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Sample records for endoreversible radiative heat

  1. Optimization of combined endoreversible Carnot heat engines with different objectives

    NASA Astrophysics Data System (ADS)

    Cheng, Xue-Tao; Liang, Xin-Gang

    2015-06-01

    Taking the output power, thermal efficiency, and thermo-economic performance as the optimization objectives, we optimize the operation parameters of a thermodynamic system with combined endoreversible Carnot heat engines in this paper. The applicabilities of the entropy generation minimization and entransy theory to the optimizations are discussed. For the discussed cases, only the entransy loss coefficient is always agreeable to the optimization of thermal efficiency. The applicabilities of the other discussed concepts to the optimizations are conditional. Different concepts and principles are needed for different optimization objectives, and the optimization principles have their application preconditions. When the preconditions are not satisfied, the principles may be not applicable. Project supported by the National Natural Science Foundation of China (Grant No. 51376101) and the Science Fund for Creative Research Groups, China (Grant No. 51321002).

  2. Comment on "A universal optimum work rate potential for continuous endoreversible Carnot heat engine cycles" [J. Appl. Phys. 80, 3619 (1996)

    NASA Astrophysics Data System (ADS)

    Chen, Jincan; Yan, Zijun

    1997-12-01

    It is pointed out that there is not a certain universal relation for the power outputs of continuous endoreversible and reversible Carnot heat engine cycles operating between the same temperature limits, and the relevant conclusion obtained by Blank and Bhattacharyya in a recent article of this journal is incorrect.

  3. On reversible, endoreversible, and irreversible heat device cycles versus the Carnot cycle: a pedagogical approach to account for losses

    NASA Astrophysics Data System (ADS)

    Gonzalez-Ayala, J.; Angulo-Brown, F.; Calvo Hernández, A.; Velasco, S.

    2016-07-01

    In this work we analyze the deviations of reversible cycles (for both heat engines and refrigerators) from the corresponding Carnot cycle operating between the same extreme temperatures, and deviations of irreversible cycles from their corresponding reversible realization while putting emphasis on the corresponding losses. The endoreversible models fit in the proposed framework. Two suitable loss factors, which do not need the explicit calculation of entropy variations, are introduced. The behavior of these factors and their interplay allow for a clear and pedagogical visualization of where external and internal irreversibilities are located, and their intensities in terms of the main variables describing the cycle. The analysis could be used as a starting point for more advanced studies on modeling and optimization of real devices and installations.

  4. An analytical study of the endoreversible Curzon-Ahlborn cycle for a non-linear heat transfer law

    NASA Astrophysics Data System (ADS)

    Páez-Hernández, Ricardo T.; Portillo-Díaz, Pedro; Ladino-Luna, Delfino; Ramírez-Rojas, Alejandro; Pacheco-Paez, Juan C.

    2016-01-01

    In the present article, an endoreversible Curzon-Ahlborn engine is studied by considering a non-linear heat transfer law, particularly the Dulong-Petit heat transfer law, using the `componendo and dividendo' rule as well as a simple differentiation to obtain the Curzon-Ahlborn efficiency as proposed by Agrawal in 2009. This rule is actually a change of variable that simplifies a two-variable problem to a one-variable problem. From elemental calculus, we obtain an analytical expression of efficiency and the power output. The efficiency is given only in terms of the temperatures of the reservoirs, such as both Carnot and Curzon-Ahlborn cycles. We make a comparison between efficiencies measured in real power plants and theoretical values from analytical expressions obtained in this article and others found in literature from several other authors. This comparison shows that the theoretical values of efficiency are close to real efficiency, and in some cases, they are exactly the same. Therefore, we can say that the Agrawal method is good in calculating thermal engine efficiencies approximately.

  5. Chemical reactions in endoreversible thermodynamics

    NASA Astrophysics Data System (ADS)

    Wagner, Katharina; Hoffmann, Karl Heinz

    2016-01-01

    Endoreversible thermodynamics is a theory for the (approximate) description of thermodynamic non-equilibrium systems, which allows us to capture the ever present irreversibilities of real processes. For instance in heat engines the dissipation due to finite heat transport capabilities, as well as the resulting limitations in the energy fluxes, can be incorporated into the theory. It has thus been very successful in closing the gap between observed and theoretically predicted efficiencies. Here an extension of the theory is provided, with which chemical reactions can be included in the formalism. This opens up a wide field of applications for endoreversible modeling and the investigation of dissipative processes, for instance in fuel cells or batteries.

  6. Irreversible and endoreversible behaviors of the LD-model for heat devices: the role of the time constraints and symmetries on the performance at maximum χ figure of merit

    NASA Astrophysics Data System (ADS)

    Gonzalez-Ayala, Julian; Calvo Hernández, A.; Roco, J. M. M.

    2016-07-01

    The main unified energetic properties of low dissipation heat engines and refrigerator engines allow for both endoreversible or irreversible configurations. This is accomplished by means of the constraints imposed on the characteristic global operation time or the contact times between the working system with the external heat baths and modulated by the dissipation symmetries. A suited unified figure of merit (which becomes power output for heat engines) is analyzed and the influence of the symmetries on the optimum performance discussed. The obtained results, independent on any heat transfer law, are faced with those obtained from Carnot-like heat models where specific heat transfer laws are needed. Thus, it is shown that only the inverse phenomenological law, often used in linear irreversible thermodynamics, correctly reproduces all optimized values for both the efficiency and coefficient of performance values.

  7. Deployable Heat Pipe Radiator

    NASA Technical Reports Server (NTRS)

    Edelstein, F.

    1975-01-01

    A 1.2- by 1.8-m variable conductance heat pipe radiator was designed, built, and tested. The radiator has deployment capability and can passively control Freon-21 fluid loop temperatures under varying loads and environments. It consists of six grooved variable conductance heat pipes attached to a 0.032-in. aluminum panel. Heat is supplied to the radiator via a fluid header or a single-fluid flexible heat pipe header. The heat pipe header is an artery design that has a flexible section capable of bending up to 90 degrees. Radiator loads as high as 850 watts were successfully tested. Over a load variation of 200 watts, the outlet temperature of the Freon-21 fluid varied by 7 F. An alternate control system was also investigated which used a variable conductance heat pipe header attached to the heat pipe radiator panel.

  8. Thermal radiation heat transfer.

    NASA Technical Reports Server (NTRS)

    Siegel, R.; Howell, J. R.

    1972-01-01

    A comprehensive discussion of heat transfer by thermal radiation is presented, including the radiative behavior of materials, radiation between surfaces, and gas radiation. Among the topics considered are property prediction by electromagnetic theory, the observed properties of solid materials, radiation in the presence of other modes of energy transfer, the equations of transfer for an absorbing-emitting gas, and radiative transfer in scattering and absorbing media. Also considered are radiation exchange between black isothermal surfaces, radiation exchange in enclosures composed of diffuse gray surfaces and in enclosures having some specularly reflecting surfaces, and radiation exchange between nondiffuse nongray surfaces. The use of the Monte Carlo technique in solving radiant-exchange problems and problems of radiative transfer through absorbing-emitting media is explained.

  9. Efficiency of Inefficient Endoreversible Thermal Machines

    NASA Astrophysics Data System (ADS)

    Palao, José P.; Correa, Luis A.; Adesso, Gerardo; Alonso, Daniel

    2016-06-01

    We present a study of the performance of endoreversible thermal machines optimized with respect to the thermodynamic force associated with the cold bath in the regime of small thermodynamic forces. These thermal machines can work either as an engine or as a refrigerator. We analyze how the optimal performances are determined by the dependence of the thermodynamic flux on the forces. The results are motivated and illustrated with a quantum model, the three level maser, and explicit analytical expressions of the engine efficiency as a function of the system parameters are given.

  10. Deployable heat-pipe radiator

    NASA Technical Reports Server (NTRS)

    Edelstein, F.

    1978-01-01

    Loop temperatures are controlled effectively under varying load conditions. Radiator has four separate pieces of hardware: heat-pipe panel, flexible heat-pipe leader, heat exchanger, fluid header. Single-fluid transport capacities of about 850 watts, corresponding to 51,000 watt-inches, have been achieved in 90 degree bend orientation of heat-pipe header.

  11. Radiative heat transfer

    NASA Astrophysics Data System (ADS)

    Chapman, K. S.; Ramadhyani, S.; Ramamurthy, H.; Viskanta, R.

    1990-04-01

    One and two-dimensional mathematical models have been developed to predict the steady state thermal performance and combustion characteristics of a natural gas-fired straight-through radiant tube. The effects of burner geometry, equivalence ratio, and preheat temperature and fuel firing rate on fuel burn-up have been investigated. The one-dimensional models for straight-through and single-ended recuperative radiant tubes have been validated using available experimental data. Thermal system models have been developed for the continuous and batch indirectly fired (radiant tube) furnaces to identify opportunities for fuel savings and enhanced productivity. Extensive parametric investigations were performed to examine the effects of load and refractory emissivities, load throughput rate and thickness on the thermal performance of the furnaces. Batch and continuous direct-fired furnace thermal system models were developed to analyze the effect of various design and operation parameters on the furnace thermal performance. An attempt was made to validate the batch furnace model by using experimental data from a small experimental furnace. Due to the size of the furnace, the two-dimensional heat conduction effects near the corners and edges of the furnace walls were significant. Since the effects were neglected in the system model, which is intended to simulate a large industrial furnace, the validation was unsuccessful. The parametric study consisted of examining the effect of the load and refractory emissivities and other operating and load parameters on the thermal performance of the batch and continuous furnaces.

  12. Active galaxies and radiative heating.

    PubMed

    Ostriker, Jeremiah P; Ciotti, Luca

    2005-03-15

    There is abundant evidence that heating processes in the central regions of elliptical galaxies have both prevented large-scale cooling flows and assisted in the expulsion of metal rich gas. We now know that each such spheroidal system harbours in its core a massive black hole weighing ca. 0.13% of the mass in stars and also know that energy was emitted by each of these black holes with an efficiency exceeding 10% of its rest mass. Since, if only 0.5% of that radiant energy were intercepted by the ambient gas, its thermal state would be drastically altered, it is worth examining in detail the interaction between the out-flowing radiation and the equilibrium or inflowing gas. On the basis of detailed hydrodynamic computations we find that relaxation oscillations are to be expected with the radiative feedback quite capable of regulating both the growth of the central black hole and also the density and thermal state of the gas in the galaxy. Mechanical input of energy by jets may assist or dominate over these radiative effects. We propose specific observational tests to identify systems which have experienced strong bursts of radiative heating from their central black holes. PMID:15681285

  13. Heat pipe radiator. [for spacecraft waste heat rejection

    NASA Technical Reports Server (NTRS)

    Swerdling, B.; Alario, J.

    1973-01-01

    A 15,000 watt spacecraft waste heat rejection system utilizing heat pipe radiator panels was investigated. Of the several concepts initially identified, a series system was selected for more in-depth analysis. As a demonstration of system feasibility, a nominal 500 watt radiator panel was designed, built and tested. The panel, which is a module of the 15,000 watt system, consists of a variable conductance heat pipe (VCHP) header, and six isothermalizer heat pipes attached to a radiating fin. The thermal load to the VCHP is supplied by a Freon-21 liquid loop via an integral heat exchanger. Descriptions of the results of the system studies and details of the radiator design are included along with the test results for both the heat pipe components and the assembled radiator panel. These results support the feasibility of using heat pipes in a spacecraft waste heat rejection system.

  14. Solid state radiative heat pump

    DOEpatents

    Berdahl, P.H.

    1984-09-28

    A solid state radiative heat pump operable at room temperature (300 K) utilizes a semiconductor having a gap energy in the range of 0.03-0.25 eV and operated reversibly to produce an excess or deficit of change carriers as compared equilibrium. In one form of the invention an infrared semiconductor photodiode is used, with forward or reverse bias, to emit an excess or deficit of infrared radiation. In another form of the invention, a homogenous semiconductor is subjected to orthogonal magnetic and electric fields to emit an excess or deficit of infrared radiation. Three methods of enhancing transmission of radiation the active surface of the semiconductor are disclosed. In one method, an anti-refection layer is coated into the active surface of the semiconductor, the anti-reflection layer having an index of refraction equal to the square root of that of the semiconductor. In the second method, a passive layer is speaced trom the active surface of the semiconductor by a submicron vacuum gap, the passive layer having an index of refractive equal to that of the semiconductor. In the third method, a coupler with a paraboloid reflecting surface surface is in contact with the active surface of the semiconductor, the coupler having an index of refraction about the same as that of the semiconductor.

  15. Solid state radiative heat pump

    DOEpatents

    Berdahl, Paul H.

    1986-01-01

    A solid state radiative heat pump (10, 50, 70) operable at room temperature (300.degree. K.) utilizes a semiconductor having a gap energy in the range of 0.03-0.25 eV and operated reversibly to produce an excess or deficit of charge carriers as compared to thermal equilibrium. In one form of the invention (10, 70) an infrared semiconductor photodiode (21, 71) is used, with forward or reverse bias, to emit an excess or deficit of infrared radiation. In another form of the invention (50), a homogeneous semiconductor (51) is subjected to orthogonal magnetic and electric fields to emit an excess or deficit of infrared radiation. Three methods of enhancing transmission of radiation through the active surface of the semiconductor are disclosed. In one method, an anti-reflection layer (19) is coated into the active surface (13) of the semiconductor (11), the anti-reflection layer (19) having an index of refraction equal to the square root of that of the semiconductor (11). In the second method, a passive layer (75) is spaced from the active surface (73) of the semiconductor (71) by a submicron vacuum gap, the passive layer having an index of refractive equal to that of the semiconductor. In the third method, a coupler (91) with a paraboloid reflecting surface (92) is in contact with the active surface (13, 53) of the semiconductor (11, 51), the coupler having an index of refraction about the same as that of the semiconductor.

  16. Radiative heat transfer in porous uranium dioxide

    SciTech Connect

    Hayes, S.L.

    1992-12-01

    Due to low thermal conductivity and high emissivity of UO{sub 2}, it has been suggested that radiative heat transfer may play a significant role in heat transfer through pores of UO{sub 2} fuel. This possibility was computationally investigated and contribution of radiative heat transfer within pores to overall heat transport in porous UO{sub 2} quantified. A repeating unit cell was developed to model approximately a porous UO{sub 2} fuel system, and the heat transfer through unit cells representing a wide variety of fuel conditions was calculated using a finite element computer program. Conduction through solid fuel matrix as wekk as pore gas, and radiative exchange at pore surface was incorporated. A variety of pore compositions were investigated: porosity, pore size, shape and orientation, temperature, and temperature gradient. Calculations were made in which pore surface radiation was both modeled and neglected. The difference between yielding the integral contribution of radiative heat transfer mechanism to overall heat transport. Results indicate that radiative component of heat transfer within pores is small for conditions representative of light water reactor fuel, typically less than 1% of total heat transport. It is much larger, however, for conditions present in liquid metal fast breeder reactor fuel; during restructuring of this fuel type early in life, the radiative heat transfer mode was shown to contribute as much as 10-20% of total heat transport in hottest regions of fuel.

  17. Indirect solar loading of waste heat radiators

    SciTech Connect

    Kirkpatrick, R.C.; Tabor, J.E.; Lindman, E.L.; Cooper, A.J.

    1988-01-01

    Waste heat from space based power systems must ultimately be radiated away into space. The local topology around the radiators must be considered from two stand-points: the scattering of sunlight onto the surfaces of the radiator and the heat load that the radiator may put on near-by components of the system. A view factor code (SNAP) developed at Los Alamos allows the computation of the steady-state radiation environment for complex 3-D geometries. An example of the code's utility is given. 4 refs., 2 figs., 1 tab.

  18. Heat Rejection from a Variable Conductance Heat Pipe Radiator Panel

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.; Gibson, M. A.; Hervol, D. S.

    2012-01-01

    A titanium-water heat pipe radiator having an innovative proprietary evaporator configuration was evaluated in a large vacuum chamber equipped with liquid nitrogen cooled cold walls. The radiator was manufactured by Advanced Cooling Technologies, Inc. (ACT), Lancaster, PA, and delivered as part of a Small Business Innovative Research effort. The radiator panel consisted of five titanium-water heat pipes operating as thermosyphons, sandwiched between two polymer matrix composite face sheets. The five variable conductance heat pipes were purposely charged with a small amount of non-condensable gas to control heat flow through the condenser. Heat rejection was evaluated over a wide range of inlet water temperature and flow conditions, and heat rejection was calculated in real-time utilizing a data acquisition system programmed with the Stefan-Boltzmann equation. Thermography through an infra-red transparent window identified heat flow across the panel. Under nominal operation, a maximum heat rejection value of over 2200 Watts was identified. The thermal vacuum evaluation of heat rejection provided critical information on understanding the radiator s performance, and in steady state and transient scenarios provided useful information for validating current thermal models in support of the Fission Power Systems Project.

  19. RADIATIVE HEATING OF THE SOLAR CORONA

    SciTech Connect

    Moran, Thomas G.

    2011-10-20

    We investigate the effect of solar visible and infrared radiation on electrons in the Sun's atmosphere using a Monte Carlo simulation of the wave-particle interaction and conclude that sunlight provides at least 40% and possibly all of the power required to heat the corona, with the exception of dense magnetic flux loops. The simulation uses a radiation waveform comprising 100 frequency components spanning the solar blackbody spectrum. Coronal electrons are heated in a stochastic manner by low coherence solar electromagnetic radiation. The wave 'coherence time' and 'coherence volume' for each component is determined from optical theory. The low coherence of solar radiation allows moving electrons to gain energy from the chaotic wave field which imparts multiple random velocity 'kicks' to these particles causing their velocity distribution to broaden or heat. Monte Carlo simulations of broadband solar radiative heating on ensembles of 1000 electrons show heating at per particle levels of 4.0 x 10{sup -21} to 4.0 x 10{sup -20} W, as compared with non-loop radiative loss rates of {approx}1 x 10{sup -20} W per electron. Since radiative losses comprise nearly all of the power losses in the corona, sunlight alone can explain the elevated temperatures in this region. The volume electron heating rate is proportional to density, and protons are assumed to be heated either by plasma waves or through collisions with electrons.

  20. Radiation heat transfer shapefactors for combustion systems

    NASA Technical Reports Server (NTRS)

    Emery, A. F.; Johansson, O.; Abrous, A.

    1987-01-01

    The computation of radiation heat transfer through absorbing media is commonly done through the zoning method which relies upon values of the geometric mean transmittance and absorptance. The computation of these values is difficult and expensive, particularly if many spectral bands are used. This paper describes the extension of a scan line algorithm, based upon surface-surface radiation, to the computation of surface-gas and gas-gas radiation transmittances.

  1. Many-body radiative heat transfer theory.

    PubMed

    Ben-Abdallah, Philippe; Biehs, Svend-Age; Joulain, Karl

    2011-09-01

    In this Letter, an N-body theory for the radiative heat exchange in thermally nonequilibrated discrete systems of finite size objects is presented. We report strong exaltation effects of heat flux which can be explained only by taking into account the presence of many-body interactions. Our theory extends the standard Polder and van Hove stochastic formalism used to evaluate heat exchanges between two objects isolated from their environment to a collection of objects in mutual interaction. It gives a natural theoretical framework to investigate the photon heat transport properties of complex systems at the mesoscopic scale. PMID:22026672

  2. Radiative heat transport instability in ICF plasmas

    NASA Astrophysics Data System (ADS)

    Rozmus, W.; Bychenkov, V. Yu.

    2015-11-01

    A laser produced high-Z plasma in which an energy balance is achieved due to radiation losses and radiative heat transfer supports ion acoustic wave instability. A linear dispersion relation is derived and instability is compared to the radiation cooling instability. This instability develops in the wide range of angles and wavenumbers with the typical growth rate on the order of cs/LT (cs is the sound speed, LT is the temperature scale length). In addition to radiation dominated systems, a similar thermal transport driven ion acoustic instability was found before in plasmas where the thermal transport coefficient depends on electron density. However, under conditions of indirect drive ICF experiments the driving term for the instability is the radiative heat flux and in particular, the density dependence of the radiative heat conductivity. A specific example of thermal Bremsstrahlung radiation source has been considered corresponding to a thermal conductivity coefficient that is inversely proportional to the square of local particle density. In the nonlinear regime this instability may lead to plasma jet formation and anisotropic x-ray generation.

  3. Radiation detector system having heat pipe based cooling

    DOEpatents

    Iwanczyk, Jan S.; Saveliev, Valeri D.; Barkan, Shaul

    2006-10-31

    A radiation detector system having a heat pipe based cooling. The radiation detector system includes a radiation detector thermally coupled to a thermo electric cooler (TEC). The TEC cools down the radiation detector, whereby heat is generated by the TEC. A heat removal device dissipates the heat generated by the TEC to surrounding environment. A heat pipe has a first end thermally coupled to the TEC to receive the heat generated by the TEC, and a second end thermally coupled to the heat removal device. The heat pipe transfers the heat generated by the TEC from the first end to the second end to be removed by the heat removal device.

  4. Radiatively heated high voltage pyroelectric crystal pulser

    NASA Astrophysics Data System (ADS)

    Antolak, A. J.; Chen, A. X.; Leung, K.-N.; Morse, D. H.; Raber, T. N.

    2014-01-01

    Thin lithium tantalate pyroelectric crystals in a multi-stage pulser were heated by quartz lamps during their charging phase to generate high voltage pulses. The charging voltage was determined empirically based on the measured breakdown voltage in air and verified by the induced breakdown voltage of an external high voltage power supply. A four-stage pyroelectric crystal device generated pulse discharges of up to 86 kV using both quartz lamps (radiative) and thermoelectric (conductive) heating. Approximately 50 mJ of electrical energy was harvested from the crystals when radiatively heated in air, and up to 720 mJ was produced when the crystals were submerged in a dielectric fluid. It is anticipated that joule-level pulse discharges could be obtained by employing additional stages and optimizing the heating configuration.

  5. Radiative heating rates near the stratospheric fountain

    NASA Technical Reports Server (NTRS)

    Doherty, G. M.; Newell, R. E.; Danielsen, E. F.

    1984-01-01

    Radiative heating rates are computed for various sets of conditions thought to be appropriate to the stratospheric fountain region: with and without a layer of cirrus cloud between 100 and 150 mbar; with standard ozone and with decreased ozone in the lower stratosphere, again with and without the cirrus cloud; and with different temperatures in the tropopause region. The presence of the cloud decreases the radiative cooling below the cloud in the upper troposphere and increases the cooling above it in the lower stratosphere. The cloud is heated at the base and cooled at the top and thus radiatively destabilized; overall it gains energy by radiation. Decreasing ozone above the cloud also tends to cool the lower stratosphere. The net effect is a tendency for vertical convergence and horizontal divergence in the cloud region. High resolution profiles of temperature, ozone, and cloudiness within the fountain region are required in order to assess the final balance of the various processes.

  6. Radiative convection with a fixed heat flux

    NASA Astrophysics Data System (ADS)

    Aumaı̂tre, S.

    2001-10-01

    We have determined the marginal stability curve of convective instability in the usual Rayleigh-Bénard configuration with radiative transfer and a fixed total heat flux at the boundaries instead of a fixed temperature. In the Milne-Eddington approximation, radiative transfer introduces a new length scale and breaks the invariance of the Boussinesq equations under an arbitrary temperature shift, which occurs when the heat flux is fixed at the boundaries. The convergence to the limits where the non-radiative cases are expected is studied in this approximation. Then, using a second-order perturbative calculation, we show that the presence of radiation can change qualitatively the instability pattern: there is a range of optical parameters where the Cahn-Hillard equation is not anymore the one appropriate to describe the instability near the threshold.

  7. Radiation drive in laser heated hohlraums

    SciTech Connect

    Suter, L.J.; Kauffman, R.L.; Darrow, C.B.

    1995-11-03

    Nearly 10 years of Nova experiments and analysis have lead to a relatively detailed quantitative and qualitative understanding of radiation drive in laser heated hohlraums. Our most successful quantitative modelling tool is 2D Lasnex numerical simulations. Analysis of the simulations provides us with insight into the details of the hohlraum drive. In particular we find hohlraum radiation conversion efficiency becomes quite high with longer pulses as the accumulated, high Z blow-off plasma begins to radiate. Extensive Nova experiments corroborate our quantitative and qualitative understanding.

  8. Radiation heating in selected NERVA engine components

    NASA Technical Reports Server (NTRS)

    Courtney, J. C.; Hertelendy, N. A.; Lindsey, B. A.

    1972-01-01

    The role of heating from nuclear radiation in design of the NERVA engine is treated. Some components are subjected to very high gamma heating rates in excess of 0.5 Btu/cubic inch/sec in steel in the primary nozzle or 0.25 Btu/cubic inch/sec in aluminum in the pressure vessel. These components must be cooled by a fraction of the liquid hydrogen propellant before it is passed through the core, heated, and expanded out the nozzle as a gas. Other components that are subjected to lower heating rates such as the thrust structure and the disk shield are designed so that they would not require liquid hydrogen cooling. Typical gamma and neutron heating rates, resulting temperatures, and their design consequences are discussed. Calculational techniques used in the nuclear and thermal analyses of the NERVA engine are briefly treated.

  9. Tropical Cloud Properties and Radiative Heating Profiles

    DOE Data Explorer

    Mather, James

    2008-01-15

    We have generated a suite of products that includes merged soundings, cloud microphysics, and radiative fluxes and heating profiles. The cloud microphysics is strongly based on the ARM Microbase value added product (Miller et al., 2003). We have made a few changes to the microbase parameterizations to address issues we observed in our initial analysis of the tropical data. The merged sounding product is not directly related to the product developed by ARM but is similar in that it uses the microwave radiometer to scale the radiosonde column water vapor. The radiative fluxes also differ from the ARM BBHRP (Broadband Heating Rate Profile) product in terms of the radiative transfer model and the sampling interval.

  10. Radiative Heating Methodology for the Huygens Probe

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher O.; Hollis, Brian R.; Sutton, Kenneth

    2007-01-01

    The radiative heating environment for the Huygens probe near peak heating conditions for Titan entry is investigated in this paper. The task of calculating the radiation-coupled flowfield, accounting for non-Boltzmann and non-optically thin radiation, is simplified to a rapid yet accurate calculation. This is achieved by using the viscous-shock layer (VSL) technique for the stagnation-line flowfield calculation and a modified smeared rotational band (SRB) model for the radiation calculation. These two methods provide a computationally efficient alternative to a Navier-Stokes flowfield and line-by-line radiation calculation. The results of the VSL technique are shown to provide an excellent comparison with the Navier-Stokes results of previous studies. It is shown that a conventional SRB approach is inadequate for the partially optically-thick conditions present in the Huygens shock-layer around the peak heating trajectory points. A simple modification is proposed to the SRB model that improves its accuracy in these partially optically-thick conditions. This modified approach, labeled herein as SRBC, is compared throughout this study with a detailed line-by-line (LBL) calculation and is shown to compare within 5% in all cases. The SRBC method requires many orders-of-magnitude less computational time than the LBL method, which makes it ideal for coupling to the flowfield. The application of a collisional-radiative (CR) model for determining the population of the CN electronic states, which govern the radiation for Huygens entry, is discussed and applied. The non-local absorption term in the CR model is formulated in terms of an escape factor, which is then curve-fit with temperature. Although the curve-fit is an approximation, it is shown to compare well with the exact escape factor calculation, which requires a computationally intensive iteration procedure.

  11. Heat pipe radiators for space. [vacuum tests

    NASA Technical Reports Server (NTRS)

    Sellers, J. P.

