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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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NASA NTRSDate not supplied

Development and Testing of a Lab-Scale Electrochemical Refrigerator

Eta Space and NASA have been developing a lab-scale electrochemical hydrogen refrigerator (ECHR) capable of providing isothermal heat exchange for applications in the 20-Kelvin range. The cryocooler utilizes an electrochemical compressor paired with Joule-Thomson expansion to cool the hydrogen working fluid down to its saturation point within a purpose-built cold box. The use of electrochemical compression allows the cycle to operate with no moving parts presenting several key advantages for a variety of applications. Testing of the integrated system occurred in Eta Space’s cryogenic test facility where the system was able to achieve and maintain saturated temperatures at low pressure. Results of this test campaign demonstrate the feasibility of the ECHR concept in practice.

D J Hollibaugh↗
NASA NTRS1978

Reduction of liquid hydrogen boiloff: Optimal reliquefaction system design and cost study

The refrigeration cycles investigated are referred to as Joule-Thomson cycles because they depend on the J-T effect to produce the low temperatures. Two basic competitive refrigeration cycles were evaluated. The first vents a portion of cold H2 gas to achieve the required precooling; the second uses LN2 for precooling. Both open loop and closed loop cycles were evaluated as well as combinations of venting to supplement the LN2 precooling. All cycles use a H2 compressor to achieve the desired high pressure (1325 psig). The heat compression was removed by cooling water. The high pressure H2 gas was cooled in counter flow heat exchangers by flowing cold H2 to the compressor. Further cooling was achieved for cycles using LN2 by passing H2 vapors through a LN2 heat exchanger. Finally, the high pressure H2 gas was expanded through a J-T valve where a portion of H2 was liquefied. The low pressure H2 gas flow back through the heat exchangers to the compressor is that portion not liquefied and makes up hydrogen gas from the dewar.

Source record↗
NASA NTRS1993

Miniature Gas-Circulating Machine

Proposed gas-circulating machine consists essentially of centrifugal pump driven by induction motor. Noncontact bearings suppress wear and contamination. Used to circulate helium (or possibly hydrogen or another gas) in regeneration sorption-compressor refrigeration system aboard spacecraft. Also proves useful in terrestrial applications in which long life, reliability, and low contamination essential.

Swift, Walter L.↗
NASA NTRS1983

LaNi5 hydride cryogenic refrigerator test results

A complete LaNi5 hydrogen absorption cryogenic refrigerator system was developed. The system uses low temperature waste heat of approximately 100 C as a power source, and has no moving parts other than self operating valves. The cycle continues automatically by an electronic sequencing timing mechanism for the three compressors which are phased such that a constant supply of high pressure hydrogen gas is provided. It is indicated that with a fully clean hydrogen system, hundreds of thousand cycles should be attainable, even though some degradation may eventually occur. Simple vacuum reactivation of the hydride of moving parts, other than self operating, long life valves, the refrigerators predicted life is extremely long.

Jones, J. A.↗
NASA NTRS1994

Generating High-Pressure Oxygen Electrolytically

Electrolytic cell generates oxygen directly at high pressure at point of use. System makes it unnecessary to use heavy, bulky air compressor or to ship compressed oxygen in heavy tanks. Produces hydrogen as byproduct, at pressure that may be different from that of oxygen, if desired. Cathode also barrier that lets gases collect at widely differing pressures.

Schubert, F. H.↗
NASA NTRS2000

Degradation study of the ZrNiH(sub 1.5) system

The ZrNi hydride has been assessed as reversible hydrogen storage material in actuators of gas gap heat switches for applications involving hydride compressors in closed-cycle Joule-Thomson sorption cryocoolers.

metal hydrides gas gap heat switches hydrogen stor↗
NASA NTRS1987

Sorption compressor/mechanical expander hybrid refrigeration

Experience with Deep Space Network (DSN) ground-based cryogenic refrigerators has proved the reliability of the basic two-stage Gifford-McMahon helium refrigerator. A very long life cryogenic refrigeration system appears possible by combining this expansion system or a turbo expansion system with a hydride sorption compressor in place of the usual motor driven piston compressor. To test the feasibility of this system, a commercial Gifford-McMahon refrigerator was tested using hydrogen gas as the working fluid. Although no attempt was made to optimize the system for hydrogen operation, the refrigerator developed 1.3 W at 30 K and 6.6 W at 60 K. The results of the test and of theoretical performances of the hybrid compressor coupled to these expansion systems are presented.

