear Collider (ILC) positron source, multi-GeV electrons or multi-MeV photons impinge on a metal target to produce the needed positrons in the resulting electromagnetic showers. The incoming beam power is hundreds of kilowatts. Various computer programs -- such as FLUKA or MARS -- can calculate how the incoming beam showers in the target and can track the particle showers through the positron source system. Most of the incoming energy ends up as heat in the various positron source elements. This paper presents results from such calculations and their impact on the design of a positron source for the ILC.

  7. Heat transfer characteristics of rectangular coolant channels with various aspect ratios in the plasma-facing components under fully developed MHD laminar flow

    SciTech Connect

    Takase, K.; Hasan, M.Z.

    1995-12-31

    Convective heat transfer in MHD laminar flow through rectangular channels in the plasma-facing components of a fusion reactor has been analyzed numerically to investigate the effects of channel aspect ratio, defined as the ratio of the lengths of the plasma-facing side to the other side. The adverse effect of the nonuniformity of surface heat flus on Nusselt number (Nu) at the plasma-facing side can be alleviated by increasing the aspect ratio of a rectangular duct. At the center and corner of the plasma-facing side of a square duct, the Nu of non-MHD flow are 6.8 and 2.2, respectively, for uniform surface heat flux. In the presence of a strong magnetic field, Nu at the center and corner increases to 22 and 3.6, respectively. However, when the heat flux is highly nonuniform, as in the plasma-facing components, Nu decreases from 22 to 3.1 at the center and from 3.6 to 3.1 at the corner. When the aspect ratio is increased to 4, Nu at the center and corner increase to 5 and 4.7. Along the circumference of a rectangular channel, there are locations where the wall temperature is equal to or less than the bulk coolant temperature, thus making the Nu with conventional definition infinity or negative. The ratio between Nu of MHD flow and Nu of non-MHD flow for various aspect ratios is constant in the region of Hartmann number of more than 200 at least. On the other hand, its ratio increases monotonously with increasing the aspect ratio.

  8. Electron beam energy chirp control with a rectangular corrugated structure at the Linac Coherent Light Source

    DOE PAGES

    Zhang, Zhen; Bane, Karl; Ding, Yuantao; ...

    2015-01-30

    In this study, electron beam energy chirp is an important parameter that affects the bandwidth and performance of a linac-based, free-electron laser. In this paper we study the wakefields generated by a beam passing between at metallic plates with small corrugations, and then apply such a device as a passive dechirper for the Linac Coherent Light Source (LCLS) energy chirp control with a multi-GeV and femtosecond electron beam. Similar devices have been tested in several places at relatively low energies (~100 MeV) and with relatively long bunches (> 1ps). In the parameter regime of the LCLS dechirper, with the corrugationmore » size similar to the gap between the plates, the analytical solutions of the wakefields are no longer applicable, and we resort to a field matching program to obtain the wakes. Based on the numerical calculations, we fit the short-range, longitudinal wakes to simple formulas, valid over a large, useful parameter range. Finally, since the transverse wakefields - both dipole and quadrupole-are strong, we compute and include them in beam dynamics simulations to investigate the error tolerances when this device is introduced in the LCLS.« less

  9. Ion plating with an induction heating source

    NASA Technical Reports Server (NTRS)

    Spalvins, T.; Brainard, W. A.

    1976-01-01

    Induction heating is introduced as an evaporation heat source in ion plating. A bare induction coil without shielding can be directly used in the glow discharge region with no arcing. The only requirement is to utilize an rf inductive generator with low operating frequency of 75 kHz. Mechanical simplicity of the ion plating apparatus and ease of operation is a great asset for industrial applications; practically any metal such as nickel, iron, and the high temperature refractories can be evaporated and ion plated.

  10. Heat transfer behaviour of silver particles containing oleic acid surfactant: application in a two phase closed rectangular cross sectional thermosyphon (RTPTC)

    NASA Astrophysics Data System (ADS)

    Bhuwakietkumjohn, N.; Parametthanuwat, T.

    2017-01-01

    This article focuses on heat transfer behaviour of silver nanoparticles containing oleic acid surfactant (OA) applied as a working fluid in a two-phase closed rectangular cross sectional thermosyphon (RTPTC). Thus, the OA could reduce the surface tension of the working fluid, which improved the colloidal ability and increased the lead-time period for nanoparticles to be uniformly dispersed. It highlights theories for investigating the effects on heat transfer characteristics of RTPTC such as heat transfer rate, thermal resistance, heat transfer coefficients and nanofluids behaviour. The most important heat transfer characteristic to be examined in this experiment is the relative thermal efficiency ( R T ). Five working fluids were tested, these include: de-ionized water; de-ionized water base with a silver nanoparticles concentration of 0.5 wt% (NP); and NP containing 0.5; 1; and 1.5 wt% of OA respectively. The results showed that 0.5 wt% NP containing 1 wt% OA produced the best results. It was further found that the heat transfer rate of 0.5 wt% NP containing 1 wt% of OA with a R T value of 1, was the highest across all experimental parameters studied. The NP containing OA demonstrated approximately 80 % higher heat transfer rate than the de-ionized water.

  11. Rectangular beam (5 X 40 cm multipole ion source). M.S. Thesis - Nov. 1979; [applications to electron bombardment in materials processing

    NASA Technical Reports Server (NTRS)

    Haynes, C. M.

    1980-01-01

    A 5 x 40 cm rectangular-beam ion source was designed and fabricated. A multipole field configuration was used to facilitate design of the modular rectangular chamber, while a three-grid ion optics system was used for increased ion current densities. For the multipole chamber, a magnetic integral of 0.000056 Tesla-m was used to contain the primary electrons. This integral value was reduced from the initial design value, with the reduction found necessary for discharge stability. The final value of magnetic integral resulted in discharge losses at typical operating conditions which ranged from 600 to 1000 eV/ion, in good agreement with the design value of 800 eV/ion. The beam current density at the ion optics was limited to about 3.2 mA/sq cm at 500 eV and to about 3.5 mA/sq cm at 1000 ev. The effects of nonuniform ion current, dimension tolerance, and grid thermal warping were considered. The use of multiple rectangular-beam ion sources to process wider areas than would be possible with a single source (approx. 40 cm) was also studied. Beam profiles were surveyed at a variety of operating conditions and the results of various amounts of beam overlap calculated.

  12. 21 CFR 872.6475 - Heat source for bleaching teeth.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a...

  13. 21 CFR 872.6475 - Heat source for bleaching teeth.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Heat source for bleaching teeth. 872.6475...

  14. 21 CFR 872.6475 - Heat source for bleaching teeth.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Heat source for bleaching teeth. 872.6475...

  15. 21 CFR 872.6475 - Heat source for bleaching teeth.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Heat source for bleaching teeth. 872.6475...

  16. 21 CFR 872.6475 - Heat source for bleaching teeth.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a...

  17. A Study of Mixed Convection in Large Baffled Rectangular Chambers with and without Internal Heat Sources

    DTIC Science & Technology

    1990-03-01

    consider some basic aerosol science to determine terminal settling ve- locities and the effects of thermophoresis induced velocities for the droplets...V = 1 d2gC0 ( _Pd ) (3.7) 18 Thermophoresis induced velocity must also be considered. This is the ve- locity induced by forces resulting in the

  18. Experimental study of heat transfer enhancement in a rectangular duct distributed by multi V-perforated baffle of different relative baffle width

    NASA Astrophysics Data System (ADS)

    Kumar, Raj; Kumar, Anil; Sharma, Ashutosh; Chauhan, Ranchan; Sethi, Muneesh

    2017-04-01

    The current research deals with the experimental investigation of the heat transfer behavior and optimum relative width parameter of the multi V-down pattern perforated baffle rectangular duct. The 60° angled multi V-down perforated pattern baffle are attached on the lower duct wall having an aspect ratio ( W D / H D ) of 10.0 and a Reynolds number ( Re) ranging from 4000 to 9000. The experiment was conducted by varying the relative baffle width ( W D / W B ) ranging from 1.0 to 6.0, relative baffle height ( H B / H D ) was 0.5, relative baffle pitch ( P B / H B ) was 10.0, relative hole position ( O B / H B ) was 0.44, open area ratio ( β O ) was 12 %. The experimental investigation shows that at a relative baffle width of 5.0 the thermal performance was maximized. Thermo-hydraulic performance ( η p ) comparison shows that multi V-down pattern perforated baffle has better outcomes as compared to other baffles shaped rectangular duct.

  19. Optimal Ground Source Heat Pump System Design

    SciTech Connect

    Ozbek, Metin; Yavuzturk, Cy; Pinder, George

    2015-04-01

    Despite the facts that GSHPs first gained popularity as early as the 1940’s and they can achieve 30 to 60 percent in energy savings and carbon emission reductions relative to conventional HVAC systems, the use of geothermal energy in the U.S. has been less than 1 percent of the total energy consumption. The key barriers preventing this technically-mature technology from reaching its full commercial potential have been its high installation cost and limited consumer knowledge and trust in GSHP systems to deliver the technology in a cost-effective manner in the market place. Led by ENVIRON, with support from University Hartford and University of Vermont, the team developed and tested a software-based a decision making tool (‘OptGSHP’) for the least-cost design of ground-source heat pump (‘GSHP’) systems. OptGSHP combines state of the art optimization algorithms with GSHP-specific HVAC and groundwater flow and heat transport simulation. The particular strength of OptGSHP is in integrating heat transport due to groundwater flow into the design, which most of the GSHP designs do not get credit for and therefore are overdesigned.

  20. A small-plane heat source method for measuring the thermal conductivities of anisotropic materials

    NASA Astrophysics Data System (ADS)

    Cheng, Liang; Yue, Kai; Wang, Jun; Zhang, Xinxin

    2017-07-01

    A new small-plane heat source method was proposed in this study to simultaneously measure the in-plane and cross-plane thermal conductivities of anisotropic insulating materials. In this method the size of the heat source element is smaller than the sample size and the boundary condition is thermal insulation due to no heat flux at the edge of the sample during the experiment. A three-dimensional model in a rectangular coordinate system was established to exactly describe the heat transfer process of the measurement system. Using the Laplace transform, variable separation, and Laplace inverse transform methods, the analytical solution of the temperature rise of the sample was derived. The temperature rises calculated by the analytical solution agree well with the results of numerical calculation. The result of the sensitivity analysis shows that the sensitivity coefficients of the estimated thermal conductivities are high and uncorrelated to each other. At room temperature and in a high-temperature environment, experimental measurements of anisotropic silica aerogel were carried out using the traditional one-dimensional plane heat source method and the proposed method, respectively. The results demonstrate that the measurement method developed in this study is effective and feasible for simultaneously obtaining the in-plane and cross-plane thermal conductivities of the anisotropic materials.

  1. A Comparison between heat transfer performance of rectangular and semicircular tubes considering boundary effects on Brownian motions in the presence of Ag / water nanofluids: Applicable in the design of cooling system of photovoltaic cells.

    PubMed

    Jafarimoghaddam, Amin; Aberoumand, Sadegh

    2017-01-01

    The present study aims to experimentally investigate heat transfer performance of rectangular and semicircular tubes in the presence of Ag / water nanofluids. The nanoparticles of Ag (silver) were used in seven different volume concentrations of 0.03%, 0.07%, 0.1%, 0.2%, 0.4%, 1% and 2%. The experiment was conducted in relatively low Reynolds numbers of 301 to 740. A heater with the power of 200 W was used to keep the outer surface of the tubes under a constant heat flux condition. In addition, the rectangular tube has been designed within the same length as the semicircular one and also within the same hydraulic diameter. Moreover, the average nanoparticles size was 20 nm. The outcome results of the present empirical work indicate that, for all the examined Reynolds numbers, the semicircular tube has higher convective heat transfer coefficient for all the utilized volume concentrations of Ag nanoparticles. The possible reasons behind this advantage are discussed through the present work mainly by taking the boundary effect on Brownian motions into account. Coming to this point that the conventional design for cooling system of photovoltaic cells is a heat sink with the rectangular graves, it is discussed that using a semicircular design may have the advantage over the rectangular one in convective heat transfer coefficient enhancement and hence a better cooling performance for these solar cells.

  2. A Comparison between heat transfer performance of rectangular and semicircular tubes considering boundary effects on Brownian motions in the presence of Ag / water nanofluids: Applicable in the design of cooling system of photovoltaic cells

    PubMed Central

    Aberoumand, Sadegh

    2017-01-01

    The present study aims to experimentally investigate heat transfer performance of rectangular and semicircular tubes in the presence of Ag / water nanofluids. The nanoparticles of Ag (silver) were used in seven different volume concentrations of 0.03%, 0.07%, 0.1%, 0.2%, 0.4%, 1% and 2%. The experiment was conducted in relatively low Reynolds numbers of 301 to 740. A heater with the power of 200 W was used to keep the outer surface of the tubes under a constant heat flux condition. In addition, the rectangular tube has been designed within the same length as the semicircular one and also within the same hydraulic diameter. Moreover, the average nanoparticles size was 20 nm. The outcome results of the present empirical work indicate that, for all the examined Reynolds numbers, the semicircular tube has higher convective heat transfer coefficient for all the utilized volume concentrations of Ag nanoparticles. The possible reasons behind this advantage are discussed through the present work mainly by taking the boundary effect on Brownian motions into account. Coming to this point that the conventional design for cooling system of photovoltaic cells is a heat sink with the rectangular graves, it is discussed that using a semicircular design may have the advantage over the rectangular one in convective heat transfer coefficient enhancement and hence a better cooling performance for these solar cells. PMID:28753603

  3. Fundamental mode rectangular waveguide system for electron-cyclotron resonant heating (ECRH) for tandem mirror experiment-upgrade (TMX-U)

    SciTech Connect

    Rubert, R.R.; Felker, B.; Stallard, B.W.; Williams, C.W.

    1983-12-01

    We present a brief history of TMX-U's electron cyclotron resonant heating (ECRH) progress. We emphasize the 2-year performance of the system, which is composed of four 200-kW pulsed gyrotrons operated at 28 GHz. This system uses WR42 waveguide inside the vacuum vessel, and includes barrier windows, twists, elbows, and antennas, as well as custom-formed waveguides. Outside the TMX-U vessel are directional couplers, detectors, elbows, and waveguide bends in WR42 rectangular waveguide. An arc detector, mode filter, eight-arm mode converter, and water load in the 2.5-in. circular waveguide are attached directly to the gyrotron. Other specific areas discussed include the operational performance of the TMX-U pulsed gyrotrons, windows and component arcing, alignment, mode generation, and extreme temperature variations. Solutions for a number of these problems are described.

  4. Alternative Radioisotopes for Heat and Power Sources

    NASA Astrophysics Data System (ADS)

    Tinsley, T.; Sarsfield, M.; Rice, T.

    Production of 238Pu requires considerable facilities including a nuclear reactor and reprocessing plants that are very expensive to build and operate. Thus, a more economical alternative is very attractive to the industry. There are many alternative radioisotopes that exist but few that satisfy the criteria of performance, availability and cost to produce. Any alternative to 238Pu must exist in a chemical form that is compatible with the materials required to safely encapsulate the heat source at the high temperatures of operation and potential launch failure scenarios. The chemical form must also have suitable thermal properties to ensure maximum energy conversion efficiencies when integrated into radioisotope thermoelectric generators over the required mission durations. In addition, the radiation dose must be low enough for operators during production and not so prohibitive that excessive shielding mass is required on the space craft. This paper will focus on the preferred European alternative of 241Am, and the issues that will need to be addressed.

  5. Desalination using low grade heat sources

    NASA Astrophysics Data System (ADS)

    Gude, Veera Gnaneswar

    A new, low temperature, energy-efficient and sustainable desalination system has been developed in this research. This system operates under near-vacuum conditions created by exploiting natural means of gravity and barometric pressure head. The system can be driven by low grade heat sources such as solar energy or waste heat streams. Both theoretical and experimental studies were conducted under this research to evaluate and demonstrate the feasibility of the proposed process. Theoretical studies included thermodynamic analysis and process modeling to evaluate the performance of the process using the following alternate energy sources for driving the process: solar thermal energy, solar photovoltaic/thermal energy, geothermal energy, and process waste heat emissions. Experimental studies included prototype scale demonstration of the process using grid power as well as solar photovoltaic/thermal sources. Finally, the feasibility of the process in reclaiming potable-quality water from the effluent of the city wastewater treatment plant was studied. The following results have been obtained from theoretical analysis and modeling: (1) The proposed process can produce up to 8 L/d of freshwater for 1 m2 area of solar collector and evaporation chamber respectively with a specific energy requirement of 3122 kJ for 1 kg of freshwater production. (2) Photovoltaic/thermal (PV/T) energy can produce up to 200 L/d of freshwater with a 25 m2 PV/T module which meets the electricity needs of 21 kWh/d of a typical household as well. This configuration requires a specific energy of 3122 kJ for 1 kg of freshwater production. (3) 100 kg/hr of geothermal water at 60°C as heat source can produce up to 60 L/d of freshwater with a specific energy requirement of 3078 kJ for 1 kg of freshwater production. (4) Waste heat released from an air conditioning system rated at 3.25 kW cooling, can produce up to 125 L/d of freshwater. This configuration requires an additional energy of 208 kJ/kg of

  6. Flow Structures and Noise Produced by a Heated Rectangular Nozzle with a Third Stream and Aft Deck

    NASA Astrophysics Data System (ADS)

    Ruscher, Christopher; Gogineni, Sivaram; Kiel, Barry

    2015-11-01

    Jet noise is a huge issue that affects both civilian and military aviation and is a two-fold problem. Near-field noise causes hearing damage and is of great concern to the Navy. Far-field noise is also a concern for military and civilian aircraft. For military jets, the trend has shown that newer and more advanced planes are louder than their predecessors. Most of these planes are designed keeping the performance as the main driver in mind while the jet noise becomes an afterthought. To remedy this and to aid the design process, we propose to create a joint noise and performance prediction tool. To create this tool, one must understand how the near-field flow structures generate noise and how they are related to far-field noise. In the current work, we considered rectangular, three-stream nozzle with an aft deck and investigated the flow structures such as corner vortices, shocks and their impact on the noise generation mechanism. We have also used state-of-the-art data analytical tools such as wavelets, POD, and stochastic estimations.

  7. Heat transfer analysis of underground U-type heat exchanger of ground source heat pump system.

    PubMed

    Pei, Guihong; Zhang, Liyin

    2016-01-01

    Ground source heat pumps is a building energy conservation technique. The underground buried pipe heat exchanging system of a ground source heat pump (GSHP) is the basis for the normal operation of an entire heat pump system. Computational-fluid-dynamics (CFD) numerical simulation software, ANSYS-FLUENT17.0 have been performed the calculations under the working conditions of a continuous and intermittent operation over 7 days on a GSHP with a single-well, single-U and double-U heat exchanger and the impact of single-U and double-U buried heat pipes on the surrounding rock-soil temperature field and the impact of intermittent operation and continuous operation on the outlet water temperature. The influence on the rock-soil temperature is approximately 13 % higher for the double-U heat exchanger than that of the single-U heat exchanger. The extracted energy of the intermittent operation is 36.44 kw·h higher than that of the continuous mode, although the running time is lower than that of continuous mode, over the course of 7 days. The thermal interference loss and quantity of heat exchanged for unit well depths at steady-state condition of 2.5 De, 3 De, 4 De, 4.5 De, 5 De, 5.5 De and 6 De of sidetube spacing are detailed in this work. The simulation results of seven working conditions are compared. It is recommended that the side-tube spacing of double-U underground pipes shall be greater than or equal to five times of outer diameter (borehole diameter: 180 mm).

  8. Heat transfer enhancement and pumping power optimization using CuO-water nanofluid through rectangular corrugated pipe

    NASA Astrophysics Data System (ADS)

    Salehin, Musfequs; Ehsan, Mohammad Monjurul; Islam, A. K. M. Sadrul

    2017-06-01

    Heat transfer enhancement by corrugation in fluid domain is a popular method. The rate of improvement is more when it is used highly thermal conductive fluid as heating or cooling medium. In this present study, heat transfer augmentation was investigated numerically by implementing corrugation in the fluid domain and nanofluid as the base fluid in the turbulent forced convection regime. Finite volume method (FVM) was applied to solve the continuity, momentum and energy equations. All the numerical simulations were considered for single phase flow. A rectangle corrugated pipe with 5000 W/m2 constant heat flux subjected to the corrugated wall was considered as the fluid domain. In the range of Reynolds number 15000 to 40000, thermo-physical and hydrodynamic behavior was investigated by using CuO-water nanofluid from 1% to 5% volume fraction as the base fluid through the corrugated fluid domain. Corrugation justification was performed by changing the amplitude of the corrugation and the corrugation wave length for obtaining the increased heat transfer rate with minimum pumping power. For using CuO-water nanofluid, augmentation was also found more in the rectangle corrugated pipe both in heat transfer and pumping power requirement with the increase of Reynolds number and the volume fraction of nanofluid. For the increased pumping power, optimization of pumping power by using nanofluid was also performed for economic finding.

  9. Flow Characteristic and Heat Transfer for Non-Newtonian Nanofluid in Rectangular Microchannels with Teardrop Dimples/Protrusions

    NASA Astrophysics Data System (ADS)

    Zhang, Zheyuan; Xie, Yonghui; Zhang, Di; Xie, Gongnan

    2017-04-01

    Porous cavity technology is one of the effective ways to improve local flow structures and thus the overall heat transfer of heat exchanging devices. In the present investigation, the flow characteristics and heat transfer in a microchannel heat sink with teardrop dimples/protrusions are studied with a numerical method. The working substances are Al2O3-water nanofluids, which are defined by power-law shear-thinning model. The relative depth and positive eccentricity of dimples/protrusions arranged in the microchannels are 0.2 and 0.3 respectively. The inlet velocity varies in the range of 1.41 mṡs-1 to 8.69 mṡs-1 and the volume fraction ranges from 0.5% to 3.5%. The effects of the flow and heat transfer characteristics are investigated by analyzing the limiting streamlines structures and temperature distributions. The overall thermal performance is evaluated by parameters of Fanning friction factor, Nusselt number and thermal performance. It is shown that the combination of teardrop dimple/protrusion structure and Al2O3-water nanofluids could effectively strengthen heat transfer with low pressure loss. Moreover, in order to obtain the best overall thermal performance, working substances with volume faction of 3.5% is preferred for the proposed microchannel structure.

  10. The heat source of the foehn revisited

    NASA Astrophysics Data System (ADS)

    Ólafsson, H.; Petersen, G. N.

    2012-04-01

    A large observational data set from Iceland is used to explore the connection between the heat surplus on the downstream side of mountains, upstream precipitation and elements of the atmospheric flow. A typical foehn case is also simulated and used to explore the role of precipitation and latent heat in heating the downstream flow. Some of the key findings are that latent heating appears not to be an important factor for heating the foehn in Iceland and that there is no clear relationship between upstream precipitation and downstream heating. The heating on the downstream side is attributed to descent of potentially warm air and insolation. The case study suggests that the latent heating may have an impact, however not through heating aloft, but through cooling at low levels and enhanced upstream blocking effect.

  11. Irregular spacing of heat sources for treating hydrocarbon containing formations

    DOEpatents

    Miller, David Scott [Katy, TX; Uwechue, Uzo Philip [Houston, TX

    2012-06-12

    A method for treating a hydrocarbon containing formation includes providing heat input to a first section of the formation from one or more heat sources located in the first section. Fluids are produced from the first section through a production well located at or near the center of the first section. The heat sources are configured such that the average heat input per volume of formation in the first section increases with distance from the production well.

  12. Thulium heat source: IR D project 91-031

    SciTech Connect

    Walter, C.E.; Kammeraad, J.E.; Newman, J.G.; Van Konynenburg, R.; VanSant, J.H.

    1991-04-10

    The goal of the Thulium Heat Source study is to determine the performance capability and evaluate the safety and environmental aspects of a thulium-170 heat source. Our approach is to study parametrically the performance of thulium-170 heat source designs in the power range of 5--50 kW{sub th}. At least three heat source designs will be characterized in this power range and integrated with various power conversion subsystems to assess their performance, mass, and volume. We will determine shielding requirements, and consider the safety and environmental aspects of their use.

  13. Passive rejection of heat from an isotope heat source through an open door

    NASA Technical Reports Server (NTRS)

    Burns, R. K.

    1971-01-01

    The isotope heat-source design for a Brayton power system includes a door in the thermal insulation through which the heat can be passively rejected to space when the power system is not operating. The results of an analysis to predict the heat-source surface temperature and the heat-source heat-exchanger temperature during passive heat rejection as a function of insulation door opening angle are presented. They show that for a door opening angle greater than 20 deg, the temperatures are less than the steady-state temperatures during power system operation.

  14. A comparison of natural convection heat transfer for a staggered versus an aligned array of horizontal spent nuclear fuel rods within a rectangular enclosure

    SciTech Connect

    Triplett, C.E.; Canaan, R.E.; Klein, D.E.

    2000-04-01

    Natural convection heat transfer was experimentally investigated in a staggered array of heated cylinders, oriented horizontally within a rectangular isothermal enclosure. The test conditions were characteristic of a spent-fuel assembly during transport or horizontal dry storage. The assembly was configured with a pitch-to-diameter ratio of 1.33 and backfilled with pressurized helium or nitrogen. The backfill pressure was varied between 1 and 5 atm, while the assembly power was varied between 1 and 5 W per heater rod. The resulting data are presented in the form of Nusselt-Rayleigh number correlations, where the Nusselt number has been corrected for thermal radiation using a numerical technique. The staggered-array data are compared to previous data for a similar-pitch aligned rod array (a simulated boiling water reactor fuel assembly) to determine if convective heat transfer is enhanced or hindered in a staggered configuration. For the overall array, both the staggered and aligned configurations yield Nusselt-Rayleigh curves with a three-regime trend, which suggests distinct conduction and convection regimes separated by a transition regime. For lower Rayleigh numbers (10{sup 6}), representative of the conduction regime, the aligned-array Nusselt number is 10 to 12% higher than the corresponding staggered-array value. However, in the convection regime at higher Rayleigh numbers, the staggered-array Nusselt number slightly exceeds the aligned-array Nusselt number. This is attributed to the fact that the staggered array begins to transition into the convection regime at lower Rayleigh number than the aligned array. For both configurations, the slope of the Nusselt-Rayleigh curve in the convection regime suggests turbulent flow conditions.

  15. Air Source Cold Climate Heat Pump

    DTIC Science & Technology

    2013-08-01

    The buildings were modified so that one zone used the cold climate heat pump and the other zone used its original modern central HVAC system . Both...been updated with insulation, a sheet metal roof, and a modern central HVAC system . Both buildings had two zones for heating and cooling, which...climate heat pump and the other zone used its original modern central HVAC system . Both zones were instrumented so that energy consumption and

  16. Loop Heat Pipe Operation Using Heat Source Temperature for Set Point Control

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

    2011-01-01

    The LHP operating temperature is governed by the saturation temperature of its reservoir. Controlling the reservoir saturation temperature is commonly accomplished by cold biasing the reservoir and using electrical heaters to provide the required control power. Using this method, the loop operating temperature can be controlled within +/- 0.5K. However, because of the thermal resistance that exists between the heat source and the LHP evaporator, the heat source temperature will vary with its heat output even if LHP operating temperature is kept constant. Since maintaining a constant heat source temperature is of most interest, a question often raised is whether the heat source temperature can be used for LHP set point temperature control. A test program with a miniature LHP has been carried out to investigate the effects on the LHP operation when the control temperature sensor is placed on the heat source instead of the reservoir. In these tests, the LHP reservoir is cold-biased and is heated by a control heater. Tests results show that it is feasible to use the heat source temperature for feedback control of the LHP operation. Using this method, the heat source temperature can be maintained within a tight range for moderate and high powers. At low powers, however, temperature oscillations may occur due to interactions among the reservoir control heater power, the heat source mass, and the heat output from the heat source. In addition, the heat source temperature could temporarily deviate from its set point during fast thermal transients. The implication is that more sophisticated feedback control algorithms need to be implemented for LHP transient operation when the heat source temperature is used for feedback control.

  17. Loop Heat Pipe Operation Using Heat Source Temperature for Set Point Control

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

    2011-01-01

    Loop heat pipes (LHPs) have been used for thermal control of several NASA and commercial orbiting spacecraft. The LHP operating temperature is governed by the saturation temperature of its compensation chamber (CC). Most LHPs use the CC temperature for feedback control of its operating temperature. There exists a thermal resistance between the heat source to be cooled by the LHP and the LHP's CC. Even if the CC set point temperature is controlled precisely, the heat source temperature will still vary with its heat output. For most applications, controlling the heat source temperature is of most interest. A logical question to ask is: "Can the heat source temperature be used for feedback control of the LHP operation?" A test program has been implemented to answer the above question. Objective is to investigate the LHP performance using the CC temperature and the heat source temperature for feedback control

  18. Heat-source specification 500 watt(e) RTG

    SciTech Connect

    Not Available

    1983-02-01

    This specification establishes the requirements for a /sup 90/SrF/sub 2/ heat source and its fuel capsule for application in a 500 W(e) thermoelectric generator. The specification covers: fuel composition and quantity; the Hastelloy S fuel capsule material and fabrication; and the quality assurance requirements for the assembled heat source. (LCL)

  19. Mantle convection with continental drift and heat source around the mantle transition zone

    NASA Astrophysics Data System (ADS)

    Ichikawa, H.; Kameyama, M.; Kawai, K.

    2012-12-01

    Geological studies have suggested that significant amount of granitic crustal materials have been lost from the surface by the delamination (~1.1 km^3/yr) [1], continental collision (~0.4-0.7 km^3/yr) [1, 2], and subduction at ocean-margin (~2.5-3 km^3/yr) [1, 2]. At ocean-margin subduction zones, most of the granitic materials subducted from the surface are expected to be conveyed through subduction channels by viscous drag to 270km depth [Ichikawa el al., in revision]. If so, then the subducted crustal materials might be expected to be trapped in the mid-mantle owing to the density difference from peridotitic materials induced by the phase transition from coesite to stishovite at 270km depth. In other words, strong heat source materials are most likely to be accumulated around the mantle transition zone, at least, near the plate subduction zones. In this study, we conducted two-dimensional numerical experiments of mantle convection with continental drift and a heat source placed around the mantle transition zone, in order to study the effect of the subducted granitic materials drifting around the mantle transition zone. The simulations deal with a time-dependent convection of fluid under the extended Boussinesq approximation in a model of a two-dimensional rectangular box of 2900km height and 11600km width, where a continent and heat source is imposed. We found that the addition of the heat source considerably reduces the time scale of continental drift. In the absence of the heat source, the resulting time scale is too long compared with that of the so-called supercontinent cycle, where the breakup is induced from a plume generated by an insulating effect of the continent. The heat source also causes massive mechanical mixing especially on the upper mantle. The result suggests that the heat source drifting around mantle transition zone can be a possible candidate inducing the supercontinent cycle in an appropriate time scale. [1] Clift, P. D., P. Vannucchi, and

  20. Natural Convection Above A Horizontal Heat Source

    DTIC Science & Technology

    1993-03-01

    surface was a thermochromic liquid crystal (TLC) sheet. Used to ensure a smooth flat surface, the sheet also provided a visualization of the temperature...a flat horizontal heated surface surrounded by an unheated area. This can contribute significantly to studies in liquid immersion cooling...Gebhart, B., "The Transition of Plane Plumes," Int. J. Heat Mass Transfer, v.18., pp. 513-526, 1975. 13. Gaiser, A.O., "Natural Convection Liquid

  1. Monitoring and evaluating ground-source heat pump. Final report

    SciTech Connect

    Stoltz, S.V.; Cade, D.; Mason, G.

    1996-05-01

    This report presents the measured performance of four advanced residential ground-source heat pump (GSHP) systems. The GSHP systems were developed by WaterFurnace International to minimize the need for electric resistance backup heating and featured multiple speed compressors, supplemental water heating, and at most sites, multiple-speed fans. Detailed data collected for a complete year starting in June 1994 shows that the advanced design is capable of maintaining comfort without the use of electric resistance backup heating. In comparison with a conventional air-source heat pump, the advanced-design GSHP reduced peak heating demand by more than 12 kilowatts (kW) per residence and provided energy savings. The report describes the cooling and heating season operation of the systems, including estimated seasonal efficiency, hours of operation, and load profiles for average days and peak days. The electrical energy input, cooling output, and efficiency are presented as a function of return air temperature and ground loop temperature.

  2. Ground Source Heat Pump Computational Results

    DOE Data Explorer

    James Menart

    2013-07-31

    This data submission includes simulation results for ground loop heat pump systems located in 6 different cities across the United States. The cities are Boston, MA, Dayton, OH, Omaha, NE, Orlando, FL, Sacramento, CA, and St. Paul, MN. These results were obtained from the two-dimensional geothermal computer code called GEO2D. GEO2D was written as part of this DOE funded grant. The results included in this submission for each of the 6 cities listed above are: 1) specific information on the building being heated or cooled by the ground loop geothermal system, 2) some extreme values for the building heating and cooling loads during the year, 3) the inputs required to carry out the simulation, 4) a plot of the hourly building heating and cooling loads throughout the year, 5) a plot of the fluid temperature exiting the ground loop for a 20 year period, 6) a plot of the heat exchange between the ground loop and the ground for a 20 year period, and 7) ground and ground loop temperature contour plots at different times of the year for the 20 year period.

  3. DUAL HEATED ION SOURCE STRUCTURE HAVING ARC SHIFTING MEANS

    DOEpatents

    Lawrence, E.O.

    1959-04-14

    An ion source is presented for calutrons, particularly an electrode arrangement for the ion generator of a calutron ion source. The ion source arc chamber is heated and an exit opening with thermally conductive plates defines the margins of the opening. These plates are electrically insulated from the body of the ion source and are connected to a suitable source of voltage to serve as electrodes for shaping the ion beam egressing from the arc chamber.

  4. Studies of heat source driven natural convection

    NASA Technical Reports Server (NTRS)

    Kulacki, F. A.; Nagle, M. E.; Cassen, P.

    1974-01-01

    Natural convection energy transport in a horizontal layer of internally heated fluid with a zero heat flux lower boundary, and an isothermal upper boundary, has been studied. Quantitative information on the time-mean temperature distribution and the fluctuating component of temperature about the mean temperature in steady turbulent convection are obtained from a small thermocouple inserted into the layer through the upper bounding plate. Data are also presented on the development of temperature at several vertical positions when the layer is subject to both a sudden increase and to a sudden decrease in power input. For changes of power input from zero to a value corresponding to a Rayleigh number much greater than the critical linear stability theory value, a slight hysteresis in temperature profiles near the upper boundary is observed between the heat-up and cool-down modes.

  5. Transient magneto-thermo-viscoelastic stresses in a rotating nonhomogeneous anisotropic solid with and without a moving heat source

    NASA Astrophysics Data System (ADS)

    Fahmy, M. A.

    2012-07-01

    Transient magneto-thermo-viscoelastic stresses in a nonhomogeneous anisotropic solid with and without a moving heat source under rotation are studied. The system of fundamental equations is solved by means of the dual reciprocity boundary element method (DRBEM). In the case of plane deformation, a numerical scheme for the implementation of the method is presented, and the numerical computations are carried out for the temperature, displacement components, and thermal stress components. The validity of the DRBEM is examined by considering a magneto-thermo-viscoelastic solid that occupies a rectangular region, and good agreement with the existent results is obtained. The results indicate that the effects of a moving heat source and rotation are very pronounced.

  6. Heat sources in proton exchange membrane (PEM) fuel cells

    NASA Astrophysics Data System (ADS)

    Ramousse, Julien; Lottin, Olivier; Didierjean, Sophie; Maillet, Denis

    In order to model accurately heat transfer in PEM fuel cell, a particular attention had to be paid to the assessment of heat sources in the cell. Although the total amount of heat released is easily computed from its voltage, local heat sources quantification and localization are not simple. This paper is thus a discussion about heat sources/sinks distribution in a single cell, for which many bold assumptions are encountered in the literature. The heat sources or sinks under consideration are: (1) half-reactions entropy, (2) electrochemical activation, (3) water sorption/desorption at the GDL/membrane interfaces, (4) Joule effect in the membrane and (5) water phase change in the GDL. A detailed thermodynamic study leads to the conclusion that the anodic half-reaction is exothermic (Δ Sr ev a = - 226 J mo l-1 K-1) , instead of being athermic as supposed in most of the thermal studies. As a consequence, the cathodic half-reaction is endothermic (Δ Sr ev c = + 62.8 J mo l-1 K-1) , which results in a heat sink at the cathode side, proportional to the current. In the same way, depending on the water flux through the membrane, sorption can create a large heat sink at one electrode and an equivalent heat source at the other. Water phase change in the GDL - condensation/evaporation - results in heat sources/sinks that should also be taken into account. All these issues are addressed in order to properly set the basis of heat transfer modeling in the cell.

  7. Structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Pirnat, Miha; Čepon, Gregor; Boltežar, Miha

    2014-03-01

    In this paper three approaches are combined to develop a structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source. The first approach results from a recently presented analysis based on the Rayleigh-Ritz method and is used to circumvent the difficulties in obtaining the natural frequencies and mode shapes of a plate with an attached, distributed mass. Furthermore, different plate boundary conditions can be accommodated. The resulting mode shapes are defined as continuous functions; this is advantageous as they can be directly used in the second approach, i.e., the classic modal-interaction approach in order to obtain the coupled equations of the system. Finally, in the third approach a group of point sources emitting a pressure pulse in the time domain is used to model an internal sound source. For the validation of the developed model an experiment was conducted in two configurations using a simply supported aluminium plate and a clamped plate coupled with a plexiglas box containing a loudspeaker. Good agreement was found between the analytical and experimental data.

  8. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Double Symplectic Eigenfunction Expansion Method of Free Vibration of Rectangular Thin Plates

    NASA Astrophysics Data System (ADS)

    Wang, Hua; Alatancang; Huang, Jun-Jie

    2009-12-01

    The free vibration problem of rectangular thin plates is rewritten as a new upper triangular matrix differential system. For the associated operator matrix, we find that the two diagonal block operators are Hamiltonian. Moreover, the existence and completeness of normed symplectic orthogonal eigenfunction systems of these two block operators are demonstrated. Based on the completeness, the general solution of the free vibration of rectangular thin plates is given by double symplectic eigenfunction expansion method.

  9. Arena retrofit includes ground-source heat pump

    SciTech Connect

    Hodgson, S.F.

    1996-01-01

    The venue for Sacramento`s first professional basketball games was the {open_quotes}old Arco Arena,{close_quotes} built in 1985 just north of the downtown area and converted to offices after a large, permanent arena was constructed. In 1994, the {open_quotes}old arena{close_quotes} was acquired by a California general partnership called Del Paso Venture. To heat and cool the 3-story, 211,000-square foot structure, Del Paso has installed a ground-source heat pump system. The project is significant for the ground-source heat pump industry, because this is the first ground-source heat pump site ever designed specifically for the energy load of the building it will serve. Other projects have been calculated by rule-of-thumb. The installation and cost of the heat pump system are discussed.

  10. Solar-assisted water-source heat pump

    NASA Astrophysics Data System (ADS)

    1982-03-01

    The usefulness of a collector array is to be extended to year-round usage by using the collectors to reject heat at night during the summer. A water source heat pump is used to cool a home by rejecting heat to water which is then held in a storage tank. At night the warm water is pumped through the collectors for radiative cooling. Two complete systems are being installed to demonstrate feasibility. One part of the system has been completed and tested.

  11. Detailed Specifications for Global Heat Treatment Sourcing and Materials

    NASA Astrophysics Data System (ADS)

    Sponzilli, Jared; Sponzilli, John

    2013-07-01

    The very nature of global sourcing means that components must carry clear and detailed specifications for material, heat treatment, and test methods. Qualified global heat treat facilities can achieve good control of not only the common features such as surface and gradient hardness, but also of microstructure, core hardness, residual stress, and other critical metallurgical parameters. This paper will discuss a new concept for material specifications and more detailed heat treatment specifications for the global marketplace.

  12. Thulium heat source IR D Project 91-031

    SciTech Connect

    Walter, C.E.; Kammeraad, J.E.; Newman, J.G.; Van Konynenburg, R.; VanSant, J.H.

    1991-01-01

    The goal of the Thulium Heat Source study is to determine the performance capability and evaluate the safety and environmental aspects of a thulium-170 heat source. Thulium-170 has several attractive features, including the fact that it decays to a stable, chemically innocuous isotope in a relatively short time. A longer-range goal is to attract government funding for the development, fabrication, and demonstration testing in an Autonomous Underwater Vehicle (AUV) of one or more thulium isotope power (TIP) prototype systems. The approach is to study parametrically the performance of thulium-170 heat source designs in the power range of 5-50 kW{sub th}. At least three heat source designs will be characterized in this power range to assess their performance, mass, and volume. The authors will determine shielding requirements, and consider the safety and environmental aspects of their use.

  13. Oceanic heat sources to Pine Island Bay

    NASA Astrophysics Data System (ADS)

    Mazloff, M. R.; Gilroy, A. R.; Gille, S. T.; Subramanian, A. C.

    2012-12-01

    The rapid melting of Pine Island Glacier, West Antarctica has been attributed to increased basal melting of its grounded ice-shelf. Recent work suggests that an increased ocean heat supply to Pine Island Bay (PIB) is responsible for this increased melting. There is no consensus, however, on the origin of this increased ocean heat. We use a 2008-2010 state estimate of the Southern Ocean to diagnose the heat budget on the PIB continental shelf. In times of minimal sea-ice coverage, air-sea fluxes dominate the budget. Sea-ice is present over much of the year, however, and on average advection and parameterized small-scale mixing are equally important. The average air-sea fluxes and small scale mixing both act to cool the continental shelf waters, while advection by the large-scale circulation tends to warm these waters. The warmest waters are found on the eastern PIB continental shelf where bathymetric features cause increased advective fluxes and mixing. The average circulation along the PIB continental shelf is eastward consisting of approximately 1 Sv along shelf flow augmented by 1 Sv of across shelf flow to be balanced by a 2 Sv outflow along the eastern PIB shelf. Numerical simulations of passive tracer releases reveal the advective pathways of these waters that reach the continental shelf.

  14. Uniqueness in the determination of vibration sources in rectangular Germain-Lagrange plates using displacement measurements over line segments with arbitrary small length

    NASA Astrophysics Data System (ADS)

    Kawano, Alexandre

    2013-08-01

    The theme of this work is related to the field of vibration and source detection, which is important in naval, aerospace and civil engineering industries. The detection of unexpected vibration sources, in general, signals malfunctioning, or even an undesired presence in the case of defense systems. The focus will be on thin plates, which are among the basic building blocks of large complex structures. Here, we consider loads acting on a rectangular plate R of the product form g(t)Q(x), where the function of time g has a continuous first derivative and the spatial load distribution Q is a square-integrable function over R. We prove that the observation of the displacement of a line segment with arbitrary length parallel to one of the sides of the plate is enough for the determination of Q, provided that the interval of time is long enough. We also prove that the normal derivative along a side of the rectangle measured for an arbitrarily small interval of time is sufficient to determine the spatial load distribution Q. The method used to obtain the results is based on the series decomposition of the dynamic response and an analysis of the almost periodic distribution that arises from it.

  15. Nuclear heat source component design considerations for HTGR process heat reactor plant concept

    SciTech Connect

    McDonald, C.F.; Kapich, D.; King, J.H.; Venkatesh, M.C.

    1982-05-01

    The coupling of a high-temperature gas-cooled reactor (HTGR) and a chemical process facility has the potential for long-term synthetic fuel production (i.e., oil, gasoline, aviation fuel, hydrogen, etc) using coal as the carbon source. Studies are in progress to exploit the high-temperature capability of an advanced HTGR variant for nuclear process heat. The process heat plant discussed in this paper has a 1170-MW(t) reactor as the heat source and the concept is based on indirect reforming, i.e., the high-temperature nuclear thermal energy is transported (via an intermediate heat exchanger (IHX)) to the externally located process plant by a secondary helium transport loop. Emphasis is placed on design considerations for the major nuclear heat source (NHS) components, and discussions are presented for the reactor core, prestressed concrete reactor vessel (PCRV), rotating machinery, and heat exchangers.

