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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Design, analysis, and tests of a shuttle-type heat-pipe-cooled leading edge

A one-half scale heat-pipe-cooled leading edge model was designed and fabricated to verify feasibility and performance of a full-scale Phase B shuttle orbiter design. Model performance was investigated experimentally by radiant heating and aerothermal tests and analytically by using a simple technique which predicts heat pipe start-up from the frozen state and also predicts transient and steady-state thermal behavior. Analytical results agree well with experimental results for start-up and steady-state heat pipe operation. The results indicate that variations in angle of attack and roll orientation had a negligible effect on heat pipe performance. The heat pipes effectively isothermalized the leading edge, and reduced peak temperatures to levels compatible with the use temperatures of superalloys. Results of these tests demonstrated the durability of the heat-pipe-cooled leading edge in withstanding earth-entry thermal and mechanical loads and indicate that the use of heat pipes in leading edge structures is a reliable concept for fully reusable hypersonic cruise and space transportation systems.

Camarda, C. J.↗
NASA NTRS1981

Assessment of solar-assisted gas-fired heat pump systems

As a possible application for the Goldstone Energy Project, the performance of a 10 ton heat pump unit using a hybrid solar gas energy source was evaluated in an effort to optimize the solar collector size. The heat pump system is designed to provide all the cooling and/or heating requirements of a selected office building. The system performance is to be augmented in the heating mode by utilizing the waste heat from the power cycle. A simplified system analysis is described to assess and compute interrrelationships of the engine, heat pump, and solar and building performance parameters, and to optimize the solar concentrator/building area ratio for a minimum total system cost. In addition, four alternative heating cooling systems, commonly used for building comfort, are described; their costs are compared, and are found to be less competitive with the gas solar heat pump system at the projected solar equipment costs.

Lansing, F. L.↗
NASA NTRS1980

Performance of entry heat shields on Pioneer Venus probes

The Pioneer Venus probes approached Venus with high relative velocity. As they entered the atmosphere, they were rapidly decelerated by aerodynamic drag, and a great deal of heat was generated. To protect the probe structure and the scientific instruments, a carbon phenolic heat shield was placed on the front of the probes. Because the design of heat shields for planetary entry is a developing technology, thermocouples were placed in the heat shields so that actual and predicted heat shield performance could be compared. The function of the heat shield is discussed, the probe environments during entry into the Venusian atmosphere are described, and some results from the heat shield experiment are presented. It was found that for the most part, the heat shields performed better than expected.

Pitts, W. C.↗
NASA NTRS1948

Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection Against Icing. 1: Unpartitioned Blades

An investigation to determine the effectiveness of icing protection afforded by air-heating hollow steel unpartitioned propeller blades has been conducted In the NACA Cleveland icing research tunnel. The propeller used was a production model modified with blade shank and tip openings to permit internal passage of heated air. Blade-surface and heated-air temperatures were obtained and photographic observations of Ice formations were made with variations In icing intensity and heating rate to the blades. For the conditions of Icing to which the propeller was subjected, it was found that adequate ice protection was afforded with a heating rate of 40 1 000 Btu per hour per blade. With less than 40,000 Btu per hour per blade, ice protection failed because of significant ice accretions on the leading edge. The chordwise distribution of heat was unsatisfactory with most of the available heat dissipated well back of the leading edge on both the thrust and camber face's instead of at the leading edge where it was most needed. A low utilization of available heat for icing protection is indicated by a beat-exchanger effectiveness of approximately 47 percent.

Mulholland, Donald R.↗
NASA NTRS1981

Solar heated fluidized bed gasification system

A solar-powered fluidized bed gasification system for gasifying carbonaceous material is presented. The system includes a solar gasifier which is heated by fluidizing gas and steam. Energy to heat the gas and steam is supplied by a high heat capacity refractory honeycomb which surrounds the fluid bed reactor zone. The high heat capacity refractory honeycomb is heated by solar energy focused on the honeycomb by solar concentrator through solar window. The fluid bed reaction zone is also heated directly and uniformly by thermal contact of the high heat capacity ceramic honeycomb with the walls of the fluidized bed reactor. Provisions are also made for recovering and recycling catalysts used in the gasification process. Back-up furnace is provided for start-up procedures and for supplying heat to the fluid bed reaction zone when adequate supplies of solar energy are not available.

