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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Thermostructural applications of heat pipes

The feasibility of integrating heat pipes in high temperature structure to reduce local hot spot temperature was evaluated for a variety of hypersonic aerospace vehicles. From an initial list of twenty-two potential applications, the single stage to orbit wing leading edge showed the greatest promise and was selected for preliminary design of an integrated heat pipe thermostructural system. The design consisted of a Hastelloy X assembly with sodium heat pipe passages aligned normal to the wing leading edge. A d-shaped heat pipe cross section was determined to be optimum from the standpoint of structural weight.

Peeples, M. E.↗
NASA NTRS1979

Description and orbit data of variable-conductance heat-pipe system for the communications technology satellite

A variable-conductance heat-pipe system (VCHPS) with methanol as the working fluid and a nitrogen and helium mixture as the control gas was used for the thermal control of a 200 W RF traveling wave tube of the Communication Technology Satellite. Three stainless steel heat pipes (one redundant) and an aluminum radiator were designed to transfer 196 watts for an evaporator temperature of 50 C. The system has operated for three years with no noticeable change in performance. On four occasions the heat pipes apparently deprimed. A short time after reducing the tube power, the heat pipes reprimed and the system continued to operate normally. The description, qualification testing, and orbit data of the VCHPS are presented.

Gedeon, L.↗
NASA NTRS1981

Heat pipes cool probe and sandwich panel

Two concepts integrate heat-pipe technology. Probe with heat-pipe cooled jacket is self-contained, passive, and has no moving parts, unlike conventional air and water cooled probes. It is used in hostile, high temperature environments like wind tunnels and powerplants or on high-speed research and hypersonic cruise vehicles. Heat-pipe sandwich panel combines structural efficiency of sandwich with thermal efficiency of heat-pipe. It is used to eliminate thermal gradients and stresses, minimize thermal distortions, and transfer heat from one face of panel to other.

Camarda, C. J.↗
NASA NTRS1980

Heat transfer, thermal control, and heat pipes

This volume provides information on recent progress in spacecraft thermal control and the supporting disciplines of conduction, thermal radiation, and heat pipe theory and application. Four problem areas are considered: conduction heat transfer, radiation heat transfer, thermal control, and heat pipes. The topics covered include finite-element methodology for transient conduction/forced-convection thermal analysis; effects of surface finish on thermal contact resistance between different materials; mathematical models for wide-band nongray gas radiation in spherical and cylindrical geometries; thermal design, analysis and testing of the Shuttle remote manipulator arm; porous heat pipe; and transient behavior of liquid trap heat-pipe thermal diodes. Also discussed is the thermal design concept for a high-resolution UV spectrometer.

Olstad, W. B.↗
NASA NTRS1980

High-performance heat pipes for heat recovery applications

Methods to improve the performance of reflux heat pipes for heat recovery applications were examined both analytically and experimentally. Various models for the estimation of reflux heat pipe transport capacity were surveyed in the literature and compared with experimental data. A high transport capacity reflux heat pipe was developed that provides up to a factor of 10 capacity improvement over conventional open tube designs; analytical models were developed for this device and incorporated into a computer program HPIPE. Good agreement of the model predictions with data for R-11 and benzene reflux heat pipes was obtained.

Saaski, E. W.↗
NASA NTRS1981

Experimental simulation of latent heat thermal energy storage and heat pipe thermal transport for dish concentrator solar receiver

Test results on a modular simulation of the thermal transport and heat storage characteristics of a heat pipe solar receiver (HPSR) with thermal energy storage (TES) are presented. The HPSR features a 15-25 kWe Stirling engine power conversion system at the focal point of a parabolic dish concentrator operating at 827 C. The system collects and retrieves solar heat with sodium pipes and stores the heat in NaF-MgF2 latent heat storage material. The trials were run with a single full scale heat pipe, three full scale TES containers, and an air-cooled heat extraction coil to replace the Stirling engine heat exchanger. Charging and discharging, constant temperature operation, mixed mode operation, thermal inertial, etc. were studied. The heat pipe performance was verified, as were the thermal energy storage and discharge rates and isothermal discharges.

