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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 757 records · Page 42

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NASA NTRS2004

Heat Shielding Characteristics and Thermostructural Performance of a Superalloy Honeycomb Sandwich Thermal Protection System (TPS)

Heat-transfer, thermal bending, and mechanical buckling analyses have been performed on a superalloy "honeycomb" thermal protection system (TPS) for future hypersonic flight vehicles. The studies focus on the effect of honeycomb cell geometry on the TPS heat-shielding performance, honeycomb cell wall buckling characteristics, and the effect of boundary conditions on the TPS thermal bending behavior. The results of the study show that the heat-shielding performance of a TPS panel is very sensitive to change in honeycomb core depth, but insensitive to change in honeycomb cell cross-sectional shape. The thermal deformations and thermal stresses in the TPS panel are found to be very sensitive to the edge support conditions. Slight corrugation of the honeycomb cell walls can greatly increase their buckling strength.

Ko, William L.↗

NASA NTRS1991

Investigation of thermal-fluid mechanical characteristics of the Capillary Pump Loop

The main purpose is the experimental and analytical study of behavior of the Capillary Pump Loop (CPL) heat pipe system during the transient mode of operating by applying a step heat pulse to one or more evaporators. Prediction of the CPL behavior when subjected to pulse heat loading requires further study before the transient response of CPL system can be fully understood. The following tasks are discussed: (1) exploratory testing of a CPL heat pipe for transient operational conditions which could generate the type of oscillatory inlet temperature behavior observed in an earlier testing of NASA/GSFC CPL-2 heat pipe system; (2) analytical investigation of the CPL inlet section temperature oscillations; (3) design, construction and testing of a bench-top CPL test system for study of the CPL transient operation; and (4) transient analysis of a CPL heat pipe by applying a step power input to the evaporators.

Kiper, Ali M.↗

NASA NTRS2009

Transient Modeling and Analysis of a Metabolic Heat-Regenerated Temperature Swing Adsorption (MTSA) System for a PLSS

A Metabolic heat-regenerated Temperature Swing Adsorption (MTSA) system is being developed for carbon dioxide, water and thermal control in a lunar and martian portable life support system (PLSS). A previous system analysis was performed to evaluate the impact of MTSA on PLSS design. That effort was Mars specific and assumed liquid carbon dioxide (LCO2) coolant made from martian resources. Transient effects were not considered but rather average conditions were used throughout the analysis. This effort takes into further consideration the transient effects inherent in the cycling MTSA system as well as assesses the use of water as coolant. Standard heat transfer, thermodynamic, and heat exchanger methods are presented to conduct the analysis. Assumptions and model verification are discussed. The tool was used to perform various system studies. Coolant selection was explored and takes into account different operational scenarios as the minimum bed temperature is driven by the sublimation temperature of the coolant (water being significantly higher than LCO2). From this, coolant mass is sized coupled with sorbent bed mass because MTSA adsorption performance decreases with increasing sublimation temperature. Reduction in heat exchanger performance and even removal of certain heat exchangers, like a recuperative one between the two sorbent beds, is also investigated. Finally, the coolant flow rate is varied over the cycle to determine if there is a more optimal means of cooling the bed from a mass perspective. Results of these studies and subsequent recommendations for system design are presented.

Iacomini, Christie↗

NASA NTRS1985

New outlook on control of crystalline and chemical perfection during growth of silicon

Significant progress has been made in our understanding of the Czochralski crystal growth process with the realization that the incorporation of oxygen into silicon is directly related to the internal gettering capability of wafers during device fabrication. It was also recognized that the electronic properties exhibited by silicon during various stages of device fabrication were significantly affected by the thermal history of the silicon during the post-growth cool-down period. Turbulent melt convection, induced by unavoidable destabilizing thermal gradients, was found to interfere with homogeneous dopant (and oxygen) incorporation and to influence markedly the dynamics of nonequilibrium point defects in the solidified silicon matrix during the cool-down period. In view of the unavoidability of destabilizing thermal gradients in conventional crystal growth configurations, melt stabilization through the application of magnetic fields is generally considered a viable approach. Control of heat input to the melt through heat pipe systems, as used during growth of germanium, cannot be applied to industrial growth of silicon. Recent studies have shown that heat exchange systems located coaxially about a growing crystal can be used to stabilize and control not only heat transfer in the grown crystal, but also in the melt adjacent to the solidification interface.