  16. Tests confirm gas heat as monoxide source

    SciTech Connect

    Besch, E.

    1984-03-01

    Six tests were conducted to demonstrate the potential for natural gas or oil-fired forced warm air heating equipment to produce carbon monoxide emission when the combustion process is impeded by typical causes found in households. In the case of the gas-fired units, impeded combustion produced a smell of aldehyde and various levels of carbon monoxide emission; all within the level dangerous to health. It was concluded that oil-fired warm air systems do not pose a carbon monoxide danger but that natural gas warm air systems do pose a real danger and should be so identified.

  17. Mathematical modeling of high and low temperature heat pipes

    NASA Technical Reports Server (NTRS)

    Chi, S. W.

    1971-01-01

    Following a review of heat and mass transfer theory relevant to heat pipe performance, math models are developed for calculating heat-transfer limitations of high-temperature heat pipes and heat-transfer limitations and temperature gradient of low temperature heat pipes. Calculated results are compared with the available experimental data from various sources to increase confidence in the present math models. Complete listings of two computer programs for high- and low-temperature heat pipes respectively are included. These programs enable the performance to be predicted of heat pipes with wrapped-screen, rectangular-groove, or screen-covered rectangular-groove wick.

  18. Helium release from radioisotope heat sources

    SciTech Connect

    Peterson, D.E.; Early, J.W.; Starzynski, J.S.; Land, C.C.

    1984-05-01

    Diffusion of helium in /sup 238/PuO/sub 2/ fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel.

  19. Infant respiratory symptoms associated with indoor heating sources.

    PubMed

    Triche, Elizabeth W; Belanger, Kathleen; Beckett, William; Bracken, Michael B; Holford, Theodore R; Gent, Janneane; Jankun, Thomas; McSharry, Jean-Ellen; Leaderer, Brian P

    2002-10-15

    This study examined the effects of indoor heating sources on infant respiratory symptoms during the heating season of the first year of life. Mothers delivering babies between 1993 and 1996 at 12 hospitals in Connecticut and Virginia were enrolled. Daily symptom and heating source use information about their infant was obtained every 2 weeks during the first year of life. Heating sources included fireplace, wood stove, kerosene heater, and gas space heater use. Four health outcomes were analyzed by reporting period: days of wheeze, episodes of wheeze, days of cough, and episodes of cough. A large percentage of infants had at least one episode of cough (88%) and wheeze (33%) during the heating season of the first year of life. Wood stove, fireplace, kerosene heater, and gas space heater use was intermittent across the study period. In adjusted Poisson regression models controlling for important confounders, gas space heater use was associated with episodes and days of wheeze. Wood stove use was associated with total days of cough, and kerosene heater use was associated with episodes of cough. Fireplace use was not associated with any of the respiratory symptoms. Use of some heating sources appears related to respiratory symptoms in infants.

  20. Ground Source Geothermal District Heating and Cooling System

    SciTech Connect

    Lowe, James William

    2016-10-21

    Ball State University converted its campus from a coal-fired steam boiler district heating system to a ground source heat pump geothermal district system that produces simultaneously hot water for heating and chilled water for cooling. This system will include the installation of 3,600 four hundred feet deep vertical closed loop boreholes making it the largest ground source geothermal district system in the country. The boreholes will act as heat exchangers and transfer heat by virtue of the earth’s ability to maintain an average temperature of 55 degree Fahrenheit. With growing international concern for global warming and the need to reduce worldwide carbon dioxide loading of the atmosphere geothermal is poised to provide the means to help reduce carbon dioxide emissions. The shift from burning coal to utilizing ground source geothermal will increase electrical consumption but an overall decrease in energy use and reduction in carbon dioxide output will be achieved. This achievement is a result of coupling the ground source geothermal boreholes with large heat pump chiller technology. The system provides the thermodynamic means to move large amounts of energy with limited energy input. Ball State University: http://cms.bsu.edu/About/Geothermal.aspx

  1. Single particle sources and quantum heat fluctuations

    NASA Astrophysics Data System (ADS)

    Battista, F.

    2014-10-01

    The miniaturisation of electronic devices has been a well-known trend in engineering over almost 50 years. The technological advancement in the field can now provide an astonishing control of charge transport in mesoscopic structures. Single particle pumping, namely the control in time and space of the flow of an arbitrarily small number of electrons or holes, has been realised in various kind of structure with, in some cases, very high accuracies. The first half of the manuscript provides a brief overview of different experimental realisations of single particle sources. Though these devices allow to minimise charge fluctuations in the charge current, because of Heisenberg's uncertainty principle, the emitted particles are characterised by energy fluctuations. The consequences of it are of great relevance and presented in the second part of the paper.

  2. Hydrothermal circulation at slow spreading ridges: Analysis of heat sources and heat transfer processes

    NASA Astrophysics Data System (ADS)

    Lowell, Robert P.

    Hydrothermal processes on slow spreading ridges exhibit several features that distinguish them from their counterparts at fast and intermediate rate spreading centers. These differences may reflect differences in magma supply rates, type of host rock, and the interplay between magmatism and tectonic extension. As a result, the heat sources and driving mechanisms for hydrothermal circulation at slow spreading ridges may differ from those on fast and intermediate spreading ridges. This paper reviews various heat sources and heat transfer processes at slow spreading ridges, including mantle heat flux, mining of crustal heat, the role of exothermic chemical reactions, and magmatic heat sources. The analyses suggest that for high-temperature, high-output systems such as TAG, Rainbow, and Lucky Strike on the Mid-Atlantic Ridge and Kairei on the Central Indian Ridge, heat transfer from convecting, an actively replenished subaxial magma chamber is required to maintain these systems on decadal time scales. Low-temperature off-axis systems such as Lost City are likely driven by heat extraction from the crust, perhaps in conjunction with downward fluid migration in reactivated faults. Serpentinization reactions appear to play a smaller role. Broken Spur is a relatively low heat output system that is likely driven by magma, but it may be in a waning phase.

  3. Feasibility of drying system using waste heat as the heating source

    NASA Astrophysics Data System (ADS)

    Xie, M. N.; Shi, Y. L.; Chen, L. X.

    2016-08-01

    In this study, a wastewater heat pump system was proposed and its thermal performance was analyzed. The proposed system includes two evaporators: an air-source evaporator and a water-source evaporator. The air-source evaporator absorbs heat from the moist hot air which exhaust from the drying oven. The water-source evaporator absorbs heat from the waste water, while the waste water recovers heat from the mechanical energy, which was produced by cutting and polishing in stone production. The thermodynamic model was developed to evaluate the performance of the proposed system. The energetic analysis was carried out to investigate the influences of the temperature of fresh air. The results show significantly higher energy efficiency, compact-sized and energy-saving compared with the system which uses air as the heat source. Among the seven of alternative refrigerants (R152a, R123, R1234yf, R1234ze, R600a, R22 and R600) investigated, R123 was suggested to be used in this heat pump for its high heating efficiency, inflammable, very low ODP(Ozone Depletion Potential) and GWP(Global warming potential).

  4. Life cycle assessment of base-load heat sources for district heating system options

    SciTech Connect

    Ghafghazi, Saeed; Sowlati, T.; Sokhansanj, Shahabaddine; Melin, Staffan

    2011-03-01

    Purpose There has been an increased interest in utilizing renewable energy sources in district heating systems. District heating systems are centralized systems that provide heat for residential and commercial buildings in a community. While various renewable and conventional energy sources can be used in such systems, many stakeholders are interested in choosing the feasible option with the least environmental impacts. This paper evaluates and compares environmental burdens of alternative energy source options for the base load of a district heating center in Vancouver, British Columbia (BC) using the life cycle assessment method. The considered energy sources include natural gas, wood pellet, sewer heat, and ground heat. Methods The life cycle stages considered in the LCA model cover all stages from fuel production, fuel transmission/transportation, construction, operation, and finally demolition of the district heating system. The impact categories were analyzed based on the IMPACT 2002+ method. Results and discussion On a life-cycle basis, the global warming effect of renewable energy options were at least 200 kgeqCO2 less than that of the natural gas option per MWh of heat produced by the base load system. It was concluded that less than 25% of the upstream global warming impact associated with the wood pellet energy source option was due to transportation activities and about 50% of that was resulted from wood pellet production processes. In comparison with other energy options, the wood pellets option has higher impacts on respiratory of inorganics, terrestrial ecotoxicity, acidification, and nutrification categories. Among renewable options, the global warming impact of heat pump options in the studied case in Vancouver, BC, were lower than the wood pellet option due to BC's low carbon electricity generation profile. Ozone layer depletion and mineral extraction were the highest for the heat pump options due to extensive construction required for these

  5. Diffusion of Heat from a Line Source in Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Uberoi, Mahinder S; Corrsin, Stanley

    1953-01-01

    An experimental and analytical study has been made of some features of the turbulent heat diffusion behind a line heated wire stretched perpendicular to a flowing isotropic turbulence. The mean temperature distributions have been measured with systematic variations in wind speed, size of turbulence-producing grid, and downstream location of heat source. The nature of the temperature fluctuation field has been studied. A comparison of Lagrangian and Eulerian analyses for diffusion in a nondecaying turbulence yields an expression for turbulent-heat-transfer coefficient in terms of turbulence velocity and a Lagrangian "scale." the ratio of Eulerian to Lagrangian microscale has been determined theoretically by generalization of a result of Heisenberg and with arbitrary constants taken from independent sources, shows rough agreement with experimental results. A convenient form has been deduced for the criterion of interchangeability of instantaneous space and time derivatives in a flowing turbulence.

  6. Assessment of dynamic energy conversion systems for radioisotope heat sources

    SciTech Connect

    Thayer, G.R.; Mangeng, C.A.

    1985-06-01

    The use of dynamic conversion systems to convert the heat generated in a 7500 W(t) 90 Sr radioisotopic heat source to electricity is examined. The systems studies were Stirling; Brayton Cycle; three organic Rankines (ORCs) (Barber-Nichols/ORMAT, Sundstrand, and TRW); and an organic Rankine plus thermoelectrics. The systems were ranked for a North Warning System mission using a Los Alamos Multiattribute Decision Theory code. Three different heat source designs were used: case I with a beginning of life (BOL) source temperature of 640 C, case II with a BOL source temperature of 745/sup 0/C, and case III with a BOL source temperature of 945/sup 0/C. The Stirling engine system was the top-ranked system of cases I and II, closely followed by the ORC systems in case I and ORC plus thermoelectrics in case II. The Brayton cycle system was top-ranked for case III, with the Stirling engine system a close second. The use of /sup 238/Pu in heat source sizes of 7500 W(t) was examined and found to be questionable because of cost and material availability and because of additional requirements for analysis of safeguards and critical mass.

  7. Performance Analysis of a Ground Source Heat Pump System Using Mine Water as Heat Sink and Source

    SciTech Connect

    Liu, Xiaobing; Malhotra, Mini; Walburger, Adam; Skinner, Jack L.; Blackketter, Donald M.

    2016-06-01

    This paper summarizes a case study of an innovative ground source heat pump (GSHP) system that uses flooded mines as a heat source and heat sink. This GSHP system provides space conditioning to a 56,000 sq ft2(5,203 m2) newly constructed research facility, in conjunction with supplementary existing steam heating and air-cooled chiller systems. Heat transfer performance and overall efficiency of the GSHP system were analysed using the available measured data from January through July 2014. The performance analysis identified some issues with using mine water for cooling and the integration of the GSHP system with the existing steam heating system. Recommendations were made to improve the control and operation of the GSHP system. These recommendations, in conjunction with the available measured data, were used to predict the annual energy use of the system. Finally, the energy and cost savings and CO2 emission reduction potential of the GSHP system were estimated by comparing with a baseline scenario. This case study provides insights into the performance of and potential issues with the mine-water source heat pump system, which is relatively under-explored compared to other GSHP system designs and configurations.

  8. Performance Analysis of a Ground Source Heat Pump System Using Mine Water as Heat Sink and Source

    DOE PAGES

    Liu, Xiaobing; Malhotra, Mini; Walburger, Adam; ...

    2016-06-01

    This paper summarizes a case study of an innovative ground source heat pump (GSHP) system that uses flooded mines as a heat source and heat sink. This GSHP system provides space conditioning to a 56,000 sq ft2(5,203 m2) newly constructed research facility, in conjunction with supplementary existing steam heating and air-cooled chiller systems. Heat transfer performance and overall efficiency of the GSHP system were analysed using the available measured data from January through July 2014. The performance analysis identified some issues with using mine water for cooling and the integration of the GSHP system with the existing steam heating system.more » Recommendations were made to improve the control and operation of the GSHP system. These recommendations, in conjunction with the available measured data, were used to predict the annual energy use of the system. Finally, the energy and cost savings and CO2 emission reduction potential of the GSHP system were estimated by comparing with a baseline scenario. This case study provides insights into the performance of and potential issues with the mine-water source heat pump system, which is relatively under-explored compared to other GSHP system designs and configurations.« less

  9. Performance Analysis of a Ground Source Heat Pump System Using Mine Water as Heat Sink and Source

    SciTech Connect

    Liu, Xiaobing; Malhotra, Mini; Walburger, Adam; Skinner, Jack L.; Blackketter, Donald M.

    2016-06-01

    This paper summarizes a case study of an innovative ground source heat pump (GSHP) system that uses flooded mines as a heat source and heat sink. This GSHP system provides space conditioning to a 56,000 sq ft2(5,203 m2) newly constructed research facility, in conjunction with supplementary existing steam heating and air-cooled chiller systems. Heat transfer performance and overall efficiency of the GSHP system were analysed using the available measured data from January through July 2014. The performance analysis identified some issues with using mine water for cooling and the integration of the GSHP system with the existing steam heating system. Recommendations were made to improve the control and operation of the GSHP system. These recommendations, in conjunction with the available measured data, were used to predict the annual energy use of the system. Finally, the energy and cost savings and CO2 emission reduction potential of the GSHP system were estimated by comparing with a baseline scenario. This case study provides insights into the performance of and potential issues with the mine-water source heat pump system, which is relatively under-explored compared to other GSHP system designs and configurations.

  10. Cooling Load Estimation in the Building Based On Heat Sources

    NASA Astrophysics Data System (ADS)

    Chairani; Sulistyo, S.; Widyawan

    2017-05-01

    Heating, ventilation and air conditioning (HVAC) is the largest source of energy consumption. In this research, we discuss cooling load in the room by considering the different heat source and the number of occupancy. Energy cooling load is affected by external and internal heat sources. External cooling load in this discussion include convection outdoor/exterior using the DOE-2 algorithm, calculation of heat using Thermal Analysis Research Program (TARP), and Conduction Transfer Function (CTF). The internal cooling load is calculated based on the activity of the occupants in the office, a number of occupants, heat gain from lighting, and heat gain from electrics equipment. Weather data used is Surakarta weather and design day used is Jakarta design day. We use the ASHRAE standard for building materials and the metabolic of occupants while on the activity. The results show that the number of occupancies have an influence of cooling load. A large number of occupancy will cause the cooling load is great as well.

  11. TEM Pump With External Heat Source And Sink

    NASA Technical Reports Server (NTRS)

    Nesmith, Bill J.

    1991-01-01

    Proposed thermoelectric/electromagnetic (TEM) pump driven by external source of heat and by two or more heat pipe radiator heat sink(s). Thermoelectrics generate electrical current to circulate liquid metal in secondary loop of two-fluid-loop system. Intended for use with space and terrestrial dual loop liquid metal nuclear reactors. Applications include spacecraft on long missions or terrestrial beacons or scientific instruments having to operate in remote areas for long times. Design modified to include multiple radiators, converters, and ducts, as dictated by particular application.

  12. TEM Pump With External Heat Source And Sink

    NASA Technical Reports Server (NTRS)

    Nesmith, Bill J.

    1991-01-01

    Proposed thermoelectric/electromagnetic (TEM) pump driven by external source of heat and by two or more heat pipe radiator heat sink(s). Thermoelectrics generate electrical current to circulate liquid metal in secondary loop of two-fluid-loop system. Intended for use with space and terrestrial dual loop liquid metal nuclear reactors. Applications include spacecraft on long missions or terrestrial beacons or scientific instruments having to operate in remote areas for long times. Design modified to include multiple radiators, converters, and ducts, as dictated by particular application.

  13. Effect of distributed heat source on low frequency thermoacoustic instabilities

    NASA Astrophysics Data System (ADS)

    Li, Lei; Yang, Lijun; Sun, Xiaofeng

    2013-06-01

    The problem of thermoacoustic instabilities in the combustor of modern air-breathing engines has become a topic of concern, which occurs as a result of unstable coupling between the heat release fluctuations and acoustic perturbations. A three-dimensional thermoacoustic model including the distributed non-uniform heat source and non-uniform flow is developed based on the domain decomposition spectral method. The importance of distributed heat source on combustion instabilities of longitudinal modes is analyzed with the help of a simplified geometrical configuration of combustor. The results show that the longitudinal distribution of heat source has a crucial effect on instabilities. In addition, the effect of circumferentially non-uniform heat source and non-uniform flow on longitudinal instabilities is also investigated. It can be found that the influence of circumferential non-uniformity can become significant on the lowest frequency instabilities, in particular, the oscillation frequency and growth rate are all evidently affected by temperature non-uniformity and time delay non-uniformity.

  14. Quantum heat fluctuations of single-particle sources.

    PubMed

    Battista, F; Moskalets, M; Albert, M; Samuelsson, P

    2013-03-22

    Optimal single electron sources emit regular streams of particles, displaying no low-frequency charge current noise. Because of the wave packet nature of the emitted particles, the energy is, however, fluctuating, giving rise to heat current noise. We investigate theoretically this quantum source of heat noise for an emitter coupled to an electronic probe in the hot-electron regime. The distribution of temperature and potential fluctuations induced in the probe is shown to provide direct information on the single-particle wave function properties and display strong nonclassical features.

  15. On an Analog Controlled Precision Heat Power Source

    NASA Astrophysics Data System (ADS)

    Seilmayer, M.; Katepally, V. K.

    2017-07-01

    The analog controlled precision heat power source is the main part of a sensor development to estimate real time properties of the primary coolant in a 300 kW process cooling system. The measurement of physical properties like thermal conductivity or thermal diffusion requires a precise and accurate heater. The constant heat flux is then applied to the liquid under test to acquire its different properties. Here, commonly established control methods of heating with constant current or constant voltage may fail because the heating resistor changes its resistance with temperature. The idea is to utilize a power monitor circuit like the LT2940, which contains an analog multiplier with a control loop around it. The initial design and its assumed uncertainties will be discussed. The first version of the power controller shows an outstanding performance in terms of precision in a steady state. Compared to conventional switching mode power sources the approach with an analog controlled heater avoids EMI issues as well. The main goal of the present design is a precise source of heat power with less than 0.5% of error.

  16. Absorptivity Measurements and Heat Source Modeling to Simulate Laser Cladding

    NASA Astrophysics Data System (ADS)

    Wirth, Florian; Eisenbarth, Daniel; Wegener, Konrad

    The laser cladding process gains importance, as it does not only allow the application of surface coatings, but also additive manufacturing of three-dimensional parts. In both cases, process simulation can contribute to process optimization. Heat source modeling is one of the main issues for an accurate model and simulation of the laser cladding process. While the laser beam intensity distribution is readily known, the other two main effects on the process' heat input are non-trivial. Namely the measurement of the absorptivity of the applied materials as well as the powder attenuation. Therefore, calorimetry measurements were carried out. The measurement method and the measurement results for laser cladding of Stellite 6 on structural steel S 235 and for the processing of Inconel 625 are presented both using a CO2 laser as well as a high power diode laser (HPDL). Additionally, a heat source model is deduced.

  17. A reference heat source for solar collector thermal testing

    NASA Astrophysics Data System (ADS)

    Harrison, S. J.; Bernier, M. A.

    1984-12-01

    A direct-comparison reference heat source (RHS), used for testing liquid-based solar collectors, is described. A major advantage of the RHS is its capability to measure the product of mass flow and specific heat directly in the test loop. Calibration tests are performed on two reference heat sources over a range of flowrates and inlet temperatures normally encountered in flat-plate solar collector testing (10 C to 95 C). It is shown that at low flowrates (less than or equal to 0.008 kg/s), localized boiling may introduce errors if the heater power density is not reduced as well, whereas operation at flowrates greater than 0.05 kg/s reduces the temperature rise across the RHS, increasing temperature measurement uncertainty. To achieve satisfactory results with an RHS, a stable inlet temperature, good flowrate control, and regulation of the power supplied to the heater are required.

  18. Multicharged iron ions produced by using induction heating vapor source.

    PubMed

    Kato, Yushi; Kubo, Takashi; Muramatsu, Masayuki; Tanaka, Kiyokatsu; Kitagawa, Atsushi; Yoshida, Yoshikazu; Asaji, Toyohisa; Sato, Fuminobu; Iida, Toshiyuki

    2008-02-01

    Multiply charged Fe ions are produced from solid pure material in an electron cyclotron resonance (ECR) ion source. We develop an evaporator by using induction heating with an induction coil which is made of bare molybdenum wire partially covered by ceramic beads in vacuum and surrounding and heating directly the pure Fe rod. Heated material has no contact with insulators, so that outgas is minimized. The evaporator is installed around the mirror end plate outside of the ECR plasma with its hole grazing the ECR zone. Helium or argon gas is usually chosen for supporting gas. The multicharged Fe ions up to Fe(13+) are extracted from the opposite side of mirror and against the evaporator, and then multicharged Fe ion beam is formed. We compare production of multicharged iron ions by using this new source with our previous methods.

  19. EnergyPlus Air Source Integrated Heat Pump Model

    SciTech Connect

    Shen, Bo; Adams, Mark B.; New, Joshua Ryan

    2016-03-30

    This report summarizes the development of the EnergyPlus air-source integrated heat pump model. It introduces its physics, sub-models, working modes, and control logic. In addition, inputs and outputs of the new model are described, and input data file (IDF) examples are given.

  20. Role of Internal Heat Source for Eruptive Plumes on Triton

    NASA Technical Reports Server (NTRS)

    Duxbury, N. S.; Brown, R. H.

    1996-01-01

    For the first time the role of the internal heat source, due to radioactive decay in Triton's core, is investigate with respect to geyser-like plumes...A new mechanism of energy supply to the Tritonian eruptive plumes is proposed...We present the critical values of these parameters for Triton. A possible origin of the subsurface vents on Triton is also suggested.

  1. Reprint of : Thermoelectricity without absorbing energy from the heat sources

    NASA Astrophysics Data System (ADS)

    Whitney, Robert S.; Sánchez, Rafael; Haupt, Federica; Splettstoesser, Janine

    2016-08-01

    We analyze the power output of a quantum dot machine coupled to two electronic reservoirs via thermoelectric contacts, and to two thermal reservoirs - one hot and one cold. This machine is a nanoscale analogue of a conventional thermocouple heat-engine, in which the active region being heated is unavoidably also exchanging heat with its cold environment. Heat exchange between the dot and the thermal reservoirs is treated as a capacitive coupling to electronic fluctuations in localized levels, modeled as two additional quantum dots. The resulting multiple-dot setup is described using a master equation approach. We observe an "exotic" power generation, which remains finite even when the heat absorbed from the thermal reservoirs is zero (in other words the heat coming from the hot reservoir all escapes into the cold environment). This effect can be understood in terms of a non-local effect in which the heat flow from heat source to the cold environment generates power via a mechanism which we refer to as Coulomb heat drag. It relies on the fact that there is no relaxation in the quantum dot system, so electrons within it have a non-thermal energy distribution. More poetically, one can say that we find a spatial separation of the first-law of thermodynamics (heat to work conversion) from the second-law of thermodynamics (generation of entropy). We present circumstances in which this non-thermal system can generate more power than any conventional macroscopic thermocouple (with local thermalization), even when the latter works with Carnot efficiency.

  2. Ground Source Heat Pump Sub-Slab Heat Exchange Loop Performance in a Cold Climate

    SciTech Connect

    Mittereder, N.; Poerschke, A.

    2013-11-01

    This report presents a cold-climate project that examines an alternative approach to ground source heat pump (GSHP) ground loop design. The innovative ground loop design is an attempt to reduce the installed cost of the ground loop heat exchange portion of the system by containing the entire ground loop within the excavated location beneath the basement slab. Prior to the installation and operation of the sub-slab heat exchanger, energy modeling using TRNSYS software and concurrent design efforts were performed to determine the size and orientation of the system. One key parameter in the design is the installation of the GSHP in a low-load home, which considerably reduces the needed capacity of the ground loop heat exchanger. This report analyzes data from two cooling seasons and one heating season. Upon completion of the monitoring phase, measurements revealed that the initial TRNSYS simulated horizontal sub-slab ground loop heat exchanger fluid temperatures and heat transfer rates differed from the measured values. To determine the cause of this discrepancy, an updated model was developed utilizing a new TRNSYS subroutine for simulating sub-slab heat exchangers. Measurements of fluid temperature, soil temperature, and heat transfer were used to validate the updated model.

  3. Ground Source Heat Pump Sub-Slab Heat Exchange Loop Performance in a Cold Climate

    SciTech Connect

    Mittereder, Nick; Poerschke, Andrew

    2013-11-01

    This report presents a cold-climate project that examines an alternative approach to ground source heat pump (GSHP) ground loop design. The innovative ground loop design is an attempt to reduce the installed cost of the ground loop heat exchange portion of the system by containing the entire ground loop within the excavated location beneath the basement slab. Prior to the installation and operation of the sub-slab heat exchanger, energy modeling using TRNSYS software and concurrent design efforts were performed to determine the size and orientation of the system. One key parameter in the design is the installation of the GSHP in a low-load home, which considerably reduces the needed capacity of the ground loop heat exchanger. This report analyzes data from two cooling seasons and one heating season.

  4. Numerical analysis of heat exchange processes for the ground source heat pump system

    NASA Astrophysics Data System (ADS)

    Saito, H.; Muto, H.; Moritani, S.; Kohgo, Y.; Hamamoto, S.; Takemura, T.; Ohnishi, J.; Komatsu, T.

    2012-12-01

    Ground source heat pump systems (GSHP) use ground or groundwater as a heat source. They can achieve much higher coefficient of performance (COP) than conventional air source heat pump systems because the temperature of the ground is much more stable than that of the air. Heat energy in the ground is then viewed as one of the renewable energy sources. GSHP has been receiving great interests among countries in North America and Western Europe, as well as some developed countries in Asia because it can potentially reduce energy consumption and greenhouse gas emission. While GSHP can inject heat from the buildings to the ground for cooling during the summer, it can pump heat stored in the ground for heating during the winter. As some physical, chemical, and biological properties of the ground and groundwater are temperature dependent, running GSHP can eventually affect groundwater quality. The main objective of this project was to develop a model that allows predicting not only ground and groundwater temperatures but also changes in physical, chemical, and biological properties of ground and groundwater with GSHP under operations. This particular study aims at simulating heat exchange and transfer processes in the ground for a vertical-loop closed GSHP system. In the closed GSHP system, an anti-freezing solution is circulated inside the closed-loop tube, called U-tube, that is buried in the ground. Heat is then transferred to the anti-freezing solution in the U-tube by a heat exchanger. In this study we used HYDRUS to predict temperature of the anti-freezing solution, as well as that of the ground. HYDRUS allows one to simulate variably-saturated water flow and solute and heat transport in porous media numerically in two- and three-dimensional domains with great flexibility in defining boundary conditions. At first changes in anti-freezing solution temperatures measured were predicted in response to Thermal Response Test (TRT) conducted at our study site. Then, heat

  5. Self-Heating Effects In Polysilicon Source Gated Transistors.

    PubMed

    Sporea, R A; Burridge, T; Silva, S R P

    2015-09-09

    Source-gated transistors (SGTs) are thin-film devices which rely on a potential barrier at the source to achieve high gain, tolerance to fabrication variability, and low series voltage drop, relevant to a multitude of energy-efficient, large-area, cost effective applications. The current through the reverse-biased source barrier has a potentially high positive temperature coefficient, which may lead to undesirable thermal runaway effects and even device failure through self-heating. Using numerical simulations we show that, even in highly thermally-confined scenarios and at high current levels, self-heating is insufficient to compromise device integrity. Performance is minimally affected through a modest increase in output conductance, which may limit the maximum attainable gain. Measurements on polysilicon devices confirm the simulated results, with even smaller penalties in performance, largely due to improved heat dissipation through metal contacts. We conclude that SGTs can be reliably used for high gain, power efficient analog and digital circuits without significant performance impact due to self-heating. This further demonstrates the robustness of SGTs.

  6. Self-Heating Effects In Polysilicon Source Gated Transistors

    PubMed Central

    Sporea, R. A.; Burridge, T.; Silva, S. R. P.

    2015-01-01

    Source-gated transistors (SGTs) are thin-film devices which rely on a potential barrier at the source to achieve high gain, tolerance to fabrication variability, and low series voltage drop, relevant to a multitude of energy-efficient, large-area, cost effective applications. The current through the reverse-biased source barrier has a potentially high positive temperature coefficient, which may lead to undesirable thermal runaway effects and even device failure through self-heating. Using numerical simulations we show that, even in highly thermally-confined scenarios and at high current levels, self-heating is insufficient to compromise device integrity. Performance is minimally affected through a modest increase in output conductance, which may limit the maximum attainable gain. Measurements on polysilicon devices confirm the simulated results, with even smaller penalties in performance, largely due to improved heat dissipation through metal contacts. We conclude that SGTs can be reliably used for high gain, power efficient analog and digital circuits without significant performance impact due to self-heating. This further demonstrates the robustness of SGTs. PMID:26351099

  7. A new finite element model for welding heat sources

    NASA Astrophysics Data System (ADS)

    Goldak, John; Chakravarti, Aditya; Bibby, Malcolm

    1984-06-01

    A mathematical model for weld heat sources based on a Gaussian distribution of power density in space is presented. In particular a double ellipsoidal geometry is proposed so that the size and shape of the heat source can be easily changed to model both the shallow penetration arc welding processes and the deeper penetration laser and electron beam processes. In addition, it has the versatility and flexibility to handle non-axisymmetric cases such as strip electrodes or dissimilar metal joining. Previous models assumed circular or spherical symmetry. The computations are performed with ASGARD, a nonlinear transient finite element (FEM) heat flow program developed for the thermal stress analysis of welds.* Computed temperature distributions for submerged arc welds in thick workpieces are compared to the measured values reported by Christensen1 and the FEM calculated values (surface heat source model) of Krutz and Segerlind.2 In addition the computed thermal history of deep penetration electron beam welds are compared to measured values reported by Chong.3 The agreement between the computed and measured values is shown to be excellent.

  8. Solar-assisted water-source heat pump

    NASA Astrophysics Data System (ADS)

    1983-01-01

    The construction of two solar assisted water source heat pump systems to evaluate the use of night sky radiation using standard solar collectors is reported. The design of the system's controller is described, and project efforts are summarized. The procedure involved in the determination of the feasibility of night sky radiation as the means of rejecting heat through solar collectors for a sample house is reported. Conclusions on different types of coatings that are used on solar collectors are presented. A system and its backup are designed and cooling tower and night sky radiation are compared.

  9. Mathematical modeling of high and low temperature heat pipes

    NASA Technical Reports Server (NTRS)

    Chi, S. W.

    1971-01-01

    Mathematical models are developed for calculating heat-transfer limitations of high-temperature heat pipes and heat-transfer limitations and temperature gradient of low temperature heat pipes. Calculated results are compared with the available experimental data from various sources to increase confidence in the present math models. Complete listings of two computer programs for high- and low-temperature heat pipes respectively are appended. These programs enable the performance of heat pipes with wrapped-screen, rectangular-groove or screen-covered rectangular-groove wick to be predicted.

  10. Desiccant Humidity Control System Using Waste Heat of Water Source Heat Pump

    NASA Astrophysics Data System (ADS)

    Wada, Kazuki; Mashimo, Kouichi; Takahashi, Mikio; Tanaka, Kitoshi; Toya, Saburo; Tateyama, Ryotaro; Miyamoto, Kazuhiro; Yamaguchi, Masahiro

    The authors hope to develop an air-conditioning system that processes the latent heat load and the sensible heat load separately. This would enable the efficiency of the chilling unit to be improved because the temperature of the chilled water used for cooling would be higher than normal. However, if lukewarm water is used, there is insufficient cooling and dehumidification. Therefore, a dehumidifier such as a desiccant air-conditioning system is needed. Using the waste heat generated when the desiccant air-conditioning system is in operation increases efficiency. The authors are developing a prototype desiccant humidity control system that makes use of the waste heat generated by a water source heat pump. This paper describes the results of an experiment that was conducted for this prototype based on the assumption that it would be installed in an office building. The dehumidification performance achieved was sufficient to process the indoor latent heat load. The prototype was able to adjust the indoor relative humidity from 40% to 60% under conditions in which the indoor latent heat load varied. Humidification without the use of water was possible even in the absence of an indoor latent heat load when the outdoor absolute humidity was 3.5 g/kg' or more.

  11. The impact of municipal waste combustion in small heat sources

    NASA Astrophysics Data System (ADS)

    Vantúch, Martin; Kaduchová, Katarína; Lenhard, Richard

    2016-06-01

    At present there is a tendency to make greater use for heating houses for burning solid fuel, such as pieces of wood, coal, coke, local sources of heat to burn natural gas. This tendency is given both the high price of natural gas as well as the availability of cheaper solid fuel. In many cases, in the context saving heating costs, respectively in the context of the disposal of waste is co-incinerated with municipal solid fuels and wastes of different composition. This co entails increased production emissions such as CO (carbon monoxide), NOx (nitrogen oxides), particulate matter (particulate matter), PM10, HCl (hydrogen chloride), PCDD/F (polychlorinated dibenzodioxins and dibenzofurans), PCBs (polychlorinated biphenyls) and others. The experiment was focused on the emission factors from the combustion of fossil fuels in combination with municipal waste in conventional boilers designed to burn solid fuel.

  12. Development of an Air-Source Heat Pump Integrated with a Water Heating / Dehumidification Module

    SciTech Connect

    Rice, C Keith; Uselton, Robert B.; Shen, Bo; Baxter, Van D; Shrestha, Som S

    2014-01-01

    A residential-sized dual air-source integrated heat pump (AS-IHP) concept is under development in partnership between ORNL and a manufacturer. The concept design consists of a two-stage air-source heat pump (ASHP) coupled on the air distribution side with a separate novel water heating/dehumidification (WH/DH) module. The motivation for this unusual equipment combination is the forecast trend for home sensible loads to be reduced more than latent loads. Integration of water heating with a space dehumidification cycle addresses humidity control while performing double-duty. This approach can be applied to retrofit/upgrade applications as well as new construction. A WH/DH module capable of ~1.47 L/h water removal and ~2 kW water heating capacity was assembled by the manufacturer. A heat pump system model was used to guide the controls design; lab testing was conducted and used to calibrate the models. Performance maps were generated and used in a TRNSYS sub-hourly simulation to predict annual performance in a well-insulated house. Annual HVAC/WH energy savings of ~35% are predicted in cold and hot-humid U.S. climates compared to a minimum efficiency baseline.

  13. Soft electrons as a possible heat source for Jupiter's thermosphere

    NASA Technical Reports Server (NTRS)

    Hunten, D. M.; Dessler, A. J.

    1977-01-01

    The 850 K exospheric temperature inferred for Jupiter from the radio-occultation experiments on Pioneers 10 and 11 is shown to imply a heat input of 0.25-0.5 erg/sq cm/sec. One possible source of this energy is precipitation of electrons from a warm plasma (temperature corresponding to energies of the order of 30-500 eV). A mechanism is suggested wherein the presence of this plasma can be accounted for by centrifugal acceleration and adiabatic compression of ionospheric electrons and protons. Present ideas of the source strength of ionospheric plasma, however, give heating rates that are too small by one to two orders of magnitude, although inferences from direct plasma measurements suggest that the required plasma is indeed present.

  14. North Village Ground Source Heat Pump Demonstration Project

    SciTech Connect

    Redderson, Jeff

    2015-08-03

    This project demonstrated the feasibility of converting from a traditional direct exchange system to a ground source heat pump system on a large scale, multiple building apartment complex on a university campus. A total of ten apartment buildings were converted using vertical well fields and a ground source loop that connected the 24 apartments in each building into a common system. The system has yielded significant operational savings in both energy and maintenance and transformed the living environments of these residential buildings for our students.

  15. Indoor heating sources and respiratory symptoms in nonsmoking women.

    PubMed

    Triche, Elizabeth W; Belanger, Kathleen; Bracken, Michael B; Beckett, William S; Holford, Theodore R; Gent, Janneane F; McSharry, Jean-Ellen; Leaderer, Brian P

    2005-05-01

    Secondary heating appliances are important indoor sources of air pollution, including particulate matter, nitrogen dioxide (NO2), and sulfur dioxide (SO2). We hypothesized that the use of secondary heating sources increases respiratory symptoms in women living in nonsmoking households and specifically that concentrations of SO2 and NO2 emitted from heating sources are associated with respiratory symptoms. Mothers who delivered babies at 12 hospitals in Connecticut and Virginia (1993-1996) were enrolled. There were 888 women who contributed symptom and exposure information during the winter heating season (15 October to 15 April), for a total of 9783 reporting periods (median = 12 reporting periods per woman, interquartile range 11-12). Adjusted rate ratios (RRs) of effects of source use and measured concentrations on rate of days with symptoms were obtained using generalized estimating equations for a log-linear Poisson model, controlling age, education, race, history of allergies, number of children, dwelling type, and residence state. In adjusted models, each hour-per-day increase in kerosene heater use is associated with an increase in wheezing (RR = 1.06; 95% confidence interval (CI) = 1.01-1.11). Each hour of fireplace use is associated with increased cough (1.05; 1.01-1.09), sore throat (1.04; 1.00-1.08), and marginally with chest tightness (1.05; 0.99-1.12). Each 10 ppb increase in SO2 (a proxy for sulfate aerosol) is associated with increased wheezing (1.57; 1.10-2.26) and chest tightness (1.32; 1.01-1.71). Emissions from fireplaces, gas space heaters, and kerosene heaters may contribute to respiratory symptoms in a population of nonsmoking women.

  16. A vortex-source combination, a source, and a vortex with distributed heat supply

    NASA Astrophysics Data System (ADS)

    Kucherov, A. N.

    1983-04-01

    An analysis is made of the effect of distributed heat supply on the gasdynamic characteristics of a vortex-source (vortex-sink) combination, a source (sink), and a vortex. It is shown that in all the cases considered, there is a minimum radius for which the radial component of M is equal to unity. It is also shown that there is a critical intensity of heat release (for a fixed similarity parameter) separating two families of integral curves and that for this critical value a solution exists only under certain conditions.

  17. Turbulence Measurements of Rectangular Nozzles with Bevel

    NASA Technical Reports Server (NTRS)

    Bridges, James; Wernet, Mark P.

    2015-01-01

    This paper covers particle image velocimetry measurements of a family of rectangular nozzles with aspect ratios 2, 4, and 8, in the high subsonic flow regime. Far-field acoustic results, presented previously, showed that increasing aspect ratios increased the high frequency noise, especially directed in the polar plane containing the minor axis of the nozzle. The measurements presented here have important implications in the modeling of turbulent sources for acoustic analogy theories. While the nonaxisymmetric mean flow from the rectangular nozzles can be studied reliably using computational solutions, the nonaxisymmetry of the turbulent fluctuations, particularly at the level of velocity components, cannot; only measurements such as these can determine the impact of nozzle geometry on acoustic source anisotropy. Additional nozzles were constructed that extended the wide lip on one side of these nozzles to form beveled nozzles. The paper first documents the velocity fields, mean and variance, from the round, rectangular, and beveled rectangular nozzles at high subsonic speeds. A second section introduces measures of the isotropy of the turbulence, such as component ratios and lengthscales, first by showing them for a round jet and then for the rectangular nozzles. From these measures the source models of acoustic analogy codes can be judged or modified to account for these anisotropies.

  18. Lunar Surface Stirling Power Systems Using Isotope Heat Sources

    NASA Technical Reports Server (NTRS)

    Schmitz, Paul C.; Penswick, L. Barry; Shaltens, Richard K.

    2010-01-01

    For many years, NASA has used the decay of plutonium-238 (Pu-238) (in the form of the General Purpose Heat Source (GPHS)) as a heat source for Radioisotope Thermoelectric Generators (RTGs), which have provided electrical power for many NASA missions. While RTGs have an impressive reliability record for the missions in which they have been used, their relatively low thermal to electric conversion efficiency and the scarcity of plutonium-238 (Pu-238) has led NASA to consider other power conversion technologies. NASA is considering returning both robotic and human missions to the lunar surface and, because of the long lunar nights (14.75 Earth days), isotope power systems are an attractive candidate to generate electrical power. NASA is currently developing the Advanced Stirling Radioisotope Generator (ASRG) as a candidate higher efficiency power system that produces greater than 160 W with two GPHS modules at the beginning of life (BOL) (32% efficiency). The ASRG uses the same Pu-238 GPHS modules, which are used in RTG, but by coupling them to a Stirling convertor provides a four-fold reduction in the number of GPHS modules. This study considers the use of americium-241 (Am-241) as a substitute for the Pu-238 in Stirling- convertor-based Radioisotope Power Systems (RPS) for power levels from tens of watts to 5 kWe. The Am-241 is used as a substitute for the Pu-238 in GPHS modules. Depending on power level, different Stirling heat input and removal systems are modeled. It was found that substituting Am-241 GPHS modules into the ASRG reduces power output by about one-fifth while maintaining approximately the same system mass. In order to obtain the nominal 160 W of electrical output of the Pu-238 ASRG requires 10 Am-241 GPHS modules. Higher power systems require changing from conductive coupling heat input and removal from the Stirling convertor to either pumped loops or heat pipes. Liquid metal pumped loops are considered as the primary heat transportation on the hot

  19. The effect of multiple heat sources on exomoon habitable zones

    NASA Astrophysics Data System (ADS)

    Dobos, Vera; Heller, René; Turner, Edwin L.

    2017-05-01

    With dozens of Jovian and super-Jovian exoplanets known to orbit their host stars in or near the stellar habitable zones, it has recently been suggested that moons the size of Mars could offer abundant surface habitats beyond the solar system. Several searches for such exomoons are now underway, and the exquisite astronomical data quality of upcoming space missions and ground-based extremely large telescopes could make the detection and characterization of exomoons possible in the near future. Here we explore the effects of tidal heating on the potential of Mars- to Earth-sized satellites to host liquid surface water, and we compare the tidal heating rates predicted by tidal equilibrium model and a viscoelastic model. In addition to tidal heating, we consider stellar radiation, planetary illumination and thermal heat from the planet. However, the effects of a possible moon atmosphere are neglected. We map the circumplanetary habitable zone for different stellar distances in specific star-planet-satellite configurations, and determine those regions where tidal heating dominates over stellar radiation. We find that the "thermostat effect" of the viscoelastic model is significant not just at large distances from the star, but also in the stellar habitable zone, where stellar radiation is prevalent. We also find that tidal heating of Mars-sized moons with eccentricities between 0.001 and 0.01 is the dominant energy source beyond 3-5 AU from a Sun-like star and beyond 0.4-0.6 AU from an M3 dwarf star. The latter would be easier to detect (if they exist), but their orbital stability might be under jeopardy due to the gravitational perturbations from the star.