Jones, J. A.↗
NASA NTRS2004

Systems Analysis Developed for All-Electric Aircraft Propulsion

There is a growing interest in the use of fuel cells as a power source for all-electric aircraft propulsion as a means to substantially reduce or eliminate environmentally harmful emissions. Among the technologies under consideration for these concepts are advanced proton exchange membrane (PEM) and solid oxide fuel cells (SOFCs), alternative fuels and fuel processing, and fuel storage. A multidisciplinary effort is underway at the NASA Glenn Research Center to develop and evaluate concepts for revolutionary, nontraditional fuel cell power and propulsion systems for aircraft applications. As part of this effort, system studies are being conducted to identify concepts with high payoff potential and associated technology areas for further development. To support this effort, a suite of component models was developed to estimate the mass, volume, and performance for a given system architecture. These models include a hydrogen-air PEM fuel cell; an SOFC; balance-of-plant components (compressor, humidifier, separator, and heat exchangers); compressed gas, cryogenic, and liquid fuel storage tanks; and gas turbine/generator models for hybrid system applications. First-order feasibility studies were completed for an all-electric personal air vehicle utilizing a fuel-cell-powered propulsion system. A representative aircraft with an internal combustion engine was chosen as a baseline to provide key parameters to the study, including engine power and subsystem mass, fuel storage volume and mass, and aircraft range. The engine, fuel tank, and associated ancillaries were then replaced with a fuel cell subsystem. Various configurations were considered including a PEM fuel cell with liquid hydrogen storage, a direct methanol PEM fuel cell, and a direct internal reforming SOFC/turbine hybrid system using liquid methane fuel. Each configuration was compared with the baseline case on a mass and range basis.

Kohout, Lisa L.↗
NASA NTRS1984

Capture of liquid hydrogen boiloff with metal hydride absorbers

A procedure which uses metal hydrides to capture some of this low pressure (,1 psig) hydrogen for subsequent reliquefaction is described. Of the five normally occurring sources of boil-off vapor the stream associated with the off-loading of liquid tankers during dewar refill was identified as the most cost effective and readily recoverable. The design, fabrication and testing of a proof-of-concept capture device, operating at a rate that is commensurate with the evolution of vapor by the target stream, is described. Liberation of the captured hydrogen gas at pressure .15 psig at normal temperatures (typical liquefier compressor suction pressure) are also demonstrated. A payback time of less than three years is projected.

Rosso, M. J.↗
NASA NTRS2003

Systems Analysis Initiated for All-Electric Aircraft Propulsion

A multidisciplinary effort is underway at the NASA Glenn Research Center to develop concepts for revolutionary, nontraditional fuel cell power and propulsion systems for aircraft applications. There is a growing interest in the use of fuel cells as a power source for electric propulsion as well as an auxiliary power unit to substantially reduce or eliminate environmentally harmful emissions. A systems analysis effort was initiated to assess potential concepts in an effort to identify those configurations with the highest payoff potential. Among the technologies under consideration are advanced proton exchange membrane (PEM) and solid oxide fuel cells, alternative fuels and fuel processing, and fuel storage. Prior to this effort, the majority of fuel cell analysis done at Glenn was done for space applications. Because of this, a new suite of models was developed. These models include the hydrogen-air PEM fuel cell; internal reforming solid oxide fuel cell; balance-of-plant components (compressor, humidifier, separator, and heat exchangers); compressed gas, cryogenic, and liquid fuel storage tanks; and gas turbine/generator models for hybrid system applications. Initial mass, volume, and performance estimates of a variety of PEM systems operating on hydrogen and reformate have been completed for a baseline general aviation aircraft. Solid oxide/turbine hybrid systems are being analyzed. In conjunction with the analysis efforts, a joint effort has been initiated with Glenn s Computer Services Division to integrate fuel cell stack and component models with the visualization environment that supports the GRUVE lab, Glenn s virtual reality facility. The objective of this work is to provide an environment to assist engineers in the integration of fuel cell propulsion systems into aircraft and provide a better understanding of the interaction between system components and the resulting effect on the overall design and performance of the aircraft. Initially, three-dimensional computer-aided design (CAD) models of representative PEM fuel cell stack and components were developed and integrated into the virtual reality environment along with an Excel-based model used to calculate fuel cell electrical performance on the basis of cell dimensions (see the figure). CAD models of a representative general aviation aircraft were also developed and added to the environment. With the use of special headgear, users will be able to virtually manipulate the fuel cell s physical characteristics and its placement within the aircraft while receiving information on the resultant fuel cell output power and performance. As the systems analysis effort progresses, we will add more component models to the GRUVE environment to help us more fully understand the effect of various system configurations on the aircraft.