Witt, A. F.↗

NASA NTRS1988

Solar dynamic heat receiver thermal characteristics in low earth orbit

A simplified system model is under development for evaluating the thermal characteristics and thermal performance of a solar dynamic spacecraft energy system's heat receiver. Results based on baseline orbit, power system configuration, and operational conditions, are generated for three basic receiver concepts and three concentrator surface slope errors. Receiver thermal characteristics and thermal behavior in LEO conditions are presented. The configuration in which heat is directly transferred to the working fluid is noted to generate the best system and thermal characteristics. as well as the lowest performance degradation with increasing slope error.

Wu, Y. C.↗

NASA NTRS1989

The systems improved numerical fluids analysis code (SINFAC)

A computer program has been developed to model the steady-state performance of single and two-phase heat transport systems. The development effort had the intent of making the program general, relatively easy to implement and easy to integrate into currently available software. The primary use of the program is for, but not limited to, heat transport system for spacecraft. In order to show the program has achieved its intended goals, the program was first applied to a small loop and a quick parametric study done. Next a verification study was done in which the temperature data from a thermal loop flown on the space shuttle was compared to modeler predictions.

Schweickart, Russell B.↗

NASA NTRS2015

Proportional and Integral Thermal Control System for Large Scale Heating Tests

The National Aeronautics and Space Administration Armstrong Flight Research Center (Edwards, California) Flight Loads Laboratory is a unique national laboratory that supports thermal, mechanical, thermal/mechanical, and structural dynamics research and testing. A Proportional Integral thermal control system was designed and implemented to support thermal tests. A thermal control algorithm supporting a quartz lamp heater was developed based on the Proportional Integral control concept and a linearized heating process. The thermal control equations were derived and expressed in terms of power levels, integral gain, proportional gain, and differences between thermal setpoints and skin temperatures. Besides the derived equations, user's predefined thermal test information generated in the form of thermal maps was used to implement the thermal control system capabilities. Graphite heater closed-loop thermal control and graphite heater open-loop power level were added later to fulfill the demand for higher temperature tests. Verification and validation tests were performed to ensure that the thermal control system requirements were achieved. This thermal control system has successfully supported many milestone thermal and thermal/mechanical tests for almost a decade with temperatures ranging from 50 F to 3000 F and temperature rise rates from -10 F/s to 70 F/s for a variety of test articles having unique thermal profiles and test setups.

Thermal Control System↗

NASA NTRS2003

Thermal Vacuum Testing of Swift XRT Ethane Heat Pipes

This paper presents the results obtained from a recent ethane heat pipe program. Three identical ethane heat pipes were tested individually, and then two selected heat pipes were tested collectively in their system configuration. Heat transport, thermal conductance, and non-condensable gas tests were performed on each heat pipe. To gain insight into the reflux operation as seen at spacecraft level ground testing, the test fixture was oriented in a vertical configuration. The system level test included a computer-controlled heater designed to emulate the heat load generated at the thermoelectric cooler interface. The system performance was successfully characterized for a wide range of environmental conditions while staying within the operating limits.

Kobel, Mark↗

NASA NTRS2008

Multi-Evaporator Miniature Loop Heat Pipe for Small Spacecraft Thermal Control

This paper presents the development of the Thermal Loop experiment under NASA's New Millennium Program Space Technology 8 (ST8) Project. The Thermal Loop experiment was originally planned for validating in space an advanced heat transport system consisting of a miniature loop heat pipe (MLHP) with multiple evaporators and multiple condensers. Details of the thermal loop concept, technical advances and benefits, Level 1 requirements and the technology validation approach are described. An MLHP breadboard has been built and tested in the laboratory and thermal vacuum environments, and has demonstrated excellent performance that met or exceeded the design requirements. The MLHP retains all features of state-of-the-art loop heat pipes and offers additional advantages to enhance the functionality, performance, versatility, and reliability of the system. In addition, an analytical model has been developed to simulate the steady state and transient operation of the MHLP, and the model predictions agreed very well with experimental results. A protoflight MLHP has been built and is being tested in a thermal vacuum chamber to validate its performance and technical readiness for a flight experiment.