  20. Io: Volcanic thermal sources and global heat flow

    NASA Astrophysics Data System (ADS)

    Veeder, Glenn J.; Davies, Ashley Gerard; Matson, Dennis L.; Johnson, Torrence V.; Williams, David A.; Radebaugh, Jani

    2012-06-01

    We have examined thermal emission from 240 active or recently-active volcanic features on Io and quantified the magnitude and distribution of their volcanic heat flow during the Galileo epoch. We use spacecraft data and a geological map of Io to derive an estimate of the maximum possible contribution from small dark areas not detected as thermally active but which nevertheless appear to be sites of recent volcanic activity. We utilize a trend analysis to extrapolate from the smallest detectable volcanic heat sources to these smallest mapped dark areas. Including the additional heat from estimates for "outburst" eruptions and for a multitude of very small ("myriad") hot spots, we account for ˜62 × 1012 W (˜59 ± 7% of Io's total thermal emission). Loki Patera contributes, on average, 9.6 × 1012 W (˜9.1 ± 1%). All dark paterae contribute 45.3 × 1012 W (˜43 ± 5%). Although dark flow fields cover a much larger area than dark paterae, they contribute only 5.6 × 1012 W (˜5.3 ± 0.6%). Bright paterae contribute ˜2.6 × 1012 W (˜2.5 ± 0.3%). Outburst eruption phases and very small hot spots contribute no more than ˜4% of Io's total thermal emission: this is probably a maximum value. About 50% of Io's volcanic heat flow emanates from only 1.2% of Io's surface. Of Io's heat flow, 41 ± 7.0% remains unaccounted for in terms of identified sources. Globally, volcanic heat flow is not uniformly distributed. Power output per unit surface area is slightly biased towards mid-latitudes, although there is a stronger bias toward the northern hemisphere when Loki Patera is included. There is a slight favoring of the northern hemisphere for outbursts where locations were well constrained. Globally, we find peaks in thermal emission at ˜315°W and ˜105°W (using 30° bins). There is a minimum in thermal emission at around 200°W (almost at the anti-jovian longitude) which is a significant regional difference. These peaks and troughs suggest a shift to the east from

  1. A multiple step random walk Monte Carlo method for heat conduction involving distributed heat sources

    NASA Astrophysics Data System (ADS)

    Naraghi, M. H. N.; Chung, B. T. F.

    1982-06-01

    A multiple step fixed random walk Monte Carlo method for solving heat conduction in solids with distributed internal heat sources is developed. In this method, the probability that a walker reaches a point a few steps away is calculated analytically and is stored in the computer. Instead of moving to the immediate neighboring point the walker is allowed to jump several steps further. The present multiple step random walk technique can be applied to both conventional Monte Carlo and the Exodus methods. Numerical results indicate that the present method compares well with finite difference solutions while the computation speed is much faster than that of single step Exodus and conventional Monte Carlo methods.

  2. Pure Material Vapor Source by Induction Heating Evaporator for an Electron Cyclotron Resonance Ion Source

    SciTech Connect

    Matsui, Y.; Watanabe, T.; Satani, T.; Sato, F.; Kato, Y.; Iida, T.; Muramatsu, M.; Kitagawa, A.; Tanaka, K.; Yoshida, Y.

    2008-11-03

    Multiply charged iron ions are produced from solid pure material in an electron cyclotron resonance (ECR) ion source. We develop an evaporator by using induction heating with the induction coil which is made from bare molybdenum wire and surrounding the pure iron rod. We optimize the shape of induction heating coil and operation of rf power supply. We conduct experiment to investigate reproducibility and stability in the operation and heating efficiency. Induction heating evaporator produces pure material vapor, because materials directly heated by eddy currents have non-contact with insulated materials which are impurity gas sources. The power and the frequency of the induction currents range from 100 to 900 W and from 48 to 23 kHz, respectively. The working pressure is about 10{sup -4} to 10{sup -3} Pa. We measure temperature of iron rod and film deposition rate by depositing iron vapor to crystal oscillator. We confirm stability and reproducibility of evaporator enough to conduct experiment in ECR ion source. We can obtain required temperature of iron under maximum power of power supply. We are aiming the evaporator higher melting point material than iron.

  3. Ground-source heat pump case studies and utility programs

    SciTech Connect

    Lienau, P.J.; Boyd, T.L.; Rogers, R.L.

    1995-04-01

    Ground-source heat pump systems are one of the promising new energy technologies that has shown rapid increase in usage over the past ten years in the United States. These systems offer substantial benefits to consumers and utilities in energy (kWh) and demand (kW) savings. The purpose of this study was to determine what existing monitored data was available mainly from electric utilities on heat pump performance, energy savings and demand reduction for residential, school and commercial building applications. In order to verify the performance, information was collected for 253 case studies from mainly utilities throughout the United States. The case studies were compiled into a database. The database was organized into general information, system information, ground system information, system performance, and additional information. Information was developed on the status of demand-side management of ground-source heat pump programs for about 60 electric utility and rural electric cooperatives on marketing, incentive programs, barriers to market penetration, number units installed in service area, and benefits.

  4. Heated birthing pools as a source of Legionnaires' disease.

    PubMed

    Collins, S L; Afshar, B; Walker, J T; Aird, H; Naik, F; Parry-Ford, F; Phin, N; Harrison, T G; Chalker, V J; Sorrell, S; Cresswell, T

    2016-03-01

    In June 2014 Public Health England confirmed a case of Legionnaires' disease (LD) in a neonate following birth at home in a hired birthing pool incorporating a heater and a recirculation pump which had been filled in advance of labour. The case triggered a public health investigation and a microbiological survey of an additional ten heated birthing pools hired or recently hired to the general public across England. The birthing pool used by the parent of the confirmed case was identified as the source of the neonate's infection following detection of Legionella pneumophila ST48 in both patient and environmental samples. Legionella species were detected by quantitative polymerase chain reaction but not culture in a further three pools together with other opportunistic pathogens identified by culture and matrix-assisted laser desorption ionization-time of flight (MALDI-ToF) mass spectrometry. A Patient Safety Alert from NHS England and Public Health England was issued stating that heated birthing pools filled in advance of labour should not be used for home births. This recommendation remains in place. This investigation in conjunction with other recent reports has highlighted a lack of awareness regarding the microbiological safety of heated birthing pools and their potential to be a source of LD and other opportunistic infections. Furthermore, the investigation raised important considerations with regards to microbiological sampling and testing in such incidents. Public health authorities and clinicians should consider LD in the differential diagnosis of severe respiratory infection in neonates within 14 days of a water birth.

  5. Nondestructive inspection of General Purpose Heat Source (GPHS) girth welds

    SciTech Connect

    Reimus, M.A.H.; George, T.G.; Lynch, C.

    1998-12-31

    The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of {sup 238}Pu decay to an array of thermoelectric elements. The GPHS is fabricated using iridium capsules, TIG welded, to contain the {sup 238}PuO{sub 2} fuel pellet. GPHS capsules will be utilized in the upcoming Cassini mission to explore Saturn and its moons. The physical integrity of the girth weld is important to mission safety and performance. Since experience in the past had revealed a potential for initiation of small cracks in the girth weld overlap zone, a nondestructive inspection of the capsule weld is required. A ultrasonic method was used to inspect the welds of capsules fabricated for the Galileo mission. The instrument, transducer, and method used were state of the art at the time (early 1980s). The ultrasonic instrumentation and methods used to inspect the Cassini GPHSs was significantly upgraded from those used for the Galileo mission. GPHSs that had ultrasonic reflectors that exceeded the reject specification level were subsequently inspected with radiography to provide additional engineering data used to accept/reject the heat source. This paper describes the Galileo-era ultrasonic instrumentation and methods and the subsequent upgrades made to support testing of Cassini GPHSs. Also discussed is the data obtained from radiographic examination and correlation to ultrasonic examination results.

  6. Formation of the lunar crust - An electrical source of heating

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.; Colburn, D. S.; Schwartz, K.

    1975-01-01

    A model for formation of the lunar crust based on heating by electrical induction is explored, while adherence is maintained to certain constraints associated with existing models of the solar system. The heating mechanism is based on eddy current induction from disordered magnetic fields swept outwards by an intense (T Tauri-like) plasma flow from the sun. The electrical theory is an alternative to intense short-period accretion as a source of heat for the evolution of lunar maria and highlands, provided that long-lived radioactives are not swept to the surface from too large a melt volume during the initial thermal episode. This formation of the lunar highlands does not intrinsically require rapid accretion, nor on this basis is the time of formation of the planets generally restricted to a very short time. The threshold temperature for eddy current heating is attained by either a solar nebula at 300-400 C during formation of the moon or a very low energy long-period accumulation of the moon, both leading to melting in ten to the fifth to ten to the seventh power years.

  7. Formation of the lunar crust - An electrical source of heating

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.; Colburn, D. S.; Schwartz, K.

    1975-01-01

    A model for formation of the lunar crust based on heating by electrical induction is explored, while adherence is maintained to certain constraints associated with existing models of the solar system. The heating mechanism is based on eddy current induction from disordered magnetic fields swept outwards by an intense (T Tauri-like) plasma flow from the sun. The electrical theory is an alternative to intense short-period accretion as a source of heat for the evolution of lunar maria and highlands, provided that long-lived radioactives are not swept to the surface from too large a melt volume during the initial thermal episode. This formation of the lunar highlands does not intrinsically require rapid accretion, nor on this basis is the time of formation of the planets generally restricted to a very short time. The threshold temperature for eddy current heating is attained by either a solar nebula at 300-400 C during formation of the moon or a very low energy long-period accumulation of the moon, both leading to melting in ten to the fifth to ten to the seventh power years.

  8. Isotope heat source simulator for testing of space power systems

    NASA Technical Reports Server (NTRS)

    Prok, G. M.; Smith, R. B.

    1973-01-01

    A reliable isotope heat source simulator was designed for use in a Brayton power system. This simulator is composed of an electrically heated tungsten wire which is wound around a boron nitride core and enclosed in a graphite jacket. Simulator testing was performed at the expected operating temperature of the Brayton power system. Endurance testing for 5012 hours was followed by cycling the simulator temperature. The integrity of this simulator was maintained throughout testing. Alumina beads served as a diffusion barrier to prevent interaction between the tungsten heater and boron nitride core. The simulator was designed to maintain a surface temperature of 1311 to 1366 K (1900 to 2000 F) with a power input of approximately 400 watts. The design concept and the materials used in the simulator make possible man different geometries. This flexibility increases its potential use.

  9. Low Temperature Heat Source Utilization Current and Advanced Technology

    SciTech Connect

    Anderson, James H. Jr.; Dambly, Benjamin W.

    1992-06-01

    Once a geothermal heat source has been identified as having the potential for development, and its thermal, physical, and chemical characteristics have been determined, a method of utilization must be decided upon. This compendium will touch upon some of these concerns, and hopefully will provide the reader with a better understanding of technologies being developed that will be applicable to geothermal development in East Africa, as well as other parts of the world. The appendices contain detailed reports on Down-the-Well Turbo Pump, The Vapor-Turbine Cycle for Geothermal Power Generation, Heat Exchanger Design for Geothermal Power Plants, and a Feasibility Study of Combined Power and Water Desalting Plant Using Hot Geothermal Water. [DJE-2005

  10. HTGR nuclear heat source component design and experience

    SciTech Connect

    Peinado, C.O.; Wunderlich, R.G.; Simon, W.A.

    1982-05-01

    The high-temperature gas-cooled reactor (HTGR) nuclear heat source components have been under design and development since the mid-1950's. Two power plants have been designed, constructed, and operated: the Peach Bottom Atomic Power Station and the Fort St. Vrain Nuclear Generating Station. Recently, development has focused on the primary system components for a 2240-MW(t) steam cycle HTGR capable of generating about 900 MW(e) electric power or alternately producing high-grade steam and cogenerating electric power. These components include the steam generators, core auxiliary heat exchangers, primary and auxiliary circulators, reactor internals, and thermal barrier system. A discussion of the design and operating experience of these components is included.

  11. Film condensation in a horizontal rectangular duct

    NASA Technical Reports Server (NTRS)

    Lu, Qing; Suryanarayana, N. V.

    1993-01-01

    Condensation heat transfer in a horizontal rectangular duct was experimentally and analytically investigated. To prevent the dripping of condensate on the film, the experiment was conducted inside a horizontal rectangular duct with vapor condensing only on the bottom cooled plate of the duct. R-113 and FC-72 (Fluorinert Electronic Fluid developed by the 3M Company) were used as the condensing fluids. The experimental program included measurements of film thickness, local and average heat transfer coefficients, wave length, wave speed, and a study of wave initiation. The measured film thickness was used to obtain the local heat transfer coefficient. The wave initiation was studied both with condensation and with an adiabatic air-liquid flow. The test sections used in both experiments were identical.

  12. Effects of aqueous humor hydrodynamics on human eye heat transfer under external heat sources.

    PubMed

    Tiang, Kor L; Ooi, Ean H

    2016-08-01

    The majority of the eye models developed in the late 90s and early 00s considers only heat conduction inside the eye. This assumption is not entirely correct, since the anterior and posterior chambers are filled aqueous humor (AH) that is constantly in motion due to thermally-induced buoyancy. In this paper, a three-dimensional model of the human eye is developed to investigate the effects AH hydrodynamics have on the human eye temperature under exposure to external heat sources. If the effects of AH flow are negligible, then future models can be developed without taking them into account, thus simplifying the modeling process. Two types of external thermal loads are considered; volumetric and surface irradiation. Results showed that heat convection due to AH flow contributes to nearly 95% of the total heat flow inside the anterior chamber. Moreover, the circulation inside the anterior chamber can cause an upward shift of the location of hotspot. This can have significant consequences to our understanding of heat-induced cataractogenesis. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  13. An Empirical Temperature Variance Source Model in Heated Jets

    NASA Technical Reports Server (NTRS)

    Khavaran, Abbas; Bridges, James

    2012-01-01

    An acoustic analogy approach is implemented that models the sources of jet noise in heated jets. The equivalent sources of turbulent mixing noise are recognized as the differences between the fluctuating and Favre-averaged Reynolds stresses and enthalpy fluxes. While in a conventional acoustic analogy only Reynolds stress components are scrutinized for their noise generation properties, it is now accepted that a comprehensive source model should include the additional entropy source term. Following Goldstein s generalized acoustic analogy, the set of Euler equations are divided into two sets of equations that govern a non-radiating base flow plus its residual components. When the base flow is considered as a locally parallel mean flow, the residual equations may be rearranged to form an inhomogeneous third-order wave equation. A general solution is written subsequently using a Green s function method while all non-linear terms are treated as the equivalent sources of aerodynamic sound and are modeled accordingly. In a previous study, a specialized Reynolds-averaged Navier-Stokes (RANS) solver was implemented to compute the variance of thermal fluctuations that determine the enthalpy flux source strength. The main objective here is to present an empirical model capable of providing a reasonable estimate of the stagnation temperature variance in a jet. Such a model is parameterized as a function of the mean stagnation temperature gradient in the jet, and is evaluated using commonly available RANS solvers. The ensuing thermal source distribution is compared with measurements as well as computational result from a dedicated RANS solver that employs an enthalpy variance and dissipation rate model. Turbulent mixing noise predictions are presented for a wide range of jet temperature ratios from 1.0 to 3.20.

  14. A capital cost comparison of commercial ground-source heat pump systems

    SciTech Connect

    Rafferty, K.

    1994-06-01

    The purpose of the report is to compare capital costs associated with the three designs of ground source heat pumps. Specifically, the costs considered are those associated with the heat source/heat sink or ground source portion of the system. In order to standardize the heat rejection over the three designs, it was assumed that the heat pump loop would operate at a temperature range of 85{degree} (to the heat pumps) to 95{degree} (from the heat pumps) under peak conditions. The assumption of constant loop temperature conditions for all three permits an apples-to-apples comparison of the alternatives.

  15. Recovery Act: Cedarville School District Retrofit of Heating and Cooling Systems with Geothermal Heat Pumps and Ground Source Water Loops

    SciTech Connect

    Jarrell, Mark

    2013-09-30

    Cedarville School District retrofitted the heating and cooling systems in three campus areas (High School, Middle School, and Upper Elementary School) with geothermal heat pumps and ground source water loops, as a demonstration project for the effective implementation of geothermal heat pump systems and other energy efficiency and air quality improvements.

  16. Effects of a Ground Source Heat Pump in Discontinuous Permafrost

    NASA Astrophysics Data System (ADS)

    Peterson, R.; Garber-Slaght, R.; Daanen, R. P.

    2015-12-01

    A ground source heat pump (GSHP) was installed in a discontinuous permafrost region of Fairbanks Alaska in 2013 with the primary aim of determining the effect of different ground cover options on the long-term subterranean temperature regime. Three different surface treatments were applied to separate loops of the GSHP; grass, sand, and gravel, and temperature monitoring was established at several depths above and below the heat sink loops. The GSHP has been actively utilized to supplement the heat in a hydronic heating system of a neighboring 5000 ft2 research facility. The ground immediately surrounding the GSHP was not permafrost when initially installed. Numerical modeling simulations were used to predict the long-term ground temperature regime surrounding the GSHP loops, and results indicate that permafrost would begin to form after the first year. A pseudo-steady state temperature regime would establish in approximately 8 years with a yearly fluctuation of -14°C to -2°C. Simulations also indicate that permafrost could be prevented with a 15 W/m recharge during the summer, such as from a solar thermal system. The ground surface treatments have negligible effect on the ground temperature below 1 meter and therefore have no long-term effect on the active region the GSHP. Data collected from thermistors in the two years since installation indicate that permafrost has not yet been established, although the ground is now becoming seasonally frozen due to the GSHP energy removal. Yearly average temperatures are declining, and extrapolation indicates that permafrost will establish in future years. The GSHP coefficient of performance (COP) was initially 3.6 and is declining with the decreasing ground temperatures. Economic modeling indicates that the system may become uneconomical in future years, although volatile energy costs have a substantial effect of the prediction.

  17. Investigation of the heat source(s) of the Surprise Valley Geothermal System, Northern California

    NASA Astrophysics Data System (ADS)

    Tanner, N.; Holt, C. D.; Hawkes, S.; McClain, J. S.; Safford, L.; Mink, L. L.; Rose, C.; Zierenberg, R. A.

    2016-12-01

    Concerns about environmental impacts and energy security have led to an increased interest in sustainable and renewable energy resources, including geothermal systems. It is essential to know the permeability structure and possible heat source(s) of a geothermal area in order to assess the capacity and extent of the potential resource. We have undertaken geophysical surveys at the Surprise Valley Hot Springs in Cedarville, California to characterize essential parameters related to a fault-controlled geothermal system. At present, the heat source(s) for the system are unknown. Igneous bodies in the area are likely too old to have retained enough heat to supply the system, so it is probable that fracture networks provide heat from some deeper or more distributed heat sources. However, the fracture system and permeability structure remain enigmatic. The goal of our research is to identify the pathways for fluid transport within the Surprise Valley geothermal system using a combination of geophysical methods including active seismic surveys and short- and long-period magnetotelluric (MT) surveys. We have collected 14 spreads, consisting of 24 geophones each, of active-source seismic data. We used a "Betsy Gun" source at 8 to 12 locations along each spread and have collected and analyzed about 2800 shot-receiver pairs. Seismic velocities reveal shallow lake sediments, as well as velocities consistent with porous basalts. The latter, with velocities of greater than 3.0 km/s, lie along strike with known hot springs and faulted and tilted basalt outcrops outside our field area. This suggests that basalts may provide a permeable pathway through impermeable lake deposits. We conducted short-period (10Hz-60kHz) MT measurements at 33 stations. Our short-period MT models indicate shallow resistive blocks (>100Ωm) with a thin cover of more conductive sediments ( 10Ωm) at the surface. Hot springs are located in gaps between resistive blocks and are connected to deeper low

  18. On the efficient use of a lowtemperature heat source by the organic Rankine cycle

    NASA Astrophysics Data System (ADS)

    Mikielewicz, Dariusz; Mikielewicz, Jarosław

    2013-09-01

    The evaporation temperature is regarded as one of the major parameters influencing the organic Rankine cycle (ORC) efficiency. Majority of contributions in literature for ORC cycle analyses treat the heat source as if it had an infinite heat capacity. Such analyses are not valuable as the resulting temperature drops of the heat source needs to be small. That leads to the fact that the heat source is not well explored and in the case of waste heat utilization it can prove the poor economics of the ORC. In the present study cooperation of the ORC cycle with the heat source available as a single phase or phase changing fluids is considered. The analytical heat balance models have been developed, which enable in a simple way calculation of heating fluid temperature variation as well as the ratio of flow rates of heating and working fluids in ORC cycle. The developed analytical expressions enable also calculation of the outlet temperature of the heating fluid.

  19. Ground Source Integrated Heat Pump (GS-IHP) Development

    SciTech Connect

    Baxter, V. D.; Rice, K.; Murphy, R.; Munk, J.; Ally, Moonis; Shen, Bo; Craddick, William; Hearn, Shawn A.

    2013-05-24

    Between October 2008 and May 2013 ORNL and ClimateMaster, Inc. (CM) engaged in a Cooperative Research and Development Agreement (CRADA) to develop a groundsource integrated heat pump (GS-IHP) system for the US residential market. A initial prototype was designed and fabricated, lab-tested, and modeled in TRNSYS (SOLAR Energy Laboratory, et al, 2010) to predict annual performance relative to 1) a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of air-source heat pump (ASHP) and resistance water heater) and 2) a state-of-the-art (SOA) two-capacity ground-source heat pump with desuperheater water heater (WH) option (GSHPwDS). Predicted total annual energy savings, while providing space conditioning and water heating for a 2600 ft{sup 2} (242 m{sup 2}) house at 5 U.S. locations, ranged from 52 to 59%, averaging 55%, relative to the minimum efficiency suite. Predicted energy use for water heating was reduced 68 to 78% relative to resistance WH. Predicted total annual savings for the GSHPwDS relative to the same baseline averaged 22.6% with water heating energy use reduced by 10 to 30% from desuperheater contributions. The 1st generation (or alpha) prototype design for the GS-IHP was finalized in 2010 and field test samples were fabricated for testing by CM and by ORNL. Two of the alpha units were installed in 3700 ft{sup 2} (345 m{sup 2}) houses at the ZEBRAlliance site in Oak Ridge and field tested during 2011. Based on the steady-state performance demonstrated by the GS-IHPs it was projected that it would achieve >52% energy savings relative to the minimum efficiency suite at this specific site. A number of operational issues with the alpha units were identified indicating design changes needed to the system before market introduction could be accomplished. These were communicated to CM throughout the field test period. Based on the alpha unit test results and the diagnostic information coming from the field test

  20. The planetary distribution of heat sources and sinks during FGGE

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Wei, M. Y.

    1985-01-01

    Heating distributions from analysis of the National Meteorological Center and European Center for Medium Range Weather Forecasts data sets; methods used and problems involved in the inference of diabatic heating; the relationship between differential heating and energy transport; and recommendations on the inference of heat soruces and heat sinks for the planetary show are discussed.

  1. External Pressure Testing of the 60-Watt Isotopic Heat Source

    SciTech Connect

    Frazier, T. A.; Christenbury, S. T.

    1995-03-15

    The purpose of this manual is to establish the capability of the IHS generator system to contain its radioisotopic source under an accident scenario in which the generator is deposited in the ocean at great depth. This procedure is to be used on assemblies designated to demonstrate the capability of the 60-watt IHS in external pressure environments. A qualified helium leak technician (NDE) performs evaluations during post test activities. Quality Engineering (QE) is present during testing to monitor activities. Testing involves a 60-watt IHS/Heater Head Assembly with the simulant yttria in place of the isotopic fuel. The standard length 0.094 inch diameter SST dowel pin is replaced with a longer pin to facilitate disassembly. The assembly is tested to 1000 atmospheres (-15,000 psi). It is then evaluated. If it shows no evidence of collapse, an additional test is conducted for information only. The Source Document is "Safety Test Program Plan for the 60-Watt Isotopic Heat Source (IHS)", TBE-32156-IHS-008 Issue

  2. Hydrogen production from coal using a nuclear heat source

    NASA Technical Reports Server (NTRS)

    Quade, R. N.

    1976-01-01

    A strong candidate for hydrogen production in the intermediate time frame of 1985 to 1995 is a coal-based process using a high-temperature gas-cooled reactor (HTGR) as a heat source. Expected process efficiencies in the range of 60 to 70% are considerably higher than all other hydrogen production processes except steam reforming of a natural gas. The process involves the preparation of a coal liquid, hydrogasification of that liquid, and steam reforming of the resulting gaseous or light liquid product. A study showing process efficiency and cost of hydrogen vs nuclear reactor core outlet temperature has been completed, and shows diminishing returns at process temperatures above about 1500 F. A possible scenario combining the relatively abundant and low-cost Western coal deposits with the Gulf Coast hydrogen users is presented which provides high-energy density transportation utilizing coal liquids and uranium.

  3. Milliwatt generator heat source. Progress report, July-December 1981

    SciTech Connect

    Mershad, E.A.

    1982-04-08

    As part of the Milliwatt Generator (MWG) Program, a second series of pressure burst capsules welded offsite was tested; the resulting data indicate that the welds are very similar to those in the first series of capsules. Sufficient hardware was fabricated to meet all scheduled commitments. To provide a unit for feasibility testing, a heat source clad with Hastelloy C was reclad with Inconel 600. Forming development tests on Inconel 600 were conducted with favorable results. A QAS-3 survey was conducted and a satisfactory rating was received. Lot 11 qualification began on T-111 materials. The production period ended with an overall process yield of 99.6%, and a dollar percent defective rate of 0.60%.

  4. Environmental assessment for radioisotope heat source fuel processing and fabrication

    SciTech Connect

    Not Available

    1991-07-01

    DOE has prepared an Environmental Assessment (EA) for radioisotope heat source fuel processing and fabrication involving existing facilities at the Savannah River Site (SRS) near Aiken, South Carolina and the Los Alamos National Laboratory (LANL) near Los Alamos, New Mexico. The proposed action is needed to provide Radioisotope Thermoelectric Generators (RTG) to support the National Aeronautics and Space Administration's (NASA) CRAF and Cassini Missions. Based on the analysis in the EA, DOE has determined that the proposed action does not constitute a major Federal action significantly affecting the quality of the human environment within the meaning of the National Environmental Policy Act (NEPA) of 1969. Therefore, an Environmental Impact Statement is not required. 30 refs., 5 figs.

  5. Characterization of Pu-238 heat source granule containment

    SciTech Connect

    Richardson Ii, P D; Thronas, D L; Romero, J P; Sandoval, F E; Neuman, A D; Duncan, W S

    2008-01-01

    The Milliwatt Radioisotopic Thermoelectric Generator (RTG) provides power for permissive-action links. These nuclear batteries convert thermal energy to electrical energy using a doped silicon-germanium thermopile. The thermal energy is provided by a heat source made of {sup 238}Pu, in the form of {sup 238}PuO{sub 2} granules. The granules are contained in 3 layers of encapsulation. A thin T-111 liner surrounds the {sup 238}PuO{sub 2} granules and protects the second layer (strength member) from exposure to the fuel granules. The T-111 strength member contains the fuel under impact condition. An outer clad of Hastelloy-C protects the T-111 from oxygen embrittlement. The T-111 strength member is considered the critical component in this {sup 238}PuO{sub 2} containment system. Any compromise in the strength member is something that needs to be characterized. Consequently, the T-111 strength member is characterized upon it's decommissioning through Scanning Electron Microscopy (SEM), and Metallography. SEM is used in Secondary Electron mode to reveal possible grain boundary deformation and/or cracking in the region of the strength member weld. Deformation and cracking uncovered by SEM are further characterized by Metallography. Metallography sections are mounted and polished, observed using optical microscopy, then documented in the form of photomicrographs. SEM may further be used to examine polished Metallography mounts to characterize elements using the SEM mode of Energy Dispersive X-ray Spectroscopy (EDS). This paper describes the characterization of the metallurgical condition of decommissioned RTG heat sources.

  6. Measured Performance of a Low Temperature Air Source Heat Pump

    SciTech Connect

    R.K. Johnson

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor “boosted heat pump” technology. The Low Temperature Heat Pump system operates with four increasing levels of capacity (heat output) as the outdoor temperature drops.

  7. Ground source heat pumps (GSHP) for heating and cooling in Greece

    NASA Astrophysics Data System (ADS)

    Dimera, Nikoletta

    This report presents the results of a theoretical study about the feasibility of closed loop Ground Source Heat Pumps (GSHP) for heating and cooling in Greece in terms of their impact on the capital and running costs of the building services systems of the buildings. The main aim of carrying out this study was to investigate if the heating and cooling potential of the ground could be utilized cost efficiently to serve the buildings energy demand in the Greek region. At first, an existing implementation of a closed loop GSHP system in Greece is presented and its efficiency is discussed. The aim of doing so was to understand the way of sizing such systems and the efficiency of this technology in Greek climatic and ground conditions. In a separate part of this report, the impact of different user behaviour and of various ways of sizing a GSHP system is investigated in terms of the cost impact of the examined different options as well as of their effect on the internal health and comfort conditions. After the building simulation under different scenarios, it was concluded that the user behavior - the operation of windows mostly - can result in great savings on the annual energy bills. The conclusions of this first part of the report about the user behaviour and the way of sizing GSHP systems were utilized in the next part of it, where a GSHP system is proposed for a building currently under construction in central Greece. A simple 30-year cost analysis was used in order to estimate the performance of the proposed GSHP system in economic terms and to compare it with the conventional HVAC system commonly used in Greece. According to the results of the analysis, the capital cost of installing a GSHP system for heating and cooling in buildings in Greece appears higher than the cost of conventional HVAC systems. More specifically, the capital cost of an installation for heating including gas boilers and a cooling system based on air conditioning split units is about the

  8. Cogeneration technology alternatives study. Volume 4: Heat Sources, balance of plant and auxiliary systems

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Data and information established for heat sources balance of plant items, thermal energy storage, and heat pumps are presented. Design case descriptions are given along with projected performance values. Capital cost estimates for representative cogeneration plants are also presented.

  9. Loop Heat Pipe Transient Behavior Using Heat Source Temperature for Set Point Control with Thermoelectric Converter on Reservoir

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

    2011-01-01

    The LHP operating temperature is governed by the saturation temperature of its reservoir. Controlling the reservoir saturation temperature is commonly done by cold biasing the reservoir and using electrical heaters to provide the required control power. With this method, the loop operating temperature can be controlled within 0.5K or better. However, because the thermal resistance that exists between the heat source and the LHP evaporator, the heat source temperature will vary with its heat output even if the LHP operating temperature is kept constant. Since maintaining a constant heat source temperature is of most interest, a question often raised is whether the heat source temperature can be used for LHP set point temperature control. A test program with a miniature LHP was carried out to investigate the effects on the LHP operation when the control temperature sensor was placed on the heat source instead of the reservoir. In these tests, the LHP reservoir was cold-biased and was heated by a control heater. Test results show that it was feasible to use the heat source temperature for feedback control of the LHP operation. In particular, when a thermoelectric converter was used as the reservoir control heater, the heat source temperature could be maintained within a tight range using a proportional-integral-derivative or on/off control algorithm. Moreover, because the TEC could provide both heating and cooling to the reservoir, temperature oscillations during fast transients such as loop startup could be eliminated or substantially reduced when compared to using an electrical heater as the control heater.

  10. Field Test of High Efficiency Residential Buildings with Ground-source and Air-source Heat Pump Systems

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D

    2011-01-01

    This paper describes the field performance of space conditioning and water heating equipment in four single-family residential structures with advanced thermal envelopes. Each structure features a different, advanced thermal envelope design: structural insulated panel (SIP); optimum value framing (OVF); insulation with embedded phase change materials (PCM) for thermal storage; and exterior insulation finish system (EIFS). Three of the homes feature ground-source heat pumps (GSHPs) for space conditioning and water heating while the fourth has a two-capacity air-source heat pump (ASHP) and a heat pump water heater (HPWH). Two of the GCHP-equipped homes feature horizontal ground heat exchange (GHX) loops that utillize the existing foundation and utility service trenches while the third features a vertical borehole with vertical u-tube GHX. All of the houses were operated under the same simulated occupancy conditions. Operational data on the house HVAC/Water heating (WH) systems are presented and factors influencing overall performance are summarized.

  11. Method of and means for passively cooling a shelter containing a heat source

    SciTech Connect

    Rambach, C.

    1981-10-06

    The passive cooling of a shelter containing a heat source is achieved by utilizing a thermal liquid in an accumulator, a first heat transfer loop for thermosiphonically transferring heat from the interior of the shelter to the liquid in the accumulator when the liquid is cooler than the interior of the shelter, and a second heat transfer loop for thermosiphonically transferring heat from the liquid in the accumulator to the environment when the latter is cooler than the liquid in the accumulator.

  12. Environmental assessment for the relocation and storage of isotopic heat sources, Hanford Site, Richland, Washington

    SciTech Connect

    1997-06-01

    As part of a bilateral agreement between the Federal Minister for Research and Technology of the Federal Republic of Germany (FRG) and the DOE, Pacific Northwest National Laboratory (PNNL) developed processes for the treatment and immobilization of high-level radioactive waste. One element of this bilateral agreement was the production of sealed isotopic heat sources. During the mid-1980s, 30 sealed isotopic heat sources were manufactured. The sources contain a total of approximately 8.3 million curies consisting predominantly of cesium-137 and strontium-90 with trace amounts of transuranic contamination. Currently, the sources are stored in A-Cell of the 324 Building. Intense radiation fields from the sources are causing the cell windows and equipment to deteriorate. Originally, it was not intended to store the isotopic heat sources for this length of time in A-cell. The 34 isotopic heat sources are classified as remote handled transuranic wastes. Thirty-one of the isotopic heat sources are sealed, and seals on the three remaining isotopic heat sources have not been verified. However, a decision has been made to place the remaining three isotopic heat sources in the CASTOR cask(s). The Washington State Department of Health (WDOH) has concurred that isotopic heat sources with verified seals or those placed into CASTOR cask(s) can be considered sealed (no potential to emit radioactive air emissions) and are exempt from WAC Chapter 246-247, Radiation Protection-Air Emissions.

  13. Calculations of non-gray gas radiative heat transfer by coupling the discrete ordinates method with the Leckner model in 3D rectangular enclosures

    NASA Astrophysics Data System (ADS)

    Fathi Azarkhavarani, M. E.; Hosseini Abardeh, R.; Rahmani, M.

    2016-11-01

    In this study a new approach for radiation heat flux calculations by coupling the discrete ordinates method with the Leckner global model is introduced. The aim is to analyze the radiative heat transfer problem within a three-dimensional enclosure filled with non-gray gas mixture of {H}2{O} and {C}{O}2. A computer code developed by this approach is applied to radiative calculations in three groups of well-known test cases published previously; considering homogeneous and inhomogeneous isothermal and non-isothermal participating media. All results are compared with well-known calculations based on statistical narrow band model. Also a new series of predictions for a medium with non-black walls and various mixture of {H}2{O} and {C}{O}2 is performed to demonstrate the applicability of the Leckner model. The effect of different compositions of {H}2{O} and {C}{O}2 on the radiative transfer within modern combustors is also examined. Based on the results obtained, it is believed that the discrete ordinates method coupled with the Leckner global model despite of its inherent simplicity and low computational cost is sufficiently accurate. For its convenient use, this method is suitable for a wide range of engineering calculations of participating media as well as for its link to previously written computational fluid dynamics codes.

  14. local alternative sources for cogeneration combined heat and power system

    NASA Astrophysics Data System (ADS)

    Agll, Abdulhakim Amer

    Global demand for energy continues to grow while countries around the globe race to reduce their reliance on fossil fuels and greenhouse gas emissions by implementing policy measures and advancing technology. Sustainability has become an important issue in transportation and infrastructure development projects. While several agencies are trying to incorporate a range of sustainability measures in their goals and missions, only a few planning agencies have been able to implement these policies and they are far from perfect. The low rate of success in implementing sustainable policies is primarily due to incomplete understanding of the system and the interaction between various elements of the system. The conventional planning efforts focuses mainly on performance measures pertaining to the system and its impact on the environment but seldom on the social and economic impacts. The objective of this study is to use clean and alternative energy can be produced from many sources, and even use existing materials for energy generation. One such pathway is using wastewater, animal and organic waste, or landfills to create biogas for energy production. There are three tasks for this study. In topic one evaluated the energy saving that produced from combined hydrogen, heat, and power and mitigate greenhouse gas emissions by using local sustainable energy at the Missouri S&T campus to reduce energy consumption and fossil fuel usage. Second topic aimed to estimate energy recovery and power generation from alternative energy source by using Rankin steam cycle from municipal solid waste at Benghazi-Libya. And the last task is in progress. The results for topics one and two have been presented.

  15. Characterization of Pu-238 Heat Source Granule Containment

    SciTech Connect

    Richardson, Paul Dean II; Sanchez, Joey Leo; Wall, Angelique Dinorah; Chavarria, Rene

    2015-02-11

    The Milliwatt Radioisotopic Themoelectric Generator (RTG) provides power for permissive-action links. Essentially these are nuclear batteries that convert thermal energy to electrical energy using a doped silicon-germanium thermopile. The thermal energy is provided by a heat source made of 238Pu, in the form of 238PuO2 granules. The granules are contained by 3 layers of encapsulation. A thin T-111 liner surrounds the 238PuO2 granules and protects the second layer (strength member) from exposure to the fuel granules. An outer layer of Hastalloy-C protects the T-111 from oxygen embrittlement. The T-111 strength member is considered the critical component in this 238PuO2 containment system. Any compromise in the strength member seen during destructive testing required by the RTG surveillance program is characterized. The T-111 strength member is characterized through Scanning Electron Microscopy (SEM), and Metallography. SEM is used in the Secondary Electron mode to reveal possible grain boundary deformation and/or cracking in the region of the strength member weld. Deformation and cracking uncovered by SEM are further characterized by Metallography. Metallography sections are mounted and polished, observed using optical microscopy, then documented in the form of microphotographs. SEM mat further be used to examine polished Metallography mounts to characterize elements using the SEM mode of Energy Dispersive X-ray spectroscopy (EDS).

  16. What does heat tell a mosquito? Characterization of the orientation behaviour of Aedes aegypti towards heat sources.

    PubMed

    Zermoglio, Paula F; Robuchon, Eddy; Leonardi, María Soledad; Chandre, Fabrice; Lazzari, Claudio R

    2017-07-01

    The use of heat as a cue for the orientation of haematophagous insects towards hot-blooded hosts has been acknowledged for many decades. In mosquitoes, thermoreception has been studied at the molecular, physiological and behavioural levels, and the response to heat has been evaluated in multimodal contexts. However, a direct characterization of how these insects evaluate thermal sources is still lacking. In this study we characterize Aedes aegypti thermal orientation using a simple dual choice paradigm, providing direct evidence on how different attributes of heat sources affect their choice. We found that female mosquitoes, but not males, are able to discriminate among heat sources that are at ambient, host-range and deleterious temperatures when no other stimuli are present, eliciting a positive response towards host-range and an avoidance response towards deleterious temperatures. We also tested the preference of females according to the size and position of the sources. We found that females do not discriminate between heat sources of different sizes, but actively orientate towards closer sources at host temperature. Furthermore, we show that females cannot use IR radiation as an orientation cue. Orientation towards a host involves the integration of cues of different nature in distinct phases of the orientation. Although such integration might be decisive for successful encounter of the host, we show that heat alone is sufficient to elicit orientation behaviour. We discuss the performance of mosquitoes' thermal behaviour compared to other blood-sucking insects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Linking potential heat source and sink to urban heat island: Heterogeneous effects of landscape pattern on land surface temperature.

    PubMed

    Li, Weifeng; Cao, Qiwen; Lang, Kun; Wu, Jiansheng

    2017-05-15

    Rapid urbanization has significantly contributed to the development of urban heat island (UHI). Regulating landscape composition and configuration would help mitigate the UHI in megacities. Taking Shenzhen, China, as a case study area, we defined heat source and heat sink and identified strong and weak sources as well as strong and weak sinks according to the natural and socioeconomic factors influencing land surface temperature (LST). Thus, the potential thermal contributions of heat source and heat sink patches were differentiated. Then, the heterogeneous effects of landscape pattern on LST were examined by using semiparametric geographically weighted regression (SGWR) models. The results showed that landscape composition has more significant effects on thermal environment than configuration. For a strong source, the percentage of patches has a positive impact on LST. Additionally, when mosaicked with some heat sink, even a small improvement in the degree of dispersion of a strong source helps to alleviate UHI. For a weak source, the percentage and density of patches have positive impacts on LST. For a strong sink, the percentage, density, and degree of aggregation of patches have negative impacts on LST. The effects of edge density and patch shape complexity vary spatially with the fragmentation of a strong sink. Similarly, the impacts of a weak sink are mainly exerted via the characteristics of percent, density, and shape complexity of patches. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Temperature and energy deficit in the ground during operation and recovery phases of closed-loop ground source heat pump system: Effect of the groundwater flow

    NASA Astrophysics Data System (ADS)

    Erol, Selcuk; Francois, Bertrand

    2016-04-01

    The advection/dispersion mechanism of the groundwater flow in the ground has a significant effect on a borehole heat exchanger (BHE) to enhance its thermal performance. However, the amount of energy extracted from the ground never disappears and only shifts with the magnitude of the effective thermal velocity in the infinite domain. In this work, we focus on the temperature and the energy balance of the ground in an advection/dispersion dominated heat transfer system during the operation period of a BHE and the subsequent recovery phase when the system is idle. The problem is treated with single BHE and multi-BHEs systems, for different representative geology and different groundwater flow velocity. In order to assess the thermal energy deficit due to heat extraction from the ground, we used the finite line source analytical model, developed recently (Erol et al., 2015) that provides the temperature distributions around the boreholes for discontinuous heat extraction. The model is developed based on the Green's function, which is the solution of heat conduction/advection/dispersion equation in porous media, for discontinuous heat extraction by analytically convoluting rectangular function or pulses in time domain. The results demonstrate the significant positive impact of the groundwater flow for the recovery in terms of temperature deficit at the location of the borehole. However, the total thermal energy deficit is not affected by the groundwater movement. The energy balance of the ground is the same no matter the prevailing heat transfer system, which can be only conduction or advection/dispersion. In addition, the energy balance of the ground is not based on either the duration of the production period operation or of the recovery phase, but depends on the total amount of heat that is extracted and on the bulk volumetric heat capacity of the ground.

  19. Instability of rectangular jets

    NASA Technical Reports Server (NTRS)

    Tam, Christopher K. W.; Thies, Andrew T.

    1992-01-01

    The instability of rectangular jets is investigated using a vortex sheet model. It is shown that such jets support four linearly independent families of instability waves. Within each family there are infinitely many modes. A way to classify these modes according to the characteristics of their mode shapes or eigenfunctions is proposed. A parametric study of the instability wave characteristics has been carried out. A sample of the numerical results is reported here. It is found that the first and third modes of each instability wave family are corner modes. The pressure fluctuations associated with these instability waves are localized near the corners of the jet. The second mode, however, is a center mode with maximum fluctuations concentrated in the central portion of the jet flow. The center mode has the largest spatial growth rate. It is anticipated that as the instability waves propagate downstream the center mode would emerge as the dominant instability of the jet.

  20. Instability of rectangular jets

    NASA Technical Reports Server (NTRS)

    Tam, Christopher K. W.; Thies, Andrew T.

    1992-01-01

    The instability of rectangular jets is investigated using a vortex sheet model. It is shown that such jets support four linearly independent families of instability waves. Within each family there are infinitely many modes. A way to classify these modes according to the characteristics of their mode shapes or eigenfunctions is proposed. A parametric study of the instability wave characteristics has been carried out. A sample of the numerical results is reported here. It is found that the first and third modes of each instability wave family are corner modes. The pressure fluctuations associated with these instability waves are localized near the corners of the jet. The second mode, however, is a center mode with maximum fluctuations concentrated in the central portion of the jet flow. The center mode has the largest spatial growth rate. It is anticipated that as the instability waves propagate downstream the center mode would emerge as the dominant instability of the jet.

  1. Adiabatic heating and convection caused by a fixed-heat-flux source in a near-critical fluid.

    PubMed

    Soboleva, E B

    2003-10-01

    Dynamics and heat transfer in a near-critical fluid in a square cavity with a finite heat source located at the bottom are studied numerically. A thermally insulated enclosure and a fixed-heat-flux source are considered. The two-dimensional simulation is based on the full Navier-Stokes equations with two-scale splitting of the pressure and the van der Waals equation of state. It is shown that the piston effect is independent of convection. Near the critical point, this effect becomes independent of criticality and convective motions are damped.