    1977-01-01

    An optimized flight-weight prototype fluid-header panel (heatpipe radiator system) was tested in a vacuum environment over a wide range of coolant inlet temperatures, coolant flow rates, and environmental absorbed heat fluxes. The maximum performance of the system was determined. Results are compared with earlier data obtained on a smaller fluid-header feasibility panel, and computer predictions. Freeze-thaw tests are described and the change in thaw recovery time due to the addition of a low-freezing point feeder heat pipe is evaluated. Experimental panel fin-temperature distributions are compared with calculated results.

  12. Heat pump processes induced by laser radiation

    NASA Technical Reports Server (NTRS)

    Garbuny, M.; Henningsen, T.

    1980-01-01

    A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

  13. Vaporization characteristics of carbon heat shields under radiative heating.

    NASA Technical Reports Server (NTRS)

    Davy, W. C.; Bar-Nun, A.

    1972-01-01

    Study of the vaporization characteristics of samples of ATJ graphite, a material that has been considered for use on a Jovian probe. These samples were subjected to radiative heating loads of approximately 2 kW/sq cm in argon atmospheres of pressures from 0.00046 to 1 atm. Surface temperatures, mass loss rates, and spatially resolved emission spectral data were recorded. These data are analyzed to determine carbon vapor pressure as a function of temperature and are compared with current models for the vapor pressure of carbon. The effects of finite vaporization (i.e., nonequilibrium) rates are considered and compared with experiment. Estimates of the heat of vaporization from an energy balance are also presented.

  14. Convective and radiative heating of a Saturn entry probe

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Szema, K. Y.; Moss, J. N.; Subramanian, S. V.

    1984-01-01

    The extent of convective and radiative heating for a Saturn entry probe is investigated in the absence and presence of ablation mass injection. The flow in the shock layer is assumed to be axisymmetric, viscous and in local thermodynamic equilibrium. The importance of chemical nonequilibrium effects for both the radiative and convective nonblowing surface heating rates is demonstrated for prescribed entry conditions. Results indicate that the nonequilibrium chemistry can significantly influence the rate of radiative heating to the entry probes. With coupled carbon-phenolic ablation injection, the convective heating rates are reduced substantially. Turbulence has little effect on radiative heating but it increases the convective heating considerably.

  15. Effect of combined heat and radiation on microbial destruction

    NASA Technical Reports Server (NTRS)

    Fisher, D. A.; Pflug, I. J.

    1977-01-01

    A series of experiments at several levels of relative humidity and radiation dose rates was carried out using spores of Bacillus subtilis var. niger to evaluate the effect of heat alone, radiation alone, and a combination of heat and radiation. Combined heat and radiation treatment of microorganisms yields a destruction rate greater than the additive rates of the independent agents. The synergistic mechanism shows a proportional dependency on radiation dose rate, an Arrhenius dependence on temperature, and a dependency on relative humidity. Maximum synergism occurs under conditions where heat and radiation individually destroy microorganisms at approximately equal rates. Larger synergistic advantage is possible at low relative humidities rather than at high relative humidities.

  16. Radiative heat transfer in coal furnaces

    SciTech Connect

    Ahluwalia, R.K.; Im, K.H.

    1992-01-01

    A hybrid technique has been developed to solve three-dimensional spectral radiation transport equations for absorbing, emitting and anisotropically scattering media. An optimal mix of computational speed and accuracy is obtained by combining the discrete ordinate method (S{sub 4}), modified differential approximation (MDA) and P{sub 1} approximation for use in different range of optical thicknesses. The technique is used in conjunction with a char burnout model and spectroscopic data for H{sub 2}O, CO{sub 2}, CO, char, soot and ash to determine the influence of ash composition, ash content and coal preparation on furnace heat absorption.

  17. Radiative heat transfer in coal furnaces

    SciTech Connect

    Ahluwalia, R.K.; Im, K.H.

    1992-09-01

    A hybrid technique has been developed to solve three-dimensional spectral radiation transport equations for absorbing, emitting and anisotropically scattering media. An optimal mix of computational speed and accuracy is obtained by combining the discrete ordinate method (S{sub 4}), modified differential approximation (MDA) and P{sub 1} approximation for use in different range of optical thicknesses. The technique is used in conjunction with a char burnout model and spectroscopic data for H{sub 2}O, CO{sub 2}, CO, char, soot and ash to determine the influence of ash composition, ash content and coal preparation on furnace heat absorption.

  18. Radiation heat transport in disordered media

    NASA Astrophysics Data System (ADS)

    Strieder, William

    Radiation heat transport through the internal void spaces of particle beds, fiber beds, packed beds, reactors and porous media with opaque, diffusely reflecting, gray body surfaces and large solid dimensions ( πd/ λth > 100) is considered. A the local particle surface radiosity, differential view factor and solid temperature, permits a rigorous solution of the dependent, long range multiple scattering problem. The conductivity results, applied to a bed of randomly overlapping spheres, agree exactly with pseudohomogeneous results in both the isotropic and anisotropic scattering limits and shed rigorous light on the anisotropic phase function expansion theory. Explicit calculations, performed for several other standard packings, e.g. fiber beds, exhibit a parallll upper and series lower bound over the various particle shapes and dispersion structures. Results show that an empirical equation first suggested by Vortmeyer (German Chem. Engng, 3, (1980) 124-137), but generalized herein from one P to four P0, P1, P2, P3 coefficients, which vary substantially with the various industrial packings, will provide a suitable generalization of the emissivity factor of krad for engineering conductivity modeling of radiation heat transport.

  19. Radiative heat transport instability in a laser produced inhomogeneous plasma

    SciTech Connect

    Bychenkov, V. Yu.; Rozmus, W.

    2015-08-15

    A laser produced high-Z plasma in which an energy balance is achieved due to radiation emission and radiative heat transfer supports ion acoustic instability. A linear dispersion relation is derived, and instability is compared to the radiation cooling instability [R. G. Evans, Plasma Phys. Controlled Fusion 27, 751 (1985)]. Under conditions of indirect drive fusion experiments, the driving term for the instability is the radiative heat flux and, in particular, the density dependence of the radiative heat conductivity. A specific example of thermal Bremsstrahlung radiation source has been considered. This instability may lead to plasma jet formation and anisotropic x-ray generation, thus affecting inertial confinement fusion related experiments.

  20. Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Schunk, Richard G.

    2011-01-01

    An active thermal control system architecture has been modified to include a regenerative heat exchanger (regenerator) inboard of the radiator. Rather than using a radiator bypass valve a regenerative heat exchanger is placed inboard of the radiators. A regenerator cold side bypass valve is used to set the return temperature. During operation, the regenerator bypass flow is varied, mixing cold radiator return fluid and warm regenerator outlet fluid to maintain the system setpoint. At the lowest heat load for stable operation, the bypass flow is closed off, sending all of the flow through the regenerator. This lowers the radiator inlet temperature well below the system set-point while maintaining full flow through the radiators. By using a regenerator bypass flow control to maintain system setpoint, the required minimum heat load to avoid radiator freezing can be reduced by more than half compared to a radiator bypass system.

  1. Effect of radiation heat transfer on thermal diffusivity measurements

    NASA Astrophysics Data System (ADS)

    Araki, N.

    1990-03-01

    Experimental data on thermal conductivity and thermal diffusivity of a semitransparent material generally include an error due to the radiation heat transfer. This error varies in accordance with the experimental conditions such as the temperature level of the sample and the measuring method. In this paper, research on the influence of radiation heat transfer on thermal diffusivity are reviewed, and as an example, the method to correct the radiation component in the apparent thermal diffusivity measured by the stepwise heating technique is presented. The transient heat transfer by simultaneous thermal conduction and radiation in a semitransparent material is analyzed when the front surface is subjected to stepwise heating. The apparent thermal diffusivity, which includes the radiation component, is calculated for various parameters.

  2. Nonequilibrium Stagnation-Line Radiative Heating for Fire II

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher O.; Hollis, Brian R.; Sutton, Kenneth

    2007-01-01

    This paper presents a detailed analysis of the shock-layer radiative heating to the Fire II vehicle using a new air radiation model and a viscous shock-layer flowfield model. This new air radiation model contains the most up-to-date properties for modeling the atomic-line, atomic photoionization, molecular band, and non-Boltzmann processes. The applied viscous shock-layer flowfield analysis contains the same thermophysical properties and nonequilibrium models as the LAURA Navier-Stokes code. Radiation-flowfield coupling, or radiation cooling, is accounted for in detail in this study. It is shown to reduce the radiative heating by about 30% for the peak radiative heating points, while reducing the convective heating only slightly. A detailed review of past Fire II radiative heating studies is presented. It is observed that the scatter in the radiation predicted by these past studies is mostly a result of the different flowfield chemistry models and the treatment of the electronic state populations. The present predictions provide, on average throughout the trajectory, a better comparison with Fire II flight data than any previous study. The magnitude of the vacuum ultraviolet (VUV) contribution to the radiative flux is estimated from the calorimeter measurements. This is achieved using the radiometer measurements and the predicted convective heating. The VUV radiation predicted by the present model agrees well with the VUV contribution inferred from the Fire II calorimeter measurement, although only when radiation-flowfield coupling is accounted for. This agreement provides evidence that the present model accurately models the VUV radiation, which is shown to contribute significantly to the Fire II radiative heating.

  3. Effect of combined heat and radiation on microbial destruction.

    PubMed Central

    Fisher, D A; Pflug, I J

    1977-01-01

    A series of experiments at several levels of relative humidity and radiation dose rates was carried out using spores of Bacillus subtilis var. niger to evaluate the effect of heat alone, radiation alone, and a combination of heat and radiation. Combined heat and radiation treatment of microorganisms yields a destruction rate greater than the additive rates of the independence agents. The synergistic mechanism shows a proportional dependency on radiation dose rate an Arrhenius dependency on temperature, and a dependency on relative humidity. Maximum synergism occurs under conditions where heat and radiation individually destroy microorganisms at approximately equal rates. Larger synergistic advantage is possible at low relative humidities rather than at high relative humidities. PMID:406843

  4. Radiative Heat Transfer During Atmosphere Entry at Parabolic Velocity

    NASA Technical Reports Server (NTRS)

    Yoshikawa, Kenneth K.; Wick, Bradford H.

    1961-01-01

    Stagnation point radiative heating rates for manned vehicles entering the earth's atmosphere at parabolic velocity are presented and compared with corresponding laminar convective heating rates. The calculations were made for both nonlifting and lifting entry trajectories for vehicles of varying nose radius, weight-to-area ratio, and drag. It is concluded from the results presented that radiative heating will be important for the entry conditions considered.

  5. Application of ray tracing in radiation heat transfer

    NASA Technical Reports Server (NTRS)

    Baumeister, Joseph F.

    1993-01-01

    This collection of presentation figures displays the capabilities of ray tracing for radiation propagation calculations as compared to an analytical approach. The goal is to introduce the terminology and solution process used in ray tracing, and provide insight into radiation heat transfer principles and analysis tools. A thermal analysis working environment is introduced that solves demanding radiation heat transfer problems based on ray tracing. This information may serve as a reference for designing and building ones own analysis environment.

  6. Analysis for radiative heat transfer in a circulating fluidized bed

    SciTech Connect

    Steward, F.R.; Couturier, M.F.; Poolpol, S.

    1995-12-31

    The radiative heat transfer from the particles within a circulating fluidized bed has been determined for a number of different assumptions. Based on temperature profiles measured in an operating circulating fluidized bed burning coal, a procedure for predicting the radiative transfer from the solid particles to a cold wall is recommended. The radiative transfer from the solid particles to a cold wall makes up approximately 50% of the total heat transfer to the wall in a circulating fluidized bed combustor.

  7. Radiative heat transfer in the extreme near field.

    PubMed

    Kim, Kyeongtae; Song, Bai; Fernández-Hurtado, Víctor; Lee, Woochul; Jeong, Wonho; Cui, Longji; Thompson, Dakotah; Feist, Johannes; Reid, M T Homer; García-Vidal, Francisco J; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

    2015-12-17

    Radiative transfer of energy at the nanometre length scale is of great importance to a variety of technologies including heat-assisted magnetic recording, near-field thermophotovoltaics and lithography. Although experimental advances have enabled elucidation of near-field radiative heat transfer in gaps as small as 20-30 nanometres (refs 4-6), quantitative analysis in the extreme near field (less than 10 nanometres) has been greatly limited by experimental challenges. Moreover, the results of pioneering measurements differed from theoretical predictions by orders of magnitude. Here we use custom-fabricated scanning probes with embedded thermocouples, in conjunction with new microdevices capable of periodic temperature modulation, to measure radiative heat transfer down to gaps as small as two nanometres. For our experiments we deposited suitably chosen metal or dielectric layers on the scanning probes and microdevices, enabling direct study of extreme near-field radiation between silica-silica, silicon nitride-silicon nitride and gold-gold surfaces to reveal marked, gap-size-dependent enhancements of radiative heat transfer. Furthermore, our state-of-the-art calculations of radiative heat transfer, performed within the theoretical framework of fluctuational electrodynamics, are in excellent agreement with our experimental results, providing unambiguous evidence that confirms the validity of this theory for modelling radiative heat transfer in gaps as small as a few nanometres. This work lays the foundations required for the rational design of novel technologies that leverage nanoscale radiative heat transfer. PMID:26641312

  8. Development of a shuttle plume radiation heating indicator

    NASA Technical Reports Server (NTRS)

    Reardon, John E.

    1988-01-01

    The primary objectives were to develop a Base Heating Indicator Code and a new plume radiation code for the Space Shuttle. Additional work included: revision of the Space Shuttle plume radiation environment for changes in configuration and correction of errors, evaluation of radiation measurements to establish a plume radiation model for the SRB High Performance Motor (HPM) plume, radiation predictions for preliminary designs, and participation in hydrogen disposal analysis and testing for the VAFB Shuttle launch site. The two most significant accomplishments were the development of the Base Heating Indicator Code and the Shuttle Engine Plume Radiation (SEPRAD) Code. The major efforts in revising the current Shuttle plume radiation environment were for the Orbiter base heat shield and the ET components in the Orbiter-ET interface region. The work performed is summarized in the technical discussion section with references to the documents containing detailed results. The technical discussion is followed by a summary of conclusions and recommendations for future work.

  9. User's Manual: Routines for Radiative Heat Transfer and Thermometry

    NASA Technical Reports Server (NTRS)

    Risch, Timothy K.

    2016-01-01

    Determining the intensity and spectral distribution of radiation emanating from a heated surface has applications in many areas of science and engineering. Areas of research in which the quantification of spectral radiation is used routinely include thermal radiation heat transfer, infrared signature analysis, and radiation thermometry. In the analysis of radiation, it is helpful to be able to predict the radiative intensity and the spectral distribution of the emitted energy. Presented in this report is a set of routines written in Microsoft Visual Basic for Applications (VBA) (Microsoft Corporation, Redmond, Washington) and incorporating functions specific to Microsoft Excel (Microsoft Corporation, Redmond, Washington) that are useful for predicting the radiative behavior of heated surfaces. These routines include functions for calculating quantities of primary importance to engineers and scientists. In addition, the routines also provide the capability to use such information to determine surface temperatures from spectral intensities and for calculating the sensitivity of the surface temperature measurements to unknowns in the input parameters.

  10. Features of Afterbody Radiative Heating for Earth Entry

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher O.; Brandis, Aaron

    2014-01-01

    Radiative heating is identified as a major contributor to afterbody heating for Earth entry capsules at velocities above 10 km/s. Because of rate-limited electron-ion recombination processes, a large fraction of the electronically-excited N and O atoms produced in the high temperature/pressure forebody remain as they expand into the afterbody region, which results in significant afterbody radiation. Large radiative heating sensitivities to electron-impact ionization rates and escape factors are identified. Ablation products from a forebody ablator are shown to increase the afterbody radiation by as much as 40%. The tangent-slab radiation transport approach is shown to over-predict the radiative flux by as much as 40% in the afterbody, therefore making the more computationally expensive ray-tracing approach necessary for accurate radiative flux predictions. For the Stardust entry, the afterbody radiation is predicted to be nearly twice as large as the convective heating during the peak heating phase of the trajectory. Comparisons between simulations and the Stardust Echelle observation measurements, which are shown to be dominated by afterbody emission, indicate agreement within 20% for various N and O lines. Similarly, calorimeter measurements from the Fire II experiment are identified as a source of validation data for afterbody radiation. For the afterbody calorimeter measurement closest to the forebody, which experiences the largest afterbody radiative heating component, the convective heating alone is shown to under-predict the measurement, even for the fullycatalytic assumption. Agreement with the measurements is improved with the addition of afterbody radiation. These comparisons with Stardust and Fire II measurements provide validation that the significant afterbody radiation values proposed in this work are legitimate.

  11. A Freezable Heat Exchanger for Space Suit Radiator Systems

    NASA Technical Reports Server (NTRS)

    Nabity, James A.; Mason, Georgia R.; Copeland, Robert J.; Trevino, Luis a.

    2008-01-01

    During an ExtraVehicular Activity (EVA), both the heat generated by the astronaut s metabolism and that produced by the Portable Life Support System (PLSS) must be rejected to space. The heat sources include the heat of adsorption of metabolic CO2, the heat of condensation of water, the heat removed from the body by the liquid cooling garment and the load from the electrical components. Although the sublimator hardware to reject this load weighs only 1.58 kg (3.48 lbm), an additional 3.6 kg (8 lbm) of water are loaded into the unit, most of which is sublimated and lost to space, thus becoming the single largest expendable during an eight-hour EVA. Using a radiator to reject heat from the astronaut during an EVA can reduce the amount of expendable water consumed in the sublimator. Radiators have no moving parts and are thus highly reliable. Past freezable radiators have been too heavy, but the weight can be greatly reduced by placing a small and freeze tolerant heat exchanger between the astronaut and radiator, instead of making the very large radiator freeze tolerant. Therefore, the key technological innovation to improve space suit radiator performance was the development of a lightweight and freezable heat exchanger that accommodates the variable heat load generated by the astronaut. Herein, we present the heat transfer performance of a newly designed heat exchanger that endured several freeze / thaw cycles without any apparent damage. The heat exchanger was also able to continuously turn down or turn up the heat rejection to follow the variable load.

  12. Long titanium heat pipes for high-temperature space radiators

    NASA Technical Reports Server (NTRS)

    Girrens, S. P.; Ernst, D. M.

    1982-01-01

    Titanium heat pipes are being developed to provide light weight, reliable heat rejection devices as an alternate radiator design for the Space Reactor Power System (SP-100). The radiator design includes 360 heat pipes, each of which is 5.2 m long and dissipates 3 kW of power at 775 K. The radiator heat pipes use potassium as the working fluid, have two screen arteries for fluid return, a roughened surface distributive wicking system, and a D shaped cross section container configuration. A prototype titanium heat pipe, 5.5 m long, was fabricated and tested in space simulating conditions. Results from startup and isothermal operation tests are presented. These results are also compared to theoretical performance predictions that were used to design the heat pipe initially.

  13. Long titanium heat pipes for high-temperature space radiators

    SciTech Connect

    Girrens, S.P.; Ernst, D.M.

    1982-01-01

    Titanium heat pipes are being developed to provide light weight, reliable heat rejection devices as an alternate radiator design for the Space Reactor Power System (SP-100). The radiator design includes 360 heat pipes, each of which is 5.2 m long and dissipates 3 kW of power at 775 K. The radiator heat pipes use potassium as the working fluid, have two screen arteries for fluid return, a roughened surface distributive wicking system, and a D-shaped cross-section container configuration. A prototype titanium heat pipe, 5.5-m long, has been fabricated and tested in space-simulating conditions. Results from startup and isothermal operation tests are presented. These results are also compared to theoretical performance predictions that were used to design the heat pipe initially.

  14. Potassium Rankine cycle vapor chamber (heat pipe) radiator study

    NASA Technical Reports Server (NTRS)

    Gerrels, E. E.; Killen, R. E.

    1971-01-01

    A structurally integrated vapor chamber fin (heat pipe) radiator is defined and evaluated as a potential candidate for rejecting waste heat from the potassium Rankine cycle powerplant. Several vapor chamber fin geometries, using stainless steel construction, are evaluated and an optimum is selected. A comparison is made with an operationally equivalent conduction fin radiator. Both radiators employ NaK-78 in the primary coolant loop. In addition, the Vapor Chamber Fin (VCF) radiator utilizes sodium in the vapor chambers. Preliminary designs are developed for the conduction fin and VCF concepts. Performance tests on a single vapor chamber were conducted to verify the VCF design. A comparison shows the conduction fin radiator easier to fabricate, but heavier in weight, particularly as meteoroid protection requirements become more stringent. While the analysis was performed assuming the potassium Rankine cycle powerplant, the results are equally applicable to any system radiating heat to space in the 900 to 1400 F temperature range.

  15. Radiation heat transfer in two-phase media

    SciTech Connect

    Adzerikho, K.S.

    1988-05-01

    The state of the art of approximate and numerical methods of the theory of radiation heat transfer is analyzed. The principles for producing engineering methods of computing the radiation heat-transfer characteristics in power plants are examined. These principles include: the integration of the transport equation, computing the radiation heat transfer in nonisothermal two-phase media bounded by emitting and reflecting surfaces, the thermal efficiency of screens as a function of the optical properties of the boundary surfaces and the furnace medium, the scattering processes, temperature distribution, and a program NOTAK in the FORTRAN-IV language.

  16. Design and Modeling of a Variable Heat Rejection Radiator

    NASA Technical Reports Server (NTRS)

    Miller, Jennifer R.; Birur, Gajanana C.; Ganapathi, Gani B.; Sunada, Eric T.; Berisford, Daniel F.; Stephan, Ryan

    2011-01-01

    Variable Heat Rejection Radiator technology needed for future NASA human rated & robotic missions Primary objective is to enable a single loop architecture for human-rated missions (1) Radiators are typically sized for maximum heat load in the warmest continuous environment resulting in a large panel area (2) Large radiator area results in fluid being susceptible to freezing at low load in cold environment and typically results in a two-loop system (3) Dual loop architecture is approximately 18% heavier than single loop architecture (based on Orion thermal control system mass) (4) Single loop architecture requires adaptability to varying environments and heat loads

  17. Performance of the Spacelab Astro-1 mission heat pipe radiator

    NASA Technical Reports Server (NTRS)

    Humphries, W. R.; Hamner, R. M.; Stallings, R. D.; Cotton, J. A.

    1985-01-01

    This paper describes the design and performance of the Astro Integrated Radiator System (IRS). The system was recently ground tested and proven successful in rejecting approximately 400 watts of heat. The radiator was constructed from an aluminum panel configured to form two orthogonal planes. Heat pipes were adhesively bonded and riveted to the radiator to isothermalize the surface. The IRS was subjected to a full thermal vacuum test to validate the thermal math model and to qualify the radiator for space flight. The thermal performance met prescribed temperature limits with margins at both extremes, and no mechanical failures occurred.

  18. Heat pipe radiation cooling of advanced hypersonic propulsion system components

    NASA Technical Reports Server (NTRS)

    Martin, R. A.; Keddy, M.; Merrigan, M. A.; Silverstein, C. C.

    1991-01-01

    Heat transfer, heat pipe, and system studies were performed to assess the newly proposed heat pipe radiation cooling (HPRC) concept. With an HPRC system, heat is removed from the ramburner and nozzle of a hypersonic aircraft engine by a surrounding, high-temperature, heat pipe nacelle structure, transported to nearby external surfaces, and rejected to the environment by thermal radiation. With HPRC, the Mach number range available for using hydrocarbon fuels for aircraft operation extends into the Mach 4 to Mach 6 range, up from the current limit of about Mach 4. Heat transfer studies using a newly developed HPRC computer code determine cooling system and ramburner and nozzle temperatures, heat loads, and weights for a representative combined-cycle engine cruising at Mach 5 at 80,000 ft altitude. Heat pipe heat transport calculations, using the Los Alamos code HTPIPE, reveal that adequate heat trasport capability is available using molybdenum-lithium heat pipe technology. Results show that the HPRC system radiator area is limited in size to the ramburner-nozzle region of the engine nacelle; reasonable system weights are expected; hot section temperatures are consistent with advanced structural materials development goals; and system impact on engine performance is minimal.

  19. Deployable radiators for waste heat dissipation from Shuttle payloads

    NASA Technical Reports Server (NTRS)

    Cox, R. L.; Dietz, J. B.; Leach, J. W.

    1976-01-01

    Thermal control of Shuttle instruments will require the use of a pumped fluid space radiator system to reject large quantities of waste heat. Many payloads, however, will have insufficient vehicle surface area available for radiators to reject this waste heat and will, therefore, require the use of deployed panels. It is desirable to utilize modularized, deployable radiator systems which have a high degree of configuration and component commonality to minimize the design, development, and fabrication costs. Prototypes of two radiator systems which meet these criteria are currently under development for Shuttle payload utilization: a 'rigid' radiator system which utilizes aluminum honeycomb panels of the Shuttle Orbiter configuration that are deployed by an Apollo Telescope Mount type scissors mechanism; and two 'flexible' radiator systems which use panels constructed from flexible metal/dielectric composite materials that are deployed by 'unrolling' or 'extending' in orbit. Detailed descriptions of these deployable radiator systems, along with design and performance features, are presented.

  20. Radiative heat transfer in low-dimensional systems -- microscopic mode

    NASA Astrophysics Data System (ADS)

    Woods, Lilia; Phan, Anh; Drosdoff, David

    2013-03-01

    Radiative heat transfer between objects can increase dramatically at sub-wavelength scales. Exploring ways to modulate such transport between nano-systems is a key issue from fundamental and applied points of view. We advance the theoretical understanding of radiative heat transfer between nano-objects by introducing a microscopic model, which takes into account the individual atoms and their atomic polarizabilities. This approach is especially useful to investigate nano-objects with various geometries and give a detailed description of the heat transfer distribution. We employ this model to study the heat exchange in graphene nanoribbon/substrate systems. Our results for the distance separations, substrates, and presence of extended or localized defects enable making predictions for tailoring the radiative heat transfer at the nanoscale. Financial support from the Department of Energy under Contract No. DE-FG02-06ER46297 is acknowledged.

  1. Heat pipe radiation cooling evaluation: Task 2 concept studies report

    SciTech Connect

    Silverstein, C.C.

    1991-10-01

    This report presents the result of Task 2, Concept Studies for Heat Pipe Radiation Cooling (HPRC), which was performed for Los Alamos National Laboratory under Contract 9-XT1-U9567. Studies under a prior contract defined a reference HPRC conceptual design for hypersonic aircraft engines operating at Mach 5 and an altitude of 80,000 ft. Task 2 involves the further investigation of heat pipe radiation cooling (HPRC) systems for additional design and operating conditions.

  2. Theory of heat transfer and hydraulic resistance of oil radiators

    NASA Technical Reports Server (NTRS)

    Mariamov, N B

    1942-01-01

    In the present report the coefficients of heat transfer and hydraulic resistance are theoretically obtained for the case of laminar flow of a heated viscous liquid in a narrow rectangular channel. The results obtained are applied to the computation of oil radiators, which to a first approximation may be considered as made up of a system of such channels. In conclusion, a comparison is given of the theoretical with the experimental results obtained from tests on airplane oil radiators.