Qader, S. A.↗
NASA NTRS1982

Heat transfer from combustion gases to a single row of closely spaced tubes in a swirl crossflow Stirling engine heater

This paper describes an experimental program to determine the heat-transfer characteristics of a combustor and heat-exchanger system in a hybrid solar receiver which utilizes a Stirling engine. The system consists of a swirl combustor with a crossflow heat exchanger composed of a single row of 48 closely spaced curved tubes. In the present study, heat-transfer characteristics of the combustor/heat-exchanger system without a Stirling engine have been studied over a range of operating conditions and output levels using water as the working fluid. Nondimensional heat-transfer coefficients based on total heat transfer have been obtained and are compared with available literature data. The results show significantly enhanced heat transfer for the present geometry and test conditions. Also, heat transfer along the length of the tubes is found to vary, the effect depending upon test condition.

Bankston, C. P.↗
NASA NTRS1981

Heat pipes containing alkali metal working fluid

A technique for improving high temperature evaporation-condensation heat-transfer devices which have important and unique advantage in terrestrial and space energy processing is described. The device is in the form of a heat pipe comprising a sealed container or envelope which contains a capillary wick. The temperature of one end of the heat pipe is raised by the input of heat from an external heat source which is extremely hot and corrosive. A working fluid of a corrosive alkali metal, such as lithium, sodium, or potassium transfers this heat to a heat receiver remote from the heat source. The container and wick are fabricated from a superalloy containing a small percentage of a corrosion inhibiting or gettering element. Lanthanum, scandium, yttrium, thorium, and hafnium are utilized as the alloying metal.

Morris, J. F.↗
NASA NTRS1983

Thermal control - Heat buses will operate like a public utility

Active thermal control for the NASA space station concept requires long life heat rejection, highly versatile thermal transport, and efficient system integration. By a significant margin, the heat radiator will be the largest and most exposed portion of the space station thermal system. Transport requirements encompass the collection and movement of thermal energy from the space station's heat sources to the radiator heat sink at required temperature levels. In a decentralized thermal system, each space station module would collect and reject all of the waste heat generated, thereby requiring no module interconnections. This scheme does not, however, allow waste heat from one module to be used by another. In a centralized system, heat must be transported across module boundaries. A high capacity monogroove heat pipe has been developed to simplify space radiators design and operation.

Ellis, W. E.↗
NASA NTRS1983

Measurement of thermoacoustic convection heat transfer phenomenon

In this paper the results of an experimental investigation of thermoacoustic convection (TAC) heat transfer phenomenon in both zero-gravity and gravity environment are presented and compared with pure conduction heat transfer. The numerical solutions of the governing equations obtained by others for TAC heat transfer phenomenon are also discussed. The experimental results show that for rapid heating rate at a boundary, the contribution of TAC heat transfer to a gas could be significantly (one order of magnitude) higher than heat transfer rate from pure conduction. The results also show significantly reduced transient time in heat transfer processes involving thermoacoustic convective heat transfer mode in both space and gravity environment.

Parang, M.↗
NASA NTRS1984

Measurement of local connective heat transfer coefficients of four ice accretion shapes

In the analytical study of ice accretions that form on aerodynamic surfaces (airfoils, engine inlets, etc.) it is often necessary to be able to calculate convective heat transfer rates. In order to do this, local convective heat transfer coefficients for the ice accretion shapes must be known. In the past, coefficients obtained for circular cylinders were used as an approximation to the actual coefficients since no better information existed. The purpose of this experimental study was to provide local convective heat transfer coefficients for four shapes that represent ice accretions. The shapes were tested with smooth and rough surfaces. The experimental method chosen was the thin-skin heat rate technique. Using this method local Nusselt numbers were determined for the ice shapes. In general it was found that the convective heat transfer was higher in regions where the model's surfaces were convex and lower in regions where the model's surfaces were concave. The effect of roughness was to increase the heat transfer in the high heat transfer regions by approximately 100% while little change was apparent in the low heat transfer regions.