  2. Variable Conductance Heat Pipe Cooling of Stirling Convertor and General Purpose Heat Source

    NASA Technical Reports Server (NTRS)

    Tarau, Calin; Schwendeman, Carl; Anderson, William G.; Cornell, Peggy A.; Schifer, Nicholas A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  3. Free convection flow of some fractional nanofluids over a moving vertical plate with uniform heat flux and heat source

    NASA Astrophysics Data System (ADS)

    Azhar, Waqas Ali; Vieru, Dumitru; Fetecau, Constantin

    2017-08-01

    Free convection flow of some water based fractional nanofluids over a moving infinite vertical plate with uniform heat flux and heat source is analytically and graphically studied. Exact solutions for dimensionless temperature and velocity fields, Nusselt numbers, and skin friction coefficients are established in integral form in terms of modified Bessel functions of the first kind. These solutions satisfy all imposed initial and boundary conditions and reduce to the similar solutions for ordinary nanofluids when the fractional parameters tend to one. Furthermore, they reduce to the known solutions from the literature when the plate is fixed and the heat source is absent. The influence of fractional parameters on heat transfer and fluid motion is graphically underlined and discussed. The enhancement of heat transfer in such flows is higher for fractional nanofluids in comparison with ordinary nanofluids. Moreover, the use of fractional models allows us to choose the fractional parameters in order to get a very good agreement between experimental and theoretical results.

  4. Climate Adaptivity and Field Test of the Space Heating Used Air-Source Transcritical CO2 Heat Pump

    NASA Astrophysics Data System (ADS)

    Song, Yulong; Ye, Zuliang; Cao, Feng

    2017-08-01

    In this study, an innovation of air-sourced transcritical CO2 heat pump which was employed in the space heating application was presented and discussed in order to solve the problem that the heating performances of the transcritical CO2 heat pump water heater deteriorated sharply with the augment in water feed temperature. An R134a cycle was adopted as a subcooling device in the proposed system. The prototype of the presented system was installed and supplied hot water for three places in northern China in winter. The field test results showed that the acceptable return water temperature can be increased up to 55°C, while the supply water temperature was raised rapidly by the presented prototype to up to 70°C directly, which was obviously appropriate to the various conditions of heating radiator in space heating application. Additionally, though the heating capacity and power dissipation decreased with the decline in ambient temperature or the augment in water temperature, the presented heat pump system performed efficiently whatever the climate and water feed temperature were. The real time COP of the presented system was generally more than 1.8 in the whole heating season, while the seasonal performance coefficient (SPC) was also appreciable, which signified that the economic efficiency of the presented system was more excellent than other space heating approaches such as fuel, gas, coal or electric boiler. As a result, the novel system will be a promising project to solve the energy issues in future space heating application.

  5. Investigation of direct expansion in ground source heat pumps

    NASA Astrophysics Data System (ADS)

    Kalman, M. D.

    A fully instrumented subscale ground coupled heat pump system was developed, and built, and used to test and obtain data on three different earth heat exchanger configurations under heating conditions (ground cooling). Various refrigerant flow control and compressor protection devices were tested for their applicability to the direct expansion system. Undistributed Earth temperature data were acquired at various depths. The problem of oil return at low evaporator temperatures and low refrigerant velocities was addressed. An analysis was performed to theoretically determine what evaporator temperature can be expected with an isolated ground pipe configuration with given length, pipe size, soil conditions and constant heat load. Technical accomplishments to data are summarized.

  6. Steady temperature and density distributions in a gas containing heat sources

    NASA Technical Reports Server (NTRS)

    Davison, H. W.

    1971-01-01

    Computer program, STADDIG, is based on steady state, one dimensional heat transfer calculation using cylindrical coordinates. Program allows for conduction across gas and container walls. Heat is dissipated from walls by forced convection cooling with incompressible coolant. Heat sources are included in coolant, gas, and walls.

  7. Possibilities of utilizing alternative energy sources for combined heat supply systems in the Baltic

    SciTech Connect

    Shipkovs, P.; Grislis, V.; Zebergs, V. )

    1991-01-01

    The problem of alternative energy sources is an issue of major importance for the Baltic republics because of the limited supply of conventional energy resources. One of the ways to solve this problem could be the introduction of combined heat supply systems (CHSS). The combined heat supply systems are such systems where various energy sources in different regimes are made use of to ensure the optimum temperature on residential and industrial premises. The influence of climatic conditions on the selection of heat supply systems has been studied at large. In the present paper the use of alternative energy sources (AES) in combined heat supply systems (CHSS) is described.

  8. Temperature and Humidity Independent Control Research on Ground Source Heat Pump Air Conditioning System

    NASA Astrophysics Data System (ADS)

    Chen, G.; Wang, L. L.

    Taking green demonstration center building air conditioning system as an example, this paper presents the temperature and humidity independent control system combined with ground source heat pump system, emphasis on the design of dry terminal device system, fresh air system and ground source heat pump system.

  9. Measured Performance of a Low Temperature Air Source Heat Pump

    SciTech Connect

    Johnson, R. K.

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor 'boosted heat pump' technology. The Low Temperature Heat Pumpsystem operates with four increasing levels of capacity (heat output) as the outdoor temperature drops. The system was shown to select capacity correctly, supplying the appropriate amount of heat to the house across the full range of outdoor temperatures. The system's Coefficient of Performance (Seasonal COP, or SCOP) over two entire winters was calculated, based on measured data, to be 3.29over the first winter and 2.68 over the second winter. A second seasonal efficiency calculation by a different method yielded a SCOP of 2.78 for the first winter and 2.83 for the second winter. This second seasonal efficiency calculation was determined by comparing measured heat pump energy use to the in situ energy use with resistance heat alone. This method is the ratio of the slopes of thedaily energy use load lines.

  10. Optimum load distribution between heat sources based on the Cournot model

    NASA Astrophysics Data System (ADS)

    Penkovskii, A. V.; Stennikov, V. A.; Khamisov, O. V.

    2015-08-01

    One of the widespread models of the heat supply of consumers, which is represented in the "Single buyer" format, is considered. The methodological base proposed for its description and investigation presents the use of principles of the theory of games, basic propositions of microeconomics, and models and methods of the theory of hydraulic circuits. The original mathematical model of the heat supply system operating under conditions of the "Single buyer" organizational structure provides the derivation of a solution satisfying the market Nash equilibrium. The distinctive feature of the developed mathematical model is that, along with problems solved traditionally within the bounds of bilateral relations of heat energy sources-heat consumer, it considers a network component with its inherent physicotechnical properties of the heat network and business factors connected with costs of the production and transportation of heat energy. This approach gives the possibility to determine optimum levels of load of heat energy sources. These levels provide the given heat energy demand of consumers subject to the maximum profit earning of heat energy sources and the fulfillment of conditions for formation of minimum heat network costs for a specified time. The practical realization of the search of market equilibrium is considered by the example of a heat supply system with two heat energy sources operating on integrated heat networks. The mathematical approach to the solution search is represented in the graphical form and illustrates computations based on the stepwise iteration procedure for optimization of levels of loading of heat energy sources (groping procedure by Cournot) with the corresponding computation of the heat energy price for consumers.

  11. Heat source reconstruction from noisy temperature fields using a gradient anisotropic diffusion filter

    NASA Astrophysics Data System (ADS)

    Beitone, C.; Balandraud, X.; Delpueyo, D.; Grédiac, M.

    2017-01-01

    This paper presents a post-processing technique for noisy temperature maps based on a gradient anisotropic diffusion (GAD) filter in the context of heat source reconstruction. The aim is to reconstruct heat source maps from temperature maps measured using infrared (IR) thermography. Synthetic temperature fields corrupted by added noise are first considered. The GAD filter, which relies on a diffusion process, is optimized to retrieve as well as possible a heat source concentration in a two-dimensional plate. The influence of the dimensions and the intensity of the heat source concentration are discussed. The results obtained are also compared with two other types of filters: averaging filter and Gaussian derivative filter. The second part of this study presents an application for experimental temperature maps measured with an IR camera. The results demonstrate the relevancy of the GAD filter in extracting heat sources from noisy temperature fields.

  12. New Insights Into the Heat Sources of Mantle Plumes, or: Where Does all the Heat Come From, Heat Producing Elements, Advective or Conductive Heat Flow?

    NASA Astrophysics Data System (ADS)

    Rushmer, T.; Beier, C.; Turner, S.

    2007-12-01

    Melting anomalies in the Earth's upper mantle have often been attributed to the presence of mantle plumes that may originate in the lower mantle, possibly from the core-mantle boundary. Globally, mantle plumes exhibit a large range in buoyancy flux that which is proportional to their temperature and volume. Plumes with higher buoyancy fluxes should have higher temperatures and experience higher degrees of partial melting. Excess heat in mantle plumes could reflect either a) an enrichment of the heat producing elements (HPE: U, Th, K) in their mantle source leading to an increase of heat production by radioactive decay or b) advective or conductive heat transport across the core-mantle boundary. The advective transport of heat may result in a physical contribution of material from the core to the lower mantle. If core material is incorporated into the lower mantle, mantle plumes with a higher buoyancy flux should have higher core tracers, e.g. increased 186Os and Fe concentrations. Geophysical and dynamic modelling indicate that at least Afar, Easter, Hawaii, Louisville and Samoa may all originate at the core-mantle boundary. These plumes encompass the whole range of known buoyancy fluxes from 1.2 Mgs -1(Afar) to 6.5 Mgs -1 (Hawaii) providing evidence that the buoyancy flux is largely independent of other geophysical parameters. In an effort to explore whether the heat producing elements are the cause of excess heat we looked for correlations between fractionation corrected concentrations of the HPE and buoyancy flux. Our results suggest that there is no correlation between HPE concentrations and buoyancy flux (with and without an additional correction for variable degrees of partial melting). As anticipated, K, Th and U are positively correlated with each other (e.g. Hawaii, Iceland and Galapagos have significantly lower concentrations than e.g. Tristan da Cunha, the Canary Islands and the Azores). We also find no correlation between currently available Fe

  13. Rectangular diagrams of surfaces: representability

    NASA Astrophysics Data System (ADS)

    Dynnikov, I. A.; Prasolov, M. V.

    2017-06-01

    Introduced here is a simple combinatorial way, which is called a rectangular diagram of a surface, to represent a surface in the three-sphere. It has a particularly nice relation to the standard contact structure on S^3 and to rectangular diagrams of links. By using rectangular diagrams of surfaces it is intended, in particular, to develop a method to distinguish Legendrian knots. This requires a lot of technical work of which the present paper addresses only the first basic question: which isotopy classes of surfaces can be represented by a rectangular diagram? Roughly speaking, the answer is this: there is no restriction on the isotopy class of the surface, but there is a restriction on the rectangular diagram of the boundary link arising from the presentation of the surface. The result extends to Giroux's convex surfaces for which this restriction on the boundary has a natural meaning. In a subsequent paper, transformations of rectangular diagrams of surfaces will be considered and their properties will be studied. By using the formalism of rectangular diagrams of surfaces an annulus in S^3 is produced here that is expected to be a counterexample to the following conjecture: if two Legendrian knots cobound an annulus and have zero Thurston-Bennequin numbers relative to this annulus, then they are Legendrian isotopic. Bibliography: 30 titles.

  14. Phasing rectangular apertures.

    PubMed

    Baker, K L; Homoelle, D; Utterback, E; Jones, S M

    2009-10-26

    Several techniques have been developed to phase apertures in the context of astronomical telescopes with segmented mirrors. Phasing multiple apertures, however, is important in a wide range of optical applications. The application of primary interest in this paper is the phasing of multiple short pulse laser beams for fast ignition fusion experiments. In this paper analytic expressions are derived for parameters such as the far-field distribution, a line-integrated form of the far-field distribution that could be fit to measured data, enclosed energy or energy-in-a-bucket and center-of-mass that can then be used to phase two rectangular apertures. Experimental data is taken with a MEMS device to simulate the two apertures and comparisons are made between the analytic parameters and those derived from the measurements. Two methods, fitting the measured far-field distribution to the theoretical distribution and measuring the ensquared energy in the far-field, produced overall phase variance between the 100 measurements of less than 0.005 rad(2) or an RMS displacement of less than 12 nm.

  15. Recent Research in Compression Refrigeration Cycle Air Source Heat Pumps.

    NASA Astrophysics Data System (ADS)

    Arai, Akira; Senshu, Takao

    The most important theme for heat pump air conditioners is the improvement of energy saving and comfort. Recently, cycle components, especially compressores and heat exchangers have been improved greatly in their performance and efficiency. As for compressors, large progress in their efficiencies have been made by detailed analysises such as mechanical losses and by the development of a new type compression mechanism. As for heat exchangers, various high heat transfer surfaces have been developed together with the improvement of the production technologies for them. Further, the effect of the capacity-modulated cycle is evaluated quantitatively through the improvements of static and transient cycle simulation technologies. And in order to realize this cffect, the electrically driven expansion valves heve been marketed. This review introduces the trends of these energy-saving technologies as well as comfort improvement studies.

  16. Steady evaporating flow in rectangular microchannels.

    SciTech Connect

    Griffiths, Stewart K.; Martinez, Mario J.; Tchikanda, Serge W.; Nilson, Robert H.

    2005-02-01

    Analytical and numerical solutions are presented for steady evaporating flow in open microchannels having a rectangular cross section and a uniform depth. The flow, driven by the axial gradient of capillary pressure, generally consists of an entry region where the meniscus is attached to the top corners of the channel followed by a jump-like transition to a corner-flow region in which the meniscus progressively recedes into the bottom corners of the channel. Illustrative numerical solutions are used to guide the derivation of an easily applied analytical approximation for the maximum sustainable heat flux or capillary limit.

  17. Measured Space Conditioning and Water Heating Performance of a Ground-Source Integrated Heat Pump in a Residential Application

    SciTech Connect

    Munk, Jeffrey D; Ally, Moonis Raza; Baxter, Van D; Gehl, Anthony C

    2014-01-01

    In an effort to reduce residential building energy consumption, a ground-source integrated heat pump was developed to meet a home s entire space conditioning and water heating needs, while providing 50% energy savings relative to a baseline suite of minimum efficiency equipment. A prototype 7.0 kW system was installed in a 344 m2 research house with simulated occupancy in Oak Ridge, TN. The equipment was monitored from June 2012 through January 2013.

  18. An analysis of the vapor flow and the heat conduction through the liquid-wick and pipe wall in a heat pipe with single or multiple heat sources

    NASA Technical Reports Server (NTRS)

    Chen, Ming-Ming; Faghri, Amir

    1990-01-01

    A numerical analysis is presented for the overall performance of heat pipes with single or multiple heat sources. The analysis includes the heat conduction in the wall and liquid-wick regions as well as the compressibility effect of the vapor inside the heat pipe. The two-dimensional elliptic governing equations in conjunction with the thermodynamic equilibrium relation and appropriate boundary conditions are solved numerically. The solutions are in agreement with existing experimental data for the vapor and wall temperatures at both low and high operating temperatures.

  19. An analysis of the vapor flow and the heat conduction through the liquid-wick and pipe wall in a heat pipe with single or multiple heat sources

    NASA Technical Reports Server (NTRS)

    Chen, Ming-Ming; Faghri, Amir

    1990-01-01

    A numerical analysis is presented for the overall performance of heat pipes with single or multiple heat sources. The analysis includes the heat conduction in the wall and liquid-wick regions as well as the compressibility effect of the vapor inside the heat pipe. The two-dimensional elliptic governing equations in conjunction with the thermodynamic equilibrium relation and appropriate boundary conditions are solved numerically. The solutions are in agreement with existing experimental data for the vapor and wall temperatures at both low and high operating temperatures.

  20. Performance improvement of air source heat pump by using gas-injected rotary compressor

    NASA Astrophysics Data System (ADS)

    Wang, B. L.; Liu, X. R.; Ding, Y. C.; Shi, W. X.

    2017-08-01

    Rotary compressor is most widely used in small capacity refrigeration and heat pump systems. For the air source heat pump, the heating capacity and the COP will be obviously degraded when it is utilized in low temperature ambient. Gas injection is an effective method to enhance its performance under those situations, which has been well applied in air source heat pump with scroll compressor. However, the development of the gas injection technology in rotary compressor is relatively slow due to limited performance improvement. In this research, the essential reason constraining the improvement of the gas injection on the rotary compressor and its heat pump system is identified. Two new injection structures for rotary compressors has been put forward to overcome the drawback of traditional injection structures. Based on a verified numerical model, the thermodynamic performance of air source heat pumps with the new gas-injected rotary compressor are investigated. The results indicate that, compared to the air source heat pump with the traditional gas injected rotary compressor, the new injection structures both can enhance heating capacity and COP of the air source heat pump obviously.

  1. Evaluation of water source heat pumps for the Juneau, Alaska Area

    SciTech Connect

    Jacobsen, J.J.; King, J.C.; Eisenhauer, J.L.; Gibson, C.I.

    1980-07-01

    The purposes of this project were to evaluate the technical and economic feasibility of water source heat pumps (WSHP) for use in Juneau, Alaska and to identify potential demonstration projects to verify their feasibility. Information is included on the design, cost, and availability of heat pumps, possible use of seawater as a heat source, heating costs with WSHP and conventional space heating systems, and life cycle costs for WSHP-based heating systems. The results showed that WSHP's are technically viable in the Juneau area, proper installation and maintenance is imperative to prevent equipment failures, use of WSHP would save fuel oil but increase electric power consumption. Life cycle costs for WSHP's are about 8% above that for electric resistance heating systems, and a field demonstration program to verify these results should be conducted. (LCL)

  2. Design of a nuclear isotope heat source assembly for a spaceborne mini-Brayton power module.

    NASA Technical Reports Server (NTRS)

    Wein, D.; Gorland, S. H.

    1973-01-01

    Results of a study to develop a feasible design definition of a heat source assembly (HSA) for use in nominal 500-, 1200-, or 2000-W(e) mini-Brayton spacecraft power systems. The HSA is a modular design which is used either as a single unit to provide thermal energy to the 500-W(e) mini-Brayton power module or in parallel with one or two additional HSAs for the 1200- or 2000-W(e) power module systems. Principal components consist of a multihundred watt RTG isotope heat source, a heat source heat exchanger which transfers the thermal energy from the heat source to the mini-Brayton power conversion system, an auxiliary cooling system which provides requisite cooling during nonoperation of the power conversion module and an emergency cooling system which precludes accidental release of isotope fuel in the event of system failure.

  3. Quantifying Systemic Efficiency using Exergy and Energy Analysis for Ground Source Heat Pumps: Domestic Space Conditioning and Water Heating Applications.

    SciTech Connect

    Ally, Moonis Raza; Baxter, Van D; Gehl, Anthony C; Munk, Jeffrey D

    2017-01-01

    Although air temperatures over land surfaces show wide seasonal and daily variations, the ground, approximately 10 meters below the earth s surface, remains relatively stable in temperature thereby serving as an energy source or sink. Ground source heat pumps can heat, cool, and supply homes with hot water efficiently by utilizing the earth s renewable and essentially inexhaustible energy resources, saving fossil fuels, reducing greenhouse gas emissions, and lowering the environmental footprint. In this paper, evidence is shown that ground source heat pumps can provide up to 79%-87% of domestic hot water energy needs, and up to 77% of space heating needs with the ground s thermal energy resources. The case refers to a 12-month study conducted at a 253 m2 research house located in Oak Ridge, Tennessee, 36.01 N 84.26 W in a mixed-humid climate with HDD of 2218 C-days and CDD of 723 C-days under simulated occupancy conditions. A single 94.5m vertical bore interfaced the heat pump with the ground. The research shows that this technology is capable of achieving US DOE targets of 25 % and 35% energy savings in HVAC, and in water heating, respectively by 2030. It is also a viable technology to meet greenhouse gas target emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources. The paper quantifies systemic efficiencies using Exergy analysis of the major components, clearly pointing areas for further improvement.

  4. Conformal mapping of rectangular heptagons

    SciTech Connect

    Bogatyrev, Andrei B

    2012-12-31

    A new effective approach to calculating the direct and inverse conformal mapping of rectangular polygons onto a half-plane is put forward; it is based on the use of Riemann theta functions. Bibliography: 14 titles.

  5. Heat source reconstruction from noisy temperature fields using an optimised derivative Gaussian filter

    NASA Astrophysics Data System (ADS)

    Delpueyo, D.; Balandraud, X.; Grédiac, M.

    2013-09-01

    The aim of this paper is to present a post-processing technique based on a derivative Gaussian filter to reconstruct heat source fields from temperature fields measured by infrared thermography. Heat sources can be deduced from temperature variations thanks to the heat diffusion equation. Filtering and differentiating are key-issues which are closely related here because the temperature fields which are processed are unavoidably noisy. We focus here only on the diffusion term because it is the most difficult term to estimate in the procedure, the reason being that it involves spatial second derivatives (a Laplacian for isotropic materials). This quantity can be reasonably estimated using a convolution of the temperature variation fields with second derivatives of a Gaussian function. The study is first based on synthetic temperature variation fields corrupted by added noise. The filter is optimised in order to reconstruct at best the heat source fields. The influence of both the dimension and the level of a localised heat source is discussed. Obtained results are also compared with another type of processing based on an averaging filter. The second part of this study presents an application to experimental temperature fields measured with an infrared camera on a thin plate in aluminium alloy. Heat sources are generated with an electric heating patch glued on the specimen surface. Heat source fields reconstructed from measured temperature fields are compared with the imposed heat sources. Obtained results illustrate the relevancy of the derivative Gaussian filter to reliably extract heat sources from noisy temperature fields for the experimental thermomechanics of materials.

  6. Millimeter waves as a source of selective heating of skin.

    PubMed

    Zhadobov, Maxim; Alekseev, Stanislav I; Le Dréan, Yves; Sauleau, Ronan; Fesenko, Evgeny E

    2015-09-01

    This study demonstrates that 20-100 GHz range can be used for spatially-accurate focusing of heating inside the skin achieved by varying frequency and exposure beam size, as well as by enforcing air convection. The latter is also used to reduce overheating of skin surface. Heating at different skin depths depending on these parameters is investigated in detail using the hybrid bio-heat equation. In particular, it is shown that decreasing frequency and/or increasing exposure beam size at forced airflow result in elevation of heating of deeper layers of tissue and decrease of skin surface temperature. Changes of water content within 15%, which exceed those due to aging and presence of tumors, only slightly affect heating. Exposure intensity necessary to reach a target temperature significantly increases in different areas of body with elevated blood flow. Dependence on exposure intensity and hyperthermia treatment duration is also investigated and discussed. Results of this study suggest that the lower part of the millimeter-wave range is an attractive alternative for non-invasive thermal treatment of skin cancer with a high spatial resolution.

  7. Analysis of rectangular microstrip antennas

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.; Deshpande, M. D.

    1984-01-01

    The problem of microstrip antennas covered by a dielectric substrate is formulated in terms of coupled integro-differential equations with the current distribution on the conducting patch as an unknown quantity. The Galerkin method is used to solve for the unknown patch current. Using the present formulation, the radiation pattern, the resonant frequency, and the bandwidth of a rectangular microstrip antenna are computed. Design data for a rectangular microstrip antenna are also presented.

  8. Transition to chaos in a square enclosure containing internal heat sources

    SciTech Connect

    Baytas, A.C.

    1995-09-01

    A numerical investigation is performed to study the transition from steady to chaotic flow of a fluid confined in a two-dimensional square cavity. The cavity has rigid walls of constant temperature containing uniformly distributed internal heat source. Effects of the Rayleigh number of flow and heat transfer rates are studied. In addition to, same problem is solved for sinusoidally changing internal heat source to show its effect on the flow model and heat transfer of the enclosures. Details of oscillatory solutions and flow bifurcations are presented.

  9. Field Investigation of an Air-Source Cold Climate Heat Pump

    SciTech Connect

    Shen, Bo; Abdelaziz, Omar; Rice, C Keith; Baxter, Van D

    2017-01-01

    In the U.S., there are approximately 2.6 million dwellings that use electricity for heating in cold and very cold regions with an annual energy consumption of 0.16 quads (0.17 EJ). A high performance cold climate heat pump (CCHP) would result in significant savings over current technologies (greater than 60% compared to electric resistance heating). We developed an air-source cold climate heat pump, which uses tandem compressors, with a single compressor rated for the building design cooling load, and running two compressors to provide, at -13 F (-25 C), 75% of rated heating capacity. The tandem compressors were optimized for heating operation and are able to tolerate discharge temperatures up to 280 F (138 C). A field investigation was conducted in the winter of 2015, in an occupied home in Ohio, USA. During the heating season, the seasonal COP was measured at 3.16, and the heat pump was able to operate down to -13 F (-25 C) and eliminate resistance heat use. The heat pump maintained an acceptable comfort level throughout the heating season. In comparison to a previous single-speed heat pump in the home, the CCHP demonstrated more than 40% energy savings in the peak heating load month. This paper illustrates the measured field performance, including compressor run time, frost/defrosting operations, distributions of building heating load and capacity delivery, comfort level, field measured COPs, etc.

  10. Gas motion through porous objects with nonuniform local distribution of heat-release sources

    NASA Astrophysics Data System (ADS)

    Levin, V. A.; Lutsenko, N. A.

    2008-09-01

    The gas motion through porous objects in the gravity force field with a non-uniform distribution of heat sources, which may arise as a result of natural or man-caused catastrophes (as the damaged power unit of the Chernobyl NPP), is investigated. The influence of different parameters of the heat-releasing zone on the process of cooling of such objects is analyzed with the aid of computational experiment. It is shown that the porous element heating is affected not only by the height of the heat-releasing zone and the heat-release intensity therein but also by the distance of the heat-releasing zone from the element inlet as well as by the width of the heat-releasing zone. The phenomenon of a reduction of the porous element heating with increasing distance of the heat-releasing zone from the porous element inlet is revealed. An ambiguous dependence of the porous object heating on the width of the heat-release zone is identified: at a growth of the heat-releasing zone width, the heating of the element may both increase and decrease depending on the distance of the heat-release zone from the element inlet.

  11. Film condensation in a horizontal rectangular duct

    NASA Technical Reports Server (NTRS)

    Lu, Qing; Suryanarayana, N. V.

    1992-01-01

    Condensation heat transfer in an annular flow regime with and without interfacial waves was experimentally investigated. The study included measurements of heat transfer rate with condensation of vapor flowing inside a horizontal rectangular duct and experiments on the initiation of interfacial waves in condensation, and adiabatic air-liquid flow. An analytical model for the condensation was developed to predict condensate film thickness and heat transfer coefficients. Some conclusions drawn from the study are that the condensate film thickness was very thin (less than 0.6 mm). The average heat transfer coefficient increased with increasing the inlet vapor velocity. The local heat transfer coefficient decreased with the axial distance of the condensing surface, with the largest change at the leading edge of the test section. The interfacial shear stress, which consisted of the momentum shear stress and the adiabatic shear stress, appeared to have a significant effect on the heat transfer coefficients. In the experiment, the condensate flow along the condensing surface experienced a smooth flow, a two-dimensional wavy flow, and a three-dimensional wavy flow. In the condensation experiment, the local wave length decreased with the axial distance of the condensing surface and the average wave length decreased with increasing inlet vapor velocity, while the wave speed increased with increasing vapor velocity. The heat transfer measurements are reliable. And, the ultrasonic technique was effective for measuring the condensate film thickness when the surface was smooth or had waves of small amplitude.

  12. Federal Technology Alert: Ground-Source Heat Pumps Applied to Federal Facilities--Second Edition

    SciTech Connect

    Hadley, Donald L.

    2001-03-01

    This Federal Technology Alert, which was sponsored by the U.S. Department of Energy's Office of Federal Energy Management Programs, provides the detailed information and procedures that a Federal energy manager needs to evaluate most ground-source heat pump applications. This report updates an earlier report on ground-source heat pumps that was published in September 1995. In the current report, general benefits of this technology to the Federal sector are described, as are ground-source heat pump operation, system types, design variations, energy savings, and other benefits. In addition, information on current manufacturers, technology users, and references for further reading are provided.

  13. Negative hydrogen ion beam extraction from an AC heated cathode driven Bernas-type ion source

    NASA Astrophysics Data System (ADS)

    Okano, Y.; Miyamoto, N.; Kasuya, T.; Wada, M.

    2015-04-01

    A plasma grid structure was installed to a Bernas-type ion source used for ion implantation equipment. A negative hydrogen (H-) ion beam was extracted by an AC driven ion source by adjusting the bias to the plasma grid. The extracted electron current was reduced by positively biasing the plasma grid, while an optimum plasma grid bias voltage for negative ion beam extraction was found to be positive 3 V with respect to the arc chamber. Source operations with AC cathode heating show extraction characteristics almost identical to that with DC cathode heating, except a minute increase in H- current at higher frequency of cathode heating current.

  14. Heat sources for tertiary metamorphism and anatexis in the Annapurna-Manaslu region, central Nepal

    NASA Astrophysics Data System (ADS)

    England, Philip; Le Fort, Patrick; Molnar, Peter; Pecher, Arnaud

    1992-02-01

    The metamorphic evolution of the rocks near the Main Central Thrust in the Annapurna-Manaslu region of central Nepal is examined. In this region, all three types of metamorphic features can be observed: regional metamorphism, anatectic granitoids, and inverted metamorphic isograds. In this work, each phase of metamorphism is treated separately to estimate the heat sources required for each process. This approach makes it possible to identify the important parameters for each process, to draw preliminary conclusions about the heat sources required for each of these phases, and to determine which parameters need to be measured more precisely in order to constrain these heat sources.

  15. Heat sources for tertiary metamorphism and anatexis in the Annapurna-Manaslu region, central Nepal

    NASA Technical Reports Server (NTRS)

    England, Philip; Le Fort, Patrick; Molnar, Peter; Pecher, Arnaud

    1992-01-01

    The metamorphic evolution of the rocks near the Main Central Thrust in the Annapurna-Manaslu region of central Nepal is examined. In this region, all three types of metamorphic features can be observed: regional metamorphism, anatectic granitoids, and inverted metamorphic isograds. In this work, each phase of metamorphism is treated separately to estimate the heat sources required for each process. This approach makes it possible to identify the important parameters for each process, to draw preliminary conclusions about the heat sources required for each of these phases, and to determine which parameters need to be measured more precisely in order to constrain these heat sources.

  16. Heat sources for tertiary metamorphism and anatexis in the Annapurna-Manaslu region, central Nepal

    NASA Technical Reports Server (NTRS)

    England, Philip; Le Fort, Patrick; Molnar, Peter; Pecher, Arnaud

    1992-01-01

    The metamorphic evolution of the rocks near the Main Central Thrust in the Annapurna-Manaslu region of central Nepal is examined. In this region, all three types of metamorphic features can be observed: regional metamorphism, anatectic granitoids, and inverted metamorphic isograds. In this work, each phase of metamorphism is treated separately to estimate the heat sources required for each process. This approach makes it possible to identify the important parameters for each process, to draw preliminary conclusions about the heat sources required for each of these phases, and to determine which parameters need to be measured more precisely in order to constrain these heat sources.

  17. High intensity heat-pulse source operates without cooling system

    NASA Technical Reports Server (NTRS)

    Russell, L. D.

    1970-01-01

    Tungsten-iodine quartz lamp with on-off control is mounted at focus of ellipsoidal reflector and shutter is mounted at conjugate focus. Flux sensor monitors lamp and actuates shutter which emits a heat pulse when the radiant flux builds up to requisite level.

  18. An experimental study of the thermal plume developed above a finite cylindrical heat source to validate the point source model

    SciTech Connect

    Bouzinaoui, Abdelhakim; Devienne, Rene; Fontaine, Jean Raymond

    2007-07-15

    An experimental study of the thermal plume developed above a variable cylindrical source of finite dimensions was conducted with the aim of verifying the corresponding point source model. The heat source was a 1 m diameter, 1 m high cylinder featuring five zones (four 0.25 m high cylindrical surfaces and a top disk) of identical surface area. Two different configurations were tested: in the first, only the top surface of the cylinder was heated and, in the second, both the top disk and the related cylindrical zone were heated. Surface temperatures were chosen to maintain the same source convective power for both situations. A battery of nine anemometric probes recorded simultaneously plume velocity and temperature distributions. These measurements allowed the plume thermal and dynamic radii above the source to be deduced. These radii vary linearly with height and they enable the plume virtual origin to be situated. If the virtual origin of each source is taken as a starting point, we observe that, in both test cases, the plumes develop in the same way, effectively validating the point source model. Velocity measurements also allowed the plume flow rate to be evaluated. The values found agree closely with those calculated using the relation that gives plume flow rate as a function of source convective power and height above the virtual origin. (author)

  19. Inverse Analysis of Heat Conduction in Hollow Cylinders with Asymmetric Source Distributions

    NASA Astrophysics Data System (ADS)

    Lambrakos, Samuel G.; Michopoulos, John G.; Jones, Harry N.; Boyer, Craig N.

    2008-10-01

    This paper presents an application of inverse analysis for determining both the temperature field histories and corresponding heat source distributions in hollow cylinders. The primary goal, however, is the development of an inversion infrastructure in a manner that allows taking advantage of all aspects related to its utility, including sensitivity analysis. The conditions generating heat sources are those resulting from intense pulsed-current electrical contact experiments. Under these conditions intense heat currents are generated due to the Joule conversion of the electric conduction currents. Asymmetry of the heat source is induced from the localized melting due to arc-enhanced electric conduction. Experimentally acquired temperature histories and melting domain boundary data are utilized to setup an inverse model of the heat conduction problem. This permits the construction of an estimate not only of the temperature field histories throughout the computational domain but also of an evaluation of the effective thermal diffusivity of the material involved.

  20. The numerical simulation of heat transfer during a hybrid laser-MIG welding using equivalent heat source approach

    NASA Astrophysics Data System (ADS)

    Bendaoud, Issam; Matteï, Simone; Cicala, Eugen; Tomashchuk, Iryna; Andrzejewski, Henri; Sallamand, Pierre; Mathieu, Alexandre; Bouchaud, Fréderic

    2014-03-01

    The present study is dedicated to the numerical simulation of an industrial case of hybrid laser-MIG welding of high thickness duplex steel UR2507Cu with Y-shaped chamfer geometry. It consists in simulation of heat transfer phenomena using heat equivalent source approach and implementing in finite element software COMSOL Multiphysics. A numerical exploratory designs method is used to identify the heat sources parameters in order to obtain a minimal required difference between the numerical results and the experiment which are the shape of the welded zone and the temperature evolution in different locations. The obtained results were found in good correspondence with experiment, both for melted zone shape and thermal history.

  1. GEO3D - Three-Dimensional Computer Model of a Ground Source Heat Pump System

    SciTech Connect

    James Menart

    2013-06-07

    This file is the setup file for the computer program GEO3D. GEO3D is a computer program written by Jim Menart to simulate vertical wells in conjunction with a heat pump for ground source heat pump (GSHP) systems. This is a very detailed three-dimensional computer model. This program produces detailed heat transfer and temperature field information for a vertical GSHP system.

  2. Energy recovery during expansion of compressed gas using power plant low-quality heat sources

    DOEpatents

    Ochs, Thomas L.; O'Connor, William K.

    2006-03-07

    A method of recovering energy from a cool compressed gas, compressed liquid, vapor, or supercritical fluid is disclosed which includes incrementally expanding the compressed gas, compressed liquid, vapor, or supercritical fluid through a plurality of expansion engines and heating the gas, vapor, compressed liquid, or supercritical fluid entering at least one of the expansion engines with a low quality heat source. Expansion engines such as turbines and multiple expansions with heating are disclosed.

  3. Interactions of /sup 238/PuO/sub 2/ heat sources with terrestrial and aquatic environments. Interim summary

    SciTech Connect

    Patterson, J.H.; Steinkruger, F.J.; Matlack, G.M.

    1980-09-01

    Observations and some conclusions made of the interactions of /sup 238/PuO/sub 2/ heat sources with terrestrial and aquatic environments may be used in predicting heat source behavior in the event of contact of these heat sources with land or ocean and in assessing the risk to the environment. These studies indicate that plutonium transport from the heat sources is mostly a physical process involving the movement of extremely fine particles rather than the chemical migration of plutonium ions.

  4. Milliwatt-generator heat source. Progress report, January-June 1983

    SciTech Connect

    Mershad, E.A.

    1983-09-20

    Progress is reported in the following: heat source shipments, reimbursable orders, hardware shipments, raw material qualification/procurement, DOE audit and milliwatt generator process review, surveillance capsule evaluations, pressure burst testing, and hardware fabrication and quality. (MHR)

  5. Material impacts and heat flux characterization of an electrothermal plasma source with an applied magnetic field

    DOE PAGES

    Gebhart, T. E.; Martinez-Rodriguez, R. A.; Baylor, L. R.; ...

    2017-08-11

    To produce a realistic tokamak-like plasma environment in linear plasma device, a transient source is needed to deliver heat and particle fluxes similar to those seen in an edge localized mode (ELM). ELMs in future large tokamaks will deliver heat fluxes of ~1 GW/m2 to the divertor plasma facing components at a few Hz. An electrothermal plasma source can deliver heat fluxes of this magnitude. These sources operate in an ablative arc regime which is driven by a DC capacitive discharge. An electrothermal source was configured in this paper with two pulse lengths and tested under a solenoidal magnetic fieldmore » to determine the resulting impact on liner ablation, plasma parameters, and delivered heat flux. The arc travels through and ablates a boron nitride liner and strikes a tungsten plate. Finally, the tungsten target plate is analyzed for surface damage using a scanning electron microscope.« less

  6. Broadband asymmetric acoustic transmission in a single medium by an array of heat sources

    NASA Astrophysics Data System (ADS)

    Guan, Yi-Jun; Sun, Hong-Xiang; Xia, Jian-Ping; Yuan, Shou-Qi

    2017-04-01

    We report the realization of a broadband asymmetric acoustic transmission with six different-temperature heat sources in air. This exotic effect arises from the desired refractive index in propagation paths induced from heat sources of different temperatures and asymmetrical distribution, which avoids acoustic impedance differences between the heat sources and air and has no reflection energy loss. In addition, the influence of the viscosity of air, the thermal convection, and the temperature and length of the heat sources on the asymmetric transmission effect is investigated in detail. The results show that the proposed device has the advantages of broad bandwidth, high transmission contrast, and simple structure, which enable it to provide more schemes for sound manipulation. It has excellent potential applications in acoustic devices.

  7. Material impacts and heat flux characterization of an electrothermal plasma source with an applied magnetic field

    NASA Astrophysics Data System (ADS)

    Gebhart, T. E.; Martinez-Rodriguez, R. A.; Baylor, L. R.; Rapp, J.; Winfrey, A. L.

    2017-08-01

    To produce a realistic tokamak-like plasma environment in linear plasma device, a transient source is needed to deliver heat and particle fluxes similar to those seen in an edge localized mode (ELM). ELMs in future large tokamaks will deliver heat fluxes of ˜1 GW/m2 to the divertor plasma facing components at a few Hz. An electrothermal plasma source can deliver heat fluxes of this magnitude. These sources operate in an ablative arc regime which is driven by a DC capacitive discharge. An electrothermal source was configured with two pulse lengths and tested under a solenoidal magnetic field to determine the resulting impact on liner ablation, plasma parameters, and delivered heat flux. The arc travels through and ablates a boron nitride liner and strikes a tungsten plate. The tungsten target plate is analyzed for surface damage using a scanning electron microscope.

  8. Prospects for using high power x-rays as a volumetric heat source

    SciTech Connect

    Rosenberg, R.A.; Farrell, W.; Ma, Q.

    1997-09-01

    Third-generation, high-intensity, x-ray synchrotron radiation sources are capable of producing high heat-flux x-ray beams. In many applications finding ways to handle these powers is viewed as a burden. However, there are some technological applications where the deep penetration length of the x-rays may find beneficial uses as a volumetric heat source. In this paper the authors discuss the prospects for using high power x-rays for volumetric heating and report some recent experimental results. The particular applications they focus on are welding and surface heat treatment. The radiation source is an undulator at the Advanced Photon Source (APS). Results of preliminary tests on aluminum, aluminum metal matrix composites, and steel will be presented.

  9. Welding Isotopic Heat Sources for the Cassini Mission to Saturn (U)

    SciTech Connect

    Franco-Ferreira, E.A.; George, T.G.

    1995-02-28

    In 1997 NASA will launch the Cassini scientific probe to the planet Saturn. Electric power for this probe will be provided by Radioisotope Thermoelectric Generators thermally driven by General Purpose Heat Source modules.

  10. Impact of various operating modes on performance and emission parameters of small heat source

    NASA Astrophysics Data System (ADS)

    Vician, Peter; Holubčík, Michal; Palacka, Matej; Jandačka, Jozef

    2016-06-01

    Thesis deals with the measurement of performance and emission parameters of small heat source for combustion of biomass in each of its operating modes. As the heat source was used pellet boiler with an output of 18 kW. The work includes design of experimental device for measuring the impact of changes in air supply and method for controlling the power and emission parameters of heat sources for combustion of woody biomass. The work describes the main factors that affect the combustion process and analyze the measurements of emissions at the heat source. The results of experiment demonstrate the values of performance and emissions parameters for the different operating modes of the boiler, which serve as a decisive factor in choosing the appropriate mode.

  11. Theoretical and experimental investigation of high-level radiation sources used to model a heat input

    NASA Astrophysics Data System (ADS)

    Gradov, V. M.; Petrikevich, B. B.; Shcherbakov, A. A.

    1980-03-01

    This paper examines high-intensity xenon-filled radiation sources for heat load simulation. A mathematical model of the discharge is proposed, and results of a theoretical and an experimental investigation are presented.

  12. Characterization of the Inductively Heated Plasma Source IPG6-B

    NASA Astrophysics Data System (ADS)

    Dropmann, Michael; Laufer, Rene; Herdrich, Georg; Matthews, Lorin; Hyde, Truell

    2014-10-01

    In close collaboration between the Center for Astrophysics, Space Physics and Engineering Research (CASPER) at Baylor University, Texas, and the Institute of Space Systems (IRS) at the University of Stuttgart, Germany, two plasma facilities have been established using the Inductively heated Plasma Generator 6 (IPG6). The facility at Baylor University (IPG6-B) works at a frequency of 13.56 MHz and a maximum power of 15 kW. A vacuum pump of 160 m3/h in combination with a butterfly valve allows pressure control over a wide range. Intended fields of research include basic investigation into thermo-chemistry and plasma radiation, space plasma environments and high heat fluxes e.g. those found in fusion devices or during atmospheric re-entry of spacecraft. After moving the IPG6-B facility to the Baylor Research and Innovation Collaborative (BRIC) it was placed back into operation during the summer of 2014. Initial characterization in the new lab, using a heat flux probe, Pitot probe and cavity calorimeter, has been conducted for Air, Argon and Helium. The results of this characterization are presented.

  13. National Certification Standard for Ground Source Heat Pump Personnel

    SciTech Connect

    Kelly, John

    2013-07-31

    The National Certification Standard for the Geothermal Heat Pump Industry adds to the understanding of the barriers to rapid growth of the geothermal heat pump (GHP) industry by bringing together for the first time an analysis of the roles and responsibilities of each of the individual job tasks involved in the design and installation of GHP systems. The standard addresses applicable qualifications for all primary personnel involved in the design, installation, commissioning, operation and maintenance of GHP systems, including their knowledge, skills and abilities. The resulting standard serves as a foundation for subsequent development of curriculum, training and certification programs, which are not included in the scope of this project, but are briefly addressed in the standard to describe ways in which the standard developed in this project may form a foundation to support further progress in accomplishing those other efforts. Follow-on efforts may use the standard developed in this project to improve the technical effectiveness and economic feasibility of curriculum development and training programs for GHP industry personnel, by providing a more complete and objective assessment of the individual job tasks necessary for successful implementation of GHP systems. When incorporated into future certification programs for GHP personnel, the standard will facilitate increased consumer confidence in GHP technology, reduce the potential for improperly installed GHP systems, and assure GHP system quality and performance, all of which benefit the public through improved energy efficiency and mitigated environmental impacts of the heating and cooling of homes and businesses.