Narayanan, R.↗
NASA NTRS1981

The OAO heat pipes - 8 1/2 years of flight data

Heat pipe performance data taken during the 8 1/2 years of flight of the OAO-C (Copernicus) spacecraft are presented. Three fixed conductance heat pipes (FCHP), each with different wicking concepts (axial groove, pedestal artery, and self-priming spiral artery), and one variable conductance heat pipe (VCHP) are onboard. Aluminum tubes (1/2 in. diameter) rolled into a 48 in. loop containing ultra high purity ammonia as the heat transfer fluid comprise all FCHP, whose purpose is to circumferentially isothermalize the central tube housing the telescope. The VCHP is a hot, non-wicked reservoir concept including a composite artery and methanol heat transfer fluid, and is used to maintain the temperature of the onboard processor. Flight thermal data analysis reveals that no degradation in performance occurred since launch and agrees well with pre-flight data; the onboard processor still shows an offset in control range of 4 F, and the pipes perform the same after 8 1/2 years in orbit.

Harwell, W.↗
NASA NTRS1978

User's Manual for Thermal Analysis Program of Axially Grooved Heat Pipe (HTGAP)

A computer program that numerically predicts the steady state temperature distribution inside an axially grooved heat pipe wall for a given groove geometry and working fluid under various heat input and output modes is described. The program computes both evaporator and condenser film coefficients. The program is able to handle both axisymmetric and nonaxisymmetric heat transfer cases. Non-axisymmetric heat transfer results either from non-uniform input at the evaporator or non-uniform heat removal from the condenser, or from both. The presence of a liquid pool in the condenser region under one-g condition also causes non-axisymmetric heat transfer, and its effect on the pipe wall temperature distribution is included in the present program. The hydrodynamic aspect of an axially grooved heat pipe is studied in the Groove Analysis Program (GAP). The present thermal analysis program assumes that the GAP program (or other similar programs) is run first so that the heat transport limit and optimum fluid charge of the heat pipe are known a priori.

Kamotani, Y.↗
NASA NTRS1983

Radiant heating tests of several liquid metal heat-pipe sandwich panels

Integral heat pipe sandwich panels, which synergistically combine the thermal efficiency of heat pipes and the structural efficiency of honeycomb sandwich construction, were conceived as a means of alleviating thermal stress problems in the Langley Scramjet Engine. Test panels which utilized two different wickable honeycomb cores, facesheets with screen mesh sintered to the internal surfaces, and a liquid metal working fluid (either sodium or potassium) were tested by radiant heating at various heat load levels. The heat pipe panels reduced maximum temperature differences by 31 percent with sodium working fluid and 45 percent with potassium working fluid. Results indicate that a heat pipe sandwich panel is a potential, simple solution to the engine thermal stress problem. Other interesting applications of the concept include: cold plates for electronic component and circuit card cooling, radiators for large space platforms, low distortion large area structures (e.g., space antennas) and laser mirrors.

Camarda, C. J.↗
NASA NTRS1983

Radiant heating tests of several liquid metal heat-pipe sandwich panels

Integral heat-pipe sandwich panels, which synergistically combine the thermal efficiency of heat pipes and the structural efficiency of honeycomb sandwich construction, were conceived as a means of alleviating thermal stress problems in the Langley Scramjet Engine. Test panels which utilized two different wickable honeycomb cores, facesheets with screen mesh sintered to the internal surfaces, and a liquid metal working fluid (either sodium or potassium) were tested by radiant heating at various heat-load levels. The heat-pipe panels reduced maximum temperature differences by 31 percent with sodium working fluid and 45 percent with potassium working fluid. Results indicate that a heat-pipe sandwich panel is a potential, simple solution to the engine thermal stress problem. Other interesting applications of the concept include: cold plates for electronic component and circuit card cooling, radiators for large space platforms, low-distortion large area structures (e.g., space antennas) and laser mirrors.

Camarda, C. J.↗
NASA NTRS1983

Aluminum/ammonia heat pipe gas generation and long term system impact for the Space Telescope's Wide Field Planetary Camera

In the Space Telescope's Wide Field Planetary Camera (WFPC) project, eight heat pipes (HPs) are used to remove heat from the camera's inner electronic sensors to the spacecraft's outer, cold radiator surface. For proper device functioning and maximization of the signal-to-noise ratios, the Charge Coupled Devices (CCD's) must be maintained at -95 C or lower. Thermoelectric coolers (TEC's) cool the CCD's, and heat pipes deliver each TEC's nominal six to eight watts of heat to the space radiator, which reaches an equilibrium temperature between -15 C to -70 C. An initial problem was related to the difficulty to produce gas-free aluminum/ammonia heat pipes. An investigation was, therefore, conducted to determine the cause of the gas generation and the impact of this gas on CCD cooling. In order to study the effect of gas slugs in the WFPC system, a separate HP was made. Attention is given to fabrication, testing, and heat pipe gas generation chemistry studies.