Smith, M. E.↗
NASA NTRS1985

Plasma heating at collisionless shocks due to the kinetic cross-field streaming instability

Heating at collisionless shocks due to the kinetic cross-field streaming instability, which is the finite beta (ratio of plasma to magnetic pressure) extension of the modified two stream instability, is studied. Heating rates are derived from quasi-linear theory and compared with results from particle simulations to show that electron heating relative to ion heating and heating parallel to the magnetic field relative to perpendicular heating for both the electrons and ions increase with beta. The simulations suggest that electron dynamics determine the saturation level of the instability, which is manifested by the formation of a flattop electron distribution parallel to the magnetic field. As a result, both the saturation levels of the fluctuations and the heating rates decrease sharply with beta. Applications of these results to plasma heating in simulations of shocks and the earth's bow shock are described.

Winske, D.↗
NASA NTRS1985

Analysis of buoyancy effect on fully developed laminar heat transfer in a rotating tube

Laminar heat transfer is analyzed in a tube rotating about an axis perpendicular to the tube axis. The solution applies for flow that is either radially outward from the axis of rotation, or radially inward toward the axis of rotation. The conditions are fully developed, and there is uniform heat addition at the tube wall. The analysis is performed by expanding velocities and temperature in power series using the Taylor number as a perturbation parameter. Coriolis and buoyancy forces caused by tube rotation are included, and the solution is calculated through second-order terms. The secondary flow induced by the Coriolis terms always tends to increase the heat transfer coefficient; this effect can dominate for small wall heating. For radial inflow, buoyancy also tends to improve heat transfer. For radial outflow, however, buoyancy tends to reduce heat transfer; for large wall heating this effect can dominate, and there is a net reduction in heat transfer coefficient.

Siegel, R.↗
NASA NTRS1984

Heat transfer investigation in the junction region of circular cylinder normal to a flat plate at 90 deg location

External heat-transfer rates were measured on a flat plate in the junction region of a circular cylinder mounted normal to the plate at a location 90 deg from the stagnation point. This configuration simulates the junction of the shroud with gas-turbine vanes. Heat-transfer results are presented for laminar, transition, and turbulent boundary layers for a Mach number of 0.14 with gas temperatures of approximately 750 deg R over a flat plate at room temperature. The measurements were made in air for a unit Reynolds number, Re/cm, range of 11,000 to 58,000. Heat-transfer measurements were conducted in the 70-ft long, 4-in. diameter shock tube. A shock-wave reflection technique was used to produce a flow Mach number of 0.14. Thin-film platinum heat gages were mounted on the flat plate and along the line of the stagnation point of the cylinder to measure the local heat flux in the junction region. The experimental heat-transfer data were correlated with the laminar and turbulent boundary-layer theories for the flat plate. With the cylinder the heat fluxes on the flat plate were greatly increased in the junction region compared to the heat flux for the plate alone.

Nagamatsu, H. T.↗
NASA NTRS1985

Methods for heat transfer and temperature field analysis of the insulated diesel phase 2 progress report

This report describes work done during Phase 2 of a 3 year program aimed at developing a comprehensive heat transfer and thermal analysis methodology for design analysis of insulated diesel engines. The overall program addresses all the key heat transfer issues: (1) spatially and time-resolved convective and radiative in-cylinder heat transfer, (2) steady-state conduction in the overall structure, and (3) cyclical and load/speed temperature transients in the engine structure. During Phase 2, radiation heat transfer model was developed, which accounts for soot formation and burn up. A methodology was developed for carrying out the multi-dimensional finite-element heat conduction calculations within the framework of thermodynamic cycle codes. Studies were carried out using the integrated methodology to address key issues in low heat rejection engines. A wide ranging design analysis matrix was covered, including a variety of insulation strategies, recovery devices and base engine configurations. A single cylinder Cummins engine was installed at Purdue University, and it was brought to a full operational status. The development of instrumentation was continued, concentrating on radiation heat flux detector, total heat flux probe, and accurate pressure-crank angle data acquisition.