  14. Magnetic pumping as a source of particle heating

    NASA Astrophysics Data System (ADS)

    Lichko, Emily; Egedal, Jan; Daughton, William; Kasper, Justin

    2016-10-01

    Magnetic pumping is a means of heating plasmas for both fusion and astrophysical applications. This study presents a generalized model, related to the compressional pumping model Fisk & Gloeckler applied to the solar wind (2006). Unlike previous models, this model includes diffusion of the anisotropic features which develop in velocity space, thereby allowing energy to be transferred to the particles directly from the turbulence. By using various orderings, the drift kinetic equation can be reduced to a more general form of Parker's equation with an anisotropic distribution function. Through expansions in both pitch angle and in space, it can be shown that this equation has power law solutions and results in an overall heating of the plasma. This form of heating is related to transit-time damping. Kinetic simulations were performed to test the theoretical model and explore regimes where spatial and velocity diffusion are of the same order of importance, regimes not easily available to analytical calculations. These simulations appear to confirm the pumping model in the appropriate limits.

  15. Differential turbulent heating of different ions in electron cyclotron resonance ion source plasma

    SciTech Connect

    Elizarov, L.I.; Ivanov, A.A.; Serebrennikov, K.S.; Vostrikova, E.A.

    2006-03-15

    The article considers the collisionless ion sound turbulent heating of different ions in an electron cyclotron resonance ion source (ECRIS). The ion sound arises due to parametric instability of pumping wave propagating along the magnetic field with the frequency close to that of electron cyclotron. Within the framework of turbulent heating model the different ions temperatures are calculated in gas-mixing ECRIS plasma.

  16. Technology Solutions Case Study: Ground Source Heat Pump Research, TaC Studios Residence, Atlanta, Georigia

    SciTech Connect

    2014-09-01

    This case study describes the construction of a new test home that demonstrates current best practices for the mixed-humid climate, including a high performance ground source heat pump for heating and cooling, a building envelope featuring advanced air sealing details and low-density spray foam insulation, and glazing that exceeds ENERGY STAR requirements.

  17. Numerical analysis of the heat source characteristics of a two-electrode TIG arc

    NASA Astrophysics Data System (ADS)

    Ogino, Y.; Hirata, Y.; Nomura, K.

    2011-06-01

    Various kinds of multi-electrode welding processes are used to ensure high productivity in industrial fields such as shipbuilding, automotive manufacturing and pipe fabrication. However, it is difficult to obtain the optimum welding conditions for a specific product, because there are many operating parameters, and because welding phenomena are very complicated. In the present research, the heat source characteristics of a two-electrode TIG arc were numerically investigated using a 3D arc plasma model with a focus on the distance between the two electrodes. The arc plasma shape changed significantly, depending on the electrode spacing. The heat source characteristics, such as the heat input density and the arc pressure distribution, changed significantly when the electrode separation was varied. The maximum arc pressure of the two-electrode TIG arc was much lower than that of a single-electrode TIG. However, the total heat input of the two-electrode TIG arc was nearly constant and was independent of the electrode spacing. These heat source characteristics of the two-electrode TIG arc are useful for controlling the heat input distribution at a low arc pressure. Therefore, these results indicate the possibility of a heat source based on a two-electrode TIG arc that is capable of high heat input at low pressures.

  18. Alternate energy source usage for in situ heat treatment processes

    DOEpatents

    Stone, Jr., Francis Marion; Goodwin, Charles R [League City, TX; Richard, Jr., James

    2011-03-22

    Systems, methods, and heaters for treating a subsurface formation are described herein. At least one system for providing power to one or more subsurface heaters is described herein. The system may include an intermittent power source; a transformer coupled to the intermittent power source, and a tap controller coupled to the transformer. The transformer may be configured to transform power from the intermittent power source to power with appropriate operating parameters for the heaters. The tap controller may be configured to monitor and control the transformer so that a constant voltage is provided to the heaters from the transformer regardless of the load of the heaters and the power output provided by the intermittent power source.

  19. Water flow calorimetry measurements of heat loads for a volume production H/sup -/ source

    SciTech Connect

    Purgalis, P.; Ackerman, G.; Kwan, J.; Wells, R.P.

    1987-10-01

    The design of volume-production H/sup -/ sources requires the knowledge of heat loads on the source components. The arc and filament heater power input to a 20 cm diameter x 23 cm long source can be 50 kW or higher, practically all of which is absorbed in the cooling water. Water flow calorimetry measurements were made to determine the heat loads on the bucket walls, grid no. 1, and magnetic filter rods. The measurements are presented for two different filament locations, for three different values of arc power, and for three values of source gas pressure. 1 ref., 4 figs., 2 tabs.

  20. An Electrothermal Plasma Source Developed for Simulation of Transient Heat Loads in Future Large Fusion Devices

    NASA Astrophysics Data System (ADS)

    Gebhart, Trey; Baylor, Larry; Winfrey, Leigh

    2016-10-01

    The realization of fusion energy requires materials that can withstand high heat and particle fluxes at the plasma material interface. In this work, an electrothermal (ET) plasma source has been designed as a possible transient heat flux source for a linear plasma material interaction device. An ET plasma source operates in the ablative arc regime, which is driven by a DC capacitive discharge. The current travels through the 4mm bore of a boron nitride liner and subsequently ablates and ionizes the liner material. This results in a high density plasma with a large unidirectional bulk flow out of the source exit. The pulse length for the ET source has been optimized using a pulse forming network to have a duration of 1ms at full-width half maximum. The peak currents and maximum source energies seen in this system are 2kA and 5kJ. The goal of this work is to show that the ET source produces electron densities and heat fluxes that are comparable to transient events in future large magnetic confinement fusion devices. Heat flux, plasma temperature, and plasma density were determined for each test shot using infrared imaging and optical spectroscopy techniques. This work will compare the ET source output (heat flux, temperature, and density) with and without an applied magnetic field. Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy.

  1. Foundation heat exchangers for residential ground source heat pump systems Numerical modeling and experimental validation

    SciTech Connect

    Xing, Lu; Cullin, James; Spitler, Jeffery; Im, Piljae; Fisher, Daniel

    2011-01-01

    A new type of ground heat exchanger that utilizes the excavation often made for basements or foundations has been proposed as an alternative to conventional ground heat exchangers. This article describes a numerical model that can be used to size these foundation heat exchanger (FHX) systems. The numerical model is a two-dimensional finite-volume model that considers a wide variety of factors, such as soil freezing and evapotranspiration. The FHX numerical model is validated with one year of experimental data collected at an experimental house located near Oak Ridge, Tennessee. The model shows good agreement with the experimental data-heat pump entering fluid temperatures typically within 1 C (1.8 F) - with minor discrepancies due to approximations, such as constant moisture content throughout the year, uniform evapotranspiration over the seasons, and lack of ground shading in the model.

  2. Electron cyclotron resonance heating by magnetic filter field in a negative hydrogen ion source

    SciTech Connect

    Kim, June Young Cho, Won-Hwi; Dang, Jeong-Jeung; Chung, Kyoung-Jae Hwang, Y. S.

    2016-02-15

    The influence of magnetic filter field on plasma properties in the heating region has been investigated in a planar-type inductively coupled radio-frequency (RF) H{sup −} ion source. Besides filtering high energy electrons near the extraction region, the magnetic filter field is clearly observed to increase the electron temperature in the heating region at low pressure discharge. With increasing the operating pressure, enhancement of electron temperature in the heating region is reduced. The possibility of electron cyclotron resonance (ECR) heating in the heating region due to stray magnetic field generated by a filter magnet located at the extraction region is examined. It is found that ECR heating by RF wave field in the discharge region, where the strength of an axial magnetic field is approximately ∼4.8 G, can effectively heat low energy electrons. Depletion of low energy electrons in the electron energy distribution function measured at the heating region supports the occurrence of ECR heating. The present study suggests that addition of axial magnetic field as small as several G by an external electromagnet or permanent magnets can greatly increase the generation of highly ro-vibrationally excited hydrogen molecules in the heating region, thus improving the performance of H{sup −} ion generation in volume-produced negative hydrogen ion sources.

  3. Numerical Prediction of Performance of Water Type Stirling Engine Considering Heat Exchange with Heat Sources

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yoshiyuki; Higuchi, Tetsuya

    Two different analytical models were developed on water type Stirling engine. One is the resonance model which qualitatively clarifies the relationship between performance and resonance tube length, and the other is the heat transfer model considering heat transfer between working gas and the tube walls of heating and cooling units. These analyses and experiments were carried out changing the resonance tube length variously, then it was confirmed that the resonance tube length which maximizes the water column amplitude of the power piston agrees well and the oscillations of water columns at that resonance tube length also agrees. In addition, a series of analysis using the heat transfer model was carried out with changing cross sectional area of the resonance tube, loss factors of the elbows, heat transfer area of heating and cooling unit, and pressure of working gas. By this numerical investigation, the effect on the resonance tube length and the work at the length in which these parameters maximize the amplitude of power piston water column was clarified.

  4. Solar Jets as Sources of Outflows, Heating and Waves

    NASA Astrophysics Data System (ADS)

    Nishizuka, N.

    2013-05-01

    Recent space solar observations of the Sun, such as Hinode and SDO, have revealed that magnetic reconnection is ubiquitous in the solar atmosphere, ranging from small scale reconnection (observed as nanoflares) to large scale one (observed as long duration flares or giant arcades). Especially recent Hinode observations has found various types of tiny chromospheric jets, such as chromospheric anemone jets, penumbral microjets and light bridge jets from sunspot umbra. It was also found that the corona is full of tiny X-ray jets. Often they are seen as helical spinning jets with Alfvenic waves in the corona. Sometimes they are seen as chromospheric jets with slow-mode magnetoacoustic waves and sometimes as unresolved jet-like events at the footpoint of recurrent outflows and waves at the edge of the active region. There is increasing evidence of magnetic reconnection in these tiny jets and its association with waves. The origin of outflows and waves is one of the issues concerning coronal heating and solar wind acceleration. To answer this question, we had a challenge to reproduce solar jets with laboratory plasma experiment and directly measured outflows and waves. As a result, we could find a propagating wave excited by magnetic reconnection, whose energy flux is 10% of the released magnetic energy. That is enough for solar wind acceleration and locally enough for coronal heating, consistent with numerical MHD simulations of solar jets. Here we would discuss recent observations with Hinode, theories and experimental results related to jets and waves by magnetic reconnection, and discuss possible implication to reconnection physics, coronal heating and solar wind acceleration.

  5. Source Contaminant Control for the Heat Melt Compactor

    NASA Technical Reports Server (NTRS)

    Roman, Monsi; Howard, David

    2015-01-01

    The Logistics Reduction and Repurposing project includes the heat melt compactor (HMC), a device that compacts waste containing plastic into a tile that will minimize volume, and may be used as materials for radiation shielding. During the process, a small purge gas stream is directed through the HMC chamber to transport out gasses and humidity released from the process. NASA Marshall Space Flight Center is tasked with developing and delivering a contamination control system to clean the purge gas prior to exhausting it back into the cabin for crew inhalation.

  6. Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems

    SciTech Connect

    Hong, Tainzhen; Liu, Xaiobing

    2009-11-01

    With the current movement toward net zero energy buildings, many technologies are promoted with emphasis on their superior energy efficiency. The variable refrigerant flow (VRF) and ground source heat pump (GSHP) systems are probably the most competitive technologies among these. However, there are few studies reporting the energy efficiency of VRF systems compared with GSHP systems. In this article, a preliminary comparison of energy efficiency between the air-source VRF and GSHP systems is presented. The computer simulation results show that GSHP system is more energy efficient than the air-source VRF system for conditioning a small office building in two selected US climates. In general, GSHP system is more energy efficient than the air-source VRV system, especially when the building has significant heating loads. For buildings with less heating loads, the GSHP system could still perform better than the air-source VRF system in terms of energy efficiency, but the resulting energy savings may be marginal.

  7. Correlating equations for impingement cooling of small heat sources with multiple circular liquid jets

    NASA Astrophysics Data System (ADS)

    Womac, D. J.; Incropera, F. P.; Ramadhyani, S.

    1994-05-01

    Experiments were performed to investigate single-phase heat transfer from a 12.7 mm x 12.7 mm heat source to 2 x 2 and 3 x 3 arrays of free-surface and submerged jets. The objective was to study the efficacy of using arrays of free surface or submerged liquid jets to cool a small, chip-like heat source. The data are correlated by obtaining area-weighted combinations of separate correlations associated with impingement and wall jet region.

  8. Experimental investigation on water quality standard of Yangtze River water source heat pump.

    PubMed

    Qin, Zenghu; Tong, Mingwei; Kun, Lin

    2012-01-01

    Due to the surface water in the upper reaches of Yangtze River in China containing large amounts of silt and algae, high content of microorganisms and suspended solids, the water in Yangtze River cannot be used for cooling a heat pump directly. In this paper, the possibility of using Yangtze River, which goes through Chongqing, a city in southwest China, as a heat source-sink was investigated. Water temperature and quality of the Yangtze River in the Chongqing area were analyzed and the performance of water source heat pump units in different sediment concentrations, turbidity and algae material conditions were tested experimentally, and the water quality standards, in particular surface water conditions, in the Yangtze River region that adapt to energy-efficient heat pumps were also proposed. The experimental results show that the coefficient of performance heat pump falls by 3.73% to the greatest extent, and the fouling resistance of cooling water in the heat exchanger increases up to 25.6% in different water conditions. When the sediment concentration and the turbidity in the river water are no more than 100 g/m3 and 50 NTU respectively, the performance of the heat pump is better, which can be used as a suitable river water quality standard for river water source heat pumps.

  9. Behavioral observations and operant procedures using microwaves as a heat source for young chicks

    SciTech Connect

    Morrison, W.D.; McMillan, I.; Bate, L.A.; Otten, L.; Pei, D.C.

    1986-08-01

    Four trials, using operant conditioning procedures, were conducted to study the response of chicks, housed at 16 C, to microwave or infrared heat. Microwave power density was 26 mW/cm2 in Trial 1, 13 mW/cm2 in Trial 2, and 10 mW/cm2 in Trials 3 and 4. Chicks voluntarily demanded between 28 and 63% as much heat (min heat/hr) from microwave source as from infrared source at all power densities. There was no correlation, however, between the ratio of heat demanded and the power density used. There were no significant differences in growth between infrared- or microwave-heated chicks. It is evident from these studies that 8-day-old broiler chicks are capable of associating the performance of a task with a thermal reward provided by the microwaves. They are also able to utilize these microwaves through operant conditioning without any visible detrimental effect to their health or behavior.

  10. The solar assisted air-source heat pump system, part 1

    NASA Astrophysics Data System (ADS)

    Hino, T.

    1980-11-01

    A new heat pump heating and air conditioning system was proposed and tested. It features the effective utilization of climatic conditions as its heat sources and sinks, to improve the thermodynamic efficiencies. Reduced electricity consumption, utility load leveling and the least environmental pollutions are expected. The outdoor unit of this heat pump is composed of aluminum panels that are painted black to enhance the radiative heat exchange and fixed almost perpendicularly to improve the natural convective heat transfer with air. The working fluid is halocarbon and commonly used in the heat transfer circuits and the refrigeration cycle. In the heating cycle, the liquid refrigerant evaporates in the passages of the panel. When insolation to the panels is sufficient to meet the heat pump evaporator capacity, the panel temperature will be almost the same as the outdoor air temperature. Thus little convective heat loss to the surrounding air occurs. As the insolation decreases the panel temperature falls several degrees below the outdoor air to absorb heat out of the air until the equilibrium condition is reached.

  11. Synchronizability of random rectangular graphs

    SciTech Connect

    Estrada, Ernesto Chen, Guanrong

    2015-08-15

    Random rectangular graphs (RRGs) represent a generalization of the random geometric graphs in which the nodes are embedded into hyperrectangles instead of on hypercubes. The synchronizability of RRG model is studied. Both upper and lower bounds of the eigenratio of the network Laplacian matrix are determined analytically. It is proven that as the rectangular network is more elongated, the network becomes harder to synchronize. The synchronization processing behavior of a RRG network of chaotic Lorenz system nodes is numerically investigated, showing complete consistence with the theoretical results.

  12. Preliminary design study of an alternate heat source assembly for a Brayton isotope power system

    NASA Technical Reports Server (NTRS)

    Strumpf, H. J.

    1978-01-01

    Results are presented for a study of the preliminary design of an alternate heat source assembly (HSA) intended for use in the Brayton isotope power system (BIPS). The BIPS converts thermal energy emitted by a radioactive heat source into electrical energy by means of a closed Brayton cycle. A heat source heat exchanger configuration was selected and optimized. The design consists of a 10 turn helically wound Hastelloy X tube. Thermal analyses were performed for various operating conditions to ensure that post impact containment shell (PICS) temperatures remain within specified limits. These limits are essentially satisfied for all modes of operation except for the emergency cooling system for which the PICS temperatures are too high. Neon was found to be the best choice for a fill gas for auxiliary cooling system operation. Low cycle fatigue life, natural frequency, and dynamic loading requirements can be met with minor modifications to the existing HSA.

  13. Heat transfer from a square source to an impinging liquid jet confined by an annular wall

    SciTech Connect

    Besserman, D.L. ); Incropera, F.P.; Ramadhyani, S. )

    1992-02-01

    The objective of this study has been to consider experimentally impingement cooling of a chiplike source by a liquid, circular jet under conditions for which single-phase convection heat transfer from the source may be influenced by annular collection of the spent fluid. The experiments were performed with water and for operating conditions that are consistent with ship cooling requirements.

  14. COMPARATIVE STUDY AMONG HYBRID GROUND SOURCE HEAT PUMP SYSTEM, COMPLETE GROUND SOURCE HEAT PUMP AND CONVENTIONAL HVAC SYSTEM

    SciTech Connect

    Jiang Zhu; Yong X. Tao

    2011-11-01

    In this paper, a hotel with hybrid geothermal heat pump system (HyGSHP) in the Pensacola is selected and simulated by the transient simulation software package TRNSYS [1]. To verify the simulation results, the validations are conducted by using the monthly average entering water temperature, monthly facility consumption data, and etc. And three types of HVAC systems are compared based on the same building model and HVAC system capacity. The results are presented to show the advantages and disadvantages of HyGSHP compared with the other two systems in terms of energy consumptions, life cycle cost analysis.

  15. Counter-current flow limitation in thin rectangular channels

    NASA Astrophysics Data System (ADS)

    Cheng, Lap Y.

    The phenomenon of counter-current flow limitation (CCFL) in thin rectangular channels is important in determining the heat removal capability of research reactors which use plate-type fuel elements similar to the MTR design. An analytical expression for predicting CCFL in narrow rectangular channels was derived from the momentum equations for the liquid and gas phase. The model assumes that the liquid downflow is in the form of a film along the narrower side walls of the channel, while the gas flow occupies the wide span of the rectangular channel. The average thickness of liquid film is related to the rate of gas flow through a stability criterion for the liquid film. The CCFL correlation agrees with air/water data taken at relatively high gas velocities. Depending on the magnitude of the dimensionless channel width, the new CCFL correlation approaches zero liquid penetration either in the form of a Wallis correlation or in terms of a Kutateladze number. The new correlation indicates that for a thin rectangular channel, the constant C in the Wallis flooding correlation depends on the aspect ratio of the channel. The approach to the appropriate asymptotic solutions also justifies the use of twice the wide span as the correct length scale for thin rectangular channels.

  16. Dynamics of charged bulk viscous collapsing cylindrical source with heat flux

    NASA Astrophysics Data System (ADS)

    Shah, S. M.; Abbas, G.

    2017-04-01

    In this paper, we have explored the effects of dissipation on the dynamics of charged bulk viscous collapsing cylindrical source which allows the out-flow of heat flux in the form of radiations. The Misner-Sharp formalism has been implemented to drive the dynamical equation in terms of proper time and radial derivatives. We have investigated the effects of charge and bulk viscosity on the dynamics of collapsing cylinder. To determine the effects of radial heat flux, we have formulated the heat transport equations in the context of Müller-Israel-Stewart theory by assuming that thermodynamics viscous/heat coupling coefficients can be neglected within some approximations. In our discussion, we have introduced the viscosity by the standard (non-causal) thermodynamics approach. The dynamical equations have been coupled with the heat transport equation; the consequences of the resulting coupled heat equation have been analyzed in detail.

  17. Interhemispheric Energy Propagation of Tropical Heat Sources: Effect of Diurnal Variability of Convection

    NASA Astrophysics Data System (ADS)

    Silva Dias, P. L.; Raupp, C. F.; Aravequia, J. A.

    2003-04-01

    The remote effect of tropical heat sources can be identified through the use of the Green's Functions (also known as Influence Functions -- IF), as discussed in Grimm and Silva Dias (J.Atmos.Sci., 1995). However, most of the previous work has been done with the IF of the barotropic non-divergent model and it is well known that tropical heat sources present significant transient behavior with significant energy in gravity-inertia waves which are not properly described by the simple model. This paper focuses on the possible impact of the diurnal variability of the tropical heat sources in the interhemispheric energy propagation with emphasis on the role of the heat source over tropical S. America using the barotropic divergent model (shallow water model -- SWM) which properly described the properties of fast waves such as Kelvin Waves. As a first step, an analysis of the IF of the SWM for target points located in Europe are presented for heat sources in S. Hemisphere summer. It is shown that the N. Hemisphere teleconnection patterns such as the Eurasian and the N. Atlantic patterns can be significantly influenced by anomalous convection in the S. Atlantic Convergence Zone (SACZ). Initial value experiments with enhanced heat sources in the SACZ are then performed in order to explore the possible role of the diurnal variability of convection over land. The results indicate that the higher latitude response is significantly more intense if the diurnal forcing is present. An analysis of the results indicates that the Kelvin waves generated by the diurnal heat source is responsible for generating strong westerly flow in the equatorial Atlantic which favors the northward energy propagation toward the action centers of the Eurasian and N. Atlantic patterns.

  18. Location of energy source for coronal heating on the photosphere

    NASA Astrophysics Data System (ADS)

    Hong, Zhen-Xiang; Yang, Xu; Wang, Ya; Ji, Kai-Fan; Ji, Hai-Sheng; Cao, Wen-Da

    2017-02-01

    It is reported that ultra-fine dynamic ejections along magnetic loops of an active region originate from intergranular lanes and they are associated with subsequent heating in the corona. As continuing work, we analyze the same set of data but focus on a quiet region and the overlying EUV/UV emission as observed by the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO). We find that there appear to be dark patches scattered across the quiet region and the dark patches always stay along intergranular lanes. Over the dark patches, the average UV/EUV emission at 131, 171, 304 and 1600 Å (middle temperature) is more intense than that of other regions and EUV brightness is negatively correlated with 10830 Å intensity, though, such a trend does not exist for high temperature lines at 94, 193, 211 and 335 Å. For the same quiet region, where both TiO 7057 Å broad band images and 10830 Å filtergrams are available, contours for the darkest lane areas on TiO images and dark patches on 10830 Å filtergrams frequently differ in space. The results suggest that the dark patches do not simply reflect the areas with the darkest lanes but are associated with a kind of enhanced absorption (EA) at 10830 Å. A strict definition for EA with narrow band 10830 Å filtergrams is found to be difficult. In this paper, we define enhanced absorption patches (EAPs) of a quiet region as the areas where emission is less than ∼90% of the mean intensity of the region. The value is equivalent to the average intensity along thin dark loops connecting two moss regions of the active region. A more strict definition for EAPs, say 88%, gives even more intense UV/EUV emission over those in the middle temperature range. The results provide further observational evidence that energy for heating the upper solar atmosphere comes from the intergranular lane area where the magnetic field is constantly brought in by convection motion in granules.

  19. Generation of Acoustic-Gravity Waves in Ionospheric HF Heating Experiments: Simulating Large-Scale Natural Heat Sources

    NASA Astrophysics Data System (ADS)

    Pradipta, Rezy

    In this thesis, we investigate the potential role played by large-scale anomalous heat sources (e.g. prolonged heat wave events) in generating acoustic-gravity waves (AGWs) that might trigger widespread plasma turbulence in the ionospheric layer. The main hypothesis is that, the thermal gradients associated with the heat wave fronts could act as a source of powerful AGW capable of triggering ionospheric plasma turbulence over extensive areas. In our investigations, first we are going to examine a case study of the summer 2006 North American heat wave event. Our examination of GPS-derived total electron content (TEC) data over the North American sector reveals a quite noticeable increase in the level of daily plasma density fluctuations during the summer 2006 heat wave period. Comparison with the summer 2005 and summer 2007 data further confirms that the observed increase of traveling ionospheric disturbances (TIDs) during the summer 2006 heat wave period was not simply a regular seasonal phenomenon. Furthermore, a series of field experiments had been carried out at the High-frequency Active Auroral Research Program (HAARP) facility in order to physically simulate the process of AGW/TID generation by large-scale thermal gradients in the ionosphere. In these ionospheric HF heating experiments, we create some time-varying artificial thermal gradients at an altitude of 200--300 km above the Earth's surface using vertically-transmitted amplitude-modulated 0-mode HF heater waves. For our experiments, a number of radio diagnostic instruments had been utilized to detect the characteristic signatures of heater-generated AGW/TID. So far, we have been able to obtain several affirmative indications that some artificial AGW/TID are indeed being radiated out from the heated plasma volume during the HAARP-AGW experiments. Based on the experimental evidence, we may conclude that it is certainly quite plausible for large-scale thermal gradients associated with severe heat wave

  20. Recuperator with microjet technology as a proposal for heat recovery from low-temperature sources

    NASA Astrophysics Data System (ADS)

    Wajs, Jan; Mikielewicz, Dariusz; Fornalik-Wajs, Elżbieta; Bajor, Michał

    2015-12-01

    A tendency to increase the importance of so-called dispersed generation, based on the local energy sources and the working systems utilizing both the fossil fuels and the renewable energy resources is observed nowadays. Generation of electricity on industrial or domestic scale together with production of heat can be obtained for example through employment of the ORC systems. It is mentioned in the EU directive 2012/27/EU for cogenerative production of heat and electricity. For such systems the crucial points are connected with the heat exchangers, which should be small in size but be able to transfer high heat fluxes. In presented paper the prototype microjet heat exchanger dedicated for heat recovery systems is introduced. Its novel construction is described together with the systematical experimental analysis of heat transfer and flow characteristics. Reported results showed high values of the overall heat transfer coefficient and slight increase in the pressure drop. The results of microjet heat exchanger were compared with the results of commercially available compact plate heat exchanger.

  1. An inductively heated hot cavity catcher laser ion source

    NASA Astrophysics Data System (ADS)

    Reponen, M.; Moore, I. D.; Pohjalainen, I.; Rothe, S.; Savonen, M.; Sonnenschein, V.; Voss, A.

    2015-12-01

    An inductively heated hot cavity catcher has been constructed for the production of low-energy ion beams of exotic, neutron-deficient Ag isotopes. A proof-of-principle experiment has been realized by implanting primary 107Ag21+ ions from a heavy-ion cyclotron into a graphite catcher. A variable-thickness nickel foil was used to degrade the energy of the primary beam in order to mimic the implantation depth expected from the heavy-ion fusion-evaporation recoils of N = Z 94Ag. Following implantation, the silver atoms diffused out of the graphite and effused into the catcher cavity and transfer tube, where they were resonantly laser ionized using a three-step excitation and ionization scheme. Following mass separation, the ions were identified by scanning the frequency of the first resonant excitation step while recording the ion count rate. Ion release time profiles were measured for different implantation depths and cavity temperatures with the mean delay time varying from 10 to 600 ms. In addition, the diffusion coefficients for silver in graphite were measured for temperatures of 1470 K, 1630 K, and 1720 K, from which an activation energy of 3.2 ± 0.3 eV could be determined.

  2. An inductively heated hot cavity catcher laser ion source

    SciTech Connect

    Reponen, M.; Moore, I. D. Pohjalainen, I.; Savonen, M.; Voss, A.; Rothe, S.; Sonnenschein, V.

    2015-12-15

    An inductively heated hot cavity catcher has been constructed for the production of low-energy ion beams of exotic, neutron-deficient Ag isotopes. A proof-of-principle experiment has been realized by implanting primary {sup 107}Ag{sup 21+} ions from a heavy-ion cyclotron into a graphite catcher. A variable-thickness nickel foil was used to degrade the energy of the primary beam in order to mimic the implantation depth expected from the heavy-ion fusion-evaporation recoils of N = Z {sup 94}Ag. Following implantation, the silver atoms diffused out of the graphite and effused into the catcher cavity and transfer tube, where they were resonantly laser ionized using a three-step excitation and ionization scheme. Following mass separation, the ions were identified by scanning the frequency of the first resonant excitation step while recording the ion count rate. Ion release time profiles were measured for different implantation depths and cavity temperatures with the mean delay time varying from 10 to 600 ms. In addition, the diffusion coefficients for silver in graphite were measured for temperatures of 1470 K, 1630 K, and 1720 K, from which an activation energy of 3.2 ± 0.3 eV could be determined.

  3. Non-rectangular towpreg architectures

    NASA Technical Reports Server (NTRS)

    Sandusky, Donald A. (Inventor); Marchello, Joseph M. (Inventor); Baucom, Robert M. (Inventor)

    1993-01-01

    A shaped towpreg ribbon having a cross-sectional geometry which promotes intimate lateral contact between adjacent composite tows was prepared. The cross-sectional geometry is non-rectangular and promotes intimate lateral contact between adjacent towpreg ribbons during normal processing.

  4. Non-rectangular towpreg architectures

    NASA Technical Reports Server (NTRS)

    Sandusky, Donald A. (Inventor); Marchello, Joseph M. (Inventor); Baucom, Robert M. (Inventor)

    1995-01-01

    A shaped towpreg ribbon having a cross-sectional geometry which promotes intimate lateral contact between adjacent composite tows was prepared. The cross-sectional geometry is non-rectangular and promotes intimate lateral contact between adjacent towpreg ribbons during normal processing.

  5. Thermionic converter with differentially heated cesium-oxygen source and method of operation

    DOEpatents

    Rasor, Ned S.; Riley, David R.; Murray, Christopher S.; Geller, Clint B.

    2000-01-01

    A thermionic converter having an emitter, a collector, and a source of cesium vapor is provided wherein the source of cesium vapor is differentially heated so that said source has a hotter end and a cooler end, with cesium vapor evaporating from said hotter end into the space between the emitter and the collector and with cesium vapor condensing at said cooler end. The condensed cesium vapor migrates through a porous element from the cooler end to the hotter end.

  6. Numerical Study on Natural Vacuum Solar Desalination System with Varying Heat Source Temperature

    NASA Astrophysics Data System (ADS)

    Ambarita, H.

    2017-03-01

    A natural vacuum desalination unit with varying low grade heat source temperature is investigated numerically. The objective is to explore the effects of the variable temperature of the low grade heat source on performances and characteristics of the desalination unit. The specifications of the desalination unit are naturally vacuumed with surface area of seawater in evaporator and heating coil are 0.2 m2 and 0.188 m2, respectively. Temperature of the heating coil is simulated based on the solar radiation in the Medan city. A program to solve the governing equations in forward time step marching technique is developed. Temperature of the evaporator, fresh water production rate, and thermal efficiency of the desalination unit are analysed. Simulation is performed for 9 hours, it starts from 8.00 and finishes at 17.00 of local time. The results show that, the desalination unit with operation time of 9 hours can produce 5.705 L of freshwater and thermal efficiency is 81.8 %. This reveals that varying temperature of the heat source of natural vacuum desalination unit shows better performance in comparison with constant temperature of the heat source.

  7. The atmospheric heat source over the Tibetan plateau May-August 1979

    NASA Technical Reports Server (NTRS)

    Chen, L.; Reiter, E. R.; Feng, Z.

    1985-01-01

    Estimates of the time and space variability of the atmospheric heat source over Tibet are presented for the summer of 1979. These estimates rely on new data from the People's Republic of China allowing a better assessment of the surface heat fluxes, and on new satellite data from Nimbus-7 giving the radiation balance at the top of the atmosphere. The estimates of the atmospheric heat source turned out to be considerably smaller than those provided earlier in the literature, mainly because of different assumptions of the drag coefficient. The atmospheric heat source over Tibet is mainly modulated by the release of latent heat. Over the southeastern and southwestern plateau regions the heat source appears to be in phase with the precipitation yield of the Indian summer monsoon, whereas central Tibet reveals an out-of-phase behavior. Over western Tibet there appears to be hardly any net import of moisture from outside the region, whereas the maintenance of the hydrological cycle over eastern Tibet requires moisture flux convergence from outside the region of up to 40 percent of the mean rainfall, in agreement with what is known about the surface hydrology of Tibet.

  8. Curing of a bisphenol E based cyanate ester using magnetic nanoparticles as an internal heat source through induction heating.

    PubMed

    Hubbard, Jeremiah W; Orange, François; Guinel, Maxime J-F; Guenthner, Andrew J; Mabry, Joseph M; Sahagun, Christopher M; Rinaldi, Carlos

    2013-11-13

    We report on the control of cyclotrimerization forming a polycyanurate polymer using magnetic iron oxide nanoparticles in an alternating-current (ac) field as an internal heat source, starting from a commercially available monomer. Magnetic nanoparticles were dispersed in the monomer and catalytic system using sonication, and the mixture was subjected to an alternating magnetic field, causing the magnetic nanoparticles to dissipate the energy of the magnetic field in the form of heat. Internal heating of the particle/monomer/catalyst system was sufficient to start and sustain the polymerization reaction, producing a cyanate ester network with conversion that compared favorably to polymerization through heating in a conventional laboratory oven. The two heating methods gave similar differential scanning calorimetry temperature profiles, conversion rates, and glass transition temperatures when using the same temperature profile. The ability of magnetic nanoparticles in an ac field to drive the curing reaction should allow for other reactions forming high-temperature thermosetting polymers and for innovative ways to process such polymers.

  9. Ion heating and flows in a high power helicon source

    NASA Astrophysics Data System (ADS)

    Thompson, Derek S.; Agnello, Riccardo; Furno, Ivo; Howling, Alan; Jacquier, Rémy; Plyushchev, Gennady; Scime, Earl E.

    2017-06-01

    We report experimental measurements of ion temperatures and flows in a high power, linear, magnetized, helicon plasma device, the Resonant Antenna Ion Device (RAID). Parallel and perpendicular ion temperatures on the order of 0.6 eV are observed for an rf power of 4 kW, suggesting that higher power helicon sources should attain ion temperatures in excess of 1 eV. The unique RAID antenna design produces broad, uniform plasma density and perpendicular ion temperature radial profiles. Measurements of the azimuthal flow indicate rigid body rotation of the plasma column of a few kHz. When configured with an expanding magnetic field, modest parallel ion flows are observed in the expansion region. The ion flows and temperatures are derived from laser induced fluorescence measurements of the Doppler resolved velocity distribution functions of argon ions.

  10. Temperature distribution in internally heated walls of heat exchangers composed of nonnuclear flow passages

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Low, George M

    1951-01-01

    In the walls of heat exchangers composed of noncircular passages, the temperature varies in the circumferential direction because of local variations of the heat-transfer coefficients. A prediction of the magnitude of this variation is necessary in order to determine the region of highest temperature and in order to determine the admissible operating temperatures. A method for the determination of these temperature distributions and of the heat-transfer characteristics of a special type of heat exchanger is developed. The heat exchanger is composed of polygonal flow passages and the passage walls are uniformly heated by internal heat sources. The coolant flow within the passages is assumed to be turbulent. The circumferential variation of the local heat-transfer coefficients is estimated from flow measurements made by Nikuradse, postulating similarity between velocity and temperature fields. Calculations of temperature distributions based on these heat-transfer coefficients are carried out and results for heat exchangers with triangular and rectangular passages are presented.

  11. Urban heat islands in the subsurface as sustainable source for geothermal energy

    NASA Astrophysics Data System (ADS)

    Menberg, Kathrin; Bayer, Peter; Blum, Philipp

    2014-05-01

    The urban heat island (UHI) is not a phenomenon that solely occurs in the atmosphere with increased air temperatures. We also observe it in the subsurface, and groundwater temperatures in shallow aquifers are strongly influenced by anthropogenic land surface alterations. Widespread thermal anomalies, which are triggered by various processes, such as increased ground surface temperatures (GST) and heat loss from buildings, can be found under many urban areas. With groundwater temperatures elevated by several degrees these aquifers represent large amounts of stored thermal energy. However, to exploit these attractive geothermal reservoirs efficiently and sustainably, the processes, which lead to the profound subsurface urban warming, need to be identified and quantified. In the current study, the spatial extension of the heat anomalies beneath several German cities, such as Berlin, Munich, Karlsruhe and Cologne, is scrutinized by mapping groundwater temperatures in a dense network of observation wells. With the high-resolved spatial distribution of groundwater temperatures, the dominant heat sources and important driving factors can be identified and incorporated into an analytical heat flux model. The annual anthropogenic heat input into the aquifer originating from several heat sources, such as increased GST, basements, sewage networks, district heating networks and reinjections of thermal waste water, is estimated by a Monte Carlo simulation for the cities of Cologne and Karlsruhe. All studied cities exhibit aquifers with significantly elevated temperatures, with the highest temperatures of up to 18°C prevailing in the densely built-up city centers. But also in suburban and industrial areas groundwater temperatures are several degrees above the rural background. The accumulated heat content in the urban aquifers can be estimated based on the thermal ground properties. This content is compared to the annual space heating demand in order to analyze the space

  12. The Prediction of Broadband Shock-Associated Noise from Dualstream and Rectangular Jets Using RANS CFD

    NASA Technical Reports Server (NTRS)

    Miller, Steven A.; Morris, Philip J.

    2010-01-01

    Supersonic jets operating off-design produce broadband shock-associated noise. Broadband shock-associated noise is characterized by multiple broadband peaks in the far-field and is often the dominant source of noise towards the sideline and upstream direction relative to the jet axis. It is due to large scale coherent turbulence structures in the jet shear layers interacting with the shock cell structure. A broadband shock-associated noise model recently developed by the authors predicts this noise component from solutions to the Reynolds averaged Navier-Stokes equations using a two-equation turbulence model. The broadband shock-associated noise model is applied to dualstream and rectangular nozzles operating supersonically, heated, and off-design. The dualstream jet broadband shock-associated noise predictions are conducted for cases when the core jet is supersonic and the fan jet is subsonic, the core jet is subsonic and the fan jet is supersonic, and when both jet streams operate supersonically. Rectangular jet predictions are shown for a convergent-divergent nozzle operating both over- and under-expanded for cold and heated conditions. The original model implementation has been heavily modified to make accurate predictions for the dualstream jets. It is also argued that for over-expanded jets the oblique shock wave attached to the nozzle lip contributes little to broadband shock-associated noise. All predictions are compared with experiments.

  13. Thermodynamic inspection of concrete using a controlled heat source

    NASA Astrophysics Data System (ADS)

    Milne, James M.

    1990-10-01

    Concrete is not quite such a non-destructable material as many are led to believe. It can deteriorate with time due to changes in the chemistry, the effect of moisture penetration and the corrosion of reinforcing steel bars. Much of this damage occurs relatively close to the surface, sometimes revealed by discolourations or the presence of cracks and sometimes as spallation when the corrosion products of steel cause delamination of the near surface concrete. These effects may occur in good quality concrete but their severity and rapidity of onset may be enhanced by fabrication defects when aggregates may not be to specification or the packing conditions cause porosity. It may thus be months or even years afterwards that these defects come to light. As a consequence a new industry has been formed to inspect concrete structures which may include X-ray equipment, linac accelerators, gamma isotope sources, ultrasonics, radar and of course thermography. Each of these nethods will have their own particular attractive features and merits. But most of these activities tend to be used more as a "fire fighting" service than as one ensuring regular maintenance of critical structures or even as quality control of structures during building. Quite often it seems that Non-destructive Testing is turned into a litigation service for dissatisfied customers and thermography is no stranger to this topic. It is heartening to see that the ASTM organisation in the USA and British Standards are encouraging and developing suitable standards for the inspection of concrete by thermographic techniques.

  14. Rotation of rectangular wire in rectangular molar tubes. Part I.

    PubMed

    Raphael, E; Sandrik, J L; Klapper, L

    1981-08-01

    The degree of angular rotation of rectangular orthodontic wires in rectangular molar tubes was measured using a rotatable mechanical stage on a Unitron metallograph and compared to theoretical data. It was found that square 0.016 inch wire did not bind in 0.018 by 0.022 inch or larger mandrel- or inconel-formed tubes, whereas rotations of 11 to 23 degrees were noted in cast tubes of this dimension. Although 0.016 by 0.022 inch wire did bind in these tubes, the degree of rotation was far greater than expected on the basis of theoretical calculations or clinical expectations. The results indicated that it was unrealistic to expect fine control of a few degrees of torque to occur as expected for delicate clinical control.

  15. Beam-induced radiation heating on the superconducting undulator at the advanced photon source

    NASA Astrophysics Data System (ADS)

    Boon, Laura Elizabeth

    2014-09-01

    In January 2013 the Advanced Photon Source (APS), a 7 GeV synchrotron X-ray source, commissioned a Superconducting Undulator (SCU). The superconducting magnet is thermally isolated from the beam vacuum chamber, which absorbs the beam-induced heating. Previous beam induced heat load studies at other laboratories had not included a robust calculation of radiation heating from the upstream dipole magnet. The mitigation of the radiation heating mechanism, and production of photoelectrons to seed an electron cloud was studied for this thesis. An analytical model was developed to predict the radiation heat load on the SCU chamber. This model was benchmarked with ray tracings and simulations. Results from this synchrotron radiation model were used to guide the design of the installed SCU beam chamber. A 3D Monte-Carlo simulation on synchrotron radiation on the beam chamber was developed. The model considered the effect of diffuse scattering and complex chamber geometries. It was found that a simulation assuming no photon scattering gave a power that agreed within 0.4% of the analytical model. Comparison between analytical calculations and measured temperature rise on the installed SCU show the analytical model agrees with the measured temperature rise within 20%. Previous models of similar superconducting devices in accelerators have reached at best 200% difference between the measured and modeled heat load. The beam heat load model presented in this thesis represents a significant improvement in modeling of superconducting devices in high energy particle accelerators. In addition to heating the SCU chamber, absorbed photons produce photoelectrons which seed electron clouds, another source of beam induced heating. Measurements of the technical aluminum samples show peaks in the quantum efficiency for photon energies equal to the K edges of oxygen, carbon, and aluminum. These results can be added to electron cloud simulation codes to improve simulation results.

  16. [Urban heat island effect based on urban heat island source and sink indices in Shenyang, Northeast China].

    PubMed

    Li, Li-Guang; Xu, Shen-Lai; Wang, Hong-Bo; Zhao, Zi-Qi; Cai, Fu; Wu, Jin-Wen; Chen, Peng-Shi; Zhang, Yu-Shu

    2013-12-01

    Based on the remote images in 2001 and 2010, the source and sink areas of urban heat island (UHI) in Shenyang City, Northeast China were determined by GIS technique. The effect of urban regional landscape pattern on UHI effect was assessed with land surface temperature (LST), area rate index (CI) of the source and sink areas and intensity index (LI) of heat island. The results indicated that the land use type changed significantly from 2001 to 2010, which significantly changed the source and sink areas of UHI, especially in the second and third circle regions. The source and sink areas were 94.3% and 5.7% in the first circle region, 64.0% and 36.0% in the third circle region in 2001, while they were 93.4% and 6.6%, 70.2% and 29.8% in 2010, respectively. It suggested that the land use pattern extended by a round shape in Shenyang led to the corresponding UHI pattern. The LST in the study area tended to decrease from the first circle region to the third. The UHI intensity was characterized with a single center in 2001 and with several centers in 2010, and the grade of UHI intensity was in a decreasing trend from 2001 to 2010. The absolute value of CI increased from the first circle region to the third, and the L1 was close to 1, suggesting the change in land use pattern had no significant influence on UHI in Shenyang.