  3. Radiative Heating in MSL Entry: Comparison of Flight Heating Discrepancy to Ground Test and Predictive Models

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Brandis, Aaron M.; White, Todd R.; Mahzari, Milad; Bose, Deepak

    2014-01-01

    During the recent entry of the Mars Science Laboratory (MSL), the heat shield was equipped with thermocouple stacks to measure in-depth heating of the thermal protection system (TPS). When only convective heating was considered, the derived heat flux from gauges in the stagnation region was found to be underpredicted by as much as 17 W/sq cm, which is significant compared to the peak heating of 32 W/sq cm. In order to quantify the contribution of radiative heating phenomena to the discrepancy, ground tests and predictive simulations that replicated the MSL entry trajectory were performed. An analysis is carried through to assess the quality of the radiation model and the impact to stagnation line heating. The impact is shown to be significant, but does not fully explain the heating discrepancy.

  4. Atmospheric heating by solar EUV radiation

    NASA Technical Reports Server (NTRS)

    Stolarski, R. S.; Hays, P. B.; Roble, R. G.

    1975-01-01

    A diurnal model of the mid-latitude ionospheric R region is used to calculate the diurnal variation of the neutral gas heating rates and neutral gas heating efficiency for conditions similar to those over Millstone Hill on March 23-24, 1970. The calculations show that the absorbed solar EUV (wavelength less than or equal to 1025 A) energy is almost equally split between photoelectrons and ion pair production. Photoelectrons heat the ambient electron gas by Coulomb collisions and by the quenching of certain excited ion species, whereas the ion gas is primarily heated by collisions with hot electrons and by chemical reactions. Heating processes above 300 km, between 170 and 300 km, and below 170 km are identified.

  5. High-Absorptance Radiative Heat Sink

    NASA Technical Reports Server (NTRS)

    Cafferty, T.

    1983-01-01

    Absorptance of black-painted open-cell aluminum honeycomb improved by cutting honeycomb at angle or bias rather than straight across. This ensures honeycomb cavities escapes. At each reflection radiation attenuated by absorption. Applications include space-background simulators, space radiators, solar absorbers, and passive coolers for terrestrial use.

  6. Thermal radiation heat transfer (3rd revised and enlarged edition)

    NASA Astrophysics Data System (ADS)

    Siegel, Robert; Howell, John R.

    This book first reviews the overall aspects and background information related to thermal radiation heat transfer and incorporates new general information, advances in analytical and computational techniques, and new reference material. Coverage focuses on radiation from opaque surfaces, radiation interchange between various types of surfaces enclosing a vacuum or transparent medium, and radiation including the effects of partially transmitting media, such as combustion gases, soot, or windows. Boundary conditions and multiple layers are discussed with information on radiation in materials with nonunity refractive indices.

  7. Stagnation Point Radiative Heating Relations for Venus Entry

    NASA Technical Reports Server (NTRS)

    Tauber, Michael E.; Palmer, Grant E.; Prabhu, Dinesh K.

    2012-01-01

    Improved analytic expressions for calculating the stagnation point radiative heating during entry into the atmosphere of Venus have been developed. These analytic expressions can be incorporated into entry trajectory simulation codes. Together with analytical expressions for convective heating at the stagnation point, the time-integrated total heat load at the stagnation point is used in determining the thickness of protective material required, and hence the mass of the fore body heatshield of uniform thickness.

  8. Vibroacoustic Analysis of Large Heat Rejection Radiators for Future Spacecraft

    NASA Technical Reports Server (NTRS)

    Larko, Jeffrey M.; McNelis, Mark E.; Hughes, William O.

    2006-01-01

    Spacecraft structures such as antennas, solar arrays and radiator panels significantly respond to high acoustic levels seen at lift-off. Some future spacecraft may utilize nuclear electric propulsion that require large radiator panels to reject waste heat. A vibroacoustic assessment was performed for two different radiator panel designs. Results from the analysis of the two designs using different analytical approaches are presented and discussed.

  9. Radiative heat transfer from a black body to dielectric nanoparticles

    NASA Astrophysics Data System (ADS)

    Chalopin, Yann; Dammak, Hichem; Laroche, Marine; Hayoun, Marc; Greffet, Jean-Jacques

    2011-12-01

    Heating of dielectric nanoparticles by black-body radiation is investigated by using molecular-dynamics simulation. The thermal interaction with the radiation is modeled by coupling the ions with a random electric field and including a radiation reaction force. This approach shows that the heat is absorbed by the polariton mode. Its subsequent redistribution among other vibration modes strongly depends on the particle size and on temperature. We observe energy trapping in a finite subset of vibrational modes and study the relaxation pathway of (MgO)4 by performing a selective excitation with a deterministic force.

  10. Selective radiative heating of nanostructures using hyperbolic metamaterials

    SciTech Connect

    Ding, Ding; Minnich, Austin J

    2015-01-01

    Hyperbolic metamaterials (HMM) are of great interest due to their ability to break the diffraction limit for imaging and enhance near-field radiative heat transfer. Here we demonstrate that an annular, transparent HMM enables selective heating of a sub-wavelength plasmonic nanowire by controlling the angular mode number of a plasmonic resonance. A nanowire emitter, surrounded by an HMM, appears dark to incoming radiation from an adjacent nanowire emitter unless the second emitter is surrounded by an identical lens such that the wavelength and angular mode of the plasmonic resonance match. Our result can find applications in radiative thermal management.

  11. Nonequilibrium radiative heating during outer planet atmospheric entry

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1983-01-01

    The contradictory results obtained by investigators assessing the influence of finite-rate ionization on the radiative heating of probes entering the atmospheres of Jupiter and Saturn are discussed. Tiwari and Szema (1979) found that the radiation heating increased, whereas Leibowitz (1973) and Liebowitz and Kuo (1976) found that it decreased in relation to the results obtained when the ionization rate was assumed to be in equilibrium at the local thermodynamic conditions. The study presented here is limited to stagnation shock layers for nonviscous, hydrogen-helium plasmas with cold, nonblowing conditions at the probe heat shield. It is found that the radiative heating comes mainly from the Balmer region of the spectrum, where the shock layer is optically thin.

  12. Advanced Design Heat PumpRadiator for EVA Suits

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Chen, Weibo; Passow, Christian; Phillips, Scott; Trevino, Luis

    2009-01-01

    Absorption cooling using a LiCl/water heat pump can enable lightweight and effective thermal control for EVA suits without venting water to the environment. The key components in the system are an absorber/radiator that rejects heat to space and a flexible evaporation cooling garment that absorbs heat from the crew member. This paper describes progress in the design, development, and testing of the absorber/radiator and evaporation cooling garment. New design concepts and fabrication approaches will significantly reduce the mass of the absorber/radiator. We have also identified materials and demonstrated fabrication approaches for production of a flexible evaporation cooling garment. Data from tests of the absorber/radiator s modular components have validated the design models and allowed predictions of the size and weight of a complete system.

  13. Nonequilibrium radiative heating of a Jovian entry body

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Subramanian, S. V.

    1979-01-01

    The influence of nonlocal thermodynamic equilibrium (NLTE) radiative transfer on radiative and convective heating of a Jovian entry body is investigated. The flow in the shock layer is assumed to be axisymmetric, viscous, and in chemical equilibrium. The chemical species considered for the collisional deactivation processes are H2, H, H+. The NLTE radiative transfer equations are derived for multilevel energy transitions. The rotational and vibrational energy modes are assumed to be in local thermodynamic equilibrium. The results indicate that higher-level energy transitions have little influence on the overall NLTE results. The NLTE results, however, are found to be greatly influenced by the temperature distributions in the shock layer. The convective and radiative heating to the entry body are reduced significantly because of the NLTE conditions; the reduction in convective heating, however, is relatively small. The influence of NLTE is found to be greater at higher entry altitudes.

  14. The Influence of Ablation on Radiative Heating for Earth Entry

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher O.; Gnoffo, Peter A.; Sutton, Kenneth

    2008-01-01

    Using the coupled ablation and radiation capability recently included in the LAURA flowfield solver, this paper investigates the influence of ablation on the shock-layer radiative heating for Earth entry. The extension of the HARA radiation model, which provides the radiation predictions in LAURA, to treat a gas consisting of the elements C, H, O, and N is discussed. It is shown that the absorption coefficient of air is increased with the introduction of the C and H elements. A simplified shock layer model is studied to show the impact of temperature, as well as the abundance of C and H, on the net absorption or emission from an ablation contaminated boundary layer. It is found that the ablation species reduce the radiative flux in the vacuum ultraviolet, through increased absorption, for all temperatures. However, in the infrared region of the spectrum, the ablation species increase the radiative flux, through strong emission, for temperatures above 3,000 K. Thus, depending on the temperature and abundance of ablation species, the contaminated boundary layer may either provide a net increase or decrease in the radiative flux reaching the wall. To assess the validity of the coupled ablation and radiation LAURA analysis, a previously analyzed Mars-return case (15.24 km/s), which contains significant ablation and radiation coupling, is studied. Exceptional agreement with previous viscous shock-layer results is obtained. A 40% decrease in the radiative flux is predicted for ablation rates equal to 20% of the free-stream mass flux. The Apollo 4 peak-heating case (10.24 km/s) is also studied. For ablation rates up to 3.4% of the free-stream mass flux, the radiative heating is reduced by up to 19%, while the convective heating is reduced by up to 87%. Good agreement with the Apollo 4 radiometer data is obtained by considering absorption in the radiometer cavity. For both the Mars return and the Apollo 4 cases, coupled radiation alone is found to reduce the radiative

  15. Deployable radiators for waste heat dissipation from Shuttle payloads

    NASA Technical Reports Server (NTRS)

    Cox, R. L.; Dietz, J. B.; Leach, J. W.

    1976-01-01

    Prototypes of two types of modularized, deployable radiator systems with a high degree of configuration and component commonality to minimize design, development and fabrication costs are currently under development for Shuttle payloads with high waste heat: a rigid radiator system which utilizes aluminum honeycomb panels that are deployed by a scissors mechanism; and two 'flexible' radiator systems which use panels constructed from flexible metal/dielectric composite materials that are deployed by 'unrolling' or 'extending' in orbit. Detail descriptions of these deployable radiator systems along with design and performance features are presented.

  16. Heat Transfer Analysis of a Closed Brayton Cycle Space Radiator

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.

    2007-01-01

    This paper presents a mathematical analysis of the heat transfer processes taking place in a radiator for a closed cycle gas turbine (CCGT), also referred to as a Closed Brayton Cycle (CBC) space power system. The resulting equations and relationships have been incorporated into a radiator sub-routine of a numerical triple objective CCGT optimization program to determine operating conditions yielding maximum cycle efficiency, minimum radiator area and minimum overall systems mass. Study results should be of interest to numerical modeling of closed cycle Brayton space power systems and to the design of fluid cooled radiators in general.

  17. Radiation Heat Transfer Procedures for Space-Related Applications

    NASA Technical Reports Server (NTRS)

    Chai, John C.

    2000-01-01

    Over the last contract year, a numerical procedure for combined conduction-radiation heat transfer using unstructured grids has been developed. As a result of this research, one paper has been published in the Numerical Heat Transfer Journal. One paper has been accepted for presentation at the International Center for Heat and Mass Transfer's International Symposium on Computational Heat Transfer to be held in Australia next year. A journal paper is under review by my NASA's contact. A conference paper for the ASME National Heat Transfer conference is under preparation. In summary, a total of four (4) papers (two journal and two conference) have been published, accepted or are under preparation. There are two (2) to three (3) more papers to be written for the project. In addition to the above publications, one book chapter, one journal paper and six conference papers have been published as a result of this project. Over the last contract year, the research project resulted in one Ph.D. thesis and partially supported another Ph.D. student. My NASA contact and myself have formulated radiation heat transfer procedures for materials with different indices of refraction and for combined conduction-radiation heat transfer. We are trying to find other applications for the procedures developed under this grant.

  18. Estimation of radiative heat transfer using a geometric human model.

    PubMed

    Kakuta, N; Yokoyama, S; Nakamura, M; Mabuchi, K

    2001-03-01

    In order to provide a detailed estimate of radiative heat transfer between a human body and its surrounding environment, we have developed a geometric model of a human form and an algorithm. The model closely resembles the actual shape of a human body and is composed of small quadrilateral surfaces. Dealing with an object or a space with an arbitrary shape, the developed algorithm can judge efficiently whether there is an obstruction between a pair of surfaces. As a result, the angle factors between a pair of surfaces that only occur during radiative heat transfer can be defined. The distribution of the radiative heat transfer rates shows the characteristics of body shape and variations in posture. PMID:11327500

  19. Development of an infrared radiative heating model

    NASA Technical Reports Server (NTRS)

    Bergstrom, R. W.; Helmle, L. C.

    1979-01-01

    Infrared radiative transfer solution algorithms used in global circulation models were assessed. Computation techniques applicable to the Ames circulation model are identified. Transmission properties of gaseous CO2, H2O, and O3 are gathered, and a computer program is developed, using the line parameter tape and Voight profile subroutine, which computes the transmission of CO2, H2O, and O3. A computer code designed to compute atmospheric cooling rates was developed.

  20. Degradation of elastomer by heat and/or radiation

    NASA Astrophysics Data System (ADS)

    Ito, Masayuki

    2007-12-01

    This article studied various problems on the degradation of elastomers by heat and/or radiation. Three kinds of elastomers were irradiated and evaluated by the radiation resistant property using the measurement of tensile test. The fluorine containing elastomer, which has excellent heat resistant properties, was found to be less durable for irradiation than ethylene-propylene-diene (EPDM) elastomer. Ten kinds of different compounding formulas of EPDM were prepared to investigate whether the compounding for heat resistant has durability for irradiation. The thermal exposure was performed in an air oven. The duration of thermal exposure at 140 °C was 384 h. The irradiation condition was 5.0 kGy/h at 70 °C, and the total dose was 0.9 MGy. Elongation retained was taken for the evaluation of the stability. It was found that the formulas for improving the thermal stability did not bring radiation resistant of samples in the experiment. The rate constant of the increase in C dbnd O concentration by heat and radiation was measured and defined as kc( h) and kc( r), respectively. The rate constant of that under the combined addition of the heat and the radiation is expressed as kc( h + r). Eq. (1) was obtained by the experiment and it was found that there is a synergistic relationship between heat and radiation on the increase in C dbnd O concentration kc(h+r)>kc(h)+k(r). Similar relationship was observed on the rate of decrease in ultimate elongation of a certain EPDM.

  1. Meteoroid Protection Methods for Spacecraft Radiators Using Heat Pipes

    NASA Technical Reports Server (NTRS)

    Ernst, D. M.

    1979-01-01

    Various aspects of achieving a low mass heat pipe radiator for the nuclear electric propulsion spacecraft were studied. Specific emphasis was placed on a concept applicable to a closed Brayton cycle power sub-system. Three aspects of inter-related problems were examined: (1) the armor for meteoroid protection, (2) emissivity of the radiator surface, and (3) the heat pipe itself. The study revealed several alternatives for the achievement of the stated goal, but a final recommendation for the best design requires further investigation.

  2. Computation of Radiation Heat Transfer in Aeroengine Combustors

    NASA Technical Reports Server (NTRS)

    Patankar, S. V.

    1996-01-01

    In this report the highlights of the research completed for the NASA are summarized. This research has been completed in the form of two Ph.D. theses by Chai (1994) and Parthasarathy (1996). Readers are referred to these theses for a complete details of the work and lists of references. In the following sections, first objectives of this research are introduced, then the finite-volume method for radiation heat transfer is described, and finally computations of radiative heat transfer in non-gray participating media is presented.

  3. Radiative heat transfer between two dielectric-filled metal gratings

    NASA Astrophysics Data System (ADS)

    Dai, J.; Dyakov, S. A.; Yan, M.

    2016-04-01

    Nanoscale surface corrugation is known to be able to drastically enhance radiative heat transfer between two metal plates. Here we numerically calculate the radiative heat transfer between two dielectric-filled metal gratings at dissimilar temperatures based on a scattering approach. It is demonstrated that, compared to unfilled metal gratings, the heat flux for a fixed geometry can be further enhanced, by up to 650% for the geometry separated by a vacuum gap of g =1 μ m and temperature values concerned in our study. The enhancement in radiative heat transfer is found to depend on refractive index of the filling dielectric, the specific grating temperatures, and naturally the gap size between the two gratings. The enhancement can be understood through examining the transmission factor spectra, especially the spectral locations of the spoof surface plasmon polariton modes. Of more practical importance, it's shown that the radiative heat flux can exceed that between two planar SiC plates with same thickness, separation, and temperature settings over a wide temperature range. This reaffirms that one can harness rich electromagnetic modal properties in nanostructured materials for efficient thermal management at nanoscale.

  4. Analytic model of an IR radiation heat pipe

    NASA Technical Reports Server (NTRS)

    Hoffman, Pamela J.

    1990-01-01

    An IR radiation heat pipe made from multilayer insulation blankets and proposed to be used aboard spacecraft to transfer waste heat was modeled analytically. A circular cross section pipe 9-in. in diameter, 10-ft long, with a specular reflectivity of 0.94 was found to have an efficiency of 58.6 percent. Several key parameters were varied for the circular model to understand their significance. In addition, square and triangular cross section pipes were investigated.

  5. Advancements in Afterbody Radiative Heating Simulations for Earth Entry

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher O.; Panesi, Marco; Brandis, Aaron M.

    2016-01-01

    Four advancements to the simulation of backshell radiative heating for Earth entry are presented. The first of these is the development of a flow field model that treats electronic levels of the dominant backshell radiator, N, as individual species. This is shown to allow improvements in the modeling of electron-ion recombination and two-temperature modeling, which are shown to increase backshell radiative heating by 10 to 40%. By computing the electronic state populations of N within the flow field solver, instead of through the quasi-steady state approximation in the radiation code, the coupling of radiative transition rates to the species continuity equations for the levels of N, including the impact of non-local absorption, becomes feasible. Implementation of this additional level of coupling between the flow field and radiation codes represents the second advancement presented in this work, which is shown to increase the backshell radiation by another 10 to 50%. The impact of radiative transition rates due to non-local absorption indicates the importance of accurate radiation transport in the relatively complex flow geometry of the backshell. This motivates the third advancement, which is the development of a ray-tracing radiation transport approach to compute the radiative transition rates and divergence of the radiative flux at every point for coupling to the flow field, therefore allowing the accuracy of the commonly applied tangent-slab approximation to be assessed for radiative source terms. For the sphere considered at lunar-return conditions, the tangent-slab approximation is shown to provide a sufficient level of accuracy for the radiative source terms, even for backshell cases. This is in contrast to the agreement between the two approaches for computing the radiative flux to the surface, which differ by up to 40%. The final advancement presented is the development of a nonequilibrium model for NO radiation, which provides significant backshell

  6. Radiative heat transfer in rocket thrust chambers and nozzles

    NASA Technical Reports Server (NTRS)

    Hammad, K. J.; Naraghi, M. H. N.

    1989-01-01

    Numerical models based on the discrete exchange factor (DEF) and the zonal methods for radiative analysis of rocket engines containing a radiatively participating medium have been developed. These models implement a new technique for calculating the direct exchange factors to account for possible blockage by the nozzle throat. Given the gas and surface temperature distributions, engine geometry, and radiative properties, the models compute the wall radiative heat fluxes at different axial positions. The results of sample calculations for a typical rocket engine (engine 700 at NASA), which uses RP-1 (a kerosene-type propellant), are presented for a wide range of surface and gas properties. It is found that the heat transfer by radiation can reach up to 50 percent of that due to convection. The maximum radiative heat flux is at the inner side of the engine, where the gas temperature is the highest. While the results of both models are in excellent agreement, the computation time of the DEF method is found to be much smaller.

  7. Lightweight moving radiators for heat rejection in space

    NASA Technical Reports Server (NTRS)

    Knapp, K.

    1981-01-01

    Low temperature droplet stream radiators, using nonmetallic fluids, can be used to radiate large amounts of waste heat from large space facilities. Moving belt radiators are suitable for use on a smaller scale, radiating as few as 10 kW from shuttle related operations. If appropriate seal technology can be developed, moving belt radiators may prove to be important for high temperature systems as well. Droplet stream radiators suitable for operation at peak temperatures near 300 K and 1000 K were studied using both freezing and nonfreezing droplets. Moving belt radiators were also investigated for operation in both temperature ranges. The potential mass and performance characteristics of both concepts were estimated on the basis of parametric variations of analytical point designs. These analyses included all consideration of the equipment required to operate the moving radiator system and take into account the mass of fluid lost by evaporation during mission lifetimes. Preliminary results indicate that low temperature droplet stream radiator appears to offer the greatest potential for improvement over conventional flat plate radiators.

  8. Prediction of radiative heat transfer in rectangular enclosures

    SciTech Connect

    Jamaluddin, A.S.; Smith, P.J.

    1987-01-01

    Discrete ordinates solutions of the radiative transport equation have been obtained for two- and three-dimensional rectangular enclosures using the S/sub 2/ and S/sub 4/ approximations. Limited evaluations indicate that both S/sub 2/ and S/sub 4/ are suitable for predicting radiative transfer in two-dimensional enclosures. However, for the three-dimensional enclosures the S/sub 2/ approximation is found inadequate. It is inferred that S/sub 4/ or higher order approximations should be used to accurately predict radiative heat transfer in three-dimensional rectangular enclosures.

  9. Feasibility of Jujube peeling using novel infrared radiation heating technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infrared (IR) radiation heating has a promising potential to be used as a sustainable and effective method to eliminate the use of water and chemicals in the jujube-peeling process and enhance the quality of peeled products. The objective of this study was to investigate the feasibility of use IR he...

  10. Radiation Transport through cylindrical foams with heated walls

    NASA Astrophysics Data System (ADS)

    Baker, Kevin; MacLaren, Steve; Kallman, Joshua; Heinz, Ken; Hsing, Warren

    2012-10-01

    Radiation transport through low density SiO2 foams has been experimentally studied on the Omega laser. In particular these experiments examined the effects on radiation transport when the boundaries of the SiO2 foam are heated such that energy loss to the boundaries is minimized. The initial density of the SiO2 foams was determined by taking an x-ray radiograph of the foams using a monochromatic Henke source at multiple x-ray energies. The radiation drive used to both study the transport in the SiO2 foam as well as to heat the higher density CRF wall was generated in a laser-heated gold hohlraum using ˜7.5 kJ of the laser energy. The time-dependent spatial profile of the heat wave breaking out of the SiO2 foam was detected with an x-ray streak camera coupled with a soft x-ray transmission grating. The Omega DANTE diagnostic measured the radiation drive in the hohlraum and the Omega VISAR diagnostic monitored the spatial temperature gradient in the foam section of the hohlraum.

  11. ASME Heat Transfer Division: Proceedings. Volume 1: Heat transfer in microgravity systems, radiative heat transfer and radiative heat transfer in low-temperature environments, and thermal contact conductance and inverse problems in heat transfer; HTD-Volume 332

    SciTech Connect

    Gopinath, A.; Sadhal, S.S.; Jones, P.D.; Seyed-Yagoobi, J.; Woodbury, K.A.

    1996-12-31

    In the first section on heat transfer in microgravity, the papers cover phase-change phenomena and thermocapillary flows and surface effects. In the second section, several papers cover solution methods for radiative heat transfer while the rest cover heat transfer in low-temperature environments. The last section covers papers containing valuable information for thermal contact conductance of various materials plus papers on inverse problems in heat transfer. Separate abstracts were prepared for most papers in this volume.

  12. Conjugate conductive, convective, and radiative heat transfer in rocket engines

    SciTech Connect

    Naraghi, M.H.N.; DeLise, J.C.

    1995-12-31

    A comprehensive conductive, convective and radiative model for thermal analysis of rocket thrust chambers and nozzles is presented. In this model, the rocket thrust chamber and nozzle are subdivided into a number of stations along the longitudinal direction. At each station a finite element scheme is used to evaluate wall temperature distribution. The hot-gas-side convective heat transport is evaluated by numerically solving the compressible boundary layer equations and the radiative fluxes are evaluated by implementing an exchange factor scheme. The convective heat flux in the cooling channel is modeled based on the existing closed form correlations for rocket cooling channels. The conductive, convective and radiative processes are conjugated through an iterative procedure. The hot-gas-side heat transfer coefficients evaluated based on this model are compared to the experimental results reported in the literature. The computed convective heat transfer coefficients agree very well with experimental data for most of the engine except the throat where a discrepancy of approximately 20% exists. The model is applied to a typical regeneratively cooled rocket engine and the resulting wall temperature and heat flux distribution are presented.

  13. Radiative heating and cooling rates in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Gille, John C.; Lyjak, Lawrence V.

    1986-01-01

    One of the limitations to the accurate calculation of radiative heating and cooling rates in the stratosphere and mesosphere has been the lack of accurate data on the atmospheric temperature and composition. Data from the LIMS experiment on Nimbus-7 has been extended to the South Pole with the aid of other observations. The data have been used as input to codes developed by Ramanathan and Dickinson to calculate the individual components and the net radiative heating rates from 100-0.1 mb. Solar heating due to ozone, nitrogen dioxide, carbon dioxide, water vapor and oxygen is shown to be nearly balanced by cooling in the thermal infrared spectral region due to carbon dioxide, ozone and water vapor. In the lower stratosphere, infrared transfer by ozone leads to heating that is sensitive to the distribution of tropospheric ozone, clouds and water vapor. The heating and cooling rates are adjusted slightly in order to satisfy the global mass balance. The results are in qualitative agreement with earlier calculations, but show additional detail. There is as strong temporal and vertical variation of cooling in the tropics. Radiative relaxation times are as short as 7 days or less at the stratopause.

  14. Temperature measurements using multicolor pyrometry in thermal radiation heating environments

    SciTech Connect

    Fu, Tairan; Liu, Jiangfan; Duan, Minghao; Zong, Anzhou

    2014-04-15

    Temperature measurements are important for thermal-structural experiments in the thermal radiation heating environments such as used for thermal-structural stress analyses. This paper describes the use of multicolor pyrometry for the measurements of diffuse surfaces in thermal radiation environments that eliminates the effects of background radiation reflections and unknown emissivities based on a least-squares algorithm. The near-infrared multicolor pyrometer had a spectral range of 1100–2400 nm, spectrum resolution of 6 nm, maximum sampling frequency of 2 kHz, working distance of 0.6 m to infinity, temperature range of 700–1700 K. The pyrometer wavelength response, nonlinear intensity response, and spectral response were all calibrated. The temperature of a graphite sample irradiated by quartz lamps was then measured during heating and cooling using the least-squares algorithm based on the calibrated irradiation data. The experiments show that higher temperatures and longer wavelengths are more suitable for the thermal measurements in the quartz lamp radiation heating system. This analysis provides a valuable method for temperature measurements of diffuse surfaces in thermal radiation environments.

  15. Radiative heat conduction and the magnetorotational instability

    NASA Astrophysics Data System (ADS)

    Araya-Góchez, Rafael A.; Vishniac, Ethan T.

    2004-12-01

    A photon or a neutrino gas, semicontained by a non-diffusive particle species through scattering, comprises a rather peculiar magnetohydrodynamic fluid where the magnetic field is truly frozen only to the comoving volume associated with the mass density. Although radiative diffusion precludes a formal adiabatic treatment of compressive perturbations, we cast the energy equation in quasi-adiabatic form by assuming a negligible rate of energy exchange among species on the time-scale of the perturbation. This leads to a simplified dispersion relation for toroidal, non-axisymmetric magnetorotational modes when the accretion disc has comparable stress contributions from diffusive and non-diffusive components. The properties of the modes of fastest growth are shown to depend strongly on the compressibility of the mode, with a reduction in growth rate consistent with the results of Blaes & Socrates for axisymmetric modes. A clumpy disc structure is anticipated on the basis of the polarization properties of the fastest-growing modes. This analysis is accurate in the near-hole region of locally cooled, hyper-accreting flows if the electron gas becomes moderately degenerate such that non-conductive, thermalizing processes with associated electron-positron release (i.e. neutrino annihilation and neutrino absorption on to nuclei) are effectively blocked by high occupation of the Fermi levels.