Jones, J. A.↗
NASA NTRS1985

Decontaminating Aluminum/Ammonia Heat Pipes

Internal gas slugs reduced or eliminated. Manufacturing method increases efficiency of aluminum heat pipes in which ammonia is working fluid by insuring pipe filled with nearly pure charge of ammonia. In new process heat pipe initially closed with stainless-steel valve instead of weld so pipe put through several cycles of filling, purging, and accelerated aging.

Jones, J. A.↗
NASA NTRS1985

Modeling of transient heat pipe operation

The overall goal is to gain a better understanding of the transient behavior of heat pipes operating under both normal and adverse conditions. Normal operation refers to cases where the capillary structure remains fully wetted. Adverse operation occurs when drying, re-wetting, choking, noncontinuum flow, freezing, thawing etc., occur within the heat pipe. The work was redirected towards developing the capability to predict operational behavior of liquid metal heat pipes used for cooling aerodynamic structures. Of particular interest is the startup of such heat pipes from an initially frozen state such as might occur during re-entry of a space vehicle into the Earth's atmosphere or during flight of hypersonic aircraft.

Colwell, G. T.↗
NASA NTRS1986

Multileg Heat-Pipe Evaporator

Parallel pipes provide high heat flow from small heat exchanger. Six parallel heat pipes extract heat from overlying heat exchanger, forming evaporator. Vapor channel in pipe contains wick that extends into screen tube in liquid channel. Rods in each channel hold wick and screen tube in place. Evaporator compact rather than extended and more compatible with existing heat-exchanger geometries. Prototype six-pipe evaporator only 0.3 m wide and 0.71 m long. With ammonia as working fluid, transports heat to finned condenser at rate of 1,200 W.

Alario, J. P.↗
NASA NTRS1986

Heat Pipe Precools and Reheats Dehumidified Air

Precooling and reheating by heat pipe reduces operating costs of air-conditioning. Warm air returned from air-conditioned space and cooled air supplied are precooled and reheated, respectively, by each other through a heat pipe. Heat-pipe technology brought to bear on problem of conserving airconditioning energy in hot, humid environments. Any increase in the cost of equipment due to installation of heat-pipe heat exchangers expected to be recovered in energy savings during service period of 2 years or less.

Koning, R. C.↗
NASA NTRS1986

Multi-leg heat pipe evaporator

A multileg heat pipe evaporator facilitates the use and application of a monogroove heat pipe by providing an evaporation section which is compact in area and structurally more compatible with certain heat exchangers or heat input apparatus. The evaporation section of a monogroove heat pipe is formed by a series of parallel legs having a liquid and a vapor channel and a communicating capillary slot therebetween. The liquid and vapor channels and interconnecting capillary slots of the evaporating section are connected to the condensing section of the heat pipe by a manifold connecting liquid and vapor channels of the parallel evaporation section legs with the corresponding liquid and vapor channels of the condensing section.

Alario, J. P.↗
NASA NTRS1986

The share flight experiment - An advanced heat pipe radiator for Space Station

This paper reports on the design and thermal vacuum certification testing of the Space Station Heat Pipe Advanced Radiator Element (SHARE) Shuttle flight experiment, with primary emphasis on the heat pipe radiator system. The main objective of the SHARE experiment is to demonstrate suitable 0 g heat transfer performance of a 50 ft-long high-capacity monogroove heat pipe radiator element being developed for possible Space Station application. All of the flight certification tests were achieved, including a maximum heat rejection of 2 kW and thawing of a frozen heat pipe; and uninterrupted operation under cycling environmental and evaporator heat loads.

Alario, J. P.↗
NASA NTRS1987

Modeling of transient heat pipe operation

The use of heat pipes is being considered as a means of reducing the peak temperature and large thermal gradients at the leading edges of reentry vehicles and hypersonic aircraft and in nuclear reactors. In the basic cooling concept, the heat pipe covers the leading edge, a portion of the lower wing surface, and a portion of the upper wing surface. Aerodynamic heat is mainly absorbed at the leading edge and transported through the heat pipe to the upper and lower wing surface, where it is rejected by thermal radiation and convection. Basic governing equations are written to determine the startup, transient, and steady state performance of a haet pipe which has initially frozen alkali-metal as the working fluid.

Colwell, Gene T.↗