  17. An evaluation of alternate production methods for Pu-238 general purpose heat source pellets

    SciTech Connect

    Mark Borland; Steve Frank

    2009-06-01

    For the past half century, the National Aeronautics and Space Administration (NASA) has used Radioisotope Thermoelectric Generators (RTG) to power deep space satellites. Fabricating heat sources for RTGs, specifically General Purpose Heat Sources (GPHSs), has remained essentially unchanged since their development in the 1970s. Meanwhile, 30 years of technological advancements have been made in the applicable fields of chemistry, manufacturing and control systems. This paper evaluates alternative processes that could be used to produce Pu 238 fueled heat sources. Specifically, this paper discusses the production of the plutonium-oxide granules, which are the input stream to the ceramic pressing and sintering processes. Alternate chemical processes are compared to current methods to determine if alternative fabrication processes could reduce the hazards, especially the production of respirable fines, while producing an equivalent GPHS product.

  18. Negative hydrogen ion beam extraction from an AC heated cathode driven Bernas-type ion source

    SciTech Connect

    Okano, Y.; Miyamoto, N.; Kasuya, T.; Wada, M.

    2015-04-08

    A plasma grid structure was installed to a Bernas-type ion source used for ion implantation equipment. A negative hydrogen (H{sup −}) ion beam was extracted by an AC driven ion source by adjusting the bias to the plasma grid. The extracted electron current was reduced by positively biasing the plasma grid, while an optimum plasma grid bias voltage for negative ion beam extraction was found to be positive 3 V with respect to the arc chamber. Source operations with AC cathode heating show extraction characteristics almost identical to that with DC cathode heating, except a minute increase in H{sup −} current at higher frequency of cathode heating current.

  19. Simulation study on laser cladding on preplaced powder layer with a tailored laser heat source

    NASA Astrophysics Data System (ADS)

    Tseng, W. C.; Aoh, J. N.

    2013-06-01

    This study proposes a tailored laser heat source model for the finite element analysis of the laser cladding process. The beam characteristics, including wavelength, beam radius, TEM mode and focusing conditions, were comprehensively considered in the heat source model. The model was integrated in a SYSWELD package to predict the temperature distribution and clad bead profile during laser cladding of preplaced cobalt powder layer on a steel substrate. Cladding process parameters were evaluated by varying the TEM mode, focusing conditions, wavelength and scanning speed. Single mode and tailored multi-mode TEMmixed laser beams were established for simulation. The numerical results were verified by performing a laser cladding experiment under the same conditions as the numerical model. The clad bead geometries predicted from the numerical simulation agreed well with those obtained from experiment. Thanks to the comprehensive feature of the proposed tailored laser heat source model, it also could be well applied to the numerical simulation of other laser material processes.

  20. Alternative Energy Sources for Heating the Stratospheres of Hot Jupiters

    NASA Astrophysics Data System (ADS)

    Marley, Mark S.; Zahnle, K.; Freedman, R.; Lodders, K.; Fortney, J.

    2009-09-01

    Spitzer Space Telescope observations have constrained the atmospheric thermal structure of many transiting extrasolar giant planets. Many of these planets, like their solar system cousins, apparently have hot stratospheres. It has been suggested that absorption in the optical by gaseous TiO and VO provides the necessary energy source to power their thermal emission. While this mechanism is certainly plausible in the hottest Jupiters, temperature inversions have also been observed in cooler planets in which TiO and VO should be condensed into grains. Motivated by the importance of photochemistry in producing important atmospheric absorbers in the solar system, we have explored the role of atmospheric sulfur photochemistry in hot Jupiter atmospheres. Our photochemical kinetics code was previously used to study various problems in solar system, including the aftermath of the S/L-9 impacts into Jupiter. We find that the optically active gases S2 and HS (mercapto) are generated photochemically and thermochemically at T > 1200 K from H2S with peak abundances between 1 and 10 mbar. S2 absorbs UV between 240 and 340 nm and is optically thick for metallicities higher than solar. HS is generally more abundant than S2 and absorbs between 300 and 460 nm. Together these species play an important role in the stratospheric energy budget of hot Jupiters and may provide a mechanism for producing temperature inversions under conditions where gaseous TiO and VO are not present. At lower temperatures, below 1200 K, we find that the atmospheric chemistry enters a different domain where the production of soots may be favored. Such soots may be responsible for the haze detected in the atmosphere of HD189733 and may also play a role in the stratospheric energy budgets of cooler planets.

  1. Evidence for an Additional Heat Source in the Warm Ionized Medium of Galaxies

    NASA Astrophysics Data System (ADS)

    Reynolds, R. J.; Haffner, L. M.; Tufte, S. L.

    1999-11-01

    Spatial variations of the [S II]/Hα and [N II]/Hα line intensity ratios observed in the gaseous halo of the Milky Way and other galaxies are inconsistent with pure photoionization models. They appear to require a supplemental heating mechanism that increases the electron temperature at low densities, ne. This would imply that in addition to photoionization, which has a heating rate per unit volume proportional to n2e, there is another source of heat with a rate per unit volume proportional to a lower power of ne. One possible mechanism is the dissipation of interstellar plasma turbulence, which, according to Minter & Spangler, heats the ionized interstellar medium in the Milky Way at a rate of ~1×10-25ne ergs cm-3 s-1. If such a source were present, it would dominate over photoionization heating in regions where ne<~0.1 cm-3, producing the observed increases in the [S II]/Hα and [N II]/Hα intensity ratios at large distances from the galactic midplane as well as accounting for the constancy of [S II]/[N II], which is not explained by pure photoionization. Other supplemental heating sources, such as magnetic reconnection, cosmic rays, or photoelectric emission from small grains, could also account for these observations, provided they supply ~10-5 ergs s-1 per square centimeter of the Galactic disk to the warm ionized medium.

  2. Demonstration of a non-contact x-ray source using an inductively heated pyroelectric accelerator

    NASA Astrophysics Data System (ADS)

    Klopfer, Michael; Satchouk, Vladimir; Cao, Anh; Wolowiec, Thomas; Alivov, Yahya; Molloi, Sabee

    2015-04-01

    X-ray emission from pyroelectric sources can be produced through non-contact thermal cycling using induction heating. In this study, we demonstrated a proof of concept non-contact x-ray source powered via induction heating. An induction heater operating at 62.5 kHz provided a total of 6.5 W of delivered peak thermal power with 140 V DC of driving voltage. The heat was applied to a ferrous substrate mechanically coupled to a cubic 1 cm3 Lithium Niobate (LiNbO3) pyroelectric crystal maintained in a 3-12 mTorr vacuum. The maximum temperature reached was 175 °C in 86 s of heating. The cooling cycle began immediately after heating and was provided by passive radiative cooling. The total combined cycle time was 250 s. x-ray photons were produced and analyzed in both heating and cooling phases. Maximum photon energies of 59 keV and 55 keV were observed during heating and cooling, respectively. Non-contact devices such as this, may find applications in cancer therapy (brachytherapy), non-destructive testing, medical imaging, and physics education fields.

  3. General-purpose heat source: Research and development program. Process evaluation, fuel pellet GF-47

    SciTech Connect

    Reimus, M.A.H.; George, T.G.

    1995-12-01

    The general-purpose heat source (GPHS) provides power for space missions by transmitting the heat of {sup 238}Pu decay to an array of thermoelectric elements. Because the potential for a launch abort or return from orbit exists for any space mission, the heat source must be designed and constructed to survive credible accident environments. Previous testing conducted in support of the Galileo and Ulysses missions has documented the response of the GPHS heat source to a variety of fragment-impact, aging, atmospheric reentry, and Earth-impact conditions. Although heat sources for previous missions were fabricated by the Westinghouse Savannah River Company (WSRC), GPHS fueled-clads required for the Cassini mission to Saturn will be fabricated by Los Alamos National Laboratory (LANL). This evaluation is part of an ongoing program to determine the similarity of GPHS fueled clads and fuel pellets fabricated at LANL to those fabricated at WSRC. Pellet GF-47, which was fabricated at LANL in late 1994, was submitted for chemical and ceramographic analysis. The results indicated that the pellet had a chemical makeup and microstructure within the range of material fabricated at WSRC in the early 1980s.

  4. Numerical simulation of precessing vortex core dumping by localized nonstationary heat source

    NASA Astrophysics Data System (ADS)

    Porfiriev, Denis; Gorbunova, Anastasiya; Zavershinsky, Igor; Sugak, Semen; Molevich, Nonna

    2016-10-01

    The precessing vortex core (PVC) is a crucial structure for many technical devices with the heat release. For this purpose, we performed the 3D numerical simulations of PVC in the swirling flow created in the open tube with the paraxial nonstationary heat source. Power of the source was modulated by sinusoidal law. We showed that three turbulence models give the qualitatively similar dependences of PVC frequency and amplitude on the heat-source power. The numerical simulation demonstrated that the obtained PVC is a left-handed co-rotated bending single-vortex structure. For considered values of the swirl and mass flow rate, we obtained that, for wide range of modulation frequencies, the growth of the heat-source power leads to gradual increase in the PVC frequency and slow change in the amplitude of vortex core oscillations. However, for specific modulation frequency, which depends on the tube geometry, dependencies of the PVC frequency and the amplitudes of oscillations have distinct maximum and minimum. Which means that, under specific conditions, flow pattern changes dramatically and precession is almost dumped at the relatively low values of heat power.

  5. Plane Strain Deformation In A Thermoelastic Microelongated Solid With Internal Heat Source

    NASA Astrophysics Data System (ADS)

    Ailawalia, P.; Sachdeva, S. K.; Pathania, D. S.

    2015-12-01

    The purpose of this paper is to study the two dimensional deformation due to an internal heat source in a thermoelastic microelongated solid. A mechanical force is applied along an overlaying elastic layer of thickness h. The normal mode analysis has been applied to obtain the exact expressions for the displacement component, force stress, temperature distribution and microelongation. The effect of the internal heat source on the displacement component, force stress, temperature distribution and microelongation has been depicted graphically for Green-Lindsay (GL) theory of thermoelasticity.

  6. Induction heating pure vapor source of high temperature melting point materials on electron cyclotron resonance ion source

    SciTech Connect

    Kutsumi, Osamu; Kato, Yushi; Matsui, Yuuki; Sato, Fuminobu; Iida, Toshiyuki; Kitagawa, Atsushi; Muramatsu, Masayuki; Uchida, Takashi; Yoshida, Yoshikazu

    2010-02-15

    Multicharged ions that are needed are produced from solid pure material with high melting point in an electron cyclotron resonance ion source. We develop an evaporator by using induction heating (IH) with multilayer induction coil, which is made from bare molybdenum or tungsten wire without water cooling and surrounding the pure vaporized material. We optimize the shapes of induction coil and vaporized materials and operation of rf power supply. We conduct experiment to investigate the reproducibility and stability in the operation and heating efficiency. IH evaporator produces pure material vapor because materials directly heated by eddy currents have no contact with insulated materials, which are usually impurity gas sources. The power and the frequency of the induction currents range from 100 to 900 W and from 48 to 23 kHz, respectively. The working pressure is about 10{sup -4}-10{sup -3} Pa. We measure the temperature of the vaporized materials with different shapes, and compare them with the result of modeling. We estimate the efficiency of the IH vapor source. We are aiming at the evaporator's higher melting point material than that of iron.

  7. Induction heating pure vapor source of high temperature melting point materials on electron cyclotron resonance ion source.

    PubMed

    Kutsumi, Osamu; Kato, Yushi; Matsui, Yuuki; Kitagawa, Atsushi; Muramatsu, Masayuki; Uchida, Takashi; Yoshida, Yoshikazu; Sato, Fuminobu; Iida, Toshiyuki

    2010-02-01

    Multicharged ions that are needed are produced from solid pure material with high melting point in an electron cyclotron resonance ion source. We develop an evaporator by using induction heating (IH) with multilayer induction coil, which is made from bare molybdenum or tungsten wire without water cooling and surrounding the pure vaporized material. We optimize the shapes of induction coil and vaporized materials and operation of rf power supply. We conduct experiment to investigate the reproducibility and stability in the operation and heating efficiency. IH evaporator produces pure material vapor because materials directly heated by eddy currents have no contact with insulated materials, which are usually impurity gas sources. The power and the frequency of the induction currents range from 100 to 900 W and from 48 to 23 kHz, respectively. The working pressure is about 10(-4)-10(-3) Pa. We measure the temperature of the vaporized materials with different shapes, and compare them with the result of modeling. We estimate the efficiency of the IH vapor source. We are aiming at the evaporator's higher melting point material than that of iron.

  8. Preparation of Hydrophilic Polymer Surfaces using Microwave Rectangular Plasma

    NASA Astrophysics Data System (ADS)

    Yoshiki, Hiroyuki; Komatsu, Yuichi; Suzuki, Ayato

    A microwave rectangular plasma was generated over 450 mm long using a sectorial horn antenna with the aperture of 400×10 mm2 and permanent magnets. High density plasma was efficiently produced due to the electron cyclotron resonance (ECR) heating. Ion saturation current density of 5-10 mA/cm2 for Ar plasma was attained in the vicinity of the ECR zone which is close to the quartz window. The spatial plasma uniformity of ±7% was obtained over 300 mm long at 400 W, 1.0 Pa at the position of 160 mm away from the quartz window. This plasma source was applied to the surface modification of the high density poly(ethylene) (HDPE) and poly(tetrafluoroethylene) (PTFE) sheets. After Ar plasma irradiation at 400 W, 10 Pa and 150 s, the contact angles on the HDPE and PTFE surfaces decreased from 82° to 31° and from 90° to 49°, respectively. In addition, the uniformity on the plasma treatment was ±7% for HDPE and ±5% for PTFE over 420 mm long. X-ray photoelectron spectroscopy (XPS) analysis showed that defluorination and the formation of C=O groups appeared on the plasma treated surfaces.

  9. Efficient computation of coherent synchrotron radiation in a rectangular chamber

    NASA Astrophysics Data System (ADS)

    Warnock, Robert L.; Bizzozero, David A.

    2016-09-01

    We study coherent synchrotron radiation (CSR) in a perfectly conducting vacuum chamber of rectangular cross section, in a formalism allowing an arbitrary sequence of bends and straight sections. We apply the paraxial method in the frequency domain, with a Fourier development in the vertical coordinate but with no other mode expansions. A line charge source is handled numerically by a new method that rids the equations of singularities through a change of dependent variable. The resulting algorithm is fast compared to earlier methods, works for short bunches with complicated structure, and yields all six field components at any space-time point. As an example we compute the tangential magnetic field at the walls. From that one can make a perturbative treatment of the Poynting flux to estimate the energy deposited in resistive walls. The calculation was motivated by a design issue for LCLS-II, the question of how much wall heating from CSR occurs in the last bend of a bunch compressor and the following straight section. Working with a realistic longitudinal bunch form of r.m.s. length 10.4 μ m and a charge of 100 pC we conclude that the radiated power is quite small (28 W at a 1 MHz repetition rate), and all radiated energy is absorbed in the walls within 7 m along the straight section.

  10. Rectangular subsonic jet flowfield study

    NASA Technical Reports Server (NTRS)

    Morrison, Gerald L.; Tatterson, Gary B.; Swan, David H.

    1987-01-01

    The flowfield of a rectangular jet with 2:1 aspect ratio was studied at an axial Reynolds number of 127,000, using a three-dimensional laser anemometer. The flowfield surveys resulted in mean velocity vector field plots and contour plots of the Reynolds stress tensor components for the major and minor axes. These data contribute substantially to currently available data of jet flowfields.

  11. GEO2D - Two-Dimensional Computer Model of a Ground Source Heat Pump System

    DOE Data Explorer

    James Menart

    2013-06-07

    This file contains a zipped file that contains many files required to run GEO2D. GEO2D is a computer code for simulating ground source heat pump (GSHP) systems in two-dimensions. GEO2D performs a detailed finite difference simulation of the heat transfer occurring within the working fluid, the tube wall, the grout, and the ground. Both horizontal and vertical wells can be simulated with this program, but it should be noted that the vertical wall is modeled as a single tube. This program also models the heat pump in conjunction with the heat transfer occurring. GEO2D simulates the heat pump and ground loop as a system. Many results are produced by GEO2D as a function of time and position, such as heat transfer rates, temperatures and heat pump performance. On top of this information from an economic comparison between the geothermal system simulated and a comparable air heat pump systems or a comparable gas, oil or propane heating systems with a vapor compression air conditioner. The version of GEO2D in the attached file has been coupled to the DOE heating and cooling load software called ENERGYPLUS. This is a great convenience for the user because heating and cooling loads are an input to GEO2D. GEO2D is a user friendly program that uses a graphical user interface for inputs and outputs. These make entering data simple and they produce many plotted results that are easy to understand. In order to run GEO2D access to MATLAB is required. If this program is not available on your computer you can download the program MCRInstaller.exe, the 64 bit version, from the MATLAB website or from this geothermal depository. This is a free download which will enable you to run GEO2D..

  12. Mini-Brayton heat source assembly design study. Volume 2: Titan 3C mission. [minimum weight modifications

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Major conclusions of the space shuttle heat source assembly study are reported that project a minimum weight design for a Titan 3 C synchronous orbit mission; requirements to recover the heat source in orbit are eliminated. This concept permits location of the heat source end enclosure supports and heat source assembly support housing in a low temperature region external to the insulation enclosure and considers titanium and beryllium alloys for these support elements. A high melting insulation blanket consisting of nickel foil coated with zirconia, or of gold foil separated with glass fiber layers, is selected to provide emergency cooling in the range 2000 to 2700 F to prevent the isotope heat source from reaching unsafe temperatures. A graphic view of the baseline heat source assembly is included.

  13. L- and U-shaped heat pipes thermal modules with twin fans for cooling of electronic system under variable heat source areas

    NASA Astrophysics Data System (ADS)

    Wang, Jung-Chang

    2014-04-01

    This study utilizes a versatile superposition method with thermal resistance network analysis to design and experiment on a thermal module with embedded six L-shaped or two U-shaped heat pipes and plate fins under different fan speeds and heat source areas. This type of heat pipes-heat sink module successively transfer heat capacity from a heat source to the heat pipes, the heat sink and their surroundings, and are suitable for cooling electronic systems via forced convection mechanism. The thermal resistances contain all major components from the thermal interface through the heat pipes and fins. Thermal performance testing shows that the lowest thermal resistances of the representative L- and U-shaped heat pipes-heat sink thermal modules are respectively 0.25 and 0.17 °C/W under twin fans of 3,000 RPM and 30 × 30 mm2 heat sources. The result of this work is a useful thermal management method to facilitate rapid analysis.

  14. Design and qualification testing of a strontium-90 fluoride heat source

    SciTech Connect

    Fullam, H.T.

    1981-12-01

    The Strontium Heat Source Development Program began at the Pacific Northwest Laboratory (PNL) in 1972 and is scheduled to be completed by the end of FY-1981. The program is currently funded by the US Department of Energy (DOE) By-Product Utilization Program. The primary objective of the program has been to develop the data and technology required to permit the licensing of power systems for terrestrial applications that utilize /sup 90/SrF/sub 2/-fueled radioisotope heat sources. A secondary objective of the program has been to design and qualification-test a general purpose /sup 90/SrF/sub 2/-fueled heat source. The effort expended in the design and testing of the heat source is described. Detailed information is included on: heat source design, licensing requirements, and qualification test requirements; the qualification test procedures; and the fabrication and testing of capsules of various materials. The results obtained in the qualification tests show that the outer capsule design proposed for the /sup 90/SrF/sub 2/ heat source is capable of meeting current licensing requirements when Hastelloy S is used as the outer capsule material. The data also indicate that an outer capsule of Hastelloy C-4 would probably also meet licensing requirements, although Hastelloy S is the preferred material. Therefore, based on the results of this study, the general purpose /sup 90/SrF/sub 2/ heat source will consist of a standard WESF Hastelloy C-276 inner capsule filled with /sup 90/SrF/sub 2/ and a Hastelloy S outer capsule having a 2.375-in. inner diameter and 0.500-in. wall thickness. The end closures for this study, the general purpose /sup 90/SrF/sub 2/ heat a Hastelloy S outer capsule having a 2.375-in. inner diameter and 0.500-in. wall thickness. The end closures for the outer capsule will utilize an interlocking joint design requiring a 0.1-in. penetration closure weld. (LCL)

  15. Exergy and Energy analysis of a ground-source heat pump for domestic water heating under simulated occupancy conditions

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D; Gehl, Anthony C

    2012-01-01

    This paper presents detailed analysis of a water to water ground source heat pump (WW-GSHP) to provide all the hot water needs in a 345 m2 house located in DOE climate zone 4 (mixed-humid). The protocol for hot water use is based on the Building America Research Benchmark Definition (Hendron 2008; Hendron and Engebrecht 2010) which aims to capture the living habits of the average American household and its impact on energy consumption. The entire house was operated under simulated occupancy conditions. Detailed energy and exergy analysis provides a complete set of information on system efficiency and sources of irreversibility, the main cause of wasted energy. The WW-GSHP was sized at 5.275 kW (1.5-ton) for this house and supplied hot water to a 303 L (80 gal) water storage tank. The WW-GSHP shared the same ground loop with a 7.56 kW (2.1-ton) water to air ground source heat pump (WA-GSHP) which provided space conditioning needs to the entire house. Data, analyses, and measures of performance for the WW-GSHP in this paper complements the results of the WA-GSHP published in this journal (Ally, Munk et al. 2012). Understanding the performance of GSHPs is vital if the ground is to be used as a viable renewable energy resource.

  16. Safe atmosphere entry of an isotope heat source with a single stable trim attitude at hypersonic speeds

    NASA Technical Reports Server (NTRS)

    Levy, L. L., Jr.; Burns, R. K.

    1972-01-01

    A theoretical investigation has been made to design an isotope heat source capable of satisfying the conflicting thermal requirements of steady-state operation and atmosphere entry. The isotope heat source must transfer heat efficiently to a heat exchange during normal operation with a power system in space, and in the event of a mission abort, it must survive the thermal environment of atmosphere entry and ground impact without releasing radioactive material. A successful design requires a compatible integration of the internal components of the heat source with the external aerodynamic shape. To this end, configurational, aerodynamic, motion, and thermal analyses were coupled and iterated during atmosphere entries at suborbital through superorbital velocities at very shallow and very steep entry angles. Results indicate that both thermal requirements can be satisfied by a heat source which has a single stable aerodynamic orientation at hypersonic speeds. For such a design, the insulation material required to adequately protect the isotope fuel from entry heating need extend only half way around the fuel capsule on the aerodynamically stable (wind-ward) side of the heat source. Thus, a low-thermal-resistance, conducting heat path is provided on the opposite side of the heat source through which heat can be transferred to an adjacent heat exchanger during normal operation without exceeding specified temperature limits.

  17. Variable Property Flow in Rectangular Ducts with Repeated Rectangular Rib Roughness

    NASA Technical Reports Server (NTRS)

    Youn, B.; Mills, A. F.

    1992-01-01

    PHOENICS was used to simulate turbulent flow of supercritical hydrogen through asymmetrically heated rectangular ducts with one side rib-roughened, in order to provide design data for active cooling systems of hypersonic aircraft where the hydrogen fuel is used as coolant. Variable property and conjugate heat transfer effects were considered. The computations using PHOENICS required provision of property sub-routines for supercritical hydrogen, a low-Reynolds number form of the k-epsilon turbulence model, a rough-wall wall function and a procedure for calculating proper diffusion coefficients at the fluid-solid interface. The effect of each design variable such as width and height of duct and wall thickness, on pressure drop and maximum wall temperature was investigated. PHOENICS version 1.4 was used on an IBM 3090 computer.

  18. Model of the heat source of the Cerro Prieto magma-hydrothermal system, Baja California, Mexico

    SciTech Connect

    Elders, W.A.; Bird, D.K.; Williams, A.E.; Schiffman, P.; Cox, B.

    1982-08-10

    Earlier studies at Cerro Prieto by UCR have led to the development of a qualitative model for field flow in the geothermal system before it was drilled and perturbed by production. Current efforts are directed towards numerical modelling of heat and mass transfer in the system in this undisturbed state. A two-dimensional model assumes that the heat sources were a single basalt/gabbro intrusion which provided heat to the system as it cooled. After compiling various information on the physical properties of the reservoir, the enthalpy contained in two 1cm thick section across the reservoir orthogonal to each other was calculated. Next various shapes, sizes and depths for the intrusion as initial conditions and boundary conditions for the calculation of heat transfer were considered. A family of numerical models which so far gives the best matches to the conditions observed in the field today have in common a funnel-shaped intrusion with a top 4km wide emplaced at a depth of 5km some 30,000 to 50,000 years ago, providing heat to the geothermal system. Numerical modelling is still in progress. Although none of the models so far computed may be a perfect match for the thermal history of the reservoir, they all indicate that the intrusive heat source is young, close and large.

  19. General-purpose heat source safety verification test series: SVT-11 through SVT-13

    SciTech Connect

    George, T.G.; Pavone, D.

    1986-05-01

    The General-Purpose Heat Source (GPHS) is a modular component of the radioisotope thermoelectric generator that will provide power for the Galileo and Ulysses (formerly ISPM) space missions. The GPHS provides power by transmitting the heat of /sup 238/Pu ..cap alpha..-decay to an array of thermoelectric elements. Because the possibility of an orbital abort always exists, the heat source was designed and constructed to minimize plutonia release in any accident environment. The Safety Verification Test (SVT) series was formulated to evaluate the effectiveness of GPHS plutonia containment after atmospheric reentry and Earth impact. The first two reports (covering SVT-1 through SVT-10) described the results of flat, side-on, and angular module impacts against steel targets at 54 m/s. This report describes flat-on module impacts against concrete and granite targets, at velocities equivalent to or higher than previous SVTs.

  20. Heat removal from the simulation electrode of a high power log pulse ion source

    NASA Astrophysics Data System (ADS)

    Horiike, H.; Kondoh, U.; Morita, H.; Tanaka, S.

    1980-10-01

    The cooling of a target that simulated an electrode of the ion source operating in a megawatt regime was investigated. A copper disk with thin parallel cooling tubes were bombarded by hydrogen beams of 1A to 4A at 30 KeV for up to 7.6 s. The average heat loading to the target surface and to the cooling surface was as high as 220 W/sq cm and 570 W/sq cm, respectively. The temperature of the target was measured by thermocouples and found to be suppressed below 2000 C owing to an increase of heat transfer coefficient by subcool boiling of the cooling water. On the basis of this result, the extraction electrode of an ion source for JT-60 can be designed to withstand the operation exceeding 35 A at 75 KeV for 10 s from the heat transfer point of view.

  1. Multipurpose insulation system for a radioisotope fueled Mini-Brayton Heat Source Assembly

    NASA Technical Reports Server (NTRS)

    Aller, P.; Saylor, W.; Schmidt, G.; Wein, D.

    1976-01-01

    The Mini-Brayton Heat Source Assembly (HSA) consists of a radioisotope fueled heat source, a heat exchanger, a multifoil thermal insulation blanket, and a hermetically sealed housing. The thermal insulation blanket is a multilayer wrap of thin metal foil separated by a sparsely coated oxide. The objectives of the insulation blanket are related to the effective insulation of the HSA during operation, the transfer of the full thermal inventory to the housing when the primary coolant is not flowing, and the transfer of the full thermal inventory to the housing in the event of a flow stoppage of the primary coolant. A description is given of the approaches which have been developed to make it possible for the insulation blanket to meet these requirements.

  2. General-purpose heat source safety verification test series: SVT-11 through SVT-13

    NASA Astrophysics Data System (ADS)

    George, T. G.; Pavone, D.

    1986-05-01

    The General-Purpose Heat Source (GPHS) is a modular component of the radioisotope thermoelectric generator that will provide power for the Galileo and Ulysses (formerly ISPM) space missions. The GPHS provides power by transmitting the heat of Pu -decay to an array of thermoelectric elements. Because the possibility of an orbital abort always exists, the heat source was designed and constructed to minimize plutonia release in any accident environment. The Safety Verification Test (SVT) series was formulated to evaluate the effectiveness of GPHS plutonia containment after atmospheric reentry and Earth impact. The first two reports (covering SVT-1 through SVT-10) described the results of flat, side-on, and angular module impacts against steel targets at 54 m/s. This report describes flat-on module impacts against concrete and granite targets, at velocities equivalent to or higher than previous SVTs.

  3. General-purpose heat source safety verification test series: SVT-7 through SVT-10

    NASA Astrophysics Data System (ADS)

    George, T. G.; Pavone, D.

    1985-09-01

    The General-Purpose Heat Source (GPHS) is a modular component of the radioisotope thermoelectric generator that will supply power for the Galileo and Ulysses (formerly ISPM) space missions. The GPHS provides power by transmitting the heat of (238)PuO2 (ALPHA)-decay to an array of thermoelectric elements. Because the possibility of an orbital abort always exists, the heat source was designed and constructed to minimize plutonia release in any accident environment. The Safety Verification Test (SVT) series was formulated to evaluate the effectiveness of GPHS plutonia containment after atmospheric reentry and Earth impact. The first report (covering SVT-1 through SVT-6) described the results of flat and side-on module impacts. This report describes module impacts at angles of 15(0) and 30(0).

  4. Mathematical Modeling of Magneto Pulsatile Blood Flow Through a Porous Medium with a Heat Source

    NASA Astrophysics Data System (ADS)

    Sharma, B. K.; Sharma, M.; Gaur, R. K.; Mishra, A.

    2015-05-01

    In the present study a mathematical model for the hydro-magnetic non-Newtonian blood flow in the non-Darcy porous medium with a heat source and Joule effect is proposed. A uniform magnetic field acts perpendicular to the porous surface. The governing non-linear partial differential equations have been solved numerically by applying the explicit finite difference Method (FDM). The effects of various parameters such as the Reynolds number, hydro-magnetic parameter, Forchheimer parameter, Darcian parameter, Prandtl number, Eckert number, heat source parameter, Schmidt number on the velocity, temperature and concentration have been examined with the help of graphs. The present study finds its applications in surgical operations, industrial material processing and various heat transfer operations.

  5. Modification of hot cells for general purpose heat source assembly at the radioisotope power systems facility

    NASA Astrophysics Data System (ADS)

    Carteret, Betty A.

    1992-01-01

    Eight existing, unused hot cells currently are being modified for use in the Radioisotope Power Systems Facility (RPSF) to assemble 238Pu-fueled heat sources for Radioisotope Thermoelectric Generators (RTGs). Four air atmosphere cells will be used for storage, decanning, and decontamination of the iridium-clad radioisotope fuel. The remaining four argon atmosphere cells will be used to assemble fuel and graphite components for production and packaging of general purpose heat source (GPHS) assembly modules, which provide heat to drive the thermoelectric conversion process in the generators. The hot cells will be equipped to perform remote and glovebox-type operations. They will provide shielding and contamination control measures to reduce worker radiation exposure to levels within current U.S. Department of Energy (DOE) guidelines. Designs emphasize the Westinghouse Hanford Company (Westinghouse Hanford) as low as reasonably achievable (ALARA) radiation protection policy.

  6. Modification of hot cells for general purpose heat source assembly at the Radioisotope Power Systems Facility

    NASA Astrophysics Data System (ADS)

    Carteret, B. A.

    1991-09-01

    Eight existing, unused hot cells currently are being modified for use in the Radioisotope Power Systems Facility (RPSF) to assemble Pu-238 fueled heat sources for radioisotope thermoelectric generators (RTGs). Four air atmosphere cells will be used for storage, decanning, and decontamination of the iridium-clad radioisotope fuel. The remaining four argon atmosphere cells will be used to assemble fuel and graphite components for production and packaging of general purpose heat source (GPHS) assembly modules, which provide heat to drive the thermoelectric conversion process in the generators. The hot cells will be equipped to perform remote and glovebox-type operations. They will provide shielding and contamination control measures to reduce worker radiation exposure to levels within current U.S. Department of Energy (DOE) guidelines. Designs emphasize the Westinghouse Hanford Company (Westinghouse Hanford) as low as reasonably achievable (ALARA) radiation protection policy.

  7. Plasma diagnostics approach to welding heat source/molten pool interaction

    SciTech Connect

    Key, J.F.; McIlwain, M.E.; Isaacson, L.

    1980-01-01

    Plasma diagnostic techniques show that weld fusion zone profile and loss of metal vapors from the molten pool are strongly dependent on both the intensity and distribution of the heat source. These plasma properties, are functions of cathode vertex angle and thermal conductivity of the shielding gas, especially near the anode.

  8. Predictable Therma-fil removal technique using the system-B heat source.

    PubMed

    Guess, Garrett M

    2004-01-01

    A clinical tip is suggested to assist in the removal of Therma-fil obturators during conventional endodontic retreatment. Using a heat source such as the System-B, the plastic carriers that are normally an obstacle to retreatment can be efficiently removed using the technique described.

  9. Evaluation and characterization of General Purpose Heat Source girth welds for the Cassini mission

    SciTech Connect

    Lynch, C.M.; Moniz, P.F.; Reimus, M.A.H.

    1998-12-31

    General Purpose Heat Sources (GPHSs) are components of Radioisotopic thermoelectric Generators (RTGs) which provide electric power for deep space missions. Each GPHS consists of a {sup 238}Pu oxide ceramic pellet encapsulated in a welded iridium alloy shell which forms a protective barrier against the release of plutonia in the unlikely event of a launch-pad failure or reentry incident. GPHS fueled clad girth weld flaw detection was paramount to ensuring this safety function, and was accomplished using both destructive and non-destructive evaluation techniques. The first girth weld produced from each welding campaign was metallographically examined for flaws such as incomplete weld penetration, cracks, or porosity which would render a GPHS unacceptable for flight applications. After an acceptable example weld was produced, the subsequently welded heat sources were evaluated non-destructively for flaws using ultrasonic immersion testing. Selected heat sources which failed ultrasonic testing would be radiographed, and/or, destructively evaluated to further characterize and document anomalous indications. Metallography was also performed on impacted heat sources to determine the condition of the welds.

  10. FRG sealed isotopic heat sources project (C-229) project management plan

    SciTech Connect

    Metcalf, I.L.

    1997-05-16

    This Project Management Plan defines the cost, scope, schedule, organizational responsibilities, and work breakdown structure for the removal of the Federal Republic of Germany (FRG) Sealed Isotopic Heat Sources from the 324 Building and placed in interim storage at the Central Waste Complex (CWC).

  11. Development of a Variable-Speed Residential Air-Source Integrated Heat Pump

    SciTech Connect

    Rice, C Keith; Shen, Bo; Munk, Jeffrey D; Ally, Moonis Raza; Baxter, Van D

    2014-01-01

    A residential air-source integrated heat pump (AS-IHP) is under development in partnership with a U.S. manufacturer. A nominal 10.6 kW (3-ton) cooling capacity variable-speed unit, the system provides both space conditioning and water heating. This multi-functional unit can provide domestic water heating (DWH) in either full condensing (FC) (dedicated water heating or simultaneous space cooling and water heating) or desuperheating (DS) operation modes. Laboratory test data were used to calibrate a vapor-compression simulation model for each mode of operation. The model was used to optimize the internal control options for efficiency while maintaining acceptable comfort conditions and refrigerant-side pressures and temperatures within allowable operating envelopes. Annual simulations were performed with the AS-IHP installed in a well-insulated house in five U.S. climate zones. The AS-IHP is predicted to use 45 to 60% less energy than a DOE minimum efficiency baseline system while meeting total annual space conditioning and water heating loads. Water heating energy use is lowered by 60 to 75% in cold to warmer climates, respectively. Plans are to field test the unit in Knoxville, TN.

  12. Optimization and Thermoeconomics Research of a Large Reclaimed Water Source Heat Pump System

    PubMed Central

    Zhang, Zi-ping; Du, Fang-hui

    2013-01-01

    This work describes a large reclaimed water source heat pump system (RWSHPS) and elaborates on the composition of the system and its design principles. According to the characteristics of the reclaimed water and taking into account the initial investment, the project is divided into two stages: the first stage adopts distributed heat pump heating system and the second adopts the combination of centralized and decentralized systems. We analyze the heating capacity of the RWSHPS, when the phase II project is completed, the system can provide hydronic heating water with the supply and return water temperature of 55°C/15°C and meet the hydronic heating demand of 8 million square meters of residential buildings. We make a thermal economics analysis by using Thermal Economics theory on RWSHPS and gas boiler system, it is known that the RWSHPS has more advantages, compared with the gas boiler heating system; both its thermal efficiency and economic efficiency are relatively high. It provides a reference for future applications of the RWSHPS. PMID:24089607

  13. Development of a High Performance Air Source Heat Pump for the US Market

    SciTech Connect

    Abdelaziz, Omar; Shen, Bo; Gao, Zhiming; Baxter, Van D; Iu, Ipseng

    2011-01-01

    Heat pumps present a significant advantage over conventional residential heating technologies due to higher energy efficiencies and less dependence on imported oil. The US development of heat pumps dates back to the 1930 s with pilot units being commercially available in the 1950 s. Reliable and cost competitive units were available in the US market by the 1960 s. The 1973 oil embargo led to increased interest in heat pumps prompting significant research to improve performance, particularly for cold climate locations. Recent increasing concerns on building energy efficiency and environmental emissions have prompted a new wave of research in heat pump technology with special emphasis on reducing performance degradation at colder outdoor air temperatures. A summary of the advantages and limitations of several performance improvement options sought for the development of high performance air source heat pump systems for cold climate applications is the primary focus of this paper. Some recommendations for a high performance cold climate heat pump system design most suitable for the US market are presented.

  14. Optimization and thermoeconomics research of a large reclaimed water source heat pump system.

    PubMed

    Zhang, Zi-ping; Du, Fang-hui

    2013-01-01

    This work describes a large reclaimed water source heat pump system (RWSHPS) and elaborates on the composition of the system and its design principles. According to the characteristics of the reclaimed water and taking into account the initial investment, the project is divided into two stages: the first stage adopts distributed heat pump heating system and the second adopts the combination of centralized and decentralized systems. We analyze the heating capacity of the RWSHPS, when the phase II project is completed, the system can provide hydronic heating water with the supply and return water temperature of 55°C/15°C and meet the hydronic heating demand of 8 million square meters of residential buildings. We make a thermal economics analysis by using Thermal Economics theory on RWSHPS and gas boiler system, it is known that the RWSHPS has more advantages, compared with the gas boiler heating system; both its thermal efficiency and economic efficiency are relatively high. It provides a reference for future applications of the RWSHPS.

  15. Melting Process of Clathrate in a Rectangular Cell

    NASA Astrophysics Data System (ADS)

    Chiba, Takashi; Okada, Masashi; Matsumoto, Koji

    In order to clarify the mechanism of heat transfer during melting of a clathrate in rectangular cells, two melting processes, namely, two-dimensional melting process with natural convection from a vertical wall and one-dimensional melting process by heat conduction from an upper horizontal wall, are studied experimentally. The R-141b was used for generating clathrate. One experiment was carried out by melting the clathrate filled into a 150mm high and 100mm wide rectangular cell from a vertical wall. And in the other experiment, the clathrate was melted from the upper horizontal wall of a rectangular cell with 88mm height and 180mm width. The temperature distributions in cells were measured. The melting front was measured by pictures taken on fixed times. The concentration of freon in the melt was measured by gas-chromatography. The following results are obtained. (1) In the melting process, the clathrate decomposes into an emulsion region which is a water-freon mixture and a liquid freon region under the emulsion. (2) Concentration gradient of freon in the emulsion plyas an important role in the natural convection in the melt. The Nusselt number on the heated vertical wall is depressed by the concentration gradients.

  16. Sensitivity analysis on the performances of a closed-loop Ground Source Heat Pump

    NASA Astrophysics Data System (ADS)

    Casasso, Alessandro; Sethi, Rajandrea

    2014-05-01

    Ground Source Heat Pumps (GSHP) permit to achieve a significant reduction of greenhouse gas emissions, and the margins for economic saving of this technology are strongly correlated to the long-term sustainability of the exploitation of the heat stored in the soil. The operation of a GSHP over its lifetime should be therefore modelled considering realistic conditions, and a thorough characterization of the physical properties of the soil is essential to avoid large errors of prediction. In this work, a BHE modelling procedure with the finite-element code FEFLOW is presented. Starting from the governing equations of the heat transport in the soil around a GSHP and inside the BHE, the most important parameters are individuated and the adopted program settings are explained. A sensitivity analysis is then carried on both the design parameters of the heat exchanger, in order to understand the margins of improvement of a careful design and installation, and the physical properties of the soil, with the aim of quantifying the uncertainty induced by their variability. The relative importance of each parameter is therefore assessed by comparing the statistical distributions of the fluid temperatures and estimating the energy consumption of the heat pump, and practical conclusions are from these results about the site characterization, the design and the installation of a BHE. References Casasso A., Sethi R., 2014 Efficiency of closed loop geothermal heat pumps: A sensitivity analysis, Renewable Energy 62 (2014), pp. 737-746 Chiasson A.C., Rees S.J., Spitler J.D., 2000, A preliminary assessment of the effects of groundwater flow on closed-loop ground-source heat pump systems, ASHRAE Transactions 106 (2000), pp. 380-393 Delaleux F., Py X., Olives R., Dominguez A., 2012, Enhancement of geothermal borehole heat exchangers performances by improvement of bentonite grouts conductivity, Applied Thermal Engineering 33-34, pp. 92-99 Diao N., Li Q., Fang Z., 2004, Heat transfer in

  17. 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.

  18. Temperature Profiles Along the Root with Gutta-percha Warmed through Different Heat Sources

    PubMed Central

    Simeone, Michele; Santis, Roberto De; Ametrano, Gianluca; Prisco, Davide; Borrelli, Marino; Paduano, Sergio; Riccitiello, Francesco; Spagnuolo, Gianrico

    2014-01-01

    Objectives: To evaluate temperature profiles developing in the root during warm compaction of gutta-percha with the heat sources System B and System MB Obtura (Analityc Technology, Redmond, WA, USA). Thirty extracted human incisor teeth were used. Root canals were cleaned and shaped by means of Protaper rotary files (Dentsply-Maillefer, Belgium), and imaging was performed by micro-CT (Skyscan 1072, Aartselaar, Belgium). Methods: Teeth were instrumented with K-type thermocouples, and the roots were filled with thermoplastic gutta-percha. Vertical compaction was achieved through the heat sources System B and System MB, and temperature profiles were detect-ed by means of NI Dac Interface controlled by the LabView System. With both heat sources, higher temperature levels were recorded in the region of the root far from the apex. When the warm plugger tip was positioned at a distance of 3 mm from the root apex, temperature levels of about 180°C were used to soften gutta-percha, and no statistically significant differences were observed between peak temperatures developed by the two heating sources at the root apex. However, a temperature level higher than 40°C was maintained for a longer time with System MB. Results: Statistically significant differences were observed in peak temperature levels recorded far from the root apex. Thus, with a temperature of about 180°C and the warm plugger positioned at 3 mm from the root apex, both heating sources led to a temperature slightly higher than 40°C at the apex of the root, suggesting that the gutta-percha was properly softened. Significance: A temperature level higher than 40°C was maintained for a longer time with System MB, thus providing an ad-equate time for warm compaction of the gutta-percha. PMID:25614768

  19. Identifying (subsurface) anthropogenic heat sources that influence temperature in the drinking water distribution system

    NASA Astrophysics Data System (ADS)

    Agudelo-Vera, Claudia M.; Blokker, Mirjam; de Kater, Henk; Lafort, Rob

    2017-09-01

    The water temperature in the drinking water distribution system and at customers' taps approaches the surrounding soil temperature at a depth of 1 m. Water temperature is an important determinant of water quality. In the Netherlands drinking water is distributed without additional residual disinfectant and the temperature of drinking water at customers' taps is not allowed to exceed 25 °C. In recent decades, the urban (sub)surface has been getting more occupied by various types of infrastructures, and some of these can be heat sources. Only recently have the anthropogenic sources and their influence on the underground been studied on coarse spatial scales. Little is known about the urban shallow underground heat profile on small spatial scales, of the order of 10 m × 10 m. Routine water quality samples at the tap in urban areas have shown up locations - so-called hotspots - in the city, with relatively high soil temperatures - up to 7 °C warmer - compared to the soil temperatures in the surrounding rural areas. Yet the sources and the locations of these hotspots have not been identified. It is expected that with climate change during a warm summer the soil temperature in the hotspots can be above 25 °C. The objective of this paper is to find a method to identify heat sources and urban characteristics that locally influence the soil temperature. The proposed method combines mapping of urban anthropogenic heat sources, retrospective modelling of the soil temperature, analysis of water temperature measurements at the tap, and extensive soil temperature measurements. This approach provided insight into the typical range of the variation of the urban soil temperature, and it is a first step to identifying areas with potential underground heat stress towards thermal underground management in cities.