  16. Assessment of Radiative Heating Uncertainty for Hyperbolic Earth Entry

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher O.; Mazaheri, Alireza; Gnoffo, Peter A.; Kleb, W. L.; Sutton, Kenneth; Prabhu, Dinesh K.; Brandis, Aaron M.; Bose, Deepak

    2011-01-01

    This paper investigates the shock-layer radiative heating uncertainty for hyperbolic Earth entry, with the main focus being a Mars return. In Part I of this work, a baseline simulation approach involving the LAURA Navier-Stokes code with coupled ablation and radiation is presented, with the HARA radiation code being used for the radiation predictions. Flight cases representative of peak-heating Mars or asteroid return are de ned and the strong influence of coupled ablation and radiation on their aerothermodynamic environments are shown. Structural uncertainties inherent in the baseline simulations are identified, with turbulence modeling, precursor absorption, grid convergence, and radiation transport uncertainties combining for a +34% and ..24% structural uncertainty on the radiative heating. A parametric uncertainty analysis, which assumes interval uncertainties, is presented. This analysis accounts for uncertainties in the radiation models as well as heat of formation uncertainties in the flow field model. Discussions and references are provided to support the uncertainty range chosen for each parameter. A parametric uncertainty of +47.3% and -28.3% is computed for the stagnation-point radiative heating for the 15 km/s Mars-return case. A breakdown of the largest individual uncertainty contributors is presented, which includes C3 Swings cross-section, photoionization edge shift, and Opacity Project atomic lines. Combining the structural and parametric uncertainty components results in a total uncertainty of +81.3% and ..52.3% for the Mars-return case. In Part II, the computational technique and uncertainty analysis presented in Part I are applied to 1960s era shock-tube and constricted-arc experimental cases. It is shown that experiments contain shock layer temperatures and radiative ux values relevant to the Mars-return cases of present interest. Comparisons between the predictions and measurements, accounting for the uncertainty in both, are made for a range

  17. Marangoni mixed convection flow with Joule heating and nonlinear radiation

    SciTech Connect

    Hayat, Tasawar; Shaheen, Uzma; Shafiq, Anum; Alsaedi, Ahmed; Asghar, Saleem

    2015-07-15

    Marangoni mixed convective flow of Casson fluid in a thermally stratified medium is addressed. Flow analysis has been carried out in presence of inclined magnetic field. Heat transfer analysis is discussed in the presence of viscous dissipation, Joule heating and nonlinear thermal radiation. The governing nonlinear partial differential equations are first converted into ordinary differential systems and then developed the convergent series solutions. Flow pattern with the influence of pertinent parameters namely the magnetic parameter, Casson fluid parameter, temperature ratio parameter, stratification parameter, Prandtl number, Eckert number and radiation parameter is investigated. Expression of local Nusselt number is computed and analyzed. It is found that the Nusselt number decreases by increasing magnetic parameter, temperature ratio parameter, angle of inclination and stratification parameter. Moreover the effect of buoyancy parameter on the velocity distribution is opposite in both the opposing and assisting flow phenomena. Thermal field and associated layer thickness are enhanced for larger radiation parameter.

  18. Partial moment entropy approximation to radiative heat transfer

    SciTech Connect

    Frank, Martin . E-mail: frank@mathematik.uni-kl.de; Dubroca, Bruno . E-mail: Bruno.Dubroca@math.u-bordeaux.fr; Klar, Axel . E-mail: klar@mathematik.uni-kl.de

    2006-10-10

    We extend the half moment entropy closure for the radiative heat transfer equations presented in Dubroca and Klar [B. Dubroca, A. Klar, Half moment closure for radiative transfer equations, J. Comput. Phys. 180 (2002) 584-596] and Turpault et al. [R. Turpault, M. Frank, B. Dubroca, A. Klar, Multigroup half space moment approximations to the radiative heat transfer equations, J. Comput. Phys. 198 (2004) 363-371] to multi-D. To that end, we consider a partial moment system with general partitions of the unit sphere closed by an entropy minimization principle. We give physical and mathematical reasons for this choice of model and study its properties. Several numerical examples in different physical regimes are presented.

  19. Protection from heat radiation in open-hearth shops

    SciTech Connect

    Parkhomenko, D.I.; Duganov, G.V.; Ilyushchenko, V.I.; Markin, A.D.

    1988-05-01

    Heat radiation studies in open-hearth shops during operations related to servicing the tap hole and cold-charging the furnace were conducted with consideration of the following factors: the capacity of the furnaces; the campaign of the furnace relative to the projected campaign for different furnace capacities; and the variety of manual tasks performed during a shift. Measurements of the thermal radiation were generalized and represented in the form of a nomogram. The results of thermal diagnosis of work stations on the rear platforms of open-hearth furnaces and the cabin of the cold-charging cranes led to the development and introduction of measures to protect workers from heat radiation and improve their working conditions.

  20. Radiation dosimetry of a conformal heat-brachytherapy applicator.

    PubMed

    Taschereau, Richard; Stauffer, Paul R; Hsu, I-Chow; Schlorff, Jaime L; Milligan, Andrew J; Pouliot, Jean

    2004-08-01

    The purpose of this paper is to report the radiation dosimetric characteristics of a new combination applicator for delivering heat and radiation simultaneously to large area superficial disease <1.5 cm deep. The applicator combines an array of brachytherapy catheters (for radiation delivery) with a conformal printed circuit board microwave antenna array (for heat generation), and a body-conforming 5-10 mm thick temperature-controlled water bolus. The rationale for applying both modalities simultaneously includes the potential for significantly higher response rate due to enhanced synergism of modalities, and lower peak toxicity due to temporal extension of heat and radiation induced toxicities. Treatment plans and radiation dosimetry are calculated with IPSA (an optimization tool developed at UCSF) for 15 x 15 cm(2) and 35 x 24 cm(2) applicators, lesion thicknesses of 5 to 15 mm, flat and curved surfaces, and catheter separation of 5 and 10 mm. The effect on skin dose of bolus thickness and presence of thin copper antenna structures between radiation source and tissue are also evaluated. Results demonstrate the ability of the applicator to provide conformal radiation dose coverage for up to 15 mm deep target volumes under the applicator. For clinically acceptable plans, tumor coverage is > 98%, homogeneity index > 0.95 and the percentage of normal tissue irradiated is < 20%. The dose gradient at the skin surface varies from 3 to 5 cGy/mm depending on bolus thickness and lesion depth. Attenuation of the photon beam by the printed circuit antenna array is of the order 0.25% and secondary electron emissions are absorbed completely within 5 mm of water bolus and plastic layers. Both phenomena can then be neglected in dose calculations allowing commercial software to be used for treatment planning. This novel applicator should prove useful for the treatment of diffuse chestwall disease located over contoured anatomy that may be difficult to treat with single field

  1. Simultaneous heat and mass transfer in polymer solutions exposed to intermittent infrared radiation heating

    SciTech Connect

    Chen, J.J.; Lin, J.D.

    1998-06-01

    Drying is one of the essential steps in a number of industrial applications, such as the preserving of food and the drying of paint, pulp, and paper. The quality of paper tubes is significantly affected by the heat and mass transfer process. The drying of polymer solution plays a crucial role in the manufacturer of photographic film, synthetic fibers, adhesives, and a variety of other polymeric products. During drying of wet materials, simultaneous heat and mass transfer occurs both inside the medium and in the boundary layer of the drying agent. Drying is one of the most energy-consuming processes in the industrial sector and can also be very time consuming as, for example, in conventional convective drying by hot air, while minimum cost and energy consumption and maximum product quality are among the main concerns in industry today. Here, a theoretical study is performed that describes heat transfer and moisture variation while a polymer solution is exposed to high-intensity infrared radiation flux and/or an airflow. While the intermittent heating is considered, the authors investigate the influences of various radiation and convection parameters on the transfer of heat and moisture variation of coated layers on an optically thick substrate. During the tempering stage in the intermittent heating process, the convective mass transfer is included to simulate the ambient air in reality. The effects of radiation and convection parameters on the transfer processes are presented in terms of the rate of water content removal, heat transfer, and moisture distributions. Numerical results show that the rate of water removal from the polymer solution is dominated by both the adsorbed radiative heat energy and the distributions of water mass fraction in the polymer solution.

  2. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Radiofrequency radiation for the heating of food... PRODUCTION, PROCESSING AND HANDLING OF FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation,...

  3. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Radiofrequency radiation for the heating of food... PRODUCTION, PROCESSING AND HANDLING OF FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation,...

  4. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Radiofrequency radiation for the heating of food... FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be...

  5. Modelling of Radiation Heat Transfer in Reacting Hot Gas Flows

    NASA Astrophysics Data System (ADS)

    Thellmann, A.; Mundt, C.

    2009-01-01

    In this work the interaction between a turbulent flow including chemical reactions and radiation transport is investigated. As a first step, the state-of-the art radiation models P1 based on the moment method and Discrete Transfer Model (DTM) based on the discrete ordinate method are used in conjunction with the CFD code ANSYS CFX. The absorbing and emitting medium (water vapor) is modeled by Weighted Sum of Gray Gases. For the chemical reactions the standard Eddy dissipation model combined with the two equation turbulence model k-epsilon is employed. A demonstration experiment is identified which delivers temperature distribution, species concentration and radiative intensity distribution in the investigated combustion enclosure. The simulation results are compared with the experiment and reveals that the P1 model predicts the location of the maximal radiation intensity unphysically. On the other hand the DTM model does better but over predicts the maximum value of the radiation intensity. This radiation sensitivity study is a first step on the way to identify a suitable radiation transport and spectral model in order to implement both in an existing 3D Navier-Stokes Code. Including radiation heat transfer we intend to investigate the influence on the overall energy balance in a hydrogen/oxygen rocket combustion chamber.

  6. High thermal-transport capacity heat pipes for space radiators

    NASA Technical Reports Server (NTRS)

    Carlson, Albert W.; Gustafson, Eric; Roukis, Susan L.

    1987-01-01

    This paper presents the results of performance tests of several dual-slot heat pipe test articles. The dual-slot configuration has a very high thermal transport capability and has been identified as a very promising candidate for the radiator system for the NASA Space Station solar dynamic power modules. Two six-foot long aluminum heat pipes were built and tested with ammonia and acetone. A 20-ft long heat pipe was also built and tested with ammonia. The test results have been compared with performance predictions. A thermal transport capacity of 2000 W at an adverse tilt of 1 in. and a 1000 W capacity at an adverse tilt of 2 in. were achieved on the 20-ft long heat pipe. These values are in close agreement with the predicted performance limits.

  7. Radiative properties of advanced spacecraft heat shield materials

    NASA Technical Reports Server (NTRS)

    Cunnington, G. R.; Funai, A. I.; Mcnab, T. K.

    1983-01-01

    Experimental results are presented to show the effects of simulated reentry exposure by convective heating and by radiant heating on spectral and total emittance of statically oxidized Inconel 617 and Haynes HS188 superalloys to 1260 K and a silicide coatea (R512E) columbium 752 alloy to 1590 K. Convective heating exposures were conducted in a supersonic arc plasma wind tunnel using a wedge-shaped specimen configuration. Radiant tests were conducted at a pressure of .003 atmospheres of dry air at a flow velocity of several meters per second. Convective heating specimens were subjected to 8, 20, and 38 15-min heating cycles, and radiant heating specimens were tested for 10, 20, 50, and 100 30-min heating cycles. Changes in radiative properties are explained in terms of changes in composition resulting from simulated reentry tests. The methods used to evaluate morphological, compositional and crystallographic changes include: Auger electron spectroscopy; scanning electron microscopy; X-ray diffraction analysis; and electron microprobe analysis.

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

    NASA Astrophysics Data System (ADS)

    Devlen, Ebru

    2016-07-01

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

  9. Perpendicular electron heating by absorption of auroral kilometric radiation

    NASA Technical Reports Server (NTRS)

    Morgan, D. D.; Menietti, J. D.; Winglee, R. M.; Wong, H. K.

    1994-01-01

    We investigate the possibility of perpendicular heating of electrons and the generation of '90 deg -electron conics' by particle diffusion in velocity space due to wave-particle interaction with intense auroral kilometric radiation. This interaction is made possible by the downward shift in the R-X cutoff below the electron cyclotron frequency that occurs in the presence of warm plasma. We stimulate this condition and solve the diffusion equation using a finite difference algorithm. The results show strong perpendicular electron heating and indicate that the main characteristics of an electron conic distribution can be reproduced under these conditions.

  10. Advanced radiator concepts utilizing honeycomb panel heat pipes (stainless steel)

    NASA Technical Reports Server (NTRS)

    Fleischman, G. L.; Tanzer, H. J.

    1985-01-01

    The feasibility of fabricating and processing moderate temperature range heat pipes in a low mass honeycomb sandwich panel configuration for highly efficient radiator fins for the NASA space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include: type of material, material and panel thicknesses, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. In addition, the overall performance of the honeycomb panel heat pipe was evaluated analytically.

  11. A multilevel method for conductive-radiative heat transfer

    SciTech Connect

    Banoczi, J.M.; Kelley, C.T.

    1996-12-31

    We present a fast multilevel algorithm for the solution of a system of nonlinear integro-differential equations that model steady-state combined radiative-conductive heat transfer. The equations can be formulated as a compact fixed point problem with a fixed point map that requires both a solution of the linear transport equation and the linear heat equation for its evaluation. We use fast transport solvers developed by the second author, to construct an efficient evaluation of the fixed point map and then apply the Atkinson-Brakhage, method, with Newton-GMRES as the coarse mesh solver, to the full nonlinear system.

  12. Radiative heat transfer in 2D Dirac materials

    DOE PAGESBeta

    Rodriguez-López, Pablo; Tse, Wang -Kong; Dalvit, Diego A. R.

    2015-05-12

    We compute the radiative heat transfer between two sheets of 2D Dirac materials, including topological Chern insulators and graphene, within the framework of the local approximation for the optical response of these materials. In this approximation, which neglects spatial dispersion, we derive both numerically and analytically the short-distance asymptotic of the near-field heat transfer in these systems, and show that it scales as the inverse of the distance between the two sheets. In conclusion, we discuss the limitations to the validity of this scaling law imposed by spatial dispersion in 2D Dirac materials.

  13. SEAC4RS Aerosol Radiative Effects and Heating Rates

    NASA Astrophysics Data System (ADS)

    Cochrane, S.; Schmidt, S.; Redemann, J.; Hair, J. W.; Ferrare, R. A.; Segal-Rosenhaimer, M.; LeBlanc, S. E.

    2015-12-01

    We will present (a) aerosol optical properties, (b) aerosol radiative forcing, (c) aerosol and gas absorption and heating rates, and (d) spectral surface albedo for cases from August 19th and 26th of the SEAC4RS mission. This analysis is based on irradiance data from the Solar Spectral Flux Radiometer (SSFR), spectral aerosol optical depth from the Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR), and extinction profiles from the DIAL/High Spectral Resolution Lidar (HSRL). We derive spectrally resolved values of single scattering albedo, asymmetry parameter, and surface albedo from the data, and determine profiles of absorption and heating rate segregated by absorber (aerosol and gas).

  14. Combined conduction and radiation heat transfer in concentric cylindrical media

    NASA Technical Reports Server (NTRS)

    Pandey, D. K.

    1987-01-01

    The exact radiative transfer expressions for gray and nongray gases which are absorbing, emitting and nonscattering, contained between infinitely long concentric cylinders with black surfaces, are given in local thermodynamic equilibrium. Resulting energy equations due to the combination of conduction and radiation modes of heat transfer, under steady state conditions for gray and nongray media, are solved numerically using the undetermined parameters method. A single 4.3-micron band of CO2 is considered for the nongray problems. The present solutions for gray and nongray gases obtained in the plane-parallel limit (radius ratio approaches to one) are compared with the plane-parallel results reported in the literature.

  15. The influence of a radiated heat exchanger surface on heat transfer

    NASA Astrophysics Data System (ADS)

    Morel, Sławomir

    2015-09-01

    The experiment leads to establish the influence of radiated surface development heat exchangers on the values of heat flux transferred with water flowing through the exchangers and placed in electric furnace chamber. The values of emissivity coefficients are given for the investigated metal and ceramic coatings. Analytical calculations have been made for the effect of the heating medium (flame) - uncoated wall and then heating medium (flame) - coated wall reciprocal emissivity coefficients. Analysis of the values of exchanged heat flux were also realized. Based on the measurement results for the base coating properties, these most suitable for spraying the walls of furnaces and heat exchangers were selected, and determined by the intensification of heat exchange effect. These coatings were used to spray the walls of a laboratory waste-heat boiler, and then measurements of fluxes of heat absorbed by the cooling water flowing through the boiler tubes covered with different type coatings were made. Laboratory tests and calculations were also confirmed by the results of full-scale operation on the metallurgical equipment.

  16. Numerical simulation of radiative heat loss in an experimental burner

    SciTech Connect

    Cloutman, L.D.; Brookshaw, L.

    1993-09-01

    We describe the numerical algorithm used in the COYOTE two-dimensional, transient, Eulerian hydrodynamics program to allow for radiative heat losses in simulations of reactive flows. The model is intended primarily for simulations of industrial burners, but it is not confined to that application. It assumes that the fluid is optically thin and that photons created by the fluid immediately escape to free space or to the surrounding walls, depending upon the application. The use of the model is illustrated by simulations of a laboratory-scale experimental burner. We find that the radiative heat losses reduce the local temperature of the combustion products by a modest amount, typically on the order of 50 K. However, they have a significant impact on NO{sub x} production.

  17. Spatial-multiblock procedure for radiation heat transfer

    SciTech Connect

    Chai, J.C.; Moder, J.P.

    1996-12-31

    A spatial-multiblock procedure for radiation heat transfer is presented in this article. The proposed procedure is applicable to isothermal or nonisothermal, absorbing, emitting and scattering of transparent media with black or reflecting walls. Although not shown in this article, the procedure is also applicable to nongray conditions. The proposed procedure can be used with the discrete ordinates method and the finite volume method. The heat transfer rate, net radiation power and other full-range and half-range moments are conserved between spatial blocks by the proposed procedure. The utilities of the proposed procedure are shown using four sample problems. The solutions indicate that the multiblock procedure can reproduce the results of a single-block procedure even when very coarse spatial grids are used in the multiblock procedure.

  18. Effects of precursor heating on chemical and radiation nonequilibrium viscous flow around a Jovian entry body

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Szema, K. Y.

    1978-01-01

    The influence of precursor heating on viscous chemical nonequilibrium radiating flow around a Jovian entry body is investigated. Results obtained for a 45-degree hyperboloid blunt body entering Jupiter's nominal atmosphere at zero angle of attack indicate that the nonequilibrium radiative heating rate is significantly higher than the corresponding equilibrium heating. The precursor heating, in general, increases the radiative and convective heating to the body, and this increase is slightly higher for the nonequilibrium conditions.

  19. A clean radiation environment for opacity measurements of radiatively heated material

    SciTech Connect

    Xu Yan; Zhang Jinyan; Yang Jiamin; Pei Wenbing; Ding Yongkun; Lai Donxian; Men Guangwei; Luo Zheng

    2007-05-15

    A clean x-ray radiation environment is essential for detailed measurements of the opacity of high-temperature radiatively heated material. A lot of laser energy is usually needed to heat a large hohlraum to produce such a clean x-ray radiation environment. A type of target is proposed that uses low-density, low-Z foam to provide a passage to radiation while isolating the sample from the disturbance from laser produced, high-temperature, high-Z plasma and heating by reflected laser light. With a smaller hohlraum, less laser energy is needed to produce high-temperature x-ray radiation for sample heating. Experiments have been done to check the proposal. The recorded clean Al self-emission spectra proved there was no gold plasma in the view-way to disturb the measurement. This type of hohlraum can provide a high-quality work-table for opacity measurement even in a relatively small laser facility.

  20. Cloud Properties and Radiative Heating Rates for TWP

    SciTech Connect

    Comstock, Jennifer

    2013-11-07

    A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

  1. Radiative Heat Transfer in a Hydrous Transition Zone

    NASA Astrophysics Data System (ADS)

    Thomas, S.; Bina, C. R.; Jacobsen, S. D.; Goncharov, A. F.

    2012-12-01

    The structure and dynamics of Earth's interior depend crucially upon heat flow and thus upon the thermal conductivity of its constituents. The bulk thermal conductivity has two components: lattice conductivity (klat) and radiative conductivity (krad) [1,2]. Whereas lattice conductivity is governed by phonon propagation, radiative conductivity arises from heat transport by emission and absorption of photons. The latter, therefore, can be indirectly measured by analyzing the visible and infrared (VIS-IR) regions of a material's optical absorption spectrum. Thermal conductivity in the mantle is controlled by temperature, pressure, the electronic structure and concentration of transition metal ions (such as iron), and the water content of the material [1,3]. The radiative component has generally been assumed to be negligible, as most ferromagnesian minerals become opaque in the VIS-IR range at high pressures due to intensification and red-shift of electronic charge-transfer bands [4, 5]. However, more recent studies have suggested that mantle minerals may, in fact, remain relatively transparent at high pressures, thereby allowing for a potentially significant contribution to thermal conductivity from the radiative component [6]. We measured optical absorbance spectra of hydrous wadsleyite and hydrous ringwoodite at simultaneous high-pressure and high-temperature conditions up to 26 GPa and 823 K in order to determine their radiative conductivities and to study the potential influence of hydration in the transition zone on thermal conductivity of the mantle. We report radiative thermal conductivities of 1.5 ± 0.2 Wm-1K-1 for hydrous wadsleyite and 1.2 ± 0.1 Wm-1K-1 for hydrous ringwoodite at transition zone conditions. The analytically derived radiative thermal conductivities of anhydrous wadsleyite and ringwoodite are 2.1 ± 0.2 Wm-1K-1 and 1.6 ± 0.2 Wm-1K-1, respectively. Our results imply that a water content of ~1 wt% H2O lowers the thermal radiative conductivity

  2. Solar dynamic heat rejection technology. Task 2: Heat pipe radiator development

    NASA Technical Reports Server (NTRS)

    League, Mark; Alario, Joe

    1988-01-01

    This report covers the design, fabrication, and test of several dual slot heat pipe engineering development units. The following dual-slot heat pipes were fabricated and tested: two 6-ft. aluminum heat pipes; a 20-ft. aluminum heat pipe; and a 20-ft. aluminum heat pipe with a four-leg evaporator section. The test results of all four test articles are presented and compared to the performance predicted by the design software. Test results from the four-leg article are incomplete. The methodology for fabricating stainless steel dual slot heat pipes was also studied by performing a tool life test with different single point cutters, and these results are also presented. Although the dual-slot heat pipe has demonstrated the potential to meet the requirements for a high capacity radiator system, uncertainties with the design still exist. The startup difficulties with the aluminum test articles must be solved, and a stainless steel/methanol heat pipe should be built and tested.

  3. Mesoscopic near-field radiative heat transfer at low temperatures

    NASA Astrophysics Data System (ADS)

    Maasilta, Ilari; Geng, Zhuoran; Chaudhuri, Saumyadip; Koppinen, Panu

    2015-03-01

    Near-field radiative heat transfer has mostly been discussed at room temperatures and/or macroscopic scale geometries. Here, we discuss our recent theoretical and experimental advances in understanding near-field transfer at ultra-low temperatures below 1K. As the thermal wavelengths increase with lowering temperature, we show that with sensitive tunnel junction bolometers it is possible to study near-field transfer up to distances ~ 10 μm currently, even though the power levels are low. In addition, these type of experiments correspond to the extreme near-field limit, as the near-field region starts at ~ mm distances at 0.1 K, and could have theoretical power enhancement factors of the order of 1010. Preliminary results on heat transfer between two parallel metallic wires are presented. We also comment on possible areas were such heat transfer might be relevant, such as densely packed arrays of low-temperature detectors.

  4. Rocket plume radiation base heating by reverse Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Everson, John; Nelson, H. F.

    1993-10-01

    A reverse Monte Carlo radiative transfer code is developed to predict rocket plume base heating. It is more computationally efficient than the forward Monte Carlo method, because only the radiation that strikes the receiving point is considered. The method easily handles both gas and particle emission and particle scattering. Band models are used for the molecular emission spectra, and the Henyey-Greenstein phase function is used for the scattering. Reverse Monte Carlo predictions are presented for (1) a gas-only model of the Space Shuttle main engine plume; (2) a purescattering plume with the radiation emitted by a hot disk at the nozzle exit; (3) a nonuniform temperature, scattering, emitting and absorbing plume; and (4) a typical solid rocket motor plume. The reverse Monte Carlo method is shown to give good agreement with previous predictions. Typical solid rocket plume results show that (1) CO2 radiation is emitted from near the edge of the plume; (2) H2O gas and Al2O3 particles emit radiation mainly from the center of the plume; and (3) Al2O3 particles emit considerably more radiation than the gases over the 400-17,000 cm(exp -1) spectral interval.

  5. Radiation transport in ultrafast heated high Z solid targets

    NASA Astrophysics Data System (ADS)

    Paraschiv, Ioana; Sentoku, Yasuhiko; Mancini, Roberto; Johzaki, Tomoyuki

    2013-10-01

    Ultra-intense laser-target interactions generate hot, dense, and radiating plasmas, especially in the case of high-Z target materials. In order to evaluate the effect of radiation and its transport on the laser-produced plasmas we have developed a radiation transport (RT) code and implemented it in a collisional particle-in-cell code, PICLS. The code uses a database of emissivities and opacities as functions of photon frequency, created for given densities and temperatures by the non-equilibrium, collisional-radiative atomic kinetics 0-D code FLYCHK together with its postprocessor FLYSPECTRA. Using the two-dimensional RT-PICLS code we have studied the X-ray transport in an ultrafast heated copper target, the X-ray conversion efficiency, and the exchange of energy between the radiation field and the target. The details of these results obtained from the implementation of the radiation transport model into the PICLS calculations will be reported in this presentation. Work supported by the DOE Office of Science grant no. DE-SC0008827 and by the NNSA/DOE grant no. DE-FC52-06NA27616.

  6. Chromospheric Heating by Acoustic Waves Compared to Radiative Cooling

    NASA Astrophysics Data System (ADS)

    Sobotka, M.; Heinzel, P.; Švanda, M.; Jurčák, J.; del Moro, D.; Berrilli, F.

    2016-07-01

    Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of the solar atmosphere. A weak chromospheric plage near the large solar pore NOAA 11005 was observed on 2008 October 15, in the Fe i 617.3 nm and Ca ii 853.2 nm lines of the Interferometric Bidimemsional Spectrometer attached to the Dunn Solar Telescope. In analyzing the Ca ii observations (with spatial and temporal resolutions of 0.″4 and 52 s) the energy deposited by acoustic waves is compared to that released by radiative losses. The deposited acoustic flux is estimated from the power spectra of Doppler oscillations measured in the Ca ii line core. The radiative losses are calculated using a grid of seven one-dimensional hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of the maps of radiative losses and acoustic flux is 72%. In a quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only about 15%. In active areas with a photospheric magnetic-field strength between 300 and 1300 G and an inclination of 20°–60°, the contribution increases from 23% (chromospheric network) to 54% (a plage). However, these values have to be considered as lower limits and it might be possible that the acoustic energy flux is the main contributor to the heating of bright chromospheric network and plages.