Morel, T.↗
NASA NTRS1985

Liquid fueled external heating system for STM4-120 Stirling engine

The STM4-120 Stirling engine, currently under development at Stirling Thermal Motors, Inc., is a 40 kW variable stroke engine with indirect heating using a sodium heat pipe. The engine is functionally separated into an application independent Energy Conversion Unit (ECU) consisting of the Stirling cycle and drive heated by condensing sodium and the application dependent External Heating System (EHS), designed to supply the ECU with sodium vapor heated by the particular energy source, connected by tubes with mechanical couplings. This paper describes an External Heating System for the STM4-120 ECU designed for the combustion of liquid fuel, comprised of a recuperative preheater, a combustion chamber, and a heat exchanger/evaporator where heat is transferred from the flue gas to the sodium causing it to evaporate. The design concept and projected performance are described and discussed.

Meijer, R. J.↗
NASA NTRS1985

Response of the mesoscale atmosphere to diabatic heating

A study was initiated to determine the influence of convective latent heat release/diabatic heating on the production of kinetic energy during AVE/SESAME I. The primary focus has been on the relative importance of thermally forced modification of the wind field through thickness and height gradient changes versus inertial-advective effects via the diabatic component of vertical motion. Preliminary results have shown that because of the strong vertical shear over the convective region, ageostrophic response is primarily caused by the latter process. The diagnostic parameterization of convective heating has been extended for use in conjunction with satellite precipitation estimates in data-poor oceanic regions. An initial application was made to a mesoscale convective system embedded in the South Pacific convergence zone. Comparison to the heating field diagnosed as a residual in the thermodynamic equation using the ECMWF III-b analyses showed that the methodology will be useful in explaining the observed heating fields and determining the relative contribution of moist processes to the total diabatic heating. Research activities are now concentrated in the following areas: (1) Determining the sensitivity of vertical heating profiles to partitioning of gridscale versus convective precipitation; (2) assessing the possible effects of incorrect analyzed gridscale vertical motions on residuals in the heat budgets computed with the ECMWF III-b data sets.

Robertson, F. R.↗
NASA NTRS1987

Development of an integrated heat pipe-thermal storage system for a solar receiver

The Organic Rankine Cycle (ORC) Solar Dynamic Power System (SDPS) is one of the candidates for Space Station prime power application. In the low Earth orbit of the Space Station approximately 34 minutes of the 94-minute orbital period is spent in eclipse with no solar energy input to the power system. For this period the SDPS will use thermal energy storage (TES) material to provide a constant power output. An integrated heat-pipe thermal storage receiver system is being developed as part of the ORC-SDPS solar receiver. This system incorporates potassium heat pipe elements to absorb and transfer the solar energy within the receiver cavity. The heat pipes contain the TES canisters within the potassium vapor space with the toluene heater tube used as the condenser region of the heat pipe. During the insolation period of the Earth orbit, solar energy is delivered to the heat pipe in the ORC-SDPS receiver cavity. The heat pipe transforms the non-uniform solar flux incident in the heat pipe surface within the receiver cavity to an essentially uniform flux at the potassium vapor condensation interface in the heat pipe. During solar insolation, part of the thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of the orbit, the balance stored in the TES units is transferred by the potassium vapor to the toluene heater tube.

Keddy, E. S.↗
NASA NTRS1989

Phase-Change Heat-Storage Module

Heat-storage module accommodates momentary heating or cooling overload in pumped-liquid heat-transfer system. Large heat-storage capacity of module provided by heat of fusion of material that freezes at or near temperature desired to maintain object to be heated or cooled. Module involves relatively small penalties in weight, cost, and size and more than compensates by enabling design of rest of system to handle only average load. Latent heat of fusion of phase-change material provides large heat-storage capacity in small volume.

Mulligan, James C.↗