  20. A distribution parameter derived for rectangular channels and simulated subchannel geometry

    SciTech Connect

    Khan, H.J. . Dept. of Mechanical Engineering)

    1990-05-01

    The distribution parameter of the drift-flux model has been developed for a rectangular channel and a simulated boiling water reactor (BWR) subchannel. The void fraction prediction by the subchannel drift-flux code CANAL is demonstrated for heated rectangular channels. Intrasubchannel flow and void profiles are considered for subchannel model development. Distribution parameter C{sub 0} is found to be very sensitive to variation of the geometric parameters and subchannel types. Since void fraction measurements corresponding to the rectangular subchannel of a BWR rod bundle are unavailable at present, assessment of the derived models remains to be performed.

  1. X-ray diffraction from rectangular slits.

    PubMed

    Le Bolloc'h, D; Livet, F; Bley, F; Schulli, T; Veron, M; Metzger, T H

    2002-07-01

    It is shown that for micrometre-sized beams the X-ray diffraction from slits is a source of strong parasitic background, even for slits of high quality. In order to illustrate this effect, the coherent diffraction from rectangular slits has been studied in detail. A large number of interference fringes with strong visibility have been observed using a single set of slits made of polished cylinders. For very small apertures, asymmetrical slits generate asymmetrical patterns. This pattern is calculated from the theory of electromagnetic field propagation and compared with experiment in the far-field regime. The use of guard slits to remove Fraunhofer diffraction from the beam-defining slits is treated theoretically. Numerical simulations yield the optimum aperture of the guard slits with respect to the distance to the primary slits. Diffraction theory is shown to be essential to understand how to reduce the background-to-signal ratio in high-resolution experiments.

  2. Improvement of efficiency and temperature control of induction heating vapor source on electron cyclotron resonance ion source.

    PubMed

    Takenaka, T; Kiriyama, R; Muramatsu, M; Kitagawa, A; Uchida, T; Kurisu, Y; Nozaki, D; Yano, K; Yoshida, Y; Sato, F; Kato, Y; Iida, T

    2012-02-01

    An electron cyclotron resonance ion source (ECRIS) is used to generate multicharged ions for many kinds of the fields. We have developed an evaporator by using induction heating method that can generate pure vapor from solid state materials in ECRIS. We develop the new matching and protecting circuit by which we can precisely control the temperature of the induction heating evaporator. We can control the temperature within ±15 °C around 1400 °C under the operation pressure about 10(-4) Pa. We are able to use this evaporator for experiment of synthesizing process to need pure vapor under enough low pressure, e.g., experiment of generation of endohedral Fe-fullerene at the ECRIS.

  3. Improvement of efficiency and temperature control of induction heating vapor source on electron cyclotron resonance ion source

    SciTech Connect

    Takenaka, T.; Kiriyama, R.; Kurisu, Y.; Nozaki, D.; Yano, K.; Sato, F.; Kato, Y.; Iida, T.; Muramatsu, M.; Kitagawa, A.; Uchida, T.; Yoshida, Y.

    2012-02-15

    An electron cyclotron resonance ion source (ECRIS) is used to generate multicharged ions for many kinds of the fields. We have developed an evaporator by using induction heating method that can generate pure vapor from solid state materials in ECRIS. We develop the new matching and protecting circuit by which we can precisely control the temperature of the induction heating evaporator. We can control the temperature within {+-}15 deg. C around 1400 deg. C under the operation pressure about 10{sup -4} Pa. We are able to use this evaporator for experiment of synthesizing process to need pure vapor under enough low pressure, e.g., experiment of generation of endohedral Fe-fullerene at the ECRIS.

  4. An experimental study of waveguide coupled microwave heating with conventional multicusp negative ion sources

    NASA Astrophysics Data System (ADS)

    Komppula, J.; Kalvas, T.; Koivisto, H.; Laulainen, J.; Tarvainen, O.

    2015-04-01

    Negative ion production with conventional multicusp plasma chambers utilizing 2.45 GHz microwave heating is demonstrated. The experimental results were obtained with the multicusp plasma chambers and extraction systems of the RF-driven RADIS ion source and the filament driven arc discharge ion source LIISA. A waveguide microwave coupling system, which is almost similar to the one used with the SILHI ion source, was used. The results demonstrate that at least one third of negative ion beam obtained with inductive RF-coupling (RADIS) or arc discharge (LIISA) can be achieved with 1 kW of 2.45 GHz microwave power in CW mode without any modification of the plasma chamber. The co-extracted electron to H- ratio and the optimum pressure range were observed to be similar for both heating methods. The behaviour of the plasma implies that the energy transfer from the microwaves to the plasma electrons is mainly an off-resonance process.

  5. Waste heat recovery from the European Spallation Source cryogenic helium plants - implications for system design

    SciTech Connect

    Jurns, John M.; Bäck, Harald; Gierow, Martin

    2014-01-29

    The European Spallation Source (ESS) neutron spallation project currently being designed will be built outside of Lund, Sweden. The ESS design includes three helium cryoplants, providing cryogenic cooling for the proton accelerator superconducting cavities, the target neutron source, and for the ESS instrument suite. In total, the cryoplants consume approximately 7 MW of electrical power, and will produce approximately 36 kW of refrigeration at temperatures ranging from 2-16 K. Most of the power consumed by the cryoplants ends up as waste heat, which must be rejected. One hallmark of the ESS design is the goal to recycle waste heat from ESS to the city of Lund district heating system. The design of the cooling system must optimize the delivery of waste heat from ESS to the district heating system and also assure the efficient operation of ESS systems. This report outlines the cooling scheme for the ESS cryoplants, and examines the effect of the cooling system design on cryoplant design, availability and operation.

  6. A self-regulating heat pump to utilize wind and wave energy sources

    SciTech Connect

    Pritchard, C.; Low, R. )

    1990-01-01

    This paper describes the efficiency of using shaft work to drive a heat pump and the utilization of variable shaft work to upgrade heat from a source at near- constant temperature. A prototype heat pump is described that enables heat from an ambient source at {approximately} 20{degrees}C to be delivered to a load at {approximately} 100{degrees}C by a vapor compression system working with variable power input, such as that deriving from wind or wave energy. The design incorporates features that enable power inputs from 0.3-3 kW to be harnessed, corresponding to the wave energy in a 0.1-m width of usable wavefront, or the wind energy abstracted by a rotor of 2.5-m diameter in windspeeds of 7-15 m/s. A c.o.p. of {approximately}3 may be obtained over this range of power input. Thus the heat output is equivalent to that obtainable directly from an energy conversion device of three times the size.

  7. General-Purpose Heat Source: Research and development program: Cold-Process Verification Test Series

    SciTech Connect

    Reimus, M.A.H.; George, T.G.

    1996-06-01

    The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of {sup 238}Pu decay to an array of thermoelectric elements. Because any space mission could experience a launch abort or return from orbit, the heat source must be designed and constructed to survive credible accident environments. Previous testing conducted in support of the Galileo and Ulysses missions documented the response of GPHSs and individual GPHS capsules fueled with {sup 238}UO{sub 2} ({sup 235}U-depleted) to a variety of explosive overpressure and impact events. In the early 1990s, Los Alamos National Laboratory (LANL) resumed fabrication of {sup 238}UO{sub 2} GPHS pellets. The Cold-Process Verification (CPV) Test Series was designed to compare the response of GPHS heat sources loaded with recently fabricated hot- and cold-pressed {sup 238}UO{sub 2} pellets to the response of urania pellets used in the Galileo and Ulysses performance tests. This report documents eleven bare-capsule impacts and one impact of a fully loaded GPHS module. All of the failures observed in the bare-clad impact tests were similar to failures observed in previous safety tests. No failures occurred in the module impact test.

  8. Performance and Economic Modeling of Horizontally Drilled Ground-Source Heat Pumps in Select California Climates

    NASA Astrophysics Data System (ADS)

    Wiryadinata, Steven

    Service life modeling was performed to gage the viability of unitary 3.5 kWt, ground-source terminal heat pumps (GTHP) employing horizontal directionally drilled geothermal heat exchangers (GHX) over air-source terminal heat pumps (PTHP) in hotels and motels and residential apartment building sectors in California's coastal and inland climates. Results suggest the GTHP can reduce hourly peak demand for the utility by 7%-25% compared to PTHP, depending on the climate and building type. The annual energy savings, which range from -1% to 5%, are highly dependent on the GTHP pump energy use relative to the energy savings attributed to the difference in ground and air temperatures (DeltaT). In mild climates with small ?T, the pump energy use may overcome any advantage to utilizing a GHX. The majority of total levelized cost savings - ranging from 0.18/ft2 to 0.3/ft 2 - are due to reduced maintenance and lifetime capital cost normally associated with geothermal heat pump systems. Without these reductions (not validated for the GTHP system studied), the GTHP technology does not appear to offer significant advantages over PTHP in the climate zones studied here. The GTHP levelized cost was most sensitive to variations in installed cost and in some cases, energy use (influenced by climate zone choice), which together highlights the importance of climate selection for installation, and the need for larger market penetration of ground-source systems in order to bring down installed costs as the technology matures.

  9. Thulium heat source for high-endurance and high-energy density power systems

    NASA Astrophysics Data System (ADS)

    Walter, C. E.; Kammeraad, J. E.; Vankonynenburg, R.; Vansant, J. H.

    1991-05-01

    We are studying the performance characteristics of radioisotope heat source designs for high-endurance and high-energy-density power systems that use thulium-170. Heat sources in the power range of 5 to 50 kW(sub th) coupled with a power conversion efficiency of approximately 30 percent, can easily satisfy current missions for autonomous underwater vehicles. New naval missions will be possible because thulium isotope power systems have a factor of one-to-two hundred higher endurance and energy density than chemical and electrochemical systems. Thulium-170 also has several other attractive features, including the fact that it decays to stable ytterbium-170 with a half-life of four months. For terrestrial applications, refueling on that time scale should be acceptable in view of the advantage of its benign decay. The heat source designs we are studying account for the requirements of isotope production, shielding, and integration with power conversion components. These requirements are driven by environmental and safety considerations. Thulium is present in the form of thin refractory thulia disks that allow power conversion at high peak temperature. We give estimates of power system state points, performance, mass, and volume characteristics. Monte Carlo radiation analysis provides a detailed assessment of shield requirements and heat transfer under normal and distressed conditions is also considered.

  10. The role of heat source for spatio-temporal variations of mantle plumes

    NASA Astrophysics Data System (ADS)

    Kumagai, I.; Yamagishi, Y.; Davaille, A.

    2014-12-01

    Hot mantle plumes ascending from the core-mantle boundary experience a filtering effect by the endothermic phase change at the 660-km discontinuity. Fluid dynamics predicts that some hot mantle plumes stagnate at the phase boundary and locally heat the bottom of the upper mantle. This generates the secondary plumes in the upper mantle originating hotspots volcanic activities on the Earth's surface. Recently, seismic tomographic images around the upper-lower mantle boundary showed that the horizontal scale of the low velocity regions, which corresponds to that of the thermally buoyant heat sources, is the order of 100-1000 km. Although most of the fluid dynamic theories on the thermal plumes have been developed using an assumption that the heat source effect is negligible, the behaviors of the starting plumes in the upper mantle should depend on the size of heat source, which is generated by the hotter plume from the CMB. In order to understand the effects of heater size on the starting plume generation, we have experimentally investigated the behaviors of thermally buoyant plumes using a localized heat source (circular plate heater). The combination of quantitative visualization techniques of temperature (Thermochromic Liquid Crystals) and velocity (Particle Image Velocimetry) fields reveals the transient nature of the plume evolution: a variety of the spatio-tempotal distribution of plumes. Simple scaling laws for their ascent velocity and spacing of the plumes are experimentally determined. We also estimate the onset time of the secondary plumes in the upper mantle which depends on the local characteristics of the thermal boundary layer developing at the upper-lower mantle boundary.

  11. Heat pipe array heat exchanger

    DOEpatents

    Reimann, Robert C.

    1987-08-25

    A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

  12. Engineering for high heat loads on ALS (Advanced Light Source) beamlines

    SciTech Connect

    DiGennaro, R.; Swain, T.

    1989-08-01

    This paper discussed general thermal engineering problems and specific categories of thermal design issues for high photon flux beam lines at the LBL Advanced Light Source: thermal distortion of optical surfaces and elevated temperatures of thermal absorbers receiving synchrotron radiation. A generic design for water-cooled heat absorbers is described for use with ALS photon shutters, beam defining apertures, and heat absorbing masks. Also, results of in- situ measurements of thermal distortion of a water-cooled mirror in a synchrotron radiation beam line are compared with calculated performance estimates. 17 refs., 2 figs.

  13. Application analysis of ground source heat pumps in building space conditioning

    SciTech Connect

    Qian, Hua; Wang, Yungang

    2013-07-01

    The adoption of geothermal energy in space conditioning of buildings through utilizing ground source heat pump (GSHP, also known as geothermal heat pump) has increased rapidly during the past several decades. However, the impacts of the GSHP utilization on the efficiency of heat pumps and soil temperature distribution remained unclear and needs further investigation. This paper presents a novel model to calculate the soil temperature distribution and the coefficient of performance (COP) of GSHP. Different scenarios were simulated to quantify the impact of different factors on the GSHP performance, including heat balance, daily running mode, and spacing between boreholes. Our results show that GSHP is suitable for buildings with balanced cooling and heating loads. It can keep soil temperature at a relatively constant level for more than 10 years. Long boreholes, additional space between boreholes, intermittent running mode will improve the performance of GSHP, but large initial investment is required. The improper design will make the COP of GSHP even lower than traditional heat pumps. Professional design and maintenance technologies are greatly needed in order to promote this promising technology in the developing world.

  14. Regularities pertinent to heat transfer between torch gas layers and steam boiler firebox waterwalls. Part I. Geometrical and physical torch model as a source of heat radiation

    NASA Astrophysics Data System (ADS)

    Makarov, A. N.

    2014-09-01

    The progress seen in the 19th-21st centuries in the development of methods for calculating heat transfer in torch furnaces, fireboxes, and combustion chambers is analyzed. Throughout the 20th century, calculations of heat transfer were carried out based on the law for radiation from solid bodies deduced by Y. Stefan and L. Boltzmann. It is shown that the use of this law for calculating heat transfer of a torch (a gaseous source of radiation) in heating furnaces and power-generating installations leads to incorrect results. It is substantiated that there is crisis of methods for calculating heat transfer in torch furnaces and power-generating installations. Geometrical and physical torch models in the form of radiating cylindrical gas volumes as sources of heat radiation are proposed for overcoming this crisis.

  15. Curing of a Bisphenol-E Based Cyanate Ester using Magnetic Nanoparticles as an Internal Heat Source through Induction Heating

    DTIC Science & Technology

    2013-11-01

    laboratory oven . The two heating methods gave similar differential scanning calorimetry temperature profiles, conversion rates, and glass transition...heating in a conventional laboratory oven . The two heating methods gave similar differential scanning calorimetry temperature profiles, conversion rates...3 microwave induction heating,4 dielectric heating,5 and photo-induced thermal front polymerization.6 Only recently have nanoparticles been embedded

  16. The nature of asteroidal differentiation processes - Implications for primordial heat sources

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.

    1979-01-01

    A review of the geochemical data on basaltic achondrite group meteorites, here defined as diogenites, eucrites, howardites, mesosiderites, main-group pallasites and IIIAB irons, suggests that the following processes and properties were important in determining the compositions of igneous materials on asteroidal sized bodies: (1) inhomogeneities in source rock compositions, (2) variable degrees of partial melting from 5-100%, (3) multiple melt genesis from a single source region, (4) fractional crystallization, and (5) remelting of earlier formed igneous rocks. All of this activity started during or shortly after the major asteroidal accretion phase as suggested by the numerous 4.6 Gyr ages for eucrites and may have lasted for at least 200 m.y. The above properties imply an early, intense heat source that was both spatially and temporally variable. A review of asteroid thermal modeling for various heat sources shows that heating by short-lived Al-26 alone appears to be incapable of supplying the observed geochemical variations.

  17. Partitioning sparse rectangular matrices for parallel processing

    SciTech Connect

    Kolda, T.G.

    1998-05-01

    The authors are interested in partitioning sparse rectangular matrices for parallel processing. The partitioning problem has been well-studied in the square symmetric case, but the rectangular problem has received very little attention. They will formalize the rectangular matrix partitioning problem and discuss several methods for solving it. They will extend the spectral partitioning method for symmetric matrices to the rectangular case and compare this method to three new methods -- the alternating partitioning method and two hybrid methods. The hybrid methods will be shown to be best.

  18. Allothermal gasification of biomass using micron size biomass as external heat source.

    PubMed

    Cheng, Gong; Li, Qian; Qi, Fangjie; Xiao, Bo; Liu, Shiming; Hu, Zhiquan; He, Piwen

    2012-03-01

    An allothermal biomass gasification system using biomass micron fuel (BMF) as external heat source was developed. In this system, heat supplied to gasifier was generated from combustion of BMF. Biomass feedstock was gasified with steam and then tar in the produced gas was decomposed in a catalytic bed with NiO/γ-Al(2)O(3) catalyst. Finally the production gas was employed as a substitute for civil fuel gas. An overall energy analysis of the system was also investigated. The results showed that the lower heating value of the product gas reached more than 12 MJ/Nm(3). The combusted BMF accounted for 26.8% of the total energy input. Allothermal gasification based on the substituted BMF for conventional energy was an efficient and economical technology to obtain bioenergy.

  19. System simulation for an untreated sewage source heat pump (USSHP) in winter

    NASA Astrophysics Data System (ADS)

    Qin, Na; Hao, Peng Z.

    2017-01-01

    The paper discusses the system characteristics of an untreated sewage source heat pump in winter. In this system, the sewage enters into the evaporator directly. The variable parameters to control the system contain the sewage temperature at evaporator inlet and the water temperature at condenser inlet. It is found that most parameters, except the condensation heat transfer coefficient, change in the form of sine wave the same as the sewage temperature at inlet. The heating load and consumed power are 12.9kW and 3.45kW when the sewage temperature at inlet is 13°C. COP is about 3.75 in the range of the sewage temperature at inlet of 12-13°C.

  20. Operation of the CAPRICE electron cyclotron resonance ion source applying frequency tuning and double frequency heating.

    PubMed

    Maimone, F; Tinschert, K; Celona, L; Lang, R; Mäder, J; Rossbach, J; Spädtke, P

    2012-02-01

    The properties of the electromagnetic waves heating the electrons of the ECR ion sources (ECRIS) plasma affect the features of the extracted ion beams such as the emittance, the shape, and the current, in particular for higher charge states. The electron heating methods such as the frequency tuning effect and the double frequency heating are widely used for enhancing the performances of ECRIS or even for the routine operation during the beam production. In order to better investigate these effects the CAPRICE ECRIS has been operated using these techniques. The ion beam properties for highly charged ions have been measured with beam diagnostic tools. The reason of the observed variations of this performance can be related to the different electromagnetic field patterns, which are changing inside the plasma chamber when the frequency is varying.

  1. Detailed heat load calculations for the conceptual design of the Advanced Neutron Source reactor

    SciTech Connect

    Wemple, C.A.

    1993-12-01

    A very detailed MCNP model of the Advanced Neutron Source reactor has been developed at Idaho National Engineering Laboratory. All reactor components inside the reflector vessel were included, and al components were highly segmented. Specific heat loads (watts per gram) have been calculated for each segment in the model, and system-integrated total powers are compared with the design value for the total reactor fission power. The calculated results agree very well with the design values. Axial profiles of the heat loads are provided for all components of the reactor. Individual segment statistical uncertainties were limited wherever possible, and the heat loads for all important reflector components have a standard deviation below 5%.

  2. ENERGY STAR Certified Non-AHRI Central Air Conditioner Equipment and Air Source Heat Pump

    EPA Pesticide Factsheets

    Certified models meet all ENERGY STAR requirements as listed in the Version 5.0 ENERGY STAR Program Requirements for Air Source Heat Pump and Central Air Conditioner Equipment that are effective as of September 15, 2015. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=airsrc_heat.pr_crit_as_heat_pumps Listed products have been submitted to EPA by ENERGY STAR partners that do not participate in the AHRI certification program. EPA will continue to update this list with products that are certified by EPA-recognized certification bodies other than AHRI. The majority of ENERGY STAR products, certified by AHRI, can be found on the CEE/AHRI Verified Directory at http://www.ceedirectory.org/

  3. Investigation of acoustic gravity waves created by anomalous heat sources: experiments and theoretical analysis

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Lee, M. C.

    2013-07-01

    We have been investigating high-power radio wave-induced acoustic gravity waves (AGWs) at Gakona, Alaska, using the High-frequency Active Aurora Research Program (HAARP) heating facility (i.e. HF heater) and extensive diagnostic instruments. This work was aimed at performing a controlled study of the space plasma turbulence triggered by the AGWs originating from anomalous heat sources, as observed in our earlier experiments at Arecibo, Puerto Rico (Pradipta 2007 MS Thesis MIT Press, Cambridge, MA). The HF heater operated in continuous wave (CW) O-mode can heat ionospheric plasmas effectively to yield a depleted magnetic flux tube as rising plasma bubbles (Lee et al 1998 Geophys. Res. Lett. 25 579). Two processes are responsible for the depletion of the magnetic flux tube: (i) thermal expansion and (ii) chemical reactions caused by heated ions. The depleted plasmas create large density gradients that can augment spread F processes via generalized Rayleigh-Taylor instabilities (Lee et al 1999 Geophys. Res. Lett. 26 37). It is thus expected that the temperature of neutral particles in the heated ionospheric region can be increased. Such a heat source in the neutral atmosphere may potentially generate AGWs in the form of traveling ionospheric plasma disturbances (TIPDs). We should point out that these TIPDs have features distinctively different from electric and magnetic field (ExB) drifts of HF wave-induced large-scale non-propagating plasma structures. Moreover, it was noted in our recent study of naturally occurring AGW-induced TIDs that only large-scale AGWs can propagate upward to reach higher altitudes. Thus, in our Gakona experiments we select optimum heating schemes for HF wave-induced AGWs that can be distinguished from the naturally occurring ones. The generation and propagation of AGWs are monitored by MUIR (Modular Ultra high-frequency Ionospheric Radar), Digisonde and GPS/low-earth-orbit satellites. Our theoretical and experimental studies have shown that

  4. Nusselt numbers in rectangular ducts with laminar viscous dissipation

    SciTech Connect

    Morini, G.L.; Spiga, M.

    1999-11-01

    The need for high thermal performance has stimulated the use of rectangular ducts in a wide variety of compact heat exchangers, mainly in tube-fin and plate-fin exchangers, in order to obtain an enhancement in heat transfer, with the same cross-sectional area of the duct. In this paper, the steady temperature distribution and the Nusselt numbers are analytically determined for a Newtonian incompressible fluid in a rectangular duct, in fully developed laminar flow with viscous dissipation, for any combination of heated and adiabatic sides of the duct, in H1 boundary condition, and neglecting the axial heat conduction in the fluid. The Navier-Stokes and the energy balance equations are solved using the technique of the finite integral transforms. For a duct with four uniformly heated sides (4 version), the temperature distribution and the Nusselt numbers are obtained as a function of the aspect ratio and of the Brinkman number and presented in graphs and tables Finally it is proved that the temperature field in a fully developed T boundary condition can be obtained as a particular case of the H1 problem and that the corresponding Nusselt numbers do not depend on the Brinkman number.

  5. Estimation of spatially varying heat transfer coefficient from a flat plate with flush mounted heat sources using Bayesian inference

    NASA Astrophysics Data System (ADS)

    Jakkareddy, Pradeep S.; Balaji, C.

    2016-09-01

    This paper employs the Bayesian based Metropolis Hasting - Markov Chain Monte Carlo algorithm to solve inverse heat transfer problem of determining the spatially varying heat transfer coefficient from a flat plate with flush mounted discrete heat sources with measured temperatures at the bottom of the plate. The Nusselt number is assumed to be of the form Nu = aReb(x/l)c . To input reasonable values of ’a’ and ‘b’ into the inverse problem, first limited two dimensional conjugate convection simulations were done with Comsol. Based on the guidance from this different values of ‘a’ and ‘b’ are input to a computationally less complex problem of conjugate conduction in the flat plate (15mm thickness) and temperature distributions at the bottom of the plate which is a more convenient location for measuring the temperatures without disturbing the flow were obtained. Since the goal of this work is to demonstrate the eficiacy of the Bayesian approach to accurately retrieve ‘a’ and ‘b’, numerically generated temperatures with known values of ‘a’ and ‘b’ are treated as ‘surrogate’ experimental data. The inverse problem is then solved by repeatedly using the forward solutions together with the MH-MCMC aprroach. To speed up the estimation, the forward model is replaced by an artificial neural network. The mean, maximum-a-posteriori and standard deviation of the estimated parameters ‘a’ and ‘b’ are reported. The robustness of the proposed method is examined, by synthetically adding noise to the temperatures.

  6. A strongly heated neutron star in the transient z source MAXI J0556-332

    SciTech Connect

    Homan, Jeroen; Remillard, Ronald A.; Fridriksson, Joel K.; Wijnands, Rudy; Cackett, Edward M.; Degenaar, Nathalie; Linares, Manuel

    2014-11-10

    We present Chandra, XMM-Newton, and Swift observations of the quiescent neutron star in the transient low-mass X-ray binary MAXI J0556-332. Observations of the source made during outburst (with the Rossi X-ray Timing Explorer) reveal tracks in its X-ray color-color and hardness-intensity diagrams that closely resemble those of the neutron-star Z sources, suggesting that MAXI J0556-332 had near- or super-Eddington luminosities for a large part of its ∼16 month outburst. A comparison of these diagrams with those of other Z sources suggests a source distance of 46 ± 15 kpc. Fits to the quiescent spectra of MAXI J0556-332 with a neutron-star atmosphere model (with or without a power-law component) result in distance estimates of 45 ± 3 kpc, for a neutron-star radius of 10 km and a mass of 1.4 M {sub ☉}. The spectra show the effective surface temperature of the neutron star decreasing monotonically over the first ∼500 days of quiescence, except for two observations that were likely affected by enhanced low-level accretion. The temperatures we obtain for the fits that include a power law (kT{sub eff}{sup ∞} = 184-308 eV) are much higher than those seen for any other neutron star heated by accretion, while the inferred cooling (e-folding) timescale (∼200 days) is similar to other sources. Fits without a power law yield higher temperatures (kT{sub eff}{sup ∞} = 190-336 eV) and a shorter e-folding time (∼160 days). Our results suggest that the heating of the neutron-star crust in MAXI J0556-332 was considerably more efficient than for other systems, possibly indicating additional or more efficient shallow heat sources in its crust.

  7. Plasmonic Photothermal Heating of Intraperitoneal Tumors through the Use of an Implanted Near-Infrared Source

    PubMed Central

    2013-01-01

    Plasmonic nanomaterials including gold nanorods are effective agents for inducing heating in tumors. Because near-infrared (NIR) light has traditionally been delivered using extracorporeal sources, most applications of plasmonic photothermal therapy have focused on isolated subcutaneous tumors. For more complex models of disease such as advanced ovarian cancer, one of the primary barriers to gold nanorod-based strategies is the adequate delivery of NIR light to tumors located at varying depths within the body. To address this limitation, a series of implanted NIR illumination sources are described for the specific heating of gold nanorod-containing tissues. Through computational modeling and ex vivo studies, a candidate device is identified and validated in a model of orthotopic ovarian cancer. As the therapeutic, imaging, and diagnostic applications of plasmonic nanomaterials progress, effective methods for NIR light delivery to challenging anatomical regions will complement ongoing efforts to advance plasmonic photothermal therapy toward clinical use. PMID:23961973

  8. Temperature distribution of air source heat pump barn with different air flow

    NASA Astrophysics Data System (ADS)

    He, X.; Li, J. C.; Zhao, G. Q.

    2016-08-01

    There are two type of airflow form in tobacco barn, one is air rising, the other is air falling. They are different in the structure layout and working principle, which affect the tobacco barn in the distribution of temperature field and velocity distribution. In order to compare the temperature and air distribution of the two, thereby obtain a tobacco barn whose temperature field and velocity distribution are more uniform. Taking the air source heat pump tobacco barn as the investigated subject and establishing relevant mathematical model, the thermodynamics of the two type of curing barn was analysed and compared based on Fluent. Provide a reasonable evidence for chamber arrangement and selection of outlet for air source heat pump tobacco barn.

  9. Organic Rankine-cycle turbine power plant utilizing low temperature heat sources

    NASA Astrophysics Data System (ADS)

    Maizza, V.

    1980-03-01

    Utilizing and converting of existing low temperature and waste heat sources by the use of a high efficiency bottoming cycle is attractive and should be possible for many locations. This paper presents a theoretical study on possible combination of an organic Rankine-cycle turbine power plate with the heat pump supplied by waste energy sources. Energy requirements and system performances are analyzed using realistic design operating condition for a middle town. Some conversion systems employing working fluids other than water are being studied for the purpose of proposed application. Thermodynamic efficiencies, with respect to available resource, have been calculated by varying some system operating parameters at various reference temperature. With reference to proposed application equations and graphs are presented which interrelate the turbine operational parameters for some possible working fluids with computation results.

  10. In situ preparation of catalytic combustion films used as micro heat source by inkjet printing method

    NASA Astrophysics Data System (ADS)

    Xiao, Jinhua; Wang, Xiaohong; Luo, Xi; Hu, Zhiyu

    2015-02-01

    Catalyst films for methanol combustion, which could be used as micro heat source to provide energy for micro-nano-scale devices, were fabricated with an inkjet printing method. The inkjet printing was used to prepare catalyst films by optimizing inkjet-printed parameters (voltage: 65-70 V; pulse width: 20-30 μs; ink viscosity: near 1 mPa s) and depositing uniform morphologies (substrate temperature: 80 °C; water/ethylene glycol (W/EG): 95:5, v/v). The performances of micro catalytic heat source were evaluated by an infrared thermography (IR) camera. The temperature response reached 95% of the steady state temperature in about 150 s, the temperature difference reached 100 °C on the catalyst surface, and the temperature of catalytic combustion was controlled by adjusting the methanol/air (10% v/v) flow rate.

  11. Sources and potential application of waste heat utilization at a gas processing facility

    NASA Astrophysics Data System (ADS)

    Alshehhi, Alyas Ali

    Waste heat recovery (WHR) has the potential to significantly improve the efficiency of oil and gas plants, chemical and other processing facilities, and reduce their environmental impact. In this Thesis a comprehensive energy audit at Abu Dhabi Gas Industries Ltd. (GASCO) ASAB gas processing facilities is undertaken to identify sources of waste heat and evaluate their potential for on-site recovery. Two plants are considered, namely ASAB0 and ASAB1. Waste heat evaluation criteria include waste heat grade (i.e., temperature), rate, accessibility (i.e., proximity) to potential on-site waste heat recovery applications, and potential impact of recovery on installation performance and safety. The operating parameters of key waste heat source producing equipment are compiled, as well as characteristics of the waste heat streams. In addition, potential waste heat recovery applications and strategies are proposed, focusing on utilities, i.e., enhancement of process cooling/heating, electrical/mechanical power generation, and steam production. The sources of waste heat identified at ASAB facilities consist of gas turbine and gas generator exhaust gases, flared gases, excess propane cooling capacity, excess process steam, process gas air-cooler heat dissipation, furnace exhaust gases and steam turbine outlet steam. Of the above waste heat sources, exhaust gases from five gas turbines and one gas generator at ASAB0 plant, as well as from four gas turbines at ASAB1 plant, were found to meet the rate (i.e., > 1 MW), grade (i.e., > 180°C), accessibility (i.e., < 50 m from potential on-site WHR applications) and minimal impact criteria on the performance and safety of existing installations, for potential waste heat recovery. The total amount of waste heat meeting these criteria were estimated at 256 MW and 289 MW at ASAB0 and ASAB1 plants, respectively, both of which are substantial. Of the 289 MW waste generated at ASAB1, approximately 173 MW are recovered by waste heat

  12. Performance prediction between horizontal and vertical source heat pump systems for greenhouse heating with the use of artificial neural networks

    NASA Astrophysics Data System (ADS)

    Benli, Hüseyin

    2016-08-01

    This paper presents the suitability of artificial neural networks (ANNs) to predict the performance and comparison between a horizontal and a vertical ground source heat pump system. Performance forecasting is the precondition for the optimal control and energy saving operation of heat pump systems. In this study, performance parameters such as air temperature entering condenser fan-coil unit, air temperature leaving condenser fan-coil unit, and ground temperatures (2 and 60 m) obtained experimental studies are input data; coefficient of performance of system (COPsys) is in output layer. The back propagation learning algorithm with three different variants such as Levenberg-Marguardt, Pola-Ribiere conjugate gradient, and scaled conjugate gradient, and also tangent sigmoid transfer function were used in the network so that the best approach can be found. The results showed that LM with three neurons in the hidden layer is the most suitable algorithm with maximum correlation coefficients R2 of 0.999, minimum root mean square RMS value and low coefficient variance COV. The reported results confirmed that the use of ANN for performance prediction of COPsys,H-V is acceptable in these studies.

  13. Axisymmetric circulations forced by heat and momentum sources - A simple model applicable to the Venus atmosphere

    NASA Technical Reports Server (NTRS)

    Hou, A. Y.

    1984-01-01

    A simple mechanistic model of a zonally averaged circulation forced by heat and momentum sources is developed and applied to the Venus atmosphere in the light of recent data. Basic equations for a steady-state axisymmetric circulation are discussed, and the parametric dependence of a nearly inviscid Hadley circulation in the absence of eddy forcing is examined and extended to a wide range of thermal Rossby numbers. The effect of diffusion is considered and found to be small for the Venus cloud region. The zonally averaged eddy sources and sinks required to support the zonal superrotation on Venus are determined.

  14. Air-Source Integrated Heat Pump for Near-Zero Energy Houses: Technology Status Report

    SciTech Connect

    Murphy, Richard W; Rice, C Keith; Baxter, Van D; Craddick, William G

    2007-07-01

    This report documents the development of an air-source integrated heat pump (AS-IHP) through the third quarter of FY2007. It describes the design, analyses and testing of the AS-IHP, and provides performance specifications for a field test prototype and proposed control strategy. The results obtained so far continue to support the AS-IHP being a promising candidate to meet the energy service needs for DOE's development of a Zero Energy Home (ZEH) by the year 2020.

  15. A custom flexible experimental setup to test air source heat pump for smart buildings

    NASA Astrophysics Data System (ADS)

    Cracium, Vasile S.; Bojesen, Carsten; Trifa, Viorel

    2012-09-01

    In this paper a custom made experimental stand is presented, named controlled lab environment (CLE or climatic box), built for testing an air source heat pump (ASHP) under controlled evaporator ambient conditions and verify the performance and behavior of a theoretical model of the ASHP as a basis for optimization and efficiency improvements. While the data acquisitions from experiments are not yet available, the paper presents the design considerations and schematics of the CLE and a thermodynamic model of an ASHP.

  16. Recovery Act: Finite Volume Based Computer Program for Ground Source Heat Pump Systems

    SciTech Connect

    James A Menart, Professor

    2013-02-22

    This report is a compilation of the work that has been done on the grant DE-EE0002805 entitled Finite Volume Based Computer Program for Ground Source Heat Pump Systems. The goal of this project was to develop a detailed computer simulation tool for GSHP (ground source heat pump) heating and cooling systems. Two such tools were developed as part of this DOE (Department of Energy) grant; the first is a two-dimensional computer program called GEO2D and the second is a three-dimensional computer program called GEO3D. Both of these simulation tools provide an extensive array of results to the user. A unique aspect of both these simulation tools is the complete temperature profile information calculated and presented. Complete temperature profiles throughout the ground, casing, tube wall, and fluid are provided as a function of time. The fluid temperatures from and to the heat pump, as a function of time, are also provided. In addition to temperature information, detailed heat rate information at several locations as a function of time is determined. Heat rates between the heat pump and the building indoor environment, between the working fluid and the heat pump, and between the working fluid and the ground are computed. The heat rates between the ground and the working fluid are calculated as a function time and position along the ground loop. The heating and cooling loads of the building being fitted with a GSHP are determined with the computer program developed by DOE called ENERGYPLUS. Lastly COP (coefficient of performance) results as a function of time are provided. Both the two-dimensional and three-dimensional computer programs developed as part of this work are based upon a detailed finite volume solution of the energy equation for the ground and ground loop. Real heat pump characteristics are entered into the program and used to model the heat pump performance. Thus these computer tools simulate the coupled performance of the ground loop and the heat pump. The

  17. Finite Volume Based Computer Program for Ground Source Heat Pump System

    SciTech Connect

    Menart, James A.

    2013-02-22

    This report is a compilation of the work that has been done on the grant DE-EE0002805 entitled ?Finite Volume Based Computer Program for Ground Source Heat Pump Systems.? The goal of this project was to develop a detailed computer simulation tool for GSHP (ground source heat pump) heating and cooling systems. Two such tools were developed as part of this DOE (Department of Energy) grant; the first is a two-dimensional computer program called GEO2D and the second is a three-dimensional computer program called GEO3D. Both of these simulation tools provide an extensive array of results to the user. A unique aspect of both these simulation tools is the complete temperature profile information calculated and presented. Complete temperature profiles throughout the ground, casing, tube wall, and fluid are provided as a function of time. The fluid temperatures from and to the heat pump, as a function of time, are also provided. In addition to temperature information, detailed heat rate information at several locations as a function of time is determined. Heat rates between the heat pump and the building indoor environment, between the working fluid and the heat pump, and between the working fluid and the ground are computed. The heat rates between the ground and the working fluid are calculated as a function time and position along the ground loop. The heating and cooling loads of the building being fitted with a GSHP are determined with the computer program developed by DOE called ENERGYPLUS. Lastly COP (coefficient of performance) results as a function of time are provided. Both the two-dimensional and three-dimensional computer programs developed as part of this work are based upon a detailed finite volume solution of the energy equation for the ground and ground loop. Real heat pump characteristics are entered into the program and used to model the heat pump performance. Thus these computer tools simulate the coupled performance of the ground loop and the heat pump

  18. Experimental Thermo-Magnetic Convection Analysis in Tall Rectangular Enclosure

    NASA Astrophysics Data System (ADS)

    Pyrda, L.; Kraszewska, A.

    2016-09-01

    Rectangular enclosure with aspect ratio (AR=height/width) 2 was investigated in experimental thermo-magnetic convection analysis. Experimental enclosure was placed inside superconducting magnet in Rayleigh-Bénard configuration, in position, where magnetic field gradient was enhancing natural convection. Two types of paramagnetic fluid behaviour were identified at different magnetic induction values. It was possible by utilization of Fast Fourier Transform of recorded temperature signals inside experimental enclosure. Presented results shown augmented heat transfer in rectangular enclosure at high magnetic field gradient up to 300%. Transition zone of fluid behaviour for presented experimental setup was observed from RaTM·4-107 to RaTM·1.3·108.

  19. Variable density effects on the mixing of turbulent rectangular jets

    NASA Astrophysics Data System (ADS)

    Sarh, B.; Goekalp, I.

    Variable density turbulent rectangular jets are investigated theoretically and experimentally. The theoretical description capitalizes on Rodi (1978), but introduces a new definition for the effective channel width. The experimental results are obtained by LDA and fine-wires in strongly heated air jets issuing vertically from a long rectangular channel into still air. Both approaches indicate that axial decay rates of the mean velocity and temperature increase when the density ratio between the ambient medium and the jet is increased. The use of the effective channel width defined here allows the global density effect to be taken into account. The effect of keeping constant jet exit parameters when the density ratio is varied is also discussed.

  20. RF Sources for the ITER Ion Cyclotron Heating and Current Drive System

    SciTech Connect

    Hosea, J.; Brunkhorst, C.; Fredd, E.; Goulding, R. H.; Goulding, R. H.; Greenough, N.; Kung, C.; Rasmussen, D. A.; Swain, D. W.; Wilson, J. R.

    2005-10-04

    The RF source requirements for the ITER ion cyclotron (IC) heating and current drive system are very challenging ? 20 MW CW power into an antenna load with a VSWR of up to 2 over the frequency range of 35-65 MHz. For the two present antenna designs under consideration, 8 sources providing 2.5 MW each are to be employed. For these sources, the outputs of two final power amplifiers (FPAs), using the high power CPI 4CM2500KG tube, are combined with a 180? hybrid combiner to easily meet the ITER IC source requirements ? 2.5 MW is supplied at a VSWR of 2 at ? 70% of the maximum tube power available in class B operation. The cylindrical cavity configuration for the FPAs is quite compact so that the 8 combined sources fit into the space allocated at the ITER site with room to spare. The source configuration is described in detail and its projected operating power curves are presented. Although the CPI tube has been shown to be stable under high power operating conditions on many facilities, a test of the combined FPA source arrangement is in preparation using existing high power 30 MHz amplifiers to assure that this configuration can be made robustly stable for all phases at a VSWR up to 2. The possibility of using 12 sources to feed a suitably modified antenna design is also discussed in the context of providing flexibility for specifying the final IC antenna design.

  1. Modeling heat generation and flow in the Advanced Neutron Source Corrosion Test Loop specimen

    SciTech Connect

    Pawel, R.E.; Yarbrough, D.W.

    1988-01-01

    A finite difference computer code HEATING5 was used to model heat generation and flow in a typical experiment envisioned for the Advanced Neutron Source Corrosion Test Loop. The electrical resistivity and thermal conductivity of the test specimen were allowed to vary with local temperature, and the corrosion layer thickness was assigned along the length of the specimen in the manner predicted by the Griess Correlation. The computer solved the two-dimensional transport problem for a given total power dissipated in the specimen and stipulated coolant temperatures and water-side heat-transfer coefficients. The computed specimen temperatures were compared with those calculated on the basis of approximate analytical equations involving the total power dissipation and the assignment of the physical properties based on temperatures at single axial points on the specimen. The comparisons indicate that when temperature variations are large along the axis of the specimen, the variation in local heat flux should not be overlooked when using approximate equations or models. The approximate equations are most accurate near the center of the specimen where the heat flux remains closest to the average value, and in that region the calculated quantities agree closely with the results of the computer code. 4 figs., 1 tab.

  2. Integration of Radioisotope Heat Source with Stirling Engine and Cooler for Venus Internal-Structure Mission

    SciTech Connect

    Schock, Alfred

    1993-10-01

    The primary mission goal is to perform long-term seismic measurements on Venus, to study its largely unknown internal structure. The principal problem is that most payload components cannot long survive Venus's harsh environment, 90 bars at 500 degrees C. To meet the mission life goal, such components must be protected by a refrigerated payload bay. JPL Investigators have proposed a mission concept employing a lander with a spherical payload bay cooled to 25 degrees C by a Stirling cooler powered by a radioisotope-heated Sitrling engine. To support JPL's mission study, NASA/Lewis and MTI have proposed a conceptual design for a hydraulically coupled Stirling engine and cooler, and Fairchild Space - with support of the Department of Energy - has proposed a design and integration scheme for a suitable radioisotope heat source. The key integration problem is to devise a simple, light-weight, and reliable scheme for forcing the radioisotope decay heat to flow through the Stirling engine during operation on Venus, but to reject that heat to the external environment when the Stirling engine and cooler are not operating (e.g., during the cruise phase, when the landers are surrounded by heat shields needed for protection during subsequent entry into the Venusian atmosphere.) A design and integration scheme for achieving these goals, together with results of detailed thermal analyses, are described in this paper. There are 7 copies in the file.