  7. Role of fuel chemical properties on combustor radiative heat load

    NASA Technical Reports Server (NTRS)

    Rosfjord, T. J.

    1984-01-01

    In an attempt to rigorously study the fuel chemical property influence on combustor radiative heat load, United Technologies Research Center (UTRC) has conducted an experimental program using 25 test fuels. The burner was a 12.7-cm dia cylindrical device fueled by a single pressure-atomizing injector. Fuel physical properties were de-emphasized by selecting injectors which produced high-atomized, and hence rapidly-vaporizing sprays. The fuels were specified to cover the following wide ranges of chemical properties; hydrogen, 9.1 to 15- (wt) pct; total aromatics, 0 to 100 (vol) pct; and naphthalene, 0 to 30 (vol) pct. They included standard fuels, specialty products and fuel blends. Fuel naphthalene content exhibited the strongest influence on radiation of the chemical properties investigated. Smoke point was a good global indicator of radiation severity.

  8. Role of fuel chemical properties on combustor radiative heat load

    NASA Technical Reports Server (NTRS)

    Rosfjord, T. J.

    1984-01-01

    In an attempt to rigorously study the fuel chemical property influence on combustor radiative heat load, UTRC has conducted an experimental program using 25 test fuels. The burner was a 12.7-cm dia cylindrical device fueled by a single pressure-atomizing injector. Fuel physical properties were de-emphasized by selecting injectors which produced highly-atomized, and hence rapidly-vaporizing sprays. The fuels were specified to cover the following wide ranges of chemical properties: hydrogen, 9.1 to 15- (wt) pct; total aromatics, 0 to 100 (vol) pct; and naphthalene, 0 to 30 (vol) pct. They included standard fuels, specialty products and fuel blends. Fuel naphthalene content exhibited the strongest influence on radiation of the chemical properties investigated. Smoke point was a good global indicator of radiation severity.

  9. A Thermokinetic Approach to Radiative Heat Transfer at the Nanoscale

    PubMed Central

    Pérez-Madrid, Agustín; Lapas, Luciano C.; Rubí, J. Miguel

    2013-01-01

    Radiative heat exchange at the nanoscale presents a challenge for several areas due to its scope and nature. Here, we provide a thermokinetic description of microscale radiative energy transfer including phonon-photon coupling manifested through a non-Debye relaxation behavior. We show that a lognormal-like distribution of modes of relaxation accounts for this non-Debye relaxation behavior leading to the thermal conductance. We also discuss the validity of the fluctuation-dissipation theorem. The general expression for the thermal conductance we obtain fits existing experimental results with remarkable accuracy. Accordingly, our approach offers an overall explanation of radiative energy transfer through micrometric gaps regardless of geometrical configurations and distances. PMID:23527019

  10. Heat Transfer from Radiatively Heated Material in a Low Reynolds Number Microgravity Environment

    NASA Technical Reports Server (NTRS)

    Yamashita, H.; Baum, H. R.; Kushida, G.; Nakabe, K.; Kashiwagi, T.

    1993-01-01

    A mathematical model of the transient three-dimensional heat transfer between a slowly moving ambient gas stream and a thermally thick or thin flat surface heated by external radiation in a microgravity environment is presented. The problem is motivated in part by fire safety issues in spacecraft. The gas phase is represented by variable property convection-diffusion energy and mass conservation equations valid at low Reynolds numbers. The absence of gravity and low Reynolds number together permit the flow to be represented by a self-consistent velocity potential determined by the ambient velocity and the thermal expansion in the gas. The solid exchanges energy with the gas by conduction/convection and with the surroundings by surface absorption and re-emission of radiation. Heat conduction in the solid is assumed to be one dimensional at each point on the surface as a consequence of the limited times (of order of 10 seconds) of interest in these simulations. Despite the apparent simplicity of the model, the results show a complex thermally induced flow near the heated surface. The thermal exchange between the gas and solid produces an outward sourcelike flow upstream of the center of the irradiated area and a sinklike flow downstream. The responses of the temperature fields and the associated flows to changes in the intensity of the external radiation and the ambient velocity are discussed.

  11. Radiative heat transfer in anisotropic many-body systems: Tuning and enhancement

    SciTech Connect

    Nikbakht, Moladad

    2014-09-07

    A general formalism for calculating the radiative heat transfer in many body systems with anisotropic component is presented. Our scheme extends the theory of radiative heat transfer in isotropic many body systems to anisotropic cases. In addition, the radiative heating of the particles by the thermal bath is taken into account in our formula. It is shown that the radiative heat exchange (HE) between anisotropic particles and their radiative cooling/heating (RCH) could be enhanced several order of magnitude than that of isotropic particles. Furthermore, we demonstrate that both the HE and RCH can be tuned dramatically by particles relative orientation in many body systems.

  12. Radiation heat transfer in SOFC materials and components

    NASA Astrophysics Data System (ADS)

    Damm, David L.; Fedorov, Andrei G.

    Radiative transport within the electrode and electrolyte layers, as well as surface-to-surface radiation within the fuel and oxygen flow channels, has the potential to dramatically influence temperature fields and overall operating conditions of solid oxide fuel cells (SOFCs). On a larger scale, radiation from the stack to the environment, including heat losses through insulation, must be accounted for in the plant design, and is of critical importance for effective thermal management of the high temperature stack. In this report, we discuss the current state-of-the-art and the challenges that remain in understanding, predicting, and quantifying the effects of radiation in SOFC materials and systems. These phenomena are of great interest and importance not only from a fundamental perspective but also from a systems design point of view. Last, but not the least in importance, the determination of radiative properties of the materials involved - either through experimental methods or predictive models - must be an ongoing effort as new materials are continuously being developed.

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

    NASA Astrophysics Data System (ADS)

    Sheng, Chunchen; Hu, Peng; Cheng, Xiaofang

    2016-06-01

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

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

    PubMed

    Sheng, Chunchen; Hu, Peng; Cheng, Xiaofang

    2016-06-01

    Radiative heat flux measurement is significantly important for a spacecraft thermal test. To satisfy the requirements of both high accuracy and fast response, a novel transient radiative heat flux meter was developed. Its thermal receiver consists of a central thermal receiver and two thermal guarded annular plates, which ensure the temperature distribution of the central thermal receiver to be uniform enough for reasonably applying lumped heat capacity method in a transient radiative heat flux measurement. This novel transient radiative heat flux meter design can also take accurate measurements regardless of spacecraft surface temperature and incident radiation spectrum. The measurement principle was elaborated and the coefficients were calibrated. Experimental results from testing a blackbody furnace and an Xenon lamp show that this novel transient radiative heat flux meter can be used to measure transient radiative heat flux up to 1400 W/m(2) with high accuracy and the response time of less than 10 s. PMID:27370482

  15. Radiation heat transfer within an optical fiber draw tower furnace

    SciTech Connect

    Issa, J.; Jaluria, Y.; Polymeropoulos, C.E.; Yin, Z.

    1995-12-31

    Study of the thermal transport and material flow processes associated with the drawing of optical fiber in a graphite draw furnace requires modeling of the heat transfer from the furnace wall. Previous work has shown that accurate knowledge of the furnace heater element axial temperature distribution is essential for proper modeling of the radiative transfer process. The present work is aimed at providing this information, as well as generating a set of data for the study of radiation exchange in the furnace cavity. The experimental procedure involved measuring the centerline temperature distribution in graphite and fused silica rods inserted into an optical fiber draw tower furnace. The temperature measurements were then used along with a model for radiative-convective heat transfer in the furnace in order to obtain the furnace temperature profile. This is an inverse problem since the centerline temperature in the rod is known whereas the furnace thermal conditions are not. The results obtained showed that the furnace temperature distribution was independent of rod material and size. The shape of the computed temperature distributions suggest that they can be well represented by a Gaussian function.

  16. Analysis of tropical radiative heating profiles: A comparison of models and observations

    SciTech Connect

    McFarlane, Sally A.; Mather, Jim H.; Ackerman, Thomas P.

    2007-07-31

    Vertical distribution of radiative heating in the atmosphere is an important driver of atmospheric circulation, especially in the tropics. Evaluation of model simulations of the Earth's radiation balance typically focus on performance at the top of the atmosphere or at the surface. This study compares the vertical distribution of clouds and radiative heating rates calculated from observations at the Department of Energy's Atmospheric Radiation Measurement (ARM) sites on the islands of Nauru and Manus to simulations performed using the Multiscale Modeling Framework (MMF) and the Community Atmosphere Model (CAM). There are significant differences between the model vertical profiles of cloud properties and radiative heating and those calculated from the ARM observations. The MMF simulation results in better representation of the observed variability in ice cloud condensed water content and resulting upper tropospheric radiative heating rates than the CAM; more realistic diurnal variability in the radiative heating profiles; and a significantly lower level of zero net radiative heating.

  17. Laser-heating-based active optics for synchrotron radiation applications.

    PubMed

    Yang, Fugui; Li, Ming; Gao, Lidan; Sheng, Weifan; Liu, Peng; Zhang, Xiaowei

    2016-06-15

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as the subnanometer scale and that the variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a one-dimensional surface correction experiment. The developed method is a promising new approach toward effective x-ray active optics coupled with at-wavelength metrology techniques. PMID:27304296

  18. Propagation of blast waves with exponential heat release and internal heat conduction and thermal radiation

    NASA Astrophysics Data System (ADS)

    Gretler, W.; Wehle, P.

    1993-09-01

    The problem of reactive blast waves in a combustible gas mixture, where the heat release at the detonation front decays exponentially with the distance from the center, is analyzed. The central theme of the paper is on the propagation of reactive blast into a uniform, quiescent, counterpressure atmosphere of a perfect gas with constant specific heats. The limiting cases of Chapman-Jouguet detonation waves are considered in the phenomenon of point explosion. In order to deal with this problem, the governing equations including thermal radiation and heat conduction were solved by the method of characteristics using a problem-specific grid and a series expansion as start solution. Numerical results for the distribution of the gas-dynamic parameters inside the flow field are shown and discussed.

  19. Chaos of radiative heat-loss-induced flame front instability.

    PubMed

    Kinugawa, Hikaru; Ueda, Kazuhiro; Gotoda, Hiroshi

    2016-03-01

    We are intensively studying the chaos via the period-doubling bifurcation cascade in radiative heat-loss-induced flame front instability by analytical methods based on dynamical systems theory and complex networks. Significant changes in flame front dynamics in the chaotic region, which cannot be seen in the bifurcation diagrams, were successfully extracted from recurrence quantification analysis and nonlinear forecasting and from the network entropy. The temporal dynamics of the fuel concentration in the well-developed chaotic region is much more complicated than that of the flame front temperature. It exhibits self-affinity as a result of the scale-free structure in the constructed visibility graph. PMID:27036182

  20. Radiative properties and heat transfer analysis of fibrous insulations

    SciTech Connect

    Yeh, H.Y.

    1986-01-01

    The spectral radiative properties of pink fiberglass insulation were determined from monochromatic directional-hemispherical reflectance or monochromatic specular reflectance data coupled with an analytical model in the wavelength range of 3 to 80 microns. The fiberglass samples were 3.18 cm square with thicknesses varying from 0.10 to 1.28 cm. Three types of spectral data were recorded for the two sets of samples. First, normal transmittance measurements in the wavelength range of 2.5-40 microns were made with a Perkin-Elmer M521 infrared grating spectrophotometer. Second, the Willey 318S Fourier transform spectrometer (FTS) was utilized to measure the directional-hemispherical reflectance in the wavelength range of 3-20 microns. The nonlinear least squares approach coupled with Chandrasekhar's discrete ordinate method for isotropic and anisotropic radiative transport was used in determining the radiative properties. Third, the specular reflectance at an incidence angle of 16 degrees was measured with a Digilab FTS-20 in the wavelength range of 3-80 microns. A method to invert the radiation properties from the experimental data was developed. Typical residential attic fiberglass insulation was chosen for the heat transfer analysis; results are compared to experimental data.

  1. Radiation Effects in a Semitransparent Gray Coating Heated by Convection and Cooled by Radiation

    NASA Technical Reports Server (NTRS)

    Spuckler, Charles M.

    2002-01-01

    A parametric study using a one dimensional model of a semitransparent gray thermal barrier coating was performed to gain an understanding of the role thermal radiation can play in the heat transferred. Some ceramic materials are semitransparent in the wavelength ranges were thermal radiation is important. Therefore, absorption, emission, and scattering of thermal radiation can affect the he at transfer through the coating. In this paper, a one dimensional layer was used to model the heat transfer process occurring, in a burner test rig. The semitransparent layer is heated by a hot gas flowing over its surface. The layer and substrate at a cooled by radiation to the surroundings. The back side of the substrate is insulated. The coating is assumed to be gray (absorption and scattering coefficients are not function of wavelength). An absorption coefficient of 0.3/cm and scatter a rig coefficients of 0 (no scattering) and 100/cm (isotropic scattering) were used. The thickness and thermal conductivity of the layer are varied. The results show that the temperatures are affected by the properties of the semitransparent .ever and the emissivity of the substrate. The substrate and surface temperatures are presented. The apparent temperature an optical pyrometer would read for the emitted energy is also given. An apparent thermal conductivity was calculated for the layer.

  2. Effective disinfection of rough rice using infrared radiation heating.

    PubMed

    Wang, Bei; Khir, Ragab; Pan, Zhongli; El-Mashad, Hamed; Atungulu, Griffiths G; Ma, Haile; McHugh, Tara H; Qu, Wenjuan; Wu, Bengang

    2014-09-01

    The objective of this study was to investigate the effect of infrared (IR) heating and tempering treatments on disinfection of Aspergillus flavus in freshly harvested rough rice and storage rice. Rice samples with initial moisture contents (IMCs) of 14.1 to 27.0% (wet basis) were infected with A. flavus spores before the tests. The infected samples were heated by IR radiation to 60°C in less than 1 min, and then samples were tempered at 60°C for 5, 10, 20, 30, 60, or 120 min. High heating rates and corresponding high levels of moisture removal were achieved using IR heating. The highest total moisture removal was 5.3% for the fresh rice with an IMC of 27.0% after IR heating and then 120 min of tempering. IR heating followed by tempering for 120 min resulted in 2.5- and 8.3-log reductions of A. flavus spores in rough rice with the lowest and highest IMCs, respectively. To study the effect on disinfection of rewetting dried storage rice, the surface of the dry rice was rewetted to achieve IMCs of 14.7 to 19.4% (wet basis). The rewetting process for the dry rice had a significant effect on disinfection. IR heating followed by tempering for 60 min resulted in 7.2-log reductions in A. flavus on rewetted rough rice. The log-linear plus tail model was applied to estimate the tempering time needed to achieve a 5-log reduction of A. flavus in rice of different IMCs. At least 30 and 20 min of tempering were needed for fresh rice and rewetted rice, respectively, with the highest IMCs. The recommended conditions of simultaneous disinfection and drying for fresh rice was IR heating to 60°C followed by tempering for 120 min and natural cooling, resulting in a final MC of 16.5 to 22.0%, depending on the IMC. For the rewetted dry rice with an IMC of 19.4%, the recommended condition for disinfection and drying involved only 20 min of tempering. The final MC of the sample was 13.8%, which is a safe MC for storage rice. PMID:25198845

  3. Method of predicting radiation heat transfer in turbine cooling test facilities

    NASA Technical Reports Server (NTRS)

    Gladden, H. J.; Liebert, C. H.

    1975-01-01

    A method is presented for calculating the average net radiation heat flux to turbine vanes and blades. The net radiation heat flux at a vane leading edge calculated by this method was compared with heat flux values independently determined from experimental tests on a vane in a cascade. The spectral emissivities of the turbine vane and the cascade wall were also measured.

  4. Nanoscale Radiative Heat Transfer between Graphene Ribbon Arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Zhuomin; Liu, Xianglei

    Near-field radiative heat transfer between two graphene sheets can exceed that between blackbodies due to surface plasmons excited by the graphene sheet. This study shows that, by patterning a single layer of graphene sheet into ribbons, a giant enhancement of the near-field radiative heat flux, by more than one order of magnitude higher than that between two graphene sheets, can be achieved. The mechanism lies in that when the graphene sheet is patterned into an array of ribbons, the closed circular dispersion of graphene plasmons is opened to become hyperbolic, leading to broadband singularities of density of states. Extremely high-k evanescent waves can now couple with hyperbolic graphene plasmons. Exact numerical simulations are used by combining the scattering theory and rigorous coupled-wave analysis. Furthermore, effective medium calculations are used to support the arguments and provide clear physical insights. The findings from this study may open promising pathways for highly efficient thermal management, energy harvesting, and subwavelength thermal imaging. This work was supported by the Department of Energy, Office of Science, Basic Energy Sciences (DE-FG02-06ER46343).

  5. Stagnation Point Nonequilibrium Radiative Heating and the Influence of Energy Exchange Models

    NASA Technical Reports Server (NTRS)

    Hartung, Lin C.; Mitcheltree, Robert A.; Gnoffo, Peter A.

    1991-01-01

    A nonequilibrium radiative heating prediction method has been used to evaluate several energy exchange models used in nonequilibrium computational fluid dynamics methods. The radiative heating measurements from the FIRE II flight experiment supply an experimental benchmark against which different formulations for these exchange models can be judged. The models which predict the lowest radiative heating are found to give the best agreement with the flight data. Examination of the spectral distribution of radiation indicates that despite close agreement of the total radiation, many of the models examined predict excessive molecular radiation. It is suggested that a study of the nonequilibrium chemical kinetics may lead to a correction for this problem.

  6. Stagnation point nonequilibrium radiative heating and the influence of energy exchange models

    NASA Technical Reports Server (NTRS)

    Hartung, Lin C.; Mitcheltree, Robert A.; Gnoffo, Peter A.

    1991-01-01

    A nonequilibrium radiative heating prediction method has been used to evaluate several energy exchange models used in nonequilibrium computational fluid dynamics methods. The radiative heating measurements from the FIRE II flight experiment supply an experimental benchmark against which different formulations for these exchange models can be judged. The models which predict the lowest radiative heating are found to give the best agreement with the flight data. Examination of the spectral distribution of radiation indicates that despite close agreement of the total radiation, many of the models examined predict excessive molecular radiation. It is suggested that a study of the nonequilibrium chemical kinetics may lead to a correction for this problem.

  7. Solar radiation in Saturn's atmosphere: maximum penetration and heating rates

    NASA Astrophysics Data System (ADS)

    Pérez-Hoyos, S.; Sánchez-Lavega, A.

    2005-08-01

    We use our previous long-term study (1994-2004) of Saturn's upper clouds and hazes vertical structure (Pérez-Hoyos et al., Icarus, 176, 155, 2005), to retrieve the internal fields and penetration levels of optical radiation in the atmosphere (wavelengths from 250 nm to 950 nm). We have used a doubling adding radiative transfer code and assumed different vertical cloud structure models, as bounded by our previous photometric analysis and other works. We analyze the levels between 1 mbar to 6 bar taking into account the seasonal and ring-shadowing effects on insolation. The main result is that the expected maximum penetration level of the visual radiation on the upper hazes along Saturn's year is ˜ 0.3 bar. Maps of the temporal and latitudinal distribution of the atmospheric heating rates are also presented. Our results provide realistic constraints on the available energy and vertical extent for general circulation -shallow- models for the giant planets based on the terrestrial circulation analogy. Acknowledgments: S.P.-H and A.S.-L. are supported by MCYT AYA2003-03216, fondos FEDER, and Grupos UPV 15946/2004. S.P.-H. acknowledges a PhD fellowship from the Spanish MEC.

  8. Transient Heat Transfer in a Semitransparent Radiating Layer with Boundary Convection and Surface Reflections

    NASA Technical Reports Server (NTRS)

    Siegel, Robert

    1996-01-01

    Surface convection and refractive index are examined during transient radiative heating or cooling of a grey semitransparent layer with internal absorption, emission and conduction. Each side of the layer is exposed to hot or cold radiative surroundings, while each boundary is heated or cooled by convection. Emission within the layer and internal reflections depend on the layer refractive index. The reflected energy and heat conduction distribute energy across the layer and partially equalize the transient temperature distributions. Solutions are given to demonstrate the effect of radiative heating for layers with various optical thicknesses, the behavior of the layer heated by radiation on one side and convectively cooled on the other, and a layer heated by convection while being cooled by radiation. The numerical method is an implicit finite difference procedure with non-uniform space and time increments. The basic method developed in earlier work is expanded to include external convection and incident radiation.

  9. Radiative heat exchange of a meteor body in the approximation of radiant heat conduction

    SciTech Connect

    Pilyugin, N.N.; Chernova, T.A.

    1986-07-01

    The problem of the thermal and dynamic destruction of large meteor bodies moving in planetary atmospheres is fundamental for the clarification of optical observations and anomalous phenomena in the atmosphere, the determination of the physicochemical properties of meteoroids, and the explanation of the fall of remnants of large meteorites. Therefore, it is important to calculate the coefficient of radiant heat exchange (which is the determining factor under these conditions) for large meteor bodies as they move with hypersonic velocities in an atmosphere. The solution of this problem enables one to find the ablation of a meteorite during its aerodynamic heating and to determine the initial conditions for the solution of problems of the breakup of large bodies and their subsequent motion and ablation. Hypersonic flow of an inviscid gas stream over an axisymmetric blunt body is analyzed with allowance for radiative transfer in a thick-thin approximation. The gas-dynamic problem of the flow of an optically thick gas over a large body is solved by the method of asymptotic joined expansions, using a hypersonic approximation and local self-similarity. An equation is obtained for the coefficient of radiant heat exchange and the peculiarities of such heat exchange for meteor bodies of large size are noted.

  10. Development of a contact heat exchanger for a constructable radiator system

    NASA Technical Reports Server (NTRS)

    Howell, H. R.

    1983-01-01

    A development program for a contact heat exchanger to be used to transfer heat from a spacecraft coolant loop to a heat pipe radiator is described. The contact heat exchanger provides for a connectable/disconnectable joint which allows for on-orbit assembly of the radiator system and replacement or exchange of radiator panels for repair and maintenance. The contact heat exchanger does not require the transfer of fluid across the joint; the spacecraft coolant loop remains contained in an all welded system with no static or dynamic fluid seals. The contact interface is also "dry' with no conductive grease or interstitial material required.

  11. Radiative and free convective heat transfer from a containerless sphere

    NASA Technical Reports Server (NTRS)

    Johnson, K.

    1979-01-01

    A mathematical model is derived for heat loss due to radiation and free convection for a small copper sphere (approximately 0.3 to 0.4 cm diameter) cooled by a helium-argon gas mixture. A FORTRAN program written to simplify calculations and extend the range of applicability to experimentation is presented. Pressures used were less than 400 torr, and resulting temperatures ranged from 500 to 4600 K. Comparison of results for initial cooling by the gas mixture with experimental data showed a 5 percent error for temperature values and a 2.7 percent error for the temperature difference caused by the cooling. Results indicate that the accuracy could be increased significantly by using better estimates for thermal conductivities.

  12. Tabulation of Fundamental Assembly Heat and Radiation Source Files

    SciTech Connect

    T. deBues; J.C. Ryman

    2006-10-25

    The purpose of this calculation is to tabulate a set of computer files for use as input to the WPLOAD thermal loading software. These files contain details regarding heat and radiation from pressurized water reactor (PWR) assemblies and boiling water reactor (BWR) assemblies. The scope of this calculation is limited to rearranging and reducing the existing file information into a more streamlined set of tables for use as input to WPLOAD. The electronic source term files used as input to this calculation were generated from the output files of the SAS2H/ORIGIN-S sequence of the SCALE Version 4.3 modular code system, as documented in References 2.1.1 and 2.1.2, and are included in Attachment II.

  13. Casimir effect and radiative heat transfer between Chern Insulators

    NASA Astrophysics Data System (ADS)

    Rodriguez Lopez, Pablo; Grushin, Adolfo; Tse, Wang-Kong; Dalvit, Diego

    2015-03-01

    Chern Insulators are a class of two-dimensional topological materials. Their electronic properties are different from conventional materials, and lead to interesting new physics as quantum Hall effect in absence of an external magnetic field. Here we will review some of their special properties and, in particular, we will discuss the radiative heat transfer and the Casimir effect between two planar Chern Insulators sheets. Finally, we will see how to control the intensity and sign of this Casimir force and the requirements to observe a repulsive Casimir force in the lab with those materials. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA Grant Agreement No. 302005.

  14. Effect of Index of Refraction on Radiation Characteristics in a Heated Absorbing, Emitting, and Scattering Layer

    NASA Technical Reports Server (NTRS)

    Siegel, R.; Spuckler, C. M.

    1992-01-01

    The effect of the index of refraction on the temperature distribution and radiative heat flux in semitransparent materials, such as some ceramics, is investigated analytically. In the case considered here, a plane layer of a ceramic material is subjected to external radiative heating incident on each of its surfaces; the material emits, absorbs, and isotropically scatters radiation. It is shown that, for radiative equilibrium in a gray layer with diffuse interfaces, the temperature distribution and radiative heat flux for any index of refraction can be obtained in a simple manner from the results for an index of refraction of unity.

  15. Spectral estimates of net radiation and soil heat flux

    USGS Publications Warehouse

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

    1990-01-01

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

  16. Advanced radiator concepts utilizing honeycomb panel heat pipes

    NASA Astrophysics Data System (ADS)

    Fleischman, G. L.; Peck, S. J.; Tanzer, H. J.

    1987-10-01

    The feasibility of fabricating and processing moderate temperature range vapor chamber type heat pipes in a low mass honeycomb panel configuration for highly efficient radiator fins for potential use on the space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include type of material, material and panel thickness, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. A thin-wall all-welded stainless steel design with methanol as the working fluid was the initial prototype unit. It was found that an aluminum panel could not be fabricated in the same manner as a stainless steel panel due to diffusion bonding and resistance welding considerations. Therefore, a formed and welded design was developed. The prototype consists of ten panels welded together into a large panel 122 by 24 by 0.15 in., with a heat rejection capability of 1000 watts and a fin efficiency of essentially 1.0.

  17. Linear irreversible heat engines based on local equilibrium assumptions

    NASA Astrophysics Data System (ADS)

    Izumida, Yuki; Okuda, Koji

    2015-08-01

    We formulate an endoreversible finite-time Carnot cycle model based on the assumptions of local equilibrium and constant energy flux, where the efficiency and the power are expressed in terms of the thermodynamic variables of the working substance. By analyzing the entropy production rate caused by the heat transfer in each isothermal process during the cycle, and using the endoreversible condition applied to the linear response regime, we identify the thermodynamic flux and force of the present system and obtain a linear relation that connects them. We calculate the efficiency at maximum power in the linear response regime by using the linear relation, which agrees with the Curzon-Ahlborn (CA) efficiency known as the upper bound in this regime. This reason is also elucidated by rewriting our model into the form of the Onsager relations, where our model turns out to satisfy the tight-coupling condition leading to the CA efficiency.

  18. Design and test of a self-controlled heat pipe radiator.

    NASA Technical Reports Server (NTRS)

    Swerdling, B.; Hembach, R.