Ku, Jentung↗

NASA NTRS2016

Optimized Heat Pipe Backup Cooling System Tested with a Stirling Convertor

Advanced Stirling Radioisotope Generator (ASRG) is an attractive energy system for select space missions, and with the addition of a VCHP, it becomes even more versatile. The ASRG is powered through thermal energy from decaying radioisotopes acting as General Purpose Heat Sources (GPHS). A Stirling engine converts the thermal energy to electrical energy and cools the GPHS [2]. The Stirling convertor must operate continuously to maintain acceptable temperatures of the GPHS and protect their cladding. The addition of alkali metal VCHP allows the Stirling to cycle on and off during a mission and can be used as a backup cooling system. The benefits of being able to turn the Stirling off are: allowing for a restart of the Stirling and reducing vibrations for sensitive measurements. The VCHP addition should also increase the efficiency of the Stirling by providing a uniform temperature distribution at the heat transfer interface into the heater head.

Stirling Radioisotope Generator↗

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 NTRS2004

Waste-Heat-Driven Cooling Using Complex Compound Sorbents

Improved complex-compound sorption pumps are undergoing development for use as prime movers in heat-pump systems for cooling and dehumidification of habitats for humans on the Moon and for residential and commercial cooling on Earth. Among the advantages of sorption heat-pump systems are that they contain no moving parts except for check valves and they can be driven by heat from diverse sources: examples include waste heat from generation of electric power, solar heat, or heat from combustion of natural gas. The use of complex compound sorbents in cooling cycles is not new in itself: Marketing of residential refrigerators using SrCl2 was attempted in the 1920s and 30s and was abandoned because heat- and mass-transfer rates of the sorbents were too low. Addressing the issue that gave rise to the prior abandonment of complex compound sorption heat pumps, the primary accomplishment of the present development program thus far has been the characterization of many candidate sorption media, leading to large increases in achievable heat- and mass-transfer rates. In particular, two complex compounds (called "CC260-1260" and "CC260-2000") were found to be capable of functioning over the temperature range of interest for the lunar-habitat application and to offer heat- and mass-transfer rates and a temperature-lift capability adequate for that application. Regarding the temperature range: A heat pump based on either of these compounds is capable of providing a 95-K lift from a habitable temperature to a heat-rejection (radiator) temperature when driven by waste heat at an input temperature .500 K. Regarding the heat- and mass-transfer rates or, more precisely, the power densities made possible by these rates: Power densities observed in tests were 0.3 kilowatt of cooling per kilogram of sorbent and 2 kilowatts of heating per kilogram of sorbent. A prototype 1-kilowatt heat pump based on CC260-2000 has been built and demonstrated to function successfully.

Rocketfeller, Uwe↗

NASA NTRS1978

Solar-powered Rankine heat pump for heating and cooling

The design, operation and performance of a familyy of solar heating and cooling systems are discussed. The systems feature a reversible heat pump operating with R-11 as the working fluid and using a motor-driven centrifugal compressor. In the cooling mode, solar energy provides the heat source for a Rankine power loop. The system is operational with heat source temperatures ranging from 155 to 220 F; the estimated coefficient of performance is 0.7. In the heating mode, the vapor-cycle heat pump processes solar energy collected at low temperatures (40 to 80 F). The speed of the compressor can be adjusted so that the heat pump capacity matches the load, allowing a seasonal coefficient of performance of about 8 to be attained.