Kohout, Lisa L.↗
NASA NTRS1981

Gas absorption/desorption temperature-differential engine

Continuously operating compressor system converts 90 percent of gas-turbine plant energy to electricity. Conventional plants work in batch mode, operating at 40 percent efficiency. Compressor uses metal hydride matrix on outside of rotating drum to generate working gas, hydrogen. Rolling valve seals allow continuous work. During operation, gas is absorbed, releasing heat, and desorbed with heat gain. System conserves nuclear and fossil fuels, reducing powerplant capital and operating costs.

Miller, C. G.↗
NASA NTRS1974

Test techniques for obtaining off-nominal compressor data during engine tests

Several unique techniques and related devices are described which are in use at the Lewis Research Center for off-design testing of fan and compressor sections in full-scale jet engines. The devices presented permit a wide range of experimental conditions and minimize downtime for hardware changes. The techniques involve use of such devices as inlet pressure distortion jets, a hydrogen burner for inlet temperature distortions, fan back pressure jets to simulate a variable area nozzle, and either an inflow-outflow bleed system or a fuel spurt system to alter compressor discharge pressure.

Biesiadny, T. J.↗
NASA NTRS1974

Test techniques for obtaining off-nominal compressor data during engine tests

Several unique techniques and related devices are in use at the Lewis Research Center for off-design testing of fan and compressor sections in full-scale jet engines. The devices presented not only permit a wide range of experimental conditions but also minimize downtime for hardware changes. The techniques involve use of such devices as inlet pressure distortion jets, a hydrogen burner for inlet temperature distortions, fan back pressure jets to simulate a variable area nozzle, and either an inflow-outflow bleed system or a fuel spurt system to alter compressor discharge pressure.

Biesiadny, T. J.↗
NASA NTRS1985

Hydride absorption refrigerator system for ten Kelvin and below

A very long-life, lightweight and efficient hydride absorption refrigerator system was built to operate at ten Kelvin and below. The system consists of four basic stages of refrigeration. The first stage is accomplished by an active refrigeration system. The second stage is operated by a hydride absorption system, wherein a heated hydride powder drives off high pressure hydrogen through a Joule-Thomson/heat exchanger expansion loop such that the hydrogen is partially liquefied. In the third stage, the vapor pressure over the collected liquid hydrogen is lowered by absorbing the hydrogen vapor onto a different low pressure, worn hydride. With a 1.7 torr partial pressure of hydrogen gas in the hydride, liquid hydrogen is solidified and sublimes at 10 K. Long-life adiabatic demagnetization refrigerators, helium desorption, or helium diaphragm compressors are used to cool to 4 K or below. It is shown that the hydride concepts provide an extremely efficient means of refrigeration to 10 K, and that an entire sorption refrigeration process can be accomplished solely by using low grade heat energy at about 150 C.

Jones, J. A.↗
NASA NTRS1979

The chemistry of sodium chloride involvement in processes related to hot corrosion

Thermodynamic and mass transport calculations, and laboratory experiments elucidating the behavior of sodium chloride in combustion environments, in the deposition process, and in reactions with certain oxides on the surfaces of superalloys are summarized. It was found that some of the ingested salt is separated out of the air stream by the compressor. However, sodium chloride does pass from the compressor to the combustor where numerous chemical reactions take place. Here some of the salt is vaporized to yield gaseous sodium chloride molecules. Hydrogen and oxygen atoms present in the combustion products react with some sodium chloride to yield other gaseous species such as sodium, and a fraction of the salt remains as particulates. Both the gas phase and condensed sodium chloride can lead to sodium sulfate formation by various routes, all of which involve reaction with sulfur oxides and oxygen. In addition to contributing to the formation of sodium sulfate, the sodium chloride can contribute to corrosion directly.

Stearns, C. A.↗
NASA NTRS1971

Relative susceptibility of titanium alloys to hot-salt stress-corrosion

Susceptibility of titanium alloys to hot-salt stress-corrosion cracking increased as follows: Ti-2Al-11Sn-5Zr-0.2Si(679), Ti-6Al-2Sn-4Zr-2Mo(6242), Ti-6Al-4V(64), Ti-6Al-4V-3Co(643), Ti-8Al-1Mo-1V(811), and Ti-13V-11Cr-3A1(13-11-3). The Ti-5Al-6Sn-2Zr-1Mo-0.25Si(5621S) alloy was both the least and most susceptible depending on heat treatment. Such rankings can be drastically altered by heat-to-heat and processing variations. Residual compressive stresses and cyclic exposures also reduce susceptibility to stress-corrosion. Simulated turbine-engine compressor environmental variables such as air velocity, pressure, dewpoint, salt concentration, and salt deposition temperature have only minor effects. Detection of substantial concentrations of hydrogen in all corroded alloys confirmed the existence of a hydrogen embrittlement mechanism.

Gray, H. R.↗