    1973-01-01

    A 15,000-W spacecraft waste heat rejection system utilizing heat pipe radiator panels has been investigated. Of the several concepts initially identified, a series system was selected for more in-depth analysis. As a demonstration of system feasibility, a nominal 500-W radiator panel has been designed, built, and bench tested. The panel, which is a module of the 15,000-W system, consists of a variable conductance heat pipe (VCHP) header, and six isothermalizer heat pipes attached to a radiator. The thermal load to the VCHP is supplied by a Freon 21 liquid loop via an integral heat exchanger. This paper describes the results of the system studies and the radiator design. Also presented are test data on the VCHP, heat exchanger and isothermalizer heat pipes.

  19. A convective and radiative heat transfer analysis for the FIRE II forebody

    NASA Technical Reports Server (NTRS)

    Greendyke, Robert B.; Hartung, Lin C.

    1993-01-01

    A Navier-Stokes flowfield solution method (LAURA code) using finite-rate chemistry and two-temperature thermal nonequilibrium was used in combination with two nonequilibrium radiative heat transfer codes to calculate heating for the FIRE II vehicle. An axisymmetric model of the actual body shape was used. One radiative heating code (NEQAIR) was used in uncoupled fashion with the flowfield solver's energy equations, while the other code (LORAN) was used in both coupled and uncoupled variations. Several trajectory points ranging from highly nonequilibrium flow to near-equilibrium flow were used for a study of both convective and radiative heating over the vehicle. Considerable variation in radiative heating was seen at the extremes, while agreement was good in the intermediate trajectory points. Total heat transfer calculations gave good comparison until the peak heating trajectory points were encountered, and returned to good agreement for the last two equilibrium points.

  20. Radiative heat transfer in molten and glassy obsidian

    SciTech Connect

    Gable, C.W.; Shankland, T.J.

    1984-08-10

    We have measured optical transmittance spectra in rhyolitic obsidian samples in the wavelength range lambda = 380-5500 nm and at temperatures T from 19/sup 0/-1145/sup 0/C, above and below the softening point. From the transmittance, we calculated the absorption coefficient ..cap alpha..(lambda,T) and the radiative thermal conductivity K/sub R/(T). K/sub R/ ranges from 3 x 10/sup -3/ cal cm/sup -1/s/sup -1/K/sup -1/ (1.2Wm/sup -1/K/sup -1/) at 700/sup 0/C to 12 x 10/sup -3/ cal cm/sup -1/s/sup -1/K/sup -1/(5Wm/sup -1/K/sup -1/) at 1145/sup 0/C. The 700/sup 0/C value is comparable with lattice thermal conductivity K/sub L/ of about 4 x 10/sup -3/ cal cm/sup -1/ s/sup -1/K/sup -1/(1.7 Wm/sup -1/K/sup -1/). Removing scattering effects due to bubbles from the transmittance spectra by lowering the absorption baseline increased K/sub R/ to 20 x 10/sup -3/ cal cm/sup -1/ s/sup -1/ K/sup -1/(8.4Wm/sup -1/K/sup -1/) at 1145/sup 0/C. Because scattering bubbles is likely to be small in confined magmas, these numbers are probably minimum values for K/sub R/ and indicate that in active plutons radiative heat transport could be greater than lattice conductivity by more than a factor of 2 at 1000/sup 0/C. Thus melting markedly strengthens K/sub R/, and radiative heat transport is probably the dominant component of the total conductivity K = K/sub L/+K/sub R/ in silicic magmas. These relatively large values of K can be applied to models of the thermal evolution of magma bodies and to cooling of intrusives.

  1. Modulation and amplification of radiative far field heat transfer: Towards a simple radiative thermal transistor

    SciTech Connect

    Joulain, Karl; Ezzahri, Younès; Drevillon, Jérémie; Ben-Abdallah, Philippe

    2015-03-30

    We show in this article that phase change materials (PCM) exhibiting a phase transition between a dielectric state and a metallic state are good candidates to perform modulation as well as amplification of radiative thermal flux. We propose a simple situation in plane parallel geometry where a so-called radiative thermal transistor could be achieved. In this configuration, we put a PCM between two blackbodies at different temperatures. We show that the transistor effect can be achieved easily when this material has its critical temperature between the two blackbody temperatures. We also see that the more the material is reflective in the metallic state, the more switching effect is realized, whereas the more PCM transition is stiff in temperature, the more thermal amplification is high. We finally take the example of VO{sub 2} that exhibits an insulator-metallic transition at 68 °C. We show that a demonstrator of a radiative transistor could easily be achieved in view of the heat flux levels predicted. Far-field thermal radiation experiments are proposed to back the results presented.

  2. Best estimate radiation heat transfer model developed for TRAC-BD1

    SciTech Connect

    Spore, J.W.; Giles, M.M.; Shumway, R.W.

    1981-01-01

    A best estimate radiation heat transfer model for analysis of BWR fuel bundles has been developed and compared with 8 x 8 fuel bundle data. The model includes surface-to-surface and surface-to-two-phase fluid radiation heat transfer. A simple method of correcting for anisotropic reflection effects has been included in the model.

  3. A detailed evaluation of the stratospheric heat budget: 1. Radiation transfer

    NASA Astrophysics Data System (ADS)

    Mertens, Christopher J.; Mlynczak, Martin G.; Garcia, Rolando R.; Portmann, Robert W.

    1999-03-01

    We present part 1 of a two-part series on a detailed evaluation of the stratospheric heat budget. In part 2 [Mlynczak et al., this issue] we present radiative heating, radiative cooling, net radiative heating, global radiation balance, radiative relaxation times, and diabatic circulations in the stratosphere using temperature and minor constituent data provided by instruments on the Upper Atmosphere Research Satellite (UARS) between 1991 and 1993 and by the limb infrared monitor of the stratosphere (LIMS) instrument, which operated on the Nimbus-7 spacecraft in 1978-1979. Here we describe the radiative transfer techniques used to compute the climatology of radiative heating and circulations given in part 2. Included in the radiation transfer calculations are heating due to absorption of solar radiation from the ultraviolet through near-infrared wavelengths and radiative cooling due to emission by carbon dioxide, water vapor, and ozone from 0 to 3000 cm-1 (∞-3.3 μm). Infrared radiative effects of stratospheric aerosols are also considered in detail.

  4. Cloud Classes and Radiative Heating profiles at the Manus and Nauru Atmospheric Radiation Measurement (ARM) Sites

    SciTech Connect

    Mather, James H.; McFarlane, Sally A.

    2009-10-07

    The Tropical Western Pacific (TWP) is a convective regime; however, the frequency and depth of convection is dependant on dynamical forcing which exhibits variability on a range of temporal scales and also on location within the region. Manus Island, Papua New Guinea lies in the heart of the western Pacific warm pool region and exhibits frequent deep convection much of the time while Nauru, which lies approximately 20 degrees to the East of Manus, lies in a transition zone where the frequency of convection is dependent on the phase of the El Nino/Southern Oscillation. Because of this difference in dynamical regime, the distribution of clouds and the associated radiative heating is quite different at the two sites. Individual cloud types: boundary layer cumulus, thin cirrus, stratiform convective outflow, do occur at both sites – but with different frequencies. In this study we compare cloud profiles and heating profiles for specific cloud types at these two sites using data from the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF). Results of this comparison indicate that, while the frequency of specific cloud types differ between the two sites as one would expect, the characteristics of individual cloud classes are remarkably similar. This information could prove to be very useful for applying tropical ARM data to the broader region.

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

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1996-01-01

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

  6. Thermodynamically compatible conservation laws in the model of heat conducting radiating gas

    NASA Astrophysics Data System (ADS)

    Ivanov, M. Ya.

    2011-01-01

    Thermodynamic compatibility of the mass, momentum, and energy conservation laws that describe the motion of heat conducting gas in the presence of radiation heat exchange is considered. The study is based on the one-velocity two-component mathematical model of continuous compressible medium with the gas and radiation components. The work uses experimental data for radiation and other experimental data of modern physics.

  7. Numerical model for combined conductive and radiative heat transfer in annular packed beds

    SciTech Connect

    Kamiuto, K.; Saito, S.; Ito, K. . Dept. of Production Systems Engineering)

    1993-06-01

    A numerical model is developed for quantitatively analyzing combined conductive and radiative heat transfer in concentric annular packed beds. A packed bed is considered to be a continuous medium for heat transfer, but the porosity distribution within a packed bed is taken into account. To examine the validity of the proposed model, combined conductive and radiative heat transfer through annular packed beds of cordierite or porcelain beads is analyzed numerically using finite differences under conditions corresponding to heat transfer experiments of these packed beds. The resultant temperature profiles and heat transfer characteristics are compared with the experimental results.

  8. Numerical calculation of the radiation heat transfer between rocket motor nozzle's wall and gas

    NASA Astrophysics Data System (ADS)

    Zhou, Yipeng; Zhu, Dingqiang

    2014-11-01

    The heat flux density of radiation heat transfer between rocket motor nozzle's wall and gas is one of the most important factors to decide temperature of nozzle's wall. It also provides an invaluable references advice for choosing the material of wall and type of cooling. The numerical calculation based on finite volume method is introduced in the paper. After analysis of the formula of FVM without the influence of scattering, a formula that is used to let spectral radiant intensity that is the calculation of FVM be converted into heat flux density of radiation heat transfer is deduced. It is compiled that the program based on FVM is used to calculate the heat flux density. At the end, the heat flux density of radiation heat transfer of 3D model of double-arc nozzle's wall is calculated under different condition, then simply analysis cooling system is performed.

  9. Simulation of planetary entry radiative heating with a CO2 gasdynamic laser

    NASA Technical Reports Server (NTRS)

    Lundell, J. H.; Dickey, R. R.; Howe, J. T.

    1975-01-01

    Heating encountered during entry into the atmospheres of Jupiter, Saturn, and Uranus is described, followed by a discussion of the use of a CO2 gasdynamic laser to simulate the radiative component of the heating. Operation and performance of the laser is briefly described. Finally, results of laser tests of some candidate heat-shield materials are presented.

  10. Drying Characteristics and Quality of Rough Rice Under Infrared Radiation Heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infrared (IR) radiation heating could provide high heating rate and rapid moisture removal for rough rice drying. The objective of this research was to investigate the effect of drying bed thickness on drying characteristics and quality of rough rice under IR heating. The samples of freshly harves...

  11. Drying characteristics and quality of rough rice under infrared radiation heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infrared (IR) radiation heating could provide high heating rate and rapid moisture removal for rough rice drying. The objective of this research was to investigate the effect of the drying bed thickness on drying characteristics and quality of rough rice subjected to IR heating. Samples of freshly ...

  12. Thermal self-oscillations in radiative heat exchange

    SciTech Connect

    Dyakov, S. A.; Dai, J.; Yan, M.; Qiu, M.

    2015-02-09

    We report the effect of relaxation-type self-induced temperature oscillations in the system of two parallel plates of SiO{sub 2} and VO{sub 2} which exchange heat by thermal radiation in vacuum. The non-linear feedback in the self-oscillating system is provided by metal-insulator transition in VO{sub 2}. Using the method of fluctuational electrodynamics, we show that under the action of an external laser of a constant power, the temperature of VO{sub 2} plate oscillates around its phase transition value. The period and amplitude of oscillations depend on the geometry of the structure. We found that at 500 nm vacuum gap separating bulk SiO{sub 2} plate and 50 nm thick VO{sub 2} plate, the period of self-oscillations is 2 s and the amplitude is 4 K, which is determined by phase switching at threshold temperatures of phase transition.

  13. Sensible heat transfer from the fowl: radiative and convective heat losses from a flock of broiler chickens.

    PubMed

    Wathes, C M; Clark, J A

    1981-03-01

    1. Measurements of the micro-climate within a poultry house and physical models of heat loss produced estimates of the sensible heat losses from broilers. The partition between radiative and convective heat losses changed with age and bird activity. 2. The birds spent approximately 67% of ;their time in a cluster, in which their sensible heat losses were between 30 and 60% of those of an individual bird. 3. body plus plumage resistance was constant at 0.09 m2K/W up to 30 d and increased linearly to 0.40 m2K/W at 54 d. PMID:7237195

  14. Coaxial radiative and convective heat transfer in gray and nongray gases

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.

    1980-01-01

    Coupled radiative and convective heat transfer is investigated for an absorbing gas flowing in a finite length channel and heated by blackbody radiation directed along the flow axis. The problem is formulated in one dimension and numerical solutions are obtained for the temperature profile of the gas and for the radiation escaping the channel entrance, assuming both gray and nongray absorption spectra. Due to radiation trapping, the flowing gas is found to have substantially smaller radiation losses for a given peak gas temperature than a solid surface that is radiatively heated to this temperature. A greenhouse effect is also evident whereby radiation losses are minimized for a gas having stronger absorption at long wavelengths.

  15. Numerical modelling and analysing of conjugate radiation- convective heat transfer of fin-tube radiator of spacecraft

    NASA Astrophysics Data System (ADS)

    Delcov, A.; Hodenkov, A.; Zhuikov, D.

    2015-10-01

    This paper covered the problem of assessing the effectiveness of the section of the fin-tube radiator of space thermal control system. The task of calculating the conjugate radiation-convective heat transfer is presented. The results of numerical simulation are described.

  16. Modular, thermal bus-to-radiator integral heat exchanger design for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Chambliss, Joe; Ewert, Michael

    1990-01-01

    The baseline concept is introduced for the 'integral heat exchanger' (IHX) which is the interface of the two-phase thermal bus with the heat-rejecting radiator panels. A direct bus-to-radiator heat-pipe integral connection replaces the present interface hardware to reduce the weight and complexity of the heat-exchange mechanism. The IHX is presented in detail and compared to the baseline system assuming certain values for heat rejection, mass per unit width, condenser capacity, contact conductance, and assembly mass. The spreadsheet comparison can be used to examine a variety of parameters such as radiator length and configuration. The IHX is shown to permit the reduction of panel size and system mass in response to better conductance and packaging efficiency. The IHX is found to be a suitable heat-rejection system for the Space Station Freedom because it uses present technology and eliminates the interface mechanisms.

  17. Performance Analysis of Potassium Heat Pipes Radiator for HP-STMCs Space Reactor Power System

    SciTech Connect

    El-Genk, Mohamed S.; Tournier, Jean-Michel

    2004-02-04

    A detailed design and performance results of C-C finned, and armored potassium heat pipes radiator for a 110 kWe Heat Pipes-Segmented Thermoelectric Module Converters (HP-STMCs) Space Reactor Power system (SRPS) are presented. The radiator consists of two sections; each serves an equal number of STMCs and has 162 longitudinal potassium heat pipes with 0.508 mm thick C-C fins. The width of the C-C fins at the minor diameter of the radiator is almost zero, but increases with distance along the radiator to reach 3.7 cm at the radiator's major diameter. The radiator's heat pipes (OD = 2.42 cm in front and 3.03 cm in rear) have thin titanium (0.0762 mm thick) liners and wicks (0.20 mm thick with an effective pore radius of 12-16 {mu}m) and a 1.016 mm thick C-C wall. The wick is separated from the titanium liner by a 0.4 mm annulus filled with liquid potassium to increase the capillary limit. The outer surfaces of the heat pipes in the front and rear sections of the radiator are protected with a C-C armor that is 2.17 mm and 1.70 mm thick, respectively. The inside surface of the heat pipes in the front radiator is thermally insulated while the C-C finned condensers of the rear heat pipes are exposed, radiating into space through the rear opening of the radiator cavity. The heat pipes in both the front and the rear radiators have a 1.5 m long evaporator section and each dissipates 4.47 kW while operating at 43.6% of the prevailing sonic limit. The front and rear radiator sections are 5.29 m and 2.61 m long with outer surface area and mass of 47.1 m2 and 314.3 kg, and 39.9 m2 and 243.2 kg, respectively. The total radiator is 7.63 m long and has minor and major diameters of 1.48 m and 5.57 m, respectively, and a total surface area of 87 m2; however, the effective radiator area, after accounting for heat rejection through the rear of the radiator cavity, is 98.8 m2. The radiator's total mass including the C-C armor is 557.5 kg and the specific area and specific mass are 6

  18. The effect of atmospheric radiative heating by clouds on the Madden-Julian Oscillation

    NASA Astrophysics Data System (ADS)

    Crueger, Traute; Stevens, Bjorn

    2015-06-01

    This article explores how atmospheric radiative heating, due to the presence of clouds, influences the Madden-Julian Oscillation (MJO) as simulated by four comprehensive atmosphere general circulation models. Simulations in which clouds are transparent to electromagnetic radiation ("clouds-off") are compared with control simulations in which clouds are allowed to interact with radiation ("clouds-on"). Making clouds transparent to radiation leads to robust changes of the mean state: the westerly winds in the equatorial Indo-Pacific area weaken and the precipitation reveals a shift from single to double Intertropical Convergence Zones. These changes are accompanied by weaker MJOs. Also, the moisture sensitivity of precipitation changes, however not consistently within our group of models. Further analyses show that within the active phase of intraseasonal variability, cloud-radiative effects amplify the heating profiles compared to clouds-off. Heating from nonradiative processes is dominated by the parameterized convection, but large-scale heating associated with cloud microphysical processes acting on the grid-scale modifies the shape of the heating profile, leading to a top-heaviness when cloud-radiative effects are accounted for. The radiative heating due to clouds slows down the phase speed of the MJO. Averaged over the entire MJO life cycle, the column-integrated radiative heating due to clouds lags the vertically integrated moist static energy by 40°-60° of longitude (equivalently 7-10 days assuming a period of 60 days). All four models studied reveal more pronounced Kelvin waves when clouds are transparent to radiation, suggesting that cloud-radiative effects on large-scale heating profiles damp smaller scale, or faster, Kelvin waves and amplify MJO-like disturbances.

  19. Effect of radiator position and mass flux on the dryer room heat transfer rate

    NASA Astrophysics Data System (ADS)

    Mirmanto, M.; Sulistyowati, E. D.; Okariawan, I. D. K.

    A room radiator as usually used in cold countries, is actually able to be used as a heat source to dry goods, especially in the rainy season where the sun seldom shines due to much rain and cloud. Experiments to investigate effects of radiator position and mass flux on heat transfer rate were performed. This study is to determine the best position of the radiator and the optimum mass flux. The radiator used was a finned radiator made of copper pipes and aluminum fins with an overall dimension of 220 mm × 50 mm × 310 mm. The prototype room was constructed using plywood and wood frame with an overall size of 1000 mm × 1000 mm × 1000 mm. The working fluid was heated water flowing inside the radiator and air circulating naturally inside the prototype room. The nominal mass fluxes employed were 800, 900 and 1000 kg/m2 s. The water was kept at 80 °C at the radiator entrance, while the initial air temperature inside the prototype room was 30 °C. Three positions of the radiator were examined. The results show that the effect of the mass flux on the forced and free convection heat transfer rate is insignificant but the radiator position strongly affects the heat transfer rate for both forced and free convection.

  20. The impact of cloud radiative heating on the Madden-Julian Oscillation

    NASA Astrophysics Data System (ADS)

    Crueger, Traute; Stevens, Bjorn

    2015-04-01

    We explore how atmospheric radiative heating, due to the presence of clouds, influences the Madden-Julian-Oscillation (MJO) as simulated by four comprehensive atmosphere general circulation models. For that reason we compare simulations in which clouds are transparent to electromagnetic radiation ('clouds-off') with control simulations in which clouds are allowed to interact with radiation ('clouds-on"). Making clouds transparent to radiation leads to robust changes of the mean state and the MJO: tropical precipitation in the Indian ocean is displaced off the equator, leading to two symmetric bands of precipitation in this basin. In addition, in clouds-off, the MJO weakens compared to clouds-on. Within the MJO cloud radiative effects lead to stronger convective heating profiles. Heating from non-radiative processes is dominated by the parameterized convection, but large-scale heating associated with cloud microphysical processes acting on the grid-scale, modifies the shape of the profile, leading to a top-heaviness when cloud radiative effects are accounted for. The radiative heating due to clouds slows down the phase speed of the MJO. Averaged over the entire MJO life-cycle the column-integrated radiative heating due to clouds lags the vertically integrated moist static energy by 40° to 60° of longitude (equivalently 7 to 10 days assuming a period of 60 days). All four models studied reveal more pronounced Kelvin waves when clouds are transparent to radiation (clouds-off) suggesting that cloud-radiative effects on large-scale heating profiles acts to damp smaller scale, or faster, Convectively Coupled Equatorial Waves and amplify MJO-like disturbances.

  1. Optimization of a heat-pipe-cooled space radiator for use with a reactor-powered Stirling engine

    NASA Technical Reports Server (NTRS)

    Moriarty, Michael P.; French, Edward P.

    1987-01-01

    The design optimization of a reactor-Stirling heat-pipe-cooled radiator is presented. The radiator is a self-deploying concept that uses individual finned heat pipe 'petals' to reject waste heat from a Stirling engine. Radiator optimization methodology is presented, and the results of a parametric analysis of the radiator design variables for a 100-kW(e) system are given. The additional steps of optiminzing the radiator resulted in a net system mass savings of 3 percent.

  2. Effect of Joule Heating and Thermal Radiation in Flow of Third Grade Fluid over Radiative Surface

    PubMed Central

    Hayat, Tasawar; Shafiq, Anum; Alsaedi, Ahmed

    2014-01-01

    This article addresses the boundary layer flow and heat transfer in third grade fluid over an unsteady permeable stretching sheet. The transverse magnetic and electric fields in the momentum equations are considered. Thermal boundary layer equation includes both viscous and Ohmic dissipations. The related nonlinear partial differential system is reduced first into ordinary differential system and then solved for the series solutions. The dependence of velocity and temperature profiles on the various parameters are shown and discussed by sketching graphs. Expressions of skin friction coefficient and local Nusselt number are calculated and analyzed. Numerical values of skin friction coefficient and Nusselt number are tabulated and examined. It is observed that both velocity and temperature increases in presence of electric field. Further the temperature is increased due to the radiation parameter. Thermal boundary layer thickness increases by increasing Eckert number. PMID:24454694

  3. Effect of Joule heating and thermal radiation in flow of third grade fluid over radiative surface.

    PubMed

    Hayat, Tasawar; Shafiq, Anum; Alsaedi, Ahmed

    2014-01-01

    This article addresses the boundary layer flow and heat transfer in third grade fluid over an unsteady permeable stretching sheet. The transverse magnetic and electric fields in the momentum equations are considered. Thermal boundary layer equation includes both viscous and Ohmic dissipations. The related nonlinear partial differential system is reduced first into ordinary differential system and then solved for the series solutions. The dependence of velocity and temperature profiles on the various parameters are shown and discussed by sketching graphs. Expressions of skin friction coefficient and local Nusselt number are calculated and analyzed. Numerical values of skin friction coefficient and Nusselt number are tabulated and examined. It is observed that both velocity and temperature increases in presence of electric field. Further the temperature is increased due to the radiation parameter. Thermal boundary layer thickness increases by increasing Eckert number. PMID:24454694

  4. Heat transfer in vertical Bridgman growth of oxides - Effects of conduction, convection, and internal radiation

    NASA Technical Reports Server (NTRS)

    Brandon, S.; Derby, J. J.

    1992-01-01

    In the present investigation of crystalline phase internal radiation and heat conduction during the vertical Bridgman growth of a YAG-like oxide crystal, where transport through the melt is dominated by convection and conduction, heat is also noted to be conducted through ampoule walls via natural convection and enclosure radiation. The results of a quasi-steady-state axisymmetric Galerkin FEM indicate that heat transfer through the system is powerfully affected by the optical absorption coefficient of the crystal. The coupling of internal radiation through the crystal with conduction through the ampoule walls promotes melt/crystal interface shapes that are highly reflected near the ampoule wall.

  5. Effects of atmospheric structure on radiative heating for Jupiter entry probe

    NASA Technical Reports Server (NTRS)

    Sutton, K.; Jones, J. J.; Powell, R. W.

    1978-01-01

    New estimates of the radiative heat load to a Jupiter entry probe have been obtained for revised models of Jupiter's atmosphere based on the latest data from Pioneer 10 and 11 missions and earth-based experiments. The new estimates of the radiative heat load are compared with results obtained for the previous atmospheric models. The changes in Jupiter's atmospheric models cause a substantial reduction in the radiative heat load for the atmosphere denoted as 'cool', but only moderate reductions for the atmospheres denoted as 'nominal' and 'warm'. Results are also presented showing the effects of inertial entry angle for off-equatorial entries in the revised model atmospheres.

  6. Cold Start of a Radiator Equipped with Titanium-Water Heat Pipes

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Sanzi, James L.; Siamidis, John

    2008-01-01

    Radiator panels utilizing titanium-water heat pipes are being considered for lunar applications. A traditional sandwich structure is envisioned where heat pipes are embedded between two high thermal conductivity face sheets. The heat pipe evaporators are to be thermally connected to the heat source through one or more manifolds containing coolant. Initial radiator operation on the lunar surface would likely follow a cold soak where the water in the heat pipes is purposely frozen. To achieve heat pipe operation, it will be necessary to thaw the heat pipes. One option is to allow the sunlight impinging on the surface at sunrise to achieve this goal. Testing was conducted in a thermal vacuum chamber to simulate the lunar sunrise and additional modeling was conducted to identify steady-state and transient response. It was found that sunlight impinging on the radiator surface at sunrise was insufficient to solely achieve the goal of thawing the water in the heat pipes. However, starting from a frozen condition was accomplished successfully by applying power to the evaporators. Start up in this fashion was demonstrated without evaporator dryout. Concern is raised over thawing thermosyphons, vertical heat pipes operating in a gravity field, with no wick in the condenser section. This paper presents the results of the simulated cold start study and identifies future work to support radiator panels equipped with titanium-water heat pipes.

  7. The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan heat low

    NASA Astrophysics Data System (ADS)

    Marsham, John H.; Parker, Douglas J.; Todd, Martin C.; Banks, Jamie R.; Brindley, Helen E.; Garcia-Carreras, Luis; Roberts, Alexander J.; Ryder, Claire L.

    2016-03-01

    The summertime Sahara heat low (SHL) is a key component of the West African monsoon (WAM) system. Considerable uncertainty remains over the relative roles of water vapour and dust aerosols in controlling the radiation budget over the Sahara and therefore our ability to explain variability and trends in the SHL, and in turn, the WAM. Here, new observations from Fennec supersite-1 in the central Sahara during June 2011 and June 2012, together with satellite retrievals from GERB, are used to quantify how total column water vapour (TCWV) and dust aerosols (from aerosol optical depth, AOD) control day-to-day variations in energy balance in both observations and ECWMF reanalyses (ERA-I). The data show that the earth-atmosphere system is radiatively heated in June 2011 and 2012. Although the empirical analysis of observational data cannot completely disentangle the roles of water vapour, clouds and dust, the analysis demonstrates that TCWV provides a far stronger control on TOA net radiation, and so the net heating of the earth-atmosphere system, than AOD does. In contrast, variations in dust provide a much stronger control on surface heating, but the decreased surface heating associated with dust is largely compensated by increased atmospheric heating, and so dust control on net TOA radiation is weak. Dust and TCWV are both important for direct atmospheric heating. ERA-I, which assimilated radiosondes from the Fennec campaign, captures the control of TOA net flux by TCWV, with a positive correlation (r = 0.6) between observed and modelled TOA net radiation, despite the use of a monthly dust climatology in ERA-I that cannot capture the daily variations in dustiness. Variations in surface net radiation, and so the vertical profile of radiative heating, are not captured in ERA-I, since it does not capture variations in dust. Results show that ventilation of the SHL by cool moist air leads to a radiative warming, stabilising the SHL with respect to such perturbations. It is

  8. Degradation of Biochemical Activity in Soil Sterilized by Dry Heat and Gamma Radiation

    NASA Technical Reports Server (NTRS)

    Shih, K. L.; Souza, K. A.