Rousseau, J.↗

NASA NTRS1979

Life characteristics assessment of the communications technology satellite transmitter experiment package

The performance characteristics of the transmitter experiment package (TEP) aboard the Communications Technology Satellite (CTS) measured during its first 2 years in orbit are presented. The TEP consists of a nominal 200 watt output stage tube (OST), a supporting power processing system (PPS), and a variable conductance heat pipe system (VCHPS). The OST, a traveling wave tube augmented with a 10 stage depressed collector has an overall saturated average efficiency of 51.5 percent and an average saturated radio frequency (rf) output power at center band frequency of 240 watts. The PPS operated with a measured efficiency of 86.5 to 88.5 percent. The VCHPS, using three pipes to conduct heat from the PPS and the OST to a 52 by 124 centimeter radiator fin, maintained the PPS baseplate temperature below 50 C for all operating conditions. The TEP performance characteristics presented include frequency response, rf output power, thermal performance, and efficiency. Communications characteristics were evaluated by using both video and audio modulated signals. On four occasions, the TEP experienced temporary thermal control system malfunctions. The anomalies were terminated safely, and the problem was investigated because of the potential for TEP damage due to the signficant temperature increases. Safe TEP operating procedures were established.

Smetana, J.↗

NASA NTRS1976

Central Data Processing System (CDPS) user's manual: Solar heating and cooling program

The software and data base management system required to assess the performance of solar heating and cooling systems installed at multiple sites is presented. The instrumentation data associated with these systems is collected, processed, and presented in a form which supported continuity of performance evaluation across all applications. The CDPS consisted of three major elements: communication interface computer, central data processing computer, and performance evaluation data base. Users of the performance data base were identified, and procedures for operation, and guidelines for software maintenance were outlined. The manual also defined the output capabilities of the CDPS in support of external users of the system.

Source record↗

NASA NTRS1992

Linear dynamic analysis of the Space Station Freedom thermal/environmental control system

A methodology for dynamic analysis of the Space Station Freedom thermal/environmental control system is described which uses linear system analysis techniques to determine the ability of the system to accommodate thermal load transients. A nonlinear integrated model of the system as it exists at Stage 6, Man Tended Capability (MTC), is described which encompasses the cabin air cooling system, avionics air cooling system, internal and external thermal control systems. The nonlinear model is linearized at an assumed design operating point, and the linear model is evaluated by comparison with the nonlinear model. Transfer functions are derived to determine the response of the heat rejection system to time-varying thermal loads applied at various points in the heat acquisition system. The frequency response calculated from the transfer functions is used to determine allowable operating envelopes of thermal load magnitude and frequency for each point of application of thermal load. The dynamic operating envelopes provide a quantitative indication of the degree and duration of peak loads which the thermal/environmental system is able to transport and reject.

Tandler, John↗

NASA NTRS2018

Europa Clipper Thermal Control Design

This paper details the design developments of the Europa Clipper spacecraft thermal control system and its primary element the Heat Redistribution System (HRS). The Europa Clipper spacecraft will launch in the early 2020s and will have multiple flybys of Jupiter’s icy moon, Europa. The HRS, which utilizes a Mechanically Pumped Fluid Loop (MPFL) to reclaim waste heat from an avionics vault module and redistribute it to the propulsion module and radiator, has become an integral part of the spacecraft architecture both in terms of mechanical configuration and spacecraft operations capability. A walkthrough on the planned implementation of the HRS on the primary spacecraft modules is provided along with a description on thermal control of spacecraft hardware not located on the HRS vault, where thermal isolation and tolerance to extreme thermal environment drives the hardware designs.

Bhandari, Pradeep↗

NASA NTRS1984

Hot melt adhesive pad surface attachment assembly concept for on-orbit operations

The use of a hot melt adhesive concept to develop a Surface Attachment Assembly (SAA) for on-orbit attachment and detachment operations for the Manned Maneuvering Unit (MMU) was investigated. The concept involved impregnation of the hot melt adhesive into a fiberglass covered pad which contained electrical heating and thermoelectric cooling devices. The polyamide hot melt adhesive selected can be repeatedly heated to its melting point in a vacuum and provide good adhesion to various surfaces, i.e., reusable surface insulation tiles, metals, and composites, when cooled. After a series of adhesive screening tests, Jet-Melt 3746 was selected from a group of commercially available thermoplastic adhesive candidates which met or exceeded many of the criteria established for the SAA system. The SAA system was designed and fabricted with the goal of proving the concept with a working model rather than attempting to optimize all facets of the system. This system evolved by investigating alternate attachment concepts, designing and fabricating electronic systems to heat and cool the adhesive, and then fabricating electronic systems to heat and cool the adhesive, and then fabricating and testing two prototype full-size units.

Progar, D. J.↗