  3. Model for the heat source of the Cerro Prieto magma-hydrothermal system, Baja California, Mexico

    SciTech Connect

    Elders, W.A.; Bird, D.K.; Williams, A.E.; Schiffman, P.; Cox, B.

    1981-01-01

    Earlier studies at Cerro Prieto led to the development of a qualitative model for fluid flow in the geothermal system before it was drilled and perturbed by production. Current efforts are directed towards numerical modeling of heat and mass transfer in the system in this undisturbed state. This one-dimensional model assumes that the heat source was a single basalt/gabbro intrusion which provided heat to the system as it cooled. After compilation of various information of the physical properties of the reservoir, the enthalpy contained in two 1 cm thick sections across the reservoir orthogonal to each other was calculated. Various shapes, sizes and depths for the intrusion were considered as initial conditions and boundary conditions for the calculations of heat transfer. A family of numerical models which so far gives the best matches to the conditions observed in the field today have in common a funnel-shaped intrusion with a top 4 km wide emplaced at a depth of 5 km some 30,000 to 50,000 years ago, providing heat to the geothermal system.

  4. Stress analysis and testing of the outer capsule design for the Strontium Heat Source Development Program

    SciTech Connect

    Simonen, F.A.; Shippell, R.J. Jr.; Atteridge, D.G.

    1980-01-01

    The objective of the Strontium Heat Source Development Program is to obtain the data needed to license /sup 90/SrF/sub 2/ heat sources - specifically the /sup 90/SrF/sub 2/ capsules produced in the Waste Encapsulation and Storage Facility (WESF) at Hanford. Toward this end, a high integrity outer capsule has been designed to replace the present outer capsule of the WESF /sup 90/SrF/sub 2/ capsule. The proposed design of a Hastelloy S outer capsule which features a mechanical interlock type of end closure is described. Qualification testing requirements are outlined, and stress analyses and developmental tests are described. These tests were performed on AISI-1018 steel stand-in capsules, and included both external pressure and impact tests. The external pressure tests showed that stress calculations seriously overestimated the pressure capability of the outer capsule. Possible reasons for the lack of agreement between the tests and the analyses are evaluated. The stress analyses and tests results indicate that the proposed outer capsule will meet the heat source qualification requirements. Future tests will be conducted to experimentally verify that the Hastelloy S outer capsule in an aged condition meets the structural integrity requirements.

  5. Development of a radioisotope heat source for the two-watt radioisotope thermoelectric generator

    NASA Astrophysics Data System (ADS)

    Howell, Edwin I.; McNeil, Dennis C.; Amos, Wayne R.

    1992-01-01

    Described is a radioisotope heat source for the Two-Watt Radioisotope Thermoelectric Generator (RTG) which is being considered for possible application by the U.S. Navy and for other Department of Defense applications. The heat source thermal energy (75 Wt) is produced from the alpha decay of plutonium-238 which is in the form of high-fired plutonium dioxide. The capsule is non-vented and consists of three domed cylindrical components each closed with a corresponding sealed end cap. Surrounding the fuel is the liner component, which is fabricated from a tantalum-based alloy, T-111. Also fabricated from T-111 is the next component, the strength member, which serves to meet pressure and impact criteria. The outermost component, or clad, is the oxidation- and corrosion-resistant nickel-based alloy, Hastelloy S. This paper defines the design considerations, details the hardware fabrication and welding processes, discusses the addition of yttrium to the fuel to reduce liner embrittlement, and describes the testing that has been conducted or is planned to assure that there is fuel containment not only during the heat source operational life, but also in case of an accident environment.

  6. Design evolution and verification of the general-purpose heat source

    SciTech Connect

    Schock, A

    1980-01-01

    The General-Purpose Heat Source (GPHS) is a radioisotope heat source for use in space power systems. It employs a modular design, to make it adaptable to a wide range of energy conversion systems and power levels. Each 250 W module is completely autonomous, with its own passive safety provisions to prevent fuel release under all abort modes, including atmospheric reentry and earth impact. Prior development tests had demonstrated good impact survival as long as the iridium fuel capsules retained their ductility. This requires high impact temperatures, typically above 900/sup 0/C and reasonably fine grain size, which in turn requires avoidance of excessive operating temperatures and reentry temperatures. These three requirements - on operating, reentry, and impact temperatures - are in mutual conflict, since thermal design changes to improve any one of these temperatures tend to worsen one or both of the others. This conflict creates a difficult design problem, which for a time threatened the success of the program. The present paper describes how this problem was overcome by successive design revisions, supplemented by thermal analyses and confirmatory vibration and impact tests; and how this may be achieved while raising the specific power of the GPHS to 83 W/lb, a 50% improvement over previously flown radioisotope heat sources.

  7. Mapping from rectangular to harmonic representation

    SciTech Connect

    Schneider, W.; Bateman, G.

    1986-08-01

    An algorithm is developed to determine the Fourier harmonics representing the level contours of a scalar function given on a rectangular grid. This method is applied to the problem of computing the flux coordinates and flux surface average needed for 1-1/2-D transport codes and MHD stability codes from an equilibrium flux function given on a rectangular grid.

  8. Buckling Analysis of Rectangular Plates With Holes

    NASA Technical Reports Server (NTRS)

    Nemeth, M. P.

    1987-01-01

    BUCKO is computer program developed to predict buckling of rectangular compression-loaded orthotropic plate with centrally located cutout. Plate assumed balanced, symmetric laminate of uniform thickness. Cutout shape elliptical, circular, rectangular, or square. Package includes sample data demonstrating essence of program and ease of use. Written in FORTRAN V.

  9. Mapping from rectangular to harmonic representation

    SciTech Connect

    Schneider, W.; Bateman, G.

    1987-07-01

    An algorithm is developed to determine the Fourier harmonics representing the level contours of a scalar function given on a rectangular grid. This method is applied to the problem of computing the flux coordinates and flux surface averages needed for 11/2D transport codes and MHD stability codes from an equilibrium flux function on a rectangular grid. copyright 1987 Academic Press, Inc.

  10. Characterizing open and non-uniform vertical heat sources: towards the identification of real vertical cracks in vibrothermography experiments

    NASA Astrophysics Data System (ADS)

    Castelo, A.; Mendioroz, A.; Celorrio, R.; Salazar, A.; López de Uralde, P.; Gorosmendi, I.; Gorostegui-Colinas, E.

    2017-05-01

    Lock-in vibrothermography is used to characterize vertical kissing and open cracks in metals. In this technique the crack heats up during ultrasound excitation due mainly to friction between the defect's faces. We have solved the inverse problem, consisting in determining the heat source distribution produced at cracks under amplitude modulated ultrasound excitation, which is an ill-posed inverse problem. As a consequence the minimization of the residual is unstable. We have stabilized the algorithm introducing a penalty term based on Total Variation functional. In the inversion, we combine amplitude and phase surface temperature data obtained at several modulation frequencies. Inversions of synthetic data with added noise indicate that compact heat sources are characterized accurately and that the particular upper contours can be retrieved for shallow heat sources. The overall shape of open and homogeneous semicircular strip-shaped heat sources representing open half-penny cracks can also be retrieved but the reconstruction of the deeper end of the heat source loses contrast. Angle-, radius- and depth-dependent inhomogeneous heat flux distributions within these semicircular strips can also be qualitatively characterized. Reconstructions of experimental data taken on samples containing calibrated heat sources confirm the predictions from reconstructions of synthetic data. We also present inversions of experimental data obtained from a real welded Inconel 718 specimen. The results are in good qualitative agreement with the results of liquids penetrants testing.

  11. Assessment of cereal-grain warming pad as a heat source for newborn transport.

    PubMed

    Jirapaet, Kriangsak; Jirapaet, Veena

    2005-11-01

    The study assessed warming pad (WP) filled with either mung beans or dry corn used in feeding livestocks as a heat source for newborn transport. Its use was to compensate for lack of transport incubator or to employ as a supplemental heat source for warming the infant or incubator when transport made in cold weather. The WP was made of a strong-cotton-cloth bag (the fabric for making jeans) with a size of A4 paper sheet. The bag was filled with one kilogram of either mung beans or dry corn (used in feeding livestocks). The WP was heated in a 800-watts microwave oven for 2 minutes with grains thoroughly mixed inside to distribute heat evenly and put in a disposable A4-size brown envelope. The temperature at the surface of the brown envelope with the WP inside was recorded every 5 minutes for 120 minutes to assess which cereal grain could emit more heat and keep the heat longer Then the WP was heated in the microwave oven for 1, 1 1/2 and 2 minutes, placed in the same size of brown envelope and covered with two towels. The temperatures at the surface of the brown envelope and each layer of towels were recorded with the same frequency and duration. The cereal-grain WPs, both mung beans and dry corn, were equally effective in producing heat when warmed in the microwave oven. The mean maximal temperatures at the surface of brown envelope were too high for direct application to newborns. The mean maximal temperatures of towels covering the paper envelope with WP heated in the microwave oven for 1 minute were as followed. At the first towel, which was close to the WP, the mean temperature reached 42 degrees C (107.6 degrees F) in 10 minutes after warming and was maintained > or = 42 degrees C for 10 minutes. All temperature measurements at the first towel was < or = 42 degrees C at 35 minutes. At 2 hours the mean temperature of the first towel was 35.6 degrees C (96.1 degrees F) which was higher than room temperature by 5.3 degrees C (41.5 degrees F). The maximal mean

  12. Existing climate data sources and Their Use in Heat IslandResearch

    SciTech Connect

    Akbari, Hashem; Pon, Brian; Smith, Craig Kenton; Stamper-Kurn, Dan Moses

    1998-10-01

    Existing climate data sources can be used in two general types of analysis for the detection of urban heat islands. Historical analyses use long-term data records-preferentially from several locations in and around an urban area-to trace the gradual influence of urban development on its climate. Primary sources of such data include the cooperative network, first-order National Weather Service stations, and military weather stations. Analyses of short-term data use information from a dense urban weather station network to discern the location, extent, and magnitude of urban heat islands. Such analyses may use the aforementioned national networks or regional networks such as agricultural, air quality monitoring, or utility networks. We demonstrate the use of existing data sources with a historical analysis of temperature trends in Los Angeles, California, and an analysis of short-term data of the urban temperature profile for Phoenix, Arizona. The Los Angeles climate was examined with eleven long-term data records from the cooperative network. Statistically significant trends of rising temperature were detected at Los Angeles Civic Center and other stations over some parts of the year, although timing of the increase varied from station to station. Observed increases in temperatures maybe due to long-term climate changes, microclimate influences, or local-scale heat islands. The analysis of short-term data was made for Phoenix using the PRISMS station network. Mean diurnal temperature profiles for a month were examined and compared with those for adjacent rural areas. Data fi-om stations in the center of Phoenix showed clear and significant nighttime and daytime temperature differences of 1- 2K (3 - 4"F). These temperature increases maybe attributable to a local-scale heat island.

  13. Enhanced primary sludge sonication by heat insulation to reclaim carbon source for biological phosphorous removal.

    PubMed

    Tian, Qing; Wang, Qi; Zhu, Yanbing; Li, Fang; Zhuang, Lin; Yang, Bo

    2017-01-01

    Ultrasound pretreatment is a potent step to disintegrate primary sludge (PS). The supernatant of sonicated PS is recycled as an alternative carbon source for biological phosphorus removal. In this study, we investigated the role of temperature on PS disintegration during sonication. We found that a temperature of 60°C yielded a dissolution rate of about 2% soluble chemical oxygen demand (SCOD) as compared to 7% SCOD using sonication at the specific energy (SE) of 7359kJ/kg TS. Using the SE of 6000kJ/kg TS with heat insulation during sonication, the SCOD dissolution rate of PS was similar to the result at the SE of 7051kJ/kg TS without heat insulation. Upon treatment with sonication, the PS released low concentrations of Cu and Zn into the supernatant. The phosphorus-accumulating organisms (PAOs) used the supernatant of sonicated PS as the carbon source. Supplementation with the diluted sonicated PS supernatant (SCOD≈1000mg/L) in anaerobic phase resulted in the release of phosphorus (36mg/L) and the production of polyhydroxyalkanoates (PHAs) (0.36g PHA/g SS). Compared with sodium acetate, higher polyhydroxyvalerate (PHV) faction in the polyhydroxyalkanoates (PHAs) was observed in the biomass when incubated with sonicated PS as the carbon source. This work provides a simple pathway to conserve energy and to enhance efficiencies of ultrasonic pretreatment and the recovery of carbon source from the sludge for improving the phosphorus removal in the ENR system.

  14. A critical evaluation of semianalytic methods in the study of centrally heated, unresolved, infrared sources

    NASA Technical Reports Server (NTRS)

    Doty, Steven D.; Leung, Chun Ming

    1994-01-01

    We critically evaluate current methods of analysis in infrared (IR) astronomy and investigate the conditions under which these semianalytic methods are reliable. Specifically we examine the usual assumptions of homogeneities in dust density and temperature, and neglect of opacity effects when applied to internally heated, unresolved IR sources. To accomplish this, a series of radiation transport models for these sources have been constructed. The model results are treated as observed quantities and analyzed to derive the source parameters, using simple semianalytic methods. The discrepancies between the derived and actual model parameters can then be attributed to the limitations of the analysis methods and provide a measure of their reliability. Applying this approach to centrally heated, unresolved IR sources, we have studied in detail the following diagnostic problems: (1) determination of dust mass from monochromatic and integrated luminosities; (2) estimation of dust temperature distribution from color temperatures derived from the flux spectrum; and (3) determination of the empirical grain emissivity law (opacity function) for both continuum and spectral features.

  15. A critical evaluation of semianalytic methods in the study of centrally heated, unresolved, infrared sources

    NASA Technical Reports Server (NTRS)

    Doty, Steven D.; Leung, Chun Ming

    1994-01-01

    We critically evaluate current methods of analysis in infrared (IR) astronomy and investigate the conditions under which these semianalytic methods are reliable. Specifically we examine the usual assumptions of homogeneities in dust density and temperature, and neglect of opacity effects when applied to internally heated, unresolved IR sources. To accomplish this, a series of radiation transport models for these sources have been constructed. The model results are treated as observed quantities and analyzed to derive the source parameters, using simple semianalytic methods. The discrepancies between the derived and actual model parameters can then be attributed to the limitations of the analysis methods and provide a measure of their reliability. Applying this approach to centrally heated, unresolved IR sources, we have studied in detail the following diagnostic problems: (1) determination of dust mass from monochromatic and integrated luminosities; (2) estimation of dust temperature distribution from color temperatures derived from the flux spectrum; and (3) determination of the empirical grain emissivity law (opacity function) for both continuum and spectral features.

  16. Sources of Meridional Heat and Freshwater Transport Anomalies in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Kelly, K. A.; Thompson, L.; Drushka, K.

    2016-02-01

    Observations of thermosteric and halosteric sea level from hydrographic data, ocean mass from GRACE and altimetric sea surface height are used to infer meridional heat transport (MHT) and freshwater convergence (FWC) anomalies for the Atlantic Ocean for 1993-2014. A Kalman filter extracts smooth estimates of heat transport convergence (HTC) and FWC from discrepancies between the sea level response to monthly surface heat and freshwater fluxes and observed heat and freshwater content in each of eight regions. Estimates of MHT anomalies are derived by summing the HTC from north to south and adding an integration constant derived from updated MHT estimates at 41N (Willis 2010). MHT estimates are relatively insensitive to the choice of heat flux products and are highly coherent spatially. Anomalies in MHT are comparable to those observed at the RAPID/MOCHA line at 26.5N and show a continued recovery from the minimum in 2010 throughout the Atlantic. MHT anomalies resemble estimates of Agulhas Leakage derived from altimeter (LeBars et al 2014) suggesting that the Indian Ocean is the source of the anomalous heat inflow. FWC estimates are also insensitive to choice of flux products. Interannual anomalies of FWC integrated from 67N to 35S resemble estimates of Atlantic river inflow (de Couet and Maurer, GRDC 2009), whereas the trend is consistent with estimates of freshwater input from Greenland. Increasing values of FWC after 2002 at a time when MHT was decreasing may indicate a feedback between the Atlantic Meridional Overturning Circulation and FWC that would accelerate the AMOC slowdown.

  17. An analytic formulation for heating source memory in the thermospheric composition

    NASA Technical Reports Server (NTRS)

    Porter, H. S.; Mayr, H. G.; Hedin, A. E.

    1981-01-01

    Numerical calculations from a spectral circulation model are utilized to construct an analytic Green's function formulation describing the meridional, time-dependent thermospheric composition and temperature response during magnetic storms. The purpose is to develop a formulation that embodies source memory while being sufficiently simple to serve as a heuristic guide for empirical modeling. By passing from the discrete Fourier series representation, utilized for the numerical circulation model, to a continuous Fourier integral representation, explicit waves are obtained for the thermospheric response times. The response times are altitude and species dependent and can exceed two days below 200 km. Thus, for certain storm scenarios, pronounced source memory signatures for the composition and temperature are predicted. Response times obtained from the formulation are shown to give a response consistent with previously published neutral composition data from AE-C for the February 1974 storm when an ap dependent heat source is employed.

  18. Freeform LED lens for rectangularly prescribed illumination

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Liu, Sheng; Chen, Fei; Qin, Zong; Liu, Zongyuan; Luo, Xiaobing

    2009-10-01

    Freeform lenses are playing a more and more important role in LED secondary optics design. In this study, based on the new light energy mapping relationship, edge ray principle, Snell's law and error control of surface construction, a modified discontinuous freeform lens design method was presented for rectangularly prescribed illumination, with the advantages of a flexible energy mapping relationship, accurate light irradiation control and easier to manufacture. A polymethyl methacrylate (PMMA) discontinuous freeform lens was designed as an example for LED tunnel illumination according to this method. The numerical simulation results demonstrated that the light pattern of the lens was in good agreement with the expected illumination performance when using a point source. Tolerance analyses were also conducted. An extended light source had little effect on the light output efficiency (LOE) of the lens but significantly decreased the effective illumination area. Installation errors had more effect on the uniformity and shape of the light pattern than the LOE of the lens. The tolerances of vertical, horizontal and rotational deviation of this lens were 0.4 mm, 0.4 mm and 2°, respectively.

  19. The feasibility of retrieving nuclear heat sources from orbit with the space shuttle

    SciTech Connect

    Pyatt, D.W.; Englehart, R.W.

    1980-01-01

    Spacecraft launched for orbital missions have a finite orbital lifetime. Current estimates for the lifetime of the nine nuclear powered U.S. satellites now in orbit range from 150 years to 10{sup 6} years. Orbital lifetime is determined primarily by altitude, solar activity, and the satellite ballistic coefficient. There is also the potential of collision with other satellites or space debris, which would reduce the lifetime in orbit. These orbiting power sources contain primarily Pu-238 and Pu-239 as the fuel material. Pu-238 has an approximate 87-year half life and so considerable amounts of daughter products are present after a few tens of years. In addition, there are minor but possibly significant amounts of impurity isotopes present with their own decay chains. Radioisotopic heat sources have been designed to evolving criteria since the first launches. Early models were designed to burn up upon reentry. Later designs were designed to reenter intact. After tens or hundreds of years in orbit, the ability of any orbiting heat source to reenter intact and impact while maintaining containment integrity is in doubt. Such ability could only be verified by design to provide protection in the case of early mission failures such as launch aborts, failure to achieve orbit, or the attainment of only a short orbit. With the development of the Space Shuttle there exists the potential ability to recover heat sources in orbit after their missions are completed. Such retrieval could allow the risk of eventual reentry burnup or impact with atmospheric dispersion and subsequent radiation doses to the public to be avoided.

  20. Focus group discussions among owners and non-owners of ground source heat pumps

    SciTech Connect

    Roberson, B.F.

    1988-07-01

    This research was sponsored by the Office of Buildings and Community Systems and conducted by the Pacific Northwest Laboratory as part of an ongoing effort to enhance the commercial use of federally developed technology. Federal dollars have supported research on the development of ground source heat pumps (GSHP) for several years. Though several companies currently sell GSHP's for residential use, their share of the total heating and air conditioning business remains less than one percent. Large manufacturing companies with national distribution have not yet added GSHP equipment to their product line. GSHP's use only about one half (Braud 1987) to one third (Bose 1987) of the energy needed to operate conventional furnaces and air conditioners. Consequently, a high level of market penetration by the GSHP offers direct benefits to both utility companies and individual users of the systems. Widespread use of these highly efficient systems will reduce both total energy consupmtion, and problems associated with high levels of energy use during peak periods. This will allow utility companies to delay capital expenditures for new facilities to meet the growing energy demand during peak periods. The cost effective use of electricity also reduces the likelihood of homeowners switching to a different fuel source for heating. 5 refs.

  1. Turbulent diffusion from a heated line source in non-equilibrium grid turbulence

    NASA Astrophysics Data System (ADS)

    Nedic, Jovan; Tavoularis, Stavros

    2015-11-01

    We have investigated turbulent diffusion of heat injected passively from a line source in equilibrium and non-equilibrium grid-generated turbulence, which are, respectively, flows in which the value of the non-dimensional rate of kinetic energy dissipation is constant or changes with streamwise distance from the grid. We used three grids with uniform square meshes and one fractal square grid (FSG), all of the same solidity, to generate non-equilibrium and equilibrium turbulence in a wind-tunnel. The regular grids have mesh sizes that are comparable to the first (RG160), second (RG80) and fourth (RG18) iterations of the fractal grid. The heated line source was inserted on the centre-plane of the grids at either of two downstream locations or an upstream one and it spanned the entire width of the wind-tunnel. We found that RG160 produced the greatest heat diffusion, followed by FSG, RG80 and RG18, in this order. The apparent turbulent diffusivity produced by the four grids also decreased in the same order. These findings conform with Taylor's theory of diffusion by continuous movements. Moreover, the present study demonstrates that the fractal space-scale unfolding (SSU) mechanism does not apply to grids with the same solidity but different effective mesh sizes. Supported by NSERC.

  2. General-Purpose Heat Source development: safety test program. Postimpact evaluation, Design Iteration Test 2

    SciTech Connect

    Schonfeld, F.W.; George, T.G.

    1984-06-01

    The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of /sup 238/PuO/sub 2/ decay to thermoelectric elements. Because of the inevitable return of certain missions, the heat source must be Designed and constructed to survive both re-entry and Earth impact. The Design Iteration Test (DIT) series is part of an ongoing test program. In the first Design Iteration Test (DIT-1), a full GPHS module ontaining four iridium-alloy capsules loaded with /sup 238/PuO/sub 2/ was impacted at 57 m/s and 930/sup 0/C. All four capsules survived and none was breached. The capsules used in DIT-1 were loaded and welded at Los Alamos. The second Design Iteration Test (DIT-2) also used a full GPHS module and was impacted at 58 m/s and 930/sup 0/C. The four iridium-alloy capsules used in this test were loaded and welded at the Savannah River Plant (SRP). Postimpact examination revealed that two capsules had survived and two capsules had breached; a small quantity (approx. = 50 ..mu..g) of /sup 238/PuO/sub 2/ was released from the breached capsules. Internal cracking similar to that observed in the DIT-1 capsules was evident in all four of the DIT-2 capsules. Postimpact analyses of the units are described with emphasis on weld structure and performance.

  3. Optimal performance of heat engines with a finite source or sink and inequalities between means.

    PubMed

    Johal, Ramandeep S

    2016-07-01

    Given a system with a finite heat capacity and a heat reservoir, and two values of initial temperatures, T_{+} and T_{-}(source at T_{+} and the system is a sink at T_{-}, or, when the reservoir is an infinite sink at T_{-} and the system acts as a source at T_{+}? It is found that in order to compare the total extracted work, and the corresponding efficiency in the two cases, we need to consider three regimes as suggested by an inequality, the so-called arithmetic mean-geometric mean inequality, involving the arithmetic and the geometric means of the two temperature values T_{+} and T_{-}. In each of these regimes, the efficiency at total work obeys certain universal bounds, given only in terms of the ratio of initial temperatures. The general theoretical results are exemplified for thermodynamic systems for which internal energy and temperature are power laws of the entropy. The conclusions may serve as benchmarks in the design of heat engines, where we can choose the nature of the finite system, so as to tune the total extractable work and/or the corresponding efficiency.

  4. Nondestructive inspection of General Purpose Heat Source (GPHS) fueled clad girth welds

    SciTech Connect

    Reimus, M. A. H.; George, T. G.; Lynch, C.; Padilla, M.; Moniz, P.; Guerrero, A.; Moyer, M. W.; Placr, A.

    1998-01-15

    The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of {sup 238}Pu decay to an array of thermoelectric elements. The GPHS is fabricated using an iridium-alloy to contain the {sup 238}PuO{sub 2} fuel pellet. GPHS capsules will be utilized in the upcoming Cassini mission to explore Saturn and its moons. The physical integrity of the girth weld is important to mission safety and performance. Because past experience had revealed a potential for initiation of small cracks in the girth weld overlap zone, a nondestructive inspection of each capsule weld is required. An ultrasonic method was used to inspect the welds of capsules fabricated for the Galileo mission. The instrument, transducer, and method used were state of the art at the time (early 1980s). The ultrasonic instrumentation and methods used to inspect the Cassini GPHSs was significantly upgraded from those used for the Galileo mission. GPHSs that had ultrasonic reflectors in excess of the reject specification level were subsequently inspected with radiography to provide additional engineering data used to accept/reject the heat source. This paper describes the Galileo-era ultrasonic instrumentation and methods and the subsequent upgrades made to support testing of Cassini GPHSs. Also discussed is the data obtained from radiographic examination and correlation to ultrasonic examination results.

  5. General-purpose heat source developmet: Safety test program. Postimpact evaluation, design iteration test 4

    NASA Astrophysics Data System (ADS)

    George, T. G.; Schonfeld, F. W.

    1984-12-01

    The general-purpose heat source (GPHS) provides power for space missions by transmitting the heat of Pu-238 decay to thermoelectric elements. Because of the inevitable return of certain aborted missions, the heat source must be designed and constructed to survive both re-entry and Earth impact. The design iteration test (DIT) series is part of an ongoing test program. The fourth test (DIT-4) was designed to evaluate the effect on impact behavior of changing the procedure used at the mount facility (MF) to remove surface defects from drawn cups. The change involved switching from a manual abrasion technique to a motorized, rubber-bonded abrasive wheel. In DIT-4 a partial GPHS module containing two fueled clads (one cleaned manually, and one cleaned with an abrasive wheel) was impacted at a velocity of 58 m/s and a temperature of 930 C. Both capsules were severely deformed by the impact and contained large interal cracks. Although the manually cleaned capsule breached, the breaching crack was only 2 microns wide and released negligible amounts of fuel. There did not appear to be any correlation between cleaning method and capsule performance. Postimpact analyses of the DIT-4 test components are described with emphasis on microstructure and impact response.

  6. Model simulation of a localized high intensity heat source interacting with cooled metal plates

    NASA Astrophysics Data System (ADS)

    Cranfill, F. M.

    The basic, generic problem of a localized high intensity heat source directed against one surface of a plate of finite thickness was investigated using the finite element program ANSYS. After reviewing similar work in nuclear fuel and laser machining, ANSYS was verified against a known solution. ANSYS was used to create a model that yields minimum heat transfer coefficients needed to prevent the initiation of melting in thin aluminum, titanium, and stainless steel (AISI 304) plates. These heat transfer coefficients were converted into minimum local Nusselt numbers and graphed against local Nusselt number correlations for constant temperature flat plates in forced and free convection regimes. A detailed listing of both laminar and turbulent correlations is presented along with references. The suitability of liquid sodium, air, and water (under high pressure) as coolants for a source intensity of 2.0 x 10 to the 7th power w/sq m was examined. For free convection, only liquid sodium cooling a titanium plate is feasible, For forced convection, liquid sodium is feasible in laminar flow fo r all three plates with velocities ranging from 0.28 m/s to 1.09 m/s. Water is feasible for aluminum and titanium in turbulent flow at velocities of approximately 4 m/s.

  7. Case study for ARRA-funded ground-source heat pump (GSHP) demonstration at Oakland University

    SciTech Connect

    Im, Piljae; Liu, Xiaobing

    2015-09-01

    High initial costs and lack of public awareness of ground-source heat pump (GSHP) technology are the two major barriers preventing rapid deployment of this energy-saving technology in the United States. Under the American Recovery and Reinvestment Act (ARRA), 26 GSHP projects have been competitively selected and carried out to demonstrate the benefits of GSHP systems and innovative technologies for cost reduction and/or performance improvement. This paper highlights the findings of a case study of one of the ARRA-funded GSHP demonstration projects, a ground-source variable refrigerant flow (GS-VRF) system installed at the Human Health Building at Oakland University in Rochester, Michigan. This case study is based on the analysis of measured performance data, maintenance records, construction costs, and simulations of the energy consumption of conventional central heating, ventilation, and air-conditioning (HVAC) systems providing the same level of space conditioning as the demonstrated GS-VRF system. The evaluated performance metrics include the energy efficiency of the heat pump equipment and the overall GS-VRF system, pumping performance, energy savings, carbon emission reductions, and cost-effectiveness of the GS-VRF system compared with conventional HVAC systems. This case study also identified opportunities for reducing uncertainties in the performance evaluation, improving the operational efficiency, and reducing the installed cost of similar GSHP systems in the future.

  8. Numerical study of conductive heat losses from a magmatic source at Phlegraean Fields

    NASA Astrophysics Data System (ADS)

    Di Maio, Rosa; Piegari, Ester; Mancini, Cecilia; Scandone, R.

    2015-01-01

    The thermal evolution of the Phlegraean magmatic system (southern Italy) is studied by analyzing the influence of the thermal property variations on the solution of the heat conduction equation. The aim of this paper is to verify if appropriate choices of thermal parameters can reproduce, at least to greater depths, the high temperatures measured in the geothermal wells, drilled inside the caldera, under the assumption of heat loss from a magma chamber by conduction. Since the main purpose is to verify the plausibility of such an assumption, rather simple models of the magmatic system are adopted and only major volcanic events (i.e., the Campanian Ignimbrite and the Neapolitan Yellow Tuff eruptions) are considered. The results of the simulated two-dimensional model scenarios show that by assuming an extended source region, whose emplacement time is longer than 40 ka, heat conduction mechanisms can provide temperatures as high as those measured at depths deeper than about 2000 m. On the other hand, the 1D simulations show that appropriate choices for the thermal conductivity depth profiles can reproduce the observed temperatures at depths deeper than about 1000 m. These findings question the apparent consensus that convection is the only dominant form of heat transfer at Phlegraean Fields and might motivate new research for reconstructing the thermal evolution of the Phlegraean magmatic system.

  9. Transient natural ventilation of a room with a distributed heat source

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Shaun D.; Woods, Andrew W.

    We report on an experimental and theoretical study of the transient flows which develop as a naturally ventilated room adjusts from one temperature to another. We focus on a room heated from below by a uniform heat source, with both high- and low-level ventilation openings. Depending on the initial temperature of the room relative to (i) the final equilibrium temperature and (ii) the exterior temperature, three different modes of ventilation may develop. First, if the room temperature lies between the exterior and the equilibrium temperature, the interior remains well-mixed and gradually heats up to the equilibrium temperature. Secondly, if the room is initially warmer than the equilibrium temperature, then a thermal stratification develops in which the upper layer of originally hot air is displaced upwards by a lower layer of relatively cool inflowing air. At the interface, some mixing occurs owing to the effects of penetrative convection. Thirdly, if the room is initially cooler than the exterior, then on opening the vents, the original air is displaced downwards and a layer of ambient air deepens from above. As this lower layer drains, it is eventually heated to the ambient temperature, and is then able to mix into the overlying layer of external air, and the room becomes well-mixed. For each case, we present new laboratory experiments and compare these with some new quantitative models of the transient flows. We conclude by considering the implications of our work for natural ventilation of large auditoria.

  10. Effect of location of a rotating circular cylinder and heat source on mixed convection heat transfer characteristics inside a square enclosure with discrete heater at the bottom wall

    NASA Astrophysics Data System (ADS)

    Alam, Muntasir; Kamruzzaman, Saha, Sumon; Hasan, Mohammad Nasim

    2017-06-01

    A numerical investigation of mixed convection heat transfer phenomena in a square enclosure containing a heat conducting rotating circular cylinder has been taken into consideration in this work. As a heat source, a discrete isoflux heater is placed at the bottom wall of the enclosure whereas the top wall is considered as adiabatic. The vertical sidewalls of the enclosure are assumed to be maintained at constant low temperature to properly describe the boundary conditions in the work. The coupled equations of the developed mathematical model are solved by using the finite element method based on the Galerkin method of weighted residuals for different rotating speeds of the cylinder varying over the range of 0-500 keeping the Rayleigh number and Prandtl number fixed. The effects of position of rotating cylinder (both horizontal and vertical) and location of the heat source on the streamlines, isotherms, variation of local Nusselt number, average Nusselt number and other heat transfer and fluid flow phenomena are numerically investigated. The results reveal that the flow field, temperature field and heat transfer rate strongly depend on cylinder and heat source position.

  11. Heating neutral beams for ITER: negative ion sources to tune fusion plasmas

    NASA Astrophysics Data System (ADS)

    Singh, M. J.; Boilson, D.; Polevoi, A. R.; Oikawa, Toshihiro; Mitteau, Raphael

    2017-05-01

    Neutral beam injection (NBI) based on a negative ion source is one of the basic heating and current drive systems designed for ITER required to reach its goals of the operation with high fusion power, P fus ∼ 500 MW with fusion gain, Q = 10 for 400 s in a baseline scenario, and P fus > 250 MW, Q = 5 operation for 3600 s in an advanced scenario. A total power of 33 MW from the two heating neutral beam (HNB) injectors is envisaged in the present scenario. The scope of the present paper is to provide an overview of the main aspects of the interaction of the HNBs with the ITER plasma. Various operational scenarios with different mixtures of the main ion species, He, H, DD and DT, foreseen at different phases of the ITER operation are considered.

  12. Second law analysis of advanced power generation systems using variable temperature heat sources

    NASA Astrophysics Data System (ADS)

    Bliem, C. J.; Mines, G. L.

    Many systems produce power using variable temperature (sensible) heat sources. The Heat Cycle Research Program is currently investigating the potential improvements to such power cycles utilizing moderate temperature geothermal resources to produce electrical power. It has been shown that mixtures of saturated hydrocarbons (alkanes) or halogenated hydrocarbons operating with a supercritical Rankine cycle gave improved performance over boiling Rankine cycles with the pure working fluids for typical applications. Recently, in addition to the supercritical Rankine Cycle, other types of cycles have been proposed for binary geothermal service. This paper explores the limits on efficiency of a feasible plant and discusses the methods used in these advanced concept plants to achieve the maximum possible efficiency. The advanced plants considered appear to be approaching the feasible limit of performance so that the designer must weigh all considerations to fine the best plant for a given service. These results would apply to power systems in other services as well as to geothermal power plants.

  13. Study of heat sources interacting in integrated circuits by laser mirage effect

    SciTech Connect

    Perpiñà, X.; Jordà, X.; Vellvehi, M.; Altet, J.

    2014-08-25

    This work exploits the mirage effect to analyze multiple heat sources thermally interacting in an integrated circuit (IC) by means of a probe IR laser beam, which strikes on the die lateral walls and passes through the die substrate. Under such conditions, the criteria for locating such hot spots, as well as their relative power dissipation, are discussed on the basis of a theoretical model inferred in this work. Finally, the technique feasibility is shown in a real application scenario, obtaining 5-μm spatial lateral resolution and an error in power dissipation measurements below 5%. This method may become a practical alternative to usual off-chip techniques for inspecting hot spots in ICs and to experimentally characterize heat flow in the semiconductor substrate.

  14. Study of heat sources interacting in integrated circuits by laser mirage effect

    NASA Astrophysics Data System (ADS)

    Perpiñà, X.; Jordà, X.; Vellvehi, M.; Altet, J.

    2014-08-01

    This work exploits the mirage effect to analyze multiple heat sources thermally interacting in an integrated circuit (IC) by means of a probe IR laser beam, which strikes on the die lateral walls and passes through the die substrate. Under such conditions, the criteria for locating such hot spots, as well as their relative power dissipation, are discussed on the basis of a theoretical model inferred in this work. Finally, the technique feasibility is shown in a real application scenario, obtaining 5-μm spatial lateral resolution and an error in power dissipation measurements below 5%. This method may become a practical alternative to usual off-chip techniques for inspecting hot spots in ICs and to experimentally characterize heat flow in the semiconductor substrate.

  15. Color Stability of Dental Restorative Materials Submitted to Heat Sources, for Forensic Purposes.

    PubMed

    Biancalana, Roberto Cesar; Vicente, Sergio Augusto de Freitas; Alves da Silva, Ricardo Henrique; Pires-de-Souza, Fernanda de Carvalho Panzeri

    2017-03-01

    During postmortem examination of the dental arches of carbonized victims, dental restorative materials may be found. The aim of this study was to evaluate the effect of heat source action on the color stability of composite resin (CR) and glass ionomer cement (GIC) restorations, to discriminate between them and compare with antemortem dental data. Sixty bovine teeth (30 CR and 30 GIC) were prepared (6 × 6 × 2 mm) and separated into groups (n = 10). The color readouts were taken by spectrophotometer, before and after heat action (100°C, 200°C, 300°C), in an oven for 15 min. There were color alterations for all coordinates (ΔE, ΔL*, Δa* eΔb*) for both materials. GIC presented greater change. The authors concluded that it is possible to distinguish between the materials by the color changes analyzed by instrumental method, helping victim identification.

  16. An experimental study of waveguide coupled microwave heating with conventional multicusp negative ion sources

    SciTech Connect

    Komppula, J.; Kalvas, T.; Koivisto, H.; Laulainen, J.; Tarvainen, O.

    2015-04-08

    Negative ion production with conventional multicusp plasma chambers utilizing 2.45 GHz microwave heating is demonstrated. The experimental results were obtained with the multicusp plasma chambers and extraction systems of the RF-driven RADIS ion source and the filament driven arc discharge ion source LIISA. A waveguide microwave coupling system, which is almost similar to the one used with the SILHI ion source, was used. The results demonstrate that at least one third of negative ion beam obtained with inductive RF-coupling (RADIS) or arc discharge (LIISA) can be achieved with 1 kW of 2.45 GHz microwave power in CW mode without any modification of the plasma chamber. The co-extracted electron to H{sup −} ratio and the optimum pressure range were observed to be similar for both heating methods. The behaviour of the plasma implies that the energy transfer from the microwaves to the plasma electrons is mainly an off-resonance process.

  17. Comparison of predicted far-field temperatures for discrete and smeared heat sources

    SciTech Connect

    Ryder, E.E.

    1992-12-16

    A fundamental concern in the design of the potential repository at Yucca Mountain. Nevada is the response of the host rock to the emplacement of heat-generating waste. The thermal perturbation of the rock mass has implications regarding the structural, hydrologic. and geochemical performance of the potential repository. The phenomenological coupling of many of these performance aspects makes repository thermal modeling a difficult task. For many of the more complex, coupled models, it is often necessary to reduce the geometry of the potential repository to a smeared heat-source approximation. Such simplifications have impacts on induced thermal profiles that in turn may influence other predicted responses through one- or two-way thermal couplings. The effect of waste employment layout on host-rock thermal was chosen as the primary emphasis of this study. Using a consistent set of modeling and input assumptions, far-field thermal response predictions made for discrete-source as well as plate source approximations of the repository geometry. Input values used in the simulations are consistent with a design-basis a real power density (APD) of 80 kW/acre as would be achieved assuming a 2010 emplacement start date, a levelized receipt schedule, and a limitation on available area as published in previous design studies. It was found that edge effects resulting from general repository layout have a significant influence on the shapes and extents of isothermal profiles, and should be accounted for in far-field modeling efforts.

  18. Case Study for the ARRA-Funded Ground Source Heat Pump Demonstration at Ball State University

    SciTech Connect

    Im, Piljae; Liu, Xiaobing; Henderson, Jr., Hugh

    2016-12-01

    With funding provided by the American Recovery and Reinvestment Act (ARRA), 26 ground-source heat pump (GSHP) projects were competitively selected in 2009 to demonstrate the benefits of GSHP systems and innovative technologies for cost reduction and/or performance improvement. One of the selected demonstration projects is a district central GSHP system installed at Ball State University (BSU) in Muncie, IN. Prior to implementing the district GSHP system, 47 major buildings in BSU were served by a central steam plant with four coal-fired and three natural-gas-fired steam boilers. Cooling was provided by five water-cooled centrifugal chillers at the District Energy Station South (DESS). The new district GSHP system replaced the existing coal-fired steam boilers and conventional water-cooled chillers. It uses ground-coupled heat recovery (HR) chillers to meet the simultaneous heating and cooling demands of the campus. The actual performance of the GSHP system was analyzed based on available measured data from August 2015 through July 2016, construction drawings, maintenance records, personal communications, and construction costs. Since Phase 1 was funded in part by the ARRA grant, it is the focus of this case study. The annual energy consumption of the GSHP system was calculated based on the available measured data and other related information. It was compared with the performance of a baseline scenario— a conventional water-cooled chiller and natural-gas-fired boiler system, both of which meet the minimum energy efficiencies allowed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE 90.1-2013). The comparison was made to determine source energy savings, energy cost savings, and CO2 emission reductions achieved by the GSHP system. A cost analysis was performed to evaluate the simple payback of the GSHP system. The following sections summarize the results of the analysis, the lessons learned, and recommendations for improvement

  19. Micro- and Nanoscale Energetic Materials as Effective Heat Energy Sources for Enhanced Gas Generators.

    PubMed

    Kim, Sang Beom; Kim, Kyung Ju; Cho, Myung Hoon; Kim, Ji Hoon; Kim, Kyung Tae; Kim, Soo Hyung

    2016-04-13

    In this study, we systematically investigated the effect of micro- and nanoscale energetic materials in formulations of aluminum microparticles (Al MPs; heat source)/aluminum nanoparticles (Al NPs; heat source)/copper oxide nanoparticles (CuO NPs; oxidizer) on the combustion and gas-generating properties of sodium azide microparticles (NaN3 MPs; gas-generating agent) for potential applications in gas generators. The burn rate of the NaN3 MP/CuO NP composite powder was only ∼0.3 m/s. However, the addition of Al MPs and Al NPs to the NaN3 MP/CuO NP matrix caused the rates to reach ∼1.5 and ∼5.3 m/s, respectively. In addition, the N2 gas volume flow rate generated by the ignition of the NaN3 MP/CuO NP composite powder was only ∼0.6 L/s, which was significantly increased to ∼1.4 and ∼3.9 L/s by adding Al MPs and Al NPs, respectively, to the NaN3 MP/CuO NP composite powder. This suggested that the highly reactive Al MPs and NPs, with the assistance of CuO NPs, were effective heat-generating sources enabling the complete thermal decomposition of NaN3 MPs upon ignition. Al NPs were more effective than Al MPs in the gas generators because of the increased reactivity induced by the reduced particle size. Finally, we successfully demonstrated that a homemade airbag with a specific volume of ∼140 mL could be rapidly and fully inflated by the thermal activation of nanoscale energetic material-added gas-generating agents (i.e., NaN3 MP/Al NP/CuO NP composites) within the standard time of ∼50 ms for airbag inflation.

  20. An optoacoustic point source for acoustic scale model measurements.

    PubMed

    Bolaños, Javier Gómez; Pulkki, Ville; Karppinen, Pasi; Hæggström, Edward

    2013-04-01

    A massless acoustic source is proposed for scale model work. This source is generated by focusing a pulsed laser beam to rapidly heat the air at the focal point. This produces an expanding small plasma ball which generates a sonic impulse that may be used as an acoustic point source. Repeatability, frequency response, and directivity of the source were measured to show that it can serve as a massless point source. The impulse response of a rectangular space was determined using this type of source. A good match was found between the predicted and the measured impulse responses of the space.