    1978-01-01

    The effect of soil sterilization by dry heat (0.08% relative humidity), gamma radiation, or both on soil phosphatase, urease, and decarboxylase activity was studied. Soil sterilized by a long exposure to dry heat at relatively low temperatures (eight weeks at 100.5 C) retained higher activities than did soil exposed to a higher temperature (two weeks at 124.5 C), while all activity was destroyed by four days at 148.5 C. Sterilization with 7.5 Mrads destroyed less activity than did heat sterilization. The effect of several individually nonsterizing doses of heat radiation is described.

  9. Environmental microbiology as related to planetary quarantine. [synergetic effect of heat and radiation

    NASA Technical Reports Server (NTRS)

    Pflug, I. J.

    1973-01-01

    The mechanistic basis of the synergetic effect of combined heat and radiation on microbial destruction was analyzed and results show that radiation intensity, temperature, and relative humidity are the determining factors. Dry heat resistance evaluation for selected bacterial spore crops indicates that different strains of Bacillus stearothermophilus demonstrate marked differences in resistance. Preliminary work to determine the effects of storage time, suspending medium, storage temperature and spore crop cleaning procedures on dry heat survival characteristics of Bacillus subtilis var. Niger, and dry heat resistance of natural microflora in soil particles is also reported.

  10. Graphene-assisted near-field radiative heat transfer between corrugated polar materials

    SciTech Connect

    Liu, X. L.; Zhang, Z. M.

    2014-06-23

    Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

  11. Effect of radiative heat transfer on the convective stability of a fluid in a slot

    NASA Astrophysics Data System (ADS)

    Kural, O.

    1988-06-01

    A fluid, confined between two vertical flat plates, with a linear temperature gradient decreasing upwards, is investigated analytically for convective stability under the influence of radiative heat transfer. The effect of radiative transfer is accounted for by use of the Milne-Eddington differential approximation. It is shown that three dimensionless parameters influence the stability: the optical thickness, tau, a parameter A which compares radiative and conductive fluxes, and E, which combines the effects of boundary surface properties with the 'color' properties of the medium. It is shown that radiative heat transfer has a stabilizing effect on the system and that A and tau exert strong influences.

  12. Near-surface silica does not increase radiative heat dissipation from plant leaves

    NASA Astrophysics Data System (ADS)

    Olof Björn, Lars; Li, Shaoshan

    2011-07-01

    It has been suggested that plants are able to increase radiative heat dissipation from their leaves by depositing near-surface silica, in this way increasing emissivity of infrared radiation and lowering leaf temperature. In order to test this theory, we have compared emissivity and radiative dissipation over the mid-infrared range 2.5-22.3 μm of leaves of plants that accumulate silica and plants that do not. Our data do not support the theory that accumulation of silica increases radiative heat dissipation by plant leaves.

  13. Radiative Heating on the After-Body of Martian Entry Vehicles

    NASA Technical Reports Server (NTRS)

    Brandis, A. M.; Saunders, D. A.; Johnston, C. O.; Cruden, B. A.; White, T. R.

    2015-01-01

    This paper presents simulations of the radiative heat flux imparted on the after-body of vehicles entering the Martian atmosphere. The radiation is dominated by CO2 bands emitting in the mid-wave infrared spectral region. This mechanism has traditionally not been considered in the design of past Mars entry vehicles. However, with recent analysis showing that the CO2 radiation can be greater than convective heating in the wake, and with several upcoming and proposed missions to Mars potentially affected, an investigation of the impact of this radiation is warranted. The focus of this paper is to provide a better understanding of the impact to aerothermal heating predictions and to provide comparisons between NASA's two main radiation codes, NEQAIR and HARA. The tangent slab approximation is shown to be overly conservative, by as much as 58 percent, for most back- shell body point locations compared to using a full angular integration method. However, due to the complexity of the wake flow, it is also shown that tangent slab does not always represent an upper limit for radiative heating. Furthermore, analysis in this paper shows that it is not possible to provide a general knock-down factor from the tangent slab results to those obtained using the more rigorous full integration method. When the radiative heating is accounted for on the after-body, the unmargined total heat flux can be as high as 14 watts per square centimeter.

  14. The Liquid Droplet Radiator - an Ultralightweight Heat Rejection System for Efficient Energy Conversion in Space

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.; Hertzberg, A.

    1984-01-01

    A heat rejection system for space is described which uses a recirculating free stream of liquid droplets in place of a solid surface to radiate waste heat. By using sufficiently small droplets ( 100 micron diameter) of low vapor pressure liquids the radiating droplet sheet can be made many times lighter than the lightest solid surface radiators (heat pipes). The liquid droplet radiator (LDR) is less vulnerable to damage by micrometeoroids than solid surface radiators, and may be transported into space far more efficiently. Analyses are presented of LDR applications in thermal and photovoltaic energy conversion which indicate that fluid handling components (droplet generator, droplet collector, heat exchanger, and pump) may comprise most of the radiator system mass. Even the unoptimized models employed yield LDR system masses less than heat pipe radiator system masses, and significant improvement is expected using design approaches that incorporate fluid handling components more efficiently. Technical problems (e.g., spacecraft contamination and electrostatic deflection of droplets) unique to this method of heat rejectioon are discussed and solutions are suggested.

  15. The liquid droplet radiator - An ultralightweight heat rejection system for efficient energy conversion in space

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.; Hertzberg, A.

    1981-01-01

    A heat rejection system for space is described which uses a recirculating free stream of liquid droplets in place of a solid surface to radiate waste heat. By using sufficiently small droplets (less than about 100 micron diameter) of low vapor pressure liquids (tin, tin-lead-bismuth eutectics, vacuum oils) the radiating droplet sheet can be made many times lighter than the lightest solid surface radiators (heat pipes). The liquid droplet radiator (LDR) is less vulnerable to damage by micrometeoroids than solid surface radiators, and may be transported into space far more efficiently. Analyses are presented of LDR applications in thermal and photovoltaic energy conversion which indicate that fluid handling components (droplet generator, droplet collector, heat exchanger, and pump) may comprise most of the radiator system mass. Even the unoptimized models employed yield LDR system masses less than heat pipe radiator system masses, and significant improvement is expected using design approaches that incorporate fluid handling components more efficiently. Technical problems (e.g., spacecraft contamination and electrostatic deflection of droplets) unique to this method of heat rejection are discussed and solutions are suggested.

  16. Analytical and experimental studies of heat pipe radiation cooling of hypersonic propulsion systems

    SciTech Connect

    Martin, R.A.; Merrigan, M.A.; Elder, M.G.; Sena, J.T.; Keddy, E.S. ); Silverstein, C.C. )

    1992-01-01

    Preliminary, research-oriented, analytical and experimental studies were completed to assess the feasibility of using high-temperature heat pipes to cool hypersonic engine components. This new approach involves using heat pipes to transport heat away from the combustor, nozzle, or inlet regions, and to reject it to the environment by thermal radiation from an external heat pipe nacelle. For propulsion systems using heat pipe radiation cooling (HPRC), it is possible to continue to use hydrocarbon fuels into the Mach 4 to Mach 6 speed range, thereby enhancing the economic attractiveness of commercial or military hypersonic flight. In the second-phase feasibility program recently completed, we found that heat loads produced by considering both convection and radiation heat transfer from the combustion gas can be handled with HPRC design modifications. The application of thermal insulation to ramburner and nozzle walls was also found to reduce the heat load by about one-half and to reduce peak HPRC system temperatures to below 2700{degrees}F. In addition, the operation of HPRC at cruise conditions of around Mach 4.5 and at an altitude of 90, 000 ft lowers peak hot section temperatures to around 2800{degrees}F. An HPRC heat pipe was successfully fabricated and tested at Mach 5 conditions of heat flux, heat load, and temperature. 24 refs.

  17. Analytical and experimental studies of heat pipe radiation cooling of hypersonic propulsion systems

    SciTech Connect

    Martin, R.A.; Merrigan, M.A.; Elder, M.G.; Sena, J.T.; Keddy, E.S.; Silverstein, C.C.

    1992-06-01

    Preliminary, research-oriented, analytical and experimental studies were completed to assess the feasibility of using high-temperature heat pipes to cool hypersonic engine components. This new approach involves using heat pipes to transport heat away from the combustor, nozzle, or inlet regions, and to reject it to the environment by thermal radiation from an external heat pipe nacelle. For propulsion systems using heat pipe radiation cooling (HPRC), it is possible to continue to use hydrocarbon fuels into the Mach 4 to Mach 6 speed range, thereby enhancing the economic attractiveness of commercial or military hypersonic flight. In the second-phase feasibility program recently completed, we found that heat loads produced by considering both convection and radiation heat transfer from the combustion gas can be handled with HPRC design modifications. The application of thermal insulation to ramburner and nozzle walls was also found to reduce the heat load by about one-half and to reduce peak HPRC system temperatures to below 2700{degrees}F. In addition, the operation of HPRC at cruise conditions of around Mach 4.5 and at an altitude of 90, 000 ft lowers peak hot section temperatures to around 2800{degrees}F. An HPRC heat pipe was successfully fabricated and tested at Mach 5 conditions of heat flux, heat load, and temperature. 24 refs.

  18. Analytical and experimental studies of heat pipe radiation cooling of hypersonic propulsion systems

    NASA Technical Reports Server (NTRS)

    Martin, R. A.; Merrigan, M. A.; Elder, M. G.; Sena, J. T.; Keddy, E. S.; Silverstein, C. C.

    1992-01-01

    Analytical and experimental studies were completed to assess the feasibility of using high-temperature heat pipes to cool hypersonic engine components. This new approach involves using heat pipes to transport heat away from the combustor, nozzle, or inlet regions, and to reject it to the environment by thermal radiation from an external heat pipe nacelle. For propulsion systems using heat pipe radiation cooling (HPRC), it is possible to continue to use hydrocarbon fuels into the Mach 4 to Mach 6 speed range, thereby enhancing the economic attractiveness of commercial or military hypersonic flight. In the second-phase feasibility program recently completed, it is found that heat loads produced by considering both convection and radiation heat transfer from the combustion gas can be handled with HPRC design modifications. The application of thermal insulation to ramburner and nozzle walls was also found to reduce the heat load by about one-half and to reduce peak HPRC system temperatures to below 2700 F. In addition, the operation of HPRC at cruise conditions of around Mach 4.5 and at an altitude of 90,000 ft lowers the peak hot-section temperatures to around 2800 F. An HPRC heat pipe was successfully fabricated and tested at Mach 5 conditions of heat flux, heat load, and temperature.

  19. Circular radiation heat shields with temperature dependent emissivities: transient and steady-state analyses

    NASA Astrophysics Data System (ADS)

    Yu, H.; Li, X.; Hu, S.; Li, Z.; Chen, A.

    2016-03-01

    Radiation heat loss is an important type of heat loss in thermal systems. In this work, a numerical study of the transient response of two circular radiation heat shields inserted between two parallel and circular surfaces of emissivities ɛ1 and ɛ2 is presented. The same dimensions have been assumed for the two main radiating surfaces and the two radiation shields. The radiation shields are assumed to have different emissivities on their top (ɛ3 and ɛ5) and bottom ( ɛ4 and ɛ6) surfaces, and both are assumed to be different but linear functions of temperature. A specific configuration is investigated in detail to highlight the transient temperature and heat transfer characteristics of the system. Some new results for the transient temperature and heat transfer characteristics of the system such as the effect of shield location, shield emissivities, the temperature dependence of shield emissivities, system dimensions, temperatures of the hot and cold surfaces and emissivities of the hot and cold surfaces are presented for future references. It has been observed that increasing the temperature of the first radiation shield by changing a parameter such as surface emissivity or distance between the radiation shield or the temperature of the hot surface, will not necessarily decrease the temperature of the second radiation shield.

  20. The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan Heat Low

    NASA Astrophysics Data System (ADS)

    Marsham, J. H.; Parker, D. J.; Todd, M. C.; Banks, J. R.; Brindley, H. E.; Garcia-Carreras, L.; Roberts, A. J.; Ryder, C. L.

    2015-07-01

    The summertime Sahara Heat Low (SHL) is a key component of the West African Monsoon (WAM) system. Considerable uncertainty remains over the relative roles of water vapour and dust aerosols in controlling the radiation budget over the Sahara and therefore our ability to explain variability and trends in the SHL, and in turn, the WAM. Here, new observations from the Fennec field campaign during June 2011 and June 2012, together with satellite retrievals from GERB, are used to quantify how total column water vapour (TCWV) and dust aerosols (from aerosol optical depth, AOD) control day-to-day variations in energy balance in both observations and ECWMF reanalyses (ERA-I). The data show that the earth-atmosphere system is radiatively heated in June 2011 and 2012. It is TCWV that largely determines variations in daily mean TOA net flux and the net heating of the earth-atmosphere system. In contrast, dust provides the primary control on surface heating, but the decreased surface heating from dust is largely compensated by increased atmospheric heating, and so dust control on net TOA radiation is weak. Dust and TCWV are both important for direct atmospheric heating. ERA-I captures the control of TOA net flux by TCWV, with a positive correlation (r=0.6) between observed and modelled TOA net radiation, despite the use of a monthly dust climatology in ERA-I that cannot capture the daily variations in dustiness. Variations in surface net radiation, and so the vertical profile of radiative heating, are not captured in ERA-I, since it does not capture variations in dust. Results show that ventilation of the SHL by cool moist air leads to a radiative warming, stabilising the SHL with respect to such perturbations. It is known that models struggle to capture the advective moistening of the SHL, especially that associated with mesoscale convective systems. Our results show that the typical model errors in Saharan water vapour will lead to substantial errors in the modelled TOA

  1. Transient analysis of heat-pipe radiators for space station applications

    SciTech Connect

    Boo, Joonhong.

    1989-01-01

    A space application of concern in this study is the use of heat pipes as candidate thermal control devices in high-power, long-life space station where heat pipes have received considerable attention owing to their high heat transport capability, reliability, light weight, ease of fabrication and durability. The objective of this research is to develop and to solve numerically a mathematical model for the transient behavior of a heat pipe radiator in a zero-gravity space environment. The modeling is focused on a typical radiator panel having a long heat pipe at the center and two extended surfaces attached to opposing sides of the heat pipe shell in the condenser section, whose length may be up to 50 ft. A finite difference formulation has been developed and the transient model can be used to predict normal transient behavior of heat pipe radiators in response to changing thermal loads, environmental conditions, and geometrical parameters. Finally, this research provides better understanding of transient characteristics of heat pipe radiators for space applications. The simulation procedure can be incorporated into large thermal management programs for applications such as the space station. Furthermore, the methodology developed in this research can be utilized in a wide variety of heat pipe designs and their applications.

  2. Effective-medium model of wire metamaterials in the problems of radiative heat transfer

    SciTech Connect

    Mirmoosa, M. S. Nefedov, I. S. Simovski, C. R.; Rüting, F.

    2014-06-21

    In the present work, we check the applicability of the effective medium model (EMM) to the problems of radiative heat transfer (RHT) through so-called wire metamaterials (WMMs)—composites comprising parallel arrays of metal nanowires. It is explained why this problem is so important for the development of prospective thermophotovoltaic (TPV) systems. Previous studies of the applicability of EMM for WMMs were targeted by the imaging applications of WMMs. The analogous study referring to the transfer of radiative heat is a separate problem that deserves extended investigations. We show that WMMs with practically realizable design parameters transmit the radiative heat as effectively homogeneous media. Existing EMM is an adequate tool for qualitative prediction of the magnitude of transferred radiative heat and of its effective frequency band.

  3. Two Experiments for Estimating Free Convection and Radiation Heat Transfer Coefficients

    ERIC Educational Resources Information Center

    Economides, Michael J.; Maloney, J. O.

    1978-01-01

    This article describes two simple undergraduate heat transfer experiments which may reinforce a student's understanding of free convection and radiation. Apparatus, experimental procedure, typical results, and discussion are included. (Author/BB)

  4. MEASUREMENT OF MICROWAVE RADIATION ABSORBED BY BIOLOGICAL SYSTEMS. 1. ANALYSIS OF HEATING AND COOLING DATA

    EPA Science Inventory

    In order for meaningful comparisons to be made between experiments from different laboratories, reliable dosimetry is needed for biological systems exposed to microwave radiation. An improved analytical method is presented for determining energy absorption which uses heating and ...

  5. A detailed evaluation of the stratospheric heat budget: 2. Global radiation balance and diabatic circulations

    NASA Astrophysics Data System (ADS)

    Mlynczak, Martin G.; Mertens, Christopher J.; Garcia, Rolando R.; Portmann, Robert W.

    1999-03-01

    We present a detailed evaluation of radiative heating, radiative cooling, net heating, global radiation balance, radiative relaxation times, and diabatic circulations in the stratosphere using temperature and minor constituent data provided by instruments on the Upper Atmosphere Research Satellite (UARS) between 1991 and 1993 and by the limb infrared monitor of the stratosphere (LIMS) instrument which operated on the Nimbus-7 spacecraft in 1978-1979. Included in the calculations are heating due to absorption of solar radiation from ultraviolet through near-infrared wavelengths and radiative cooling due to emission by carbon dioxide, water vapor, and ozone from 0 to 3000 cm-1 (∞ - 3.3 μm). Infrared radiative effects of Pinatubo aerosols are also considered in some detail. In general, we find the stratosphere to be in a state of global mean radiative equilibrium on monthly timescales to within the uncertainty of the satellite-provided measurements. Radiative relaxation times are found to be larger in the lower stratosphere during UARS than LIMS because of the presence of Pinatubo aerosols. The meridional circulations in the upper stratosphere as diagnosed from the calculated fields of net heating are generally stronger in the UARS period than during the LIMS period, while the lower stratosphere meridional circulations are stronger during the LIMS period. A climatology of these calculations is available to the community via a World Wide Web interface described herein.

  6. Impact of cloud radiative heating on East Asian summer monsoon circulation

    SciTech Connect

    Guo, Zhun; Zhou, Tianjun; Wang, Minghuai; Qian, Yun

    2015-07-17

    The impacts of cloud radiative heating on East Asian Summer Monsoon (EASM) over the southeastern China (105°-125°E, 20°-35°N) are explained by using the Community Atmosphere Model version 5 (CAM5). Sensitivity experiments demonstrate that the radiative heating of clouds leads to a positive effect on the local EASM circulation over southeastern China. Without the radiative heating of cloud, the EASM circulation and precipitation would be much weaker than that in the normal condition. The longwave heating of clouds dominates the changes of EASM circulation. The positive effect of clouds on EASM circulation is explained by the thermodynamic energy equation, i.e. the different heating rate between cloud base and cloud top enhances the convective instability over southeastern China, which enhances updraft consequently. The strong updraft would further result in a southward meridional wind above the center of the updraft through Sverdrup vorticity balance.

  7. Impact of cloud radiative heating on East Asian summer monsoon circulation

    DOE PAGESBeta

    Guo, Zhun; Zhou, Tianjun; Wang, Minghuai; Qian, Yun

    2015-07-17

    The impacts of cloud radiative heating on East Asian Summer Monsoon (EASM) over the southeastern China (105°-125°E, 20°-35°N) are explained by using the Community Atmosphere Model version 5 (CAM5). Sensitivity experiments demonstrate that the radiative heating of clouds leads to a positive effect on the local EASM circulation over southeastern China. Without the radiative heating of cloud, the EASM circulation and precipitation would be much weaker than that in the normal condition. The longwave heating of clouds dominates the changes of EASM circulation. The positive effect of clouds on EASM circulation is explained by the thermodynamic energy equation, i.e. themore » different heating rate between cloud base and cloud top enhances the convective instability over southeastern China, which enhances updraft consequently. The strong updraft would further result in a southward meridional wind above the center of the updraft through Sverdrup vorticity balance.« less

  8. Nanoscale radiative heat flow due to surface plasmons in graphene and doped silicon.

    PubMed

    van Zwol, P J; Thiele, S; Berger, C; de Heer, W A; Chevrier, J

    2012-12-28

    Owing to its two-dimensional electronic structure, graphene exhibits many unique properties. One of them is a wave vector and temperature dependent plasmon in the infrared range. Theory predicts that due to these plasmons, graphene can be used as a universal material to enhance nanoscale radiative heat exchange for any dielectric substrate. Here we report on radiative heat transfer experiments between SiC and a SiO2 sphere that have nonmatching phonon polariton frequencies, and thus only weakly exchange heat in near field. We observed that the heat flux contribution of graphene epitaxially grown on SiC dominates at short distances. The influence of plasmons on radiative heat transfer is further supported with measurements for doped silicon. These results highlight graphene's strong potential in photonic near field and energy conversion devices. PMID:23368565

  9. Design and demonstration of a high-temperature, deployable, membrane heat-pipe radiator element

    SciTech Connect

    Trujillo, V.L.; Keddy, E.S.; Merrigan, M.A.

    1989-01-01

    Demonstration of a high-temperature, deployable, membrane heat-pipe radiator element has been conducted. Membrane heat pipes offer the potential for compact storage, ease of transportation, self-deployment, and a high specific radiator performance (kg/kW) for use in thermal reflection systems of space nuclear power plants. A demonstration heat pipe 8-cm wide and 100-cm long was fabricated. The heat pipe containment and wick structure were made of stainless steel and sodium used as the working fluid. The tests demonstrated passive deployment of the high-temperature membrane radiator, simulating a single segment in a flat array, at a temperature of 800 K. Details of test procedures and results of the tests are presented in this paper together with a discussion of the design and development of a full-scale, segmented high-temperature, deployable membrane heat pipe. 5 refs., 7 figs.

  10. Laminar and turbulent flow solutions with radiation and ablation injection for Jovian entry. [radiative heating rates for the Galileo probe

    NASA Technical Reports Server (NTRS)

    Kumar, A.; Tiwari, S. N.

    1980-01-01

    Laminar and turbulent flow-field solutions with coupled carbon-phenolic mass injection are presented for the forebody of a probe entering a nominal Jupiter atmosphere. Solutions are obtained for a 35-degree hyperboloid and for a 45-degree spherically blunted cone using a time-dependent, finite-difference method. The radiative heating rates for the coupled laminar flow are significantly reduced as compared to the corresponding no-blowing case; however, for the coupled turbulent flow, it is found that the surface radiative heating rates are substantially increased and often exceed the corresponding no-blowing values. Turbulence is found to have no effect on the surface radiative heating rates for the no-blowing solutions. The present results are compared with the other available solutions, and some additional solutions are presented.

  11. Wavelets in the solution of nongray radiative heat transfer equation

    SciTech Connect

    Bayazitoglu, Y.; Wang, B.Y.

    1996-12-31

    The wavelet basis functions are introduced into the radiative transfer equation in the frequency domain. The intensity of radiation is expanded in terms of Daubechies` wrapped around wavelet functions. It is shown that the wavelet basis approach to modeling nongrayness can be incorporated into any solution method for the equation of transfer. In this paper the resulting system of equations is solved for the one-dimensional radiative equilibrium problem using the P-N approximation.

  12. Cloud properties and associated radiative heating rates in the tropical western Pacific

    SciTech Connect

    Mather, Jim H.; McFarlane, Sally A.; Miller, Mark A.; Johnson, Karen L.

    2007-03-01

    Radiative heating of the atmosphere affects cloud evolution on the cloud scale and it influences large-scale vertical motion. Obtaining good estimates of radiative heating rate profiles has been difficult due to a lack of cloud profile observations. The Atmospheric Radiation Measurement (ARM) program has been measuring cloud property distributions at sites around the globe including three in the tropical western Pacific (TWP) region. We have analyzed a month of these remote sensing observations at Manus and Nauru to calculate time series of vertical cloud property profiles and radiative heating rates. This data set will be an important tool for describing radiative processes in the tropics and assessing the simulation of these processes in dynamical models.

  13. Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1982-01-01

    The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiative heating of probes entering the hydrogen-helium atmosphere of the major plants was investigated. Two opposing conclusions were reached as to how the ionization rate assumption affects the radiative transfer. Hydrogen-helium shock waves with a cold nonblowing wall boundary condition at the probe heat shield are emphasized. The study is limited to the stagnation shock layer.

  14. Heat flux splitter for near-field thermal radiation

    SciTech Connect

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

    2015-08-03

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

  15. Moisture Diffusivity Characteristics of Rough Rice Under Infrared Radiation Heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To design an efficient infrared (IR) dryer for rough rice, it is important to understand the drying behavior of rice grains under infrared heating. The objective of this study was to determine the moisture diffusivity and moisture diffusivity coefficient of rough rice under IR heating and cooling. ...

  16. Monte Carlo prediction of radiative heat transfer in inhomogeneous, anisotropic, nongray media

    NASA Technical Reports Server (NTRS)

    Farmer, Jeff T.; Howell, John R.

    1994-01-01

    A Monte Carlo solution technique has been formulated to predict the radiative heat transfer in three-dimensional, inhomogeneous participating media which exhibit spectrally dependent emission and absorption and anisotropic scattering. Details of the technique and selected numerical sensitivities are discussed. The technique was applied to a problem involving a medium composed of a gas mixture of carbon dioxide and nitrogen and suspended carbon particles. A homogeneous medium was modeled to examine the effect of total pressure and carbon-particle concentration on radiative heat transfer. Variation in total pressure, over the range studied, had minimal effect on the amount of heat radiated to the enclosure walls and on the radiative-flux distribution within the medium. Increases in the carbon particle concentration produced significantly higher heat fluxes at the boundaries and altered the radiative flux distribution. The technique was then applied to an inhomogeneous medium to examine effects of specific temperature and carbon particle concentration distributions on radiative heat transfer. For the inhomogeneous conditions examined, the largest radiative flux divergence occurs near the center of the medium and the regions near some enclosure walls act as energy sinks.

  17. Design considerations for a thermophotovoltaic energy converter using heat pipe radiators

    SciTech Connect

    Ashcroft, J.; DePoy, D.

    1997-06-01

    The purpose of this paper is to discuss concepts for using high temperature heat pipes to transport energy from a heat source to a thermophotovoltaic (TPV) converter. Within the converter, the condenser portion of each heat pipe acts as a photon radiator, providing a radiant flux to adjacent TPV cells, which in turn create electricity. Using heat pipes in this way could help to increase the power output and the power density of TPV systems. TPV systems with radiator temperatures in the range of 1,500 K are expected to produce as much as 3.6 W/cm{sup 3} of heat exchanger volume at an efficiency of 20% or greater. Four different arrangements of heat pipe-TPV energy converters are considered. Performance and sizing calculations for each of the concepts are presented. Finally, concerns with this concept and issues which remain to be considered are discussed.

  18. Numerical Investigation of Radiative Heat Transfer in Laser Induced Air Plasmas

    NASA Technical Reports Server (NTRS)

    Liu, J.; Chen, Y. S.; Wang, T. S.; Turner, James E. (Technical Monitor)

    2001-01-01

    Radiative heat transfer is one of the most important phenomena in the laser induced plasmas. This study is intended to develop accurate and efficient methods for predicting laser radiation absorption and plasma radiative heat transfer, and investigate the plasma radiation effects in laser propelled vehicles. To model laser radiation absorption, a ray tracing method along with the Beer's law is adopted. To solve the radiative transfer equation in the air plasmas, the discrete transfer method (DTM) is selected and explained. The air plasma radiative properties are predicted by the LORAN code. To validate the present nonequilibrium radiation model, several benchmark problems are examined and the present results are found to match the available solutions. To investigate the effects of plasma radiation in laser propelled vehicles, the present radiation code is coupled into a plasma aerodynamics code and a selected problem is considered. Comparisons of results at different cases show that plasma radiation plays a role of cooling plasma and it lowers the plasma temperature by about 10%. This change in temperature also results in a reduction of the coupling coefficient by about 10-20%. The present study indicates that plasma radiation modeling is very important for accurate modeling of aerodynamics in a laser propelled vehicle.

  19. Radiation from Large Gas Volumes and Heat Exchange in Steam Boiler Furnaces

    SciTech Connect

    Makarov, A. N.

    2015-09-15

    Radiation from large cylindrical gas volumes is studied as a means of simulating the flare in steam boiler furnaces. Calculations of heat exchange in a furnace by the zonal method and by simulation of the flare with cylindrical gas volumes are described. The latter method is more accurate and yields more reliable information on heat transfer processes taking place in furnaces.

  20. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., including microwave frequencies. 179.30 Section 179.30 Food and Drugs FOOD AND DRUG ADMINISTRATION... for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be safely used for heating food under the following conditions: (a) The...

  1. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., including microwave frequencies. 179.30 Section 179.30 Food and Drugs FOOD AND DRUG ADMINISTRATION... for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be safely used for heating food under the following conditions: (a) The...

  2. Study of Banana Dehydration using Sequential Infrared Radiation Heating and Freeze-Drying

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The drying and quality characteristics of banana slices processed with a sequential infrared radiation and freeze drying (SIRFD) method were investigated. Cavendish banana slices with 5 mm thickness were predehydrated using IR heating at each one of three radiation intensities, 3000, 4000, and 5000...

  3. Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1981-01-01

    The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiation heating of probes entering the hydrogen helium atmospere of the major planets was investigated. At the present time, there is disagreement as to whether the radiative flux increases or decreases relative to its equilibrium value when finite rate ionization is considered. Leibowitz and Kuo content that the finite rate ionization in the hydrogen gas just behind the shock wave reduces the radiative flux to the probe, whereas Tiwari and Szema predict that it increases the radiative flux. The radiation modeling used in the calculations of both pairs of these investigators was reviewed. It is concluded that finite rate ionization in the inviscid region of the shock layer should reduce the cold wall radiative heating below the values predicted by equilibrium chemistry assumptions.

  4. Radiation and gas conduction heat transport across a helium dewer multilayer insulation system

    SciTech Connect

    Green, M.A.

    1995-02-01

    This report describes a method for calculating mixed heat transfer through the multilayer insulation used to insulated a 4K liquid helium cryostat. The method described permits one to estimate the insulation potential for a multilayer insulation system from first principles. The heat transfer regimes included are: radiation, conduction by free molecule gas conduction, and conduction through continuum gas conduction. Heat transfer in the transition region between the two gas conduction regimes is also included.

  5. Radiation Heat Transfer in 3 Dimensions for Semi-Transparent Materials....

    Energy Science and Technology Software Center (ESTSC)

    2010-12-02

    The RAD3D software solves the critical heat transfer mechanisms that occur in production glass furnaces. The code includes state-of-the-art solution algorithms for efficient radiant interaction of the heating elements, furnace walls and internal furnace components. The code specifically solves the coupled radiative and conductive heating of semi-transparent materials such as glass to calculate the temperature distribution in the glass during processing.

  6. Sandwich Core Heat-Pipe Radiator for Power and Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gibson, Marc; Sanzi, James; Locci, Ivan

    2013-01-01

    Next-generation heat-pipe radiator technologies are being developed at the NASA Glenn Research Center to provide advancements in heat-rejection systems for space power and propulsion systems. All spacecraft power and propulsion systems require their waste heat to be rejected to space in order to function at their desired design conditions. The thermal efficiency of these heat-rejection systems, balanced with structural requirements, directly affect the total mass of the system. Terrestrially, this technology could be used for thermal control of structural systems. One potential use is radiant heating systems for residential and commercial applications. The thin cross section and efficient heat transportability could easily be applied to flooring and wall structures that could evenly heat large surface areas. Using this heat-pipe technology, the evaporator of the radiators could be heated using any household heat source (electric, gas, etc.), which would vaporize the internal working fluid and carry the heat to the condenser sections (walls and/or floors). The temperature could be easily controlled, providing a comfortable and affordable living environment. Investigating the appropriate materials and working fluids is needed to determine this application's potential success and usage.

  7. Thermal radiation of laser heated niobium clusters Nb(+)(N), 8 ⩽ N ⩽ 22.

    PubMed

    Hansen, Klavs; Li, Yejun; Kaydashev, Vladimir; Janssens, Ewald

    2014-07-14

    The thermal radiation from small, laser heated, positively charged niobium clusters has been measured. The emitted power was determined by the quenching effect on the metastable decay, employing two different experimental protocols. The radiative power decreases slightly with cluster size and shows no strong size-to-size variations. The magnitude is 40-50 keV/s at the timescale of several microseconds, which is the measured crossover time from evaporative to radiative cooling. PMID:25028014

  8. Latest Development of Infrared Radiation Heating for Food Processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infrared (IR) heating could be an alternative technology for thermal and dehydration processing of food and agricultural products with many advantages, including high process and energy efficiencies, high product quality, improved food safety and reduced environmental pollution. This paper reviews ...

  9. Radiator Heat Pipes with Carbon-Carbon Fins and Armor for Space Nuclear Reactor Power Systems

    SciTech Connect

    Tournier, Jean-Michel; El-Genk, Mohamed

    2005-02-06

    Technologies for Space Reactor Power Systems are being developed to enable future NASA's missions early next decade to explore the farthest planets in the solar system. The choices of the energy conversion technology for these power systems require radiator temperatures that span a wide range, from 350 K to 800 K. Heat pipes with carbon-carbon fins and armor are the preferred choice for these radiators because of inherent redundancy and efficient spreading and rejection of waste heat into space at a relatively small mass penalty. The performance results and specific masses of radiator heat pipes with cesium, rubidium, and potassium working fluids are presented and compared in this paper. The heat pipes operate at 40% of the prevailing operation limit (a design margin of 60%), typically the sonic and/or capillary limit. The thickness of the carbon-carbon fins is 0.5 mm but the width is varied, and the evaporator and condenser sections are 0.15 and 1.35 m long, respectively. The 400-mesh wick and the heat pipe thin metal wall are titanium, and the carbon-carbon armor ({approx} 2 mm-thick) provides both structural strength and protection against meteoroids impacts. The cross-section area of the D-shaped radiator heat pipes is optimized for minimum mass. Because of the low vapor pressure of potassium and its very high Figure-Of-Merit (FOM), radiator potassium heat pipes are the best performers at temperatures above 800 K, where the sonic limit is no longer an issue. On the other hand, rubidium heat pipes are limited by the sonic limit below 762 K and by the capillary limit at higher temperature. The transition temperature between these two limits for the cesium heat pipes occurs at a lower temperature of 724 K, since cesium has lower FOM than rubidium. The present results show that with a design margin of 60%, the cesium heat pipes radiator is best at 680-720 K, the rubidium heat pipes radiator is best at 720-800 K, while the potassium heat pipes radiator is the best

  10. Comparison of Methods for Calculating Radiative Heat Transfer

    SciTech Connect

    Schock, Alfred; Abbate, M J

    2012-01-19

    Various approximations for calculating radioactive heat transfer between parallel surfaces are evaluated. This is done by applying the approximations based on total emissivities to a special case of known spectral emissivities, for which exact heat transfer calculations are possible. Comparison of results indicates that the best approximation is obtained by basing the emissivity of the receiving surface primarily on the temperature of the emitter. A specific model is shown to give excellent agreement over a very wide range of values.

  11. The radiated noise from isotropic turbulence and heated jets

    NASA Technical Reports Server (NTRS)

    Lilley, G. M.

    1995-01-01

    prevented the full deployment of Lighthill's theory from being achieved. However, the growth of the supercomputer and its applications in the study of the structure of turbulent shear flows in both unbounded and wall bounded flows, which complements and in certain cases extends the work of the few dedicated experimental groups working in this field for the past forty years, provides an opportunity and challenge to accurately predict the noise from jets. Moreover a combination of numerical and laboratory experiments offers the hope that in the not too distant future the physics of noise generation and flow interaction will be better understood and it will then be possible to not only improve the accuracy of noise prediction but also to explore and optimize schemes for noise reduction. The present challenge is to provide time and space accurate numerical databases for heated subsonic and supersonic jets to provide information on the fourth-order space-time covariance of Lighthill's equivalent stress tensor, T(ij), which governs the characteristics of the farfield radiated noise and the total acoustic power. Validation with available experimental databases will establish how close Lighthill's theory is to the accurate prediction of the directivity and spectrum of jet noise and the total acoustic power, and the need, in the applications of the theory, to include the effects of flow-acoustic interaction.

  12. Radiative Peristaltic Flow of Jeffrey Nanofluid with Slip Conditions and Joule Heating

    PubMed Central

    Hayat, Tasawar; Shafique, Maryam; Tanveer, Anum; Alsaedi, Ahmed

    2016-01-01

    Mixed convection peristaltic flow of Jeffrey nanofluid in a channel with compliant walls is addressed here. The present investigation includes the viscous dissipation, thermal radiation and Joule heating. Whole analysis is performed for velocity, thermal and concentration slip conditions. Related problems through long wavelength and low Reynolds number are examined for stream function, temperature and concentration. Impacts of thermal radiation, Hartman number, Brownian motion parameter, thermophoresis, Joule heating and slip parameters are explored in detail. Clearly temperature is a decreasing function of Hartman number and radiation parameter. PMID:26886919

  13. Radiative Peristaltic Flow of Jeffrey Nanofluid with Slip Conditions and Joule Heating.

    PubMed

    Hayat, Tasawar; Shafique, Maryam; Tanveer, Anum; Alsaedi, Ahmed

    2016-01-01

    Mixed convection peristaltic flow of Jeffrey nanofluid in a channel with compliant walls is addressed here. The present investigation includes the viscous dissipation, thermal radiation and Joule heating. Whole analysis is performed for velocity, thermal and concentration slip conditions. Related problems through long wavelength and low Reynolds number are examined for stream function, temperature and concentration. Impacts of thermal radiation, Hartman number, Brownian motion parameter, thermophoresis, Joule heating and slip parameters are explored in detail. Clearly temperature is a decreasing function of Hartman number and radiation parameter. PMID:26886919

  14. Flame radiation and liner heat transfer in a tubular-can combustor

    NASA Technical Reports Server (NTRS)

    Claus, R. W.; Neely, G. M.; Humenik, F. M.

    1983-01-01

    Heat transfer within a combuster were examined. Total and spectral flame radiation in a tubular can combustor at a series of parametric operating conditions was measured. Radiation measurements were taken for a range of inlet air pressures from 0.34 to 2.0 MPa, inlet air temperatures from 533 to 700 K, with two different fuels, Jet-A and ERBS. Measurements of liner temperatures combined with the parametric radiation results allowed a calculation of the combustor liner heat loads. Flame emissivity was determined from the spectral measurements.

  15. Radiation temperature measurements in laser-heated hohlraums

    SciTech Connect

    Cobble, J.A.; Goldman, S.R.; Bessarab, A.V.; Kunin, A.V.; Tokarev, V.A.

    1997-11-01

    Two x-ray spectrographs have been used on the Trident laser at LANL to monitor the radiation temperature of small Au hohlraums. The cylindrical targets are smaller than 1 mm. The x radiation produced by {approximately} 400 J of 0.53-{micro}m laser light is detected with a 7-channel VNIIEF soft-x-ray spectrometer. Each channel employs a multi-layer mirror and a filter to limit the channel bandwidth to 1--3% of the channel energy. X rays are detected with calibrated Al x-ray diodes. A second spectrometer is based on a free-standing Au transmission grating for spectral dispersion and a multi-channel diamond photo-conductive device detector. The small hohlraum results are consistent with radiation temperatures exceeding 100 eV. Simple computer modeling shows that late in the plasma discharge, radiation of this temperature is emitted from the target.

  16. Preliminary Convective-Radiative Heating Environments for a Neptune Aerocapture Mission

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.; Wright, Michael J.; Olejniczak, Joseph; Takashima, Naruhisa; Sutton, Kenneth; Prabhu, Dinesh

    2004-01-01

    Convective and radiative heating environments have been computed for a three-dimensional ellipsled configuration which would perform an aerocapture maneuver at Neptune. This work was performed as part of a one-year Neptune aerocapture spacecraft systems study that also included analyses of trajectories, atmospheric modeling, aerodynamics, structural design, and other disciplines. Complementary heating analyses were conducted by separate teams using independent sets of aerothermodynamic modeling tools (i.e. Navier-Stokes and radiation transport codes). Environments were generated for a large 5.50 m length ellipsled and a small 2.88 m length ellipsled. Radiative heating was found to contribute up to 80% of the total heating rate at the ellipsled nose depending on the trajectory point. Good agreement between convective heating predictions from the two Navier-Stokes solvers was obtained. However, the radiation analysis revealed several uncertainties in the computational models employed in both sets of codes, as well as large differences between the predicted radiative heating rates.

  17. Radiation Heat Transfer Between Diffuse-Gray Surfaces Using Higher Order Finite Elements

    NASA Technical Reports Server (NTRS)

    Gould, Dana C.

    2000-01-01

    This paper presents recent work on developing methods for analyzing radiation heat transfer between diffuse-gray surfaces using p-version finite elements. The work was motivated by a thermal analysis of a High Speed Civil Transport (HSCT) wing structure which showed the importance of radiation heat transfer throughout the structure. The analysis also showed that refining the finite element mesh to accurately capture the temperature distribution on the internal structure led to very large meshes with unacceptably long execution times. Traditional methods for calculating surface-to-surface radiation are based on assumptions that are not appropriate for p-version finite elements. Two methods for determining internal radiation heat transfer are developed for one and two-dimensional p-version finite elements. In the first method, higher-order elements are divided into a number of sub-elements. Traditional methods are used to determine radiation heat flux along each sub-element and then mapped back to the parent element. In the second method, the radiation heat transfer equations are numerically integrated over the higher-order element. Comparisons with analytical solutions show that the integration scheme is generally more accurate than the sub-element method. Comparison to results from traditional finite elements shows that significant reduction in the number of elements in the mesh is possible using higher-order (p-version) finite elements.

  18. Radiative Heating Profiles in the Convective Tropics: A Comparison of Observations and Models

    SciTech Connect

    McFarlane, Sally A.; Mather, Jim H.; Ackerman, Thomas P.

    2005-01-10

    Radiative heating is one of the principal drivers of tropical circulation. While we have good knowledge of radiative fluxes at the top-of-atmosphere and at specific surface sites, observations of atmospheric profiles of radiative heating, particular in cloudy conditions, have been largely unavailable. The Atmospheric Radiation Measurement (ARM) Program has begun a program to compute radiative heating profiles routinely at its observational sites at Nauru and Manus Island, Papua New Guinea, using observed and retrieved inputs of water vapor and condensed water phase, particle size, and mass. The accuracy of these profiles can be assessed by comparing the calculated TOA and surface fluxes with observations. We have computed radiative heating profiles every 20 minutes for several months at each of these two sites in the 1999-2000 time period, which represent a unique dataset for model comparison. Here, we compare this dataset to model output from the European Center for Medium-Range Weather Forecasting (ECMWF) analysis, the NCAR Community Atmosphere Model (CAM 3.0) and the Multi-Scale Modeling Framework (MMF). These three models, all run using observed SST for this comparison, provide an interesting range of resolution from the 4 km cloud resolving model in the MMF to the approximately 280 km grid-scale of the CAM and a contrast between forecasting and climate models. In general, the model results fail to capture the structure of the observed heating in the upper troposphere because of their failure to simulate cirrus and stratiform cloud adequately.

  19. Single-node orbit analsyis with radiation heat transfer only

    NASA Technical Reports Server (NTRS)

    Peoples, J. A.

    1977-01-01

    The steady-state temperature of a single node which dissipates energy by radiation only is discussed for a nontime varying thermal environment. Relationships are developed to illustrate how shields can be utilized to represent a louver system. A computer program is presented which can assess periodic temperature characteristics of a single node in a time varying thermal environment having energy dissipation by radiation only. The computer program performs thermal orbital analysis for five combinations of plate, shields, and louvers.

  20. Method for heat treating and sintering metal oxides with microwave radiation

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.; Meek, Thomas T.

    1989-01-01

    A method for microwave sintering materials, primarily metal oxides, is described. Metal oxides do not normally absorb microwave radiation at temperatures ranging from about room temperature to several hundred degrees centrigrade are sintered with microwave radiation without the use of the heretofore required sintering aids. This sintering is achieved by enclosing a compact of the oxide material in a housing or capsule formed of a oxide which has microwave coupling properties at room temprature up to at least the microwave coupling temperature of the oxide material forming the compact. The heating of the housing effects the initial heating of the oxide material forming the compact by heat transference and then functions as a thermal insulator for the encased oxide material after the oxide material reaches a sufficient temperature to adequately absorb or couple with microwave radiation for heating thereof to sintering temperature.

  1. Comparison of measured and modeled radiation, heat and water vapor fluxes: FIFE pilot study

    NASA Technical Reports Server (NTRS)

    Blad, Blaine L.; Hubbard, Kenneth G.; Verma, Shashi B.; Starks, Patrick; Norman, John M.; Walter-Shea, Elizabeth

    1987-01-01

    The feasibility of using radio frequency receivers to collect data from automated weather stations to model fluxes of latent heat, sensible heat, and radiation using routine weather data collected by automated weather stations was tested and the estimated fluxes were compared with fluxes measured over wheat. The model Cupid was used to model the fluxes. Two or more automated weather stations, interrogated by radio frequency and other means, were utilized to examine some of the climatic variability of the First ISLSCP (International Satellite Land-Surface Climatology Project) Field Experiment (FIFE) site, to measure and model reflected and emitted radiation streams from various locations at the site and to compare modeled latent and sensible heat fluxes with measured values. Some bidirectional reflected and emitted radiation data were collected from 23 locations throughout the FIFE site. Analysis of these data along with analysis of the measured sensible and latent heat fluxes is just beginning.

  2. Experimental investigation of panel radiator heat output enhancement for efficient thermal use under actual operating conditions

    NASA Astrophysics Data System (ADS)

    Calisir, Tamer; Baskaya, Senol; Onur Yazar, Hakan; Yucedag, Sinan

    2015-05-01

    In this study the heat output of a panel-convector-convector-panel radiator (PCCP) under controlled laboratory conditions under Turkish household and especially Ankara conditions was investigated experimentally. In this sense, investigations were performed for different heating water mass flow rates, water inlet temperatures and radiator inlet and outlet connection positions, which are most commonly used in Turkey. An experimental setup was built for this purpose in a test room where temperature was controlled and held constant during the experiments. Inlet and outlet water temperatures and mass flow rates were measured and heat output of the radiator was calculated. Infrared thermal camera visualizations of the steel panel radiator front surface were also performed.

  3. Numerical identification of boundary conditions on nonlinearly radiating inverse heat conduction problems

    NASA Technical Reports Server (NTRS)

    Murio, Diego A.

    1991-01-01

    An explicit and unconditionally stable finite difference method for the solution of the transient inverse heat conduction problem in a semi-infinite or finite slab mediums subject to nonlinear radiation boundary conditions is presented. After measuring two interior temperature histories, the mollification method is used to determine the surface transient heat source if the energy radiation law is known. Alternatively, if the active surface is heated by a source at a rate proportional to a given function, the nonlinear surface radiation law is then recovered as a function of the interface temperature when the problem is feasible. Two typical examples corresponding to Newton cooling law and Stefan-Boltzmann radiation law respectively are illustrated. In all cases, the method predicts the surface conditions with an accuracy suitable for many practical purposes.

  4. Comparison of vibration dissociation coupling and radiative heat transfer models for AOTV/AFE flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.; Bobskill, Glenn J.; Greendyke, Robert B.

    1988-01-01

    A series of detailed studies comparing various vibration dissociation coupling models, reaction systems and rates, and radiative heating models has been conducted for the nonequilibrium stagnation region of an AFE/AOTV vehicle. Atomic and molecular nonequilibrium radiation correction factors have been developed and applied to various absorption coefficient step models, and a modified vibration dissociation coupling model has been shown to yield good vibration/electronic temperature and concentration profiles. While results indicate sensitivity to the choice of vibration dissociation coupling model and to the nitrogen electron impact ionization rate, by proper combinations accurate flowfield and radiative heating results can be obtained. These results indicate that nonequilibrium effects significantly affect the flowfield and the radiative heat transfer. However, additional work is needed in ionization chemistry and absorption coefficient modeling.

  5. Liquid metal micro heat pipes for space radiator applications

    NASA Technical Reports Server (NTRS)

    Gerner, F. M.; Henderson, H. T.

    1995-01-01

    Micromachining is a chemical means of etching three-dimensional structures, typically in single-crystalline silicon. These techniques are leading toward what is coming to be referred to as MEMS (micro electro mechanical systems), where in addition to the ordinary two dimensional (planar) microelectronics, it is possible to build three-dimensional micromotors, electrically-actuated microvalves, hydraulic systems, and much more on the same microchip. These techniques become possible because of differential etching rates of various crystallographic planes and materials used for semiconductor microfabrication. The University of Cincinnati group in collaboration with NASA Lewis formed micro heat pipes in silicon by the above techniques. Work is ongoing at a modest level, but several essential bonding and packaging techniques have been recently developed. Currently, we have constructed and filled water/silicon micro heat pipes. Preliminary thermal tests of arrays of 125 micro heat pipes etched in a 1 inch x 1 inch x 250 micron silicon wafer have been completed. These pipes are instrumented with extremely small P-N junctions to measure their effective conductivity and their maximum operating power. A relatively simple one-dimensional model has been developed in order to predict micro heat pipes' operating characteristics. This information can be used to optimize micro heat pipe design with respect to length, hydraulic diameter, and number of pipes. Work is progressing on the fabrication of liquid-metal micro heat pipes. In order to be compatible with liquid metal (sodium or potassium), the inside of the micro heat pipes will be coated with a refractory metal (such as tungsten, molybdenum, or titanium).

  6. Comparison of DSMC and CFD Solutions of Fire II Including Radiative Heating

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Johnston, Christopher O.; Lewis, Mark J.

    2011-01-01

    The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. These flows may also contain significant radiative heating. To prepare for these missions, NASA is developing the capability to simulate rarefied, ionized flows and to then calculate the resulting radiative heating to the vehicle's surface. In this study, the DSMC codes DAC and DS2V are used to obtain charge-neutral ionization solutions. NASA s direct simulation Monte Carlo code DAC is currently being updated to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced Quantum-Kinetic chemistry model, and to include electronic energy levels as an additional internal energy mode. The Fire II flight test is used in this study to assess these new capabilities. The 1634 second data point was chosen for comparisons to be made in order to include comparisons to computational fluid dynamics solutions. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid. It is shown that there can be quite a bit of variability in the vibrational temperature inferred from DSMC solutions and that, from how radiative heating is computed, the electronic temperature is much better suited for radiative calculations. To include the radiative portion of heating, the flow-field solutions are post-processed by the non-equilibrium radiation code HARA. Acceptable agreement between CFD and DSMC flow field solutions is demonstrated and the progress of the updates to DAC, along with an appropriate radiative heating solution, are discussed. In addition, future plans to generate more high fidelity radiative heat transfer solutions are discussed.

  7. Measurement of heat pump processes induced by laser radiation

    NASA Technical Reports Server (NTRS)

    Garbuny, M.; Henningsen, T.

    1983-01-01

    A series of experiments was performed in which a suitably tuned CO2 laser, frequency doubled by a Tl3AsSe37 crystal, was brought into resonance with a P-line or two R-lines in the fundamental vibration spectrum of CO. Cooling or heating produced by absorption in CO was measured in a gas-thermometer arrangement. P-line cooling and R-line heating could be demonstrated, measured, and compared. The experiments were continued with CO mixed with N2 added in partial pressures from 9 to 200 Torr. It was found that an efficient collisional resonance energy transfer from CO to N2 existed which increased the cooling effects by one to two orders of magnitude over those in pure CO. Temperature reductions in the order of tens of degrees Kelvin were obtained by a single pulse in the core of the irradiated volume. These measurements followed predicted values rather closely, and it is expected that increase of pulse energies and durations will enhance the heat pump effects. The experiments confirm the feasibility of quasi-isentropic engines which convert laser power into work without the need for heat rejection. Of more immediate potential interest is the possibility of remotely powered heat pumps for cryogenic use, such applications are discussed to the extent possible at the present stage.

  8. Dynamic instabilities in radiation-heated boiler tubes for solar central receivers

    NASA Astrophysics Data System (ADS)

    Wolf, S.; Chan, K. C.; Chen, K.; Yadigaroglu, G.

    1982-11-01

    Density-wave instabilities have been investigated in circumferentially nonuniform radiation-heated boiler tubes, simulating solar heating. Analysis and experimental data are presented. The analysis provides the basis for a computer code, STEAMFREQ-I, for the prediction of density-wave instabilities in boiler tubes with imposed heat flux. The key model features include a drift-flux flow model in the boiling region, spatial variation of heat flux, wall dynamics, and variable steam properties in the superheat region. The experimental data include results from two radiation heated boiler panel tests. The data are applicable to central receivers for solar electric power plants. Data for stable and unstable conditions are compared with predictions from STEAMFREQ-I.

  9. Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger with Bypass Setpoint Temperature Control

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.

    2008-01-01

    Spacecraft radiators are sized for their maximum heat load in their warmest thermal environment, but must operate at reduced heat loads and in colder environments. For systems where the radiator environment can be colder than the working fluid freezing temperature, radiator freezing becomes an issue. Radiator freezing has not been a major issue for the Space Shuttle and the International Space Station (ISS) active thermal control systems (ATCSs) because they operate in environments that are warm relative to the freezing point of their external coolants (Freon-21 and ammonia, respectively). For a vehicle that lands at the Lunar South Pole, the design thermal environment is 215K, but the radiator working fluid must also be kept from freezing during the 0 K sink of transit. A radiator bypass flow control design such as those used on the Space Shuttle and ISS requires more than 30% of the design heat load to avoid radiator freezing during transit - even with a very low freezing point working fluid. By changing the traditional ATCS architecture to include a regenerating heat exchanger inboard of the radiator and by using a regenerator bypass flow control valve to maintain system setpoint, the required minimum heat load can be reduced by more than half. This gives the spacecraft much more flexibility in design and operation. The present work describes the regenerator bypass ATCS setpoint control methodology. It includes analytical results comparing the performance of this system to the traditional radiator bypass system. Finally, a summary of the advantages of the regenerator bypass system are presented.

  10. The role of atomic lines in radiation heating of the experimental space vehicle Fire-II

    NASA Astrophysics Data System (ADS)

    Surzhikov, S. T.

    2015-10-01

    The results of calculating the convective and radiation heating of the Fire-II experimental space vehicle allowing for atomic lines of atoms and ions using the NERAT-ASTEROID computer platform are presented. This computer platform is intended to solve the complete set of equations of radiation gas dynamics of viscous, heat-conductive, and physically and chemically nonequilibrium gas, as well as radiation transfer. The spectral optical properties of high temperature gases are calculated using ab initio quasi-classical and quantum-mechanical methods. The calculation of the transfer of selective thermal radiation is performed using a line-by-line method using specially generated computational grids over the radiation wavelengths, which make it possible to attain a noticeable economy of computational resources.