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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Semi-interpenetrating networks of LARC-TPI

In a previous research project at NASA-Langley, a novel semi-2-interpenetrating polymer network (semi-2-IPN) was prepared from the linear, thermoplastic polyimidesulfone, and the more brittle, crosslinked, acetylene-terminated imidesulfone. Synergistic qualities such as improved thermooxidative stability and better processability were achieved from this combination. The novelty of the system lay in the fact that the structures of the linear and crosslinking components were nearly identical. This similarity in structure eliminates any phase separation problems common to many-IPNs. In a similar way, a semi-2-IPN was prepared from linear, thermoplastic LARC-TPI and acetylene-terminated LARC-TPI (ATLARC-TPI). The preparation and characterization of this system will be discussed as well as adhesive and composite data.

Egli, Annemarie H.↗
NASA NTRS1986

The liquid-vapor transition in porous plug operation

The porous plug is a proven method for phase separation in superfluid helium dewars operating in zero gravity. The principal operating regimes have been identified in laboratory experiments on porous plugs. In this paper, a description of porous plug operation is given, and a new explanation is presented for the observed transition in the mass flow rate vs Delta-P characteristic. Theoretical results are in qualitative agreement with experimental data.

Hendricks, John B.↗
NASA NTRS1987

Utilization of FEP energetics

The research and development work on Fountain Effect Pump Systems (FEP systems) has been of interest in the competition between mechanical pumps for He II and FEP units. The latter do not have moving parts. In the course of the work, the energetics have been addressed using one part of a simple four-changes-of-state cycle. One option is the FEP ideal change of state at constant chemical potential (mu). The other option is the two-state sequence mu-P with a d mu=0 state change followed by an isobar. Questions of pump behavior, of flow rate response to temperature difference at the hot end, and related questions of thermodynamic cycle completion and heat transfer have been addressed. Porous media data obtained elucidate differences between vapor-liquid phase separation (VLPS) and Zero Net Mass Transfer (ZNMF).

Frederking, T. H. K.↗
NASA NTRS1988

Preparation for microgravity: The role of the microgravity materials science laboratory

A laboratory dedicated to ground based materials processing in preparation for space flight was established at the NASA Lewis Research Center. Experiments are performed to delineate the effects of gravity on processes of both scientific and commercial interest. Processes are modeled physically and mathematically. Transport model systems are used where possible to visually track convection, settling, crystal growth, phase separation, agglomeration, vapor transport, diffusive flow, and polymers reactions. The laboratory contains apparatus which functionally duplicates apparatus available for flight experiments and other pieces instrumented specifically to allow process characterization. Materials addressed include metals, alloys, salts, glasses, ceramics, and polymers. The Microgravity Materials Science Laboratory is staffed by engineers and technicians from a variety of disciplines and is open to users from industry and academia as well as the government. Examples will be given of the laboratory apparatus typical experiments and results.

Johnston, J. Christopher↗
NASA NTRS1988

Industrial Processes Influenced by Gravity

In considering new directions for low gravity research with particular regard to broadening the number and types of industrial involvements, it is noted that transport phenomena play a vital role in diverse processes in the chemical, pharmaceutical, food, and biotech industries. Relatively little attention has been given to the role of gravity in such processes. Accordingly, numerous industrial processes and phenomena are identified which involve gravity and/or surface tension forces. Phase separations and mixing are examples that will be significantly different in low gravity conditions. A basis is presented for expanding the scope of the low gravity research program and the potential benefits of such research is indicated.

Ostrach, Simon↗
NASA NTRS1988

Early intense cratering: Effects on growth of earth's crust

The disrupting effects of early intense meteorite bombardment on Earth's protocrustal evolution is discussed. The author emphasized that one should not consider the Earth's impact history as a discrete phase separate from an early crust forming event, and also that the end of the impacts was not a singular event that destroyed all previously formed crust.

Hartmann, William K.↗
NASA NTRS1987

Technology base for microgravity horticulture

Advanced microgravity plant biology research and life support system development for the spacecraft environment are critically hampered by the lack of a technology base. This inadequacy stems primarily from the fact that microgravity results in a lack of convective currents and phase separation as compared to the one gravity environment. A program plan is being initiated to develop this technology base. This program will provide an iterative flight development effort that will be closely integrated with both basic science investigations and advanced life support system development efforts incorporating biological processes. The critical considerations include optimum illumination methods, root aeration, root and shoot support, and heat rejection and gas exchange in the plant canopy.

Sauer, R. L.↗
NASA NTRS1987

Performance evaluation of SPE electrolyzer for Space Station life support

An static water-vapor feed electrolyzer has been developed as a candidate for Space Station life-support oxygen generation. The five-cell electrolysis module has eliminated the need for phase separation devices, pumps, and deionizers by transporting only water vapor to the solid polymer electrolyte cells. The introduction of an innovative electrochemical hydrogen pump allows the use of low-pressure reclaimed water to generate gas pressures of up to 230 psia. The electrolyzer has been tested in a computer-controlled test stand featuring continuous, cyclic, and standby operation (including automatic shutdown with fault detection).

Erickson, A. C.↗
NASA NTRS1987

PbO reduction and crucible reactions of 70 wt pct PbO-30 wt pct B2O3 glass

NASA has conducted an investigation of PbO-B2O3 glass with a view to PbO reduction and subsequent crucible reactions as a function of temperature and oxygen partial pressure, in order to establish the optimum processing conditions for subcentimetric glass hollow spheres applicable to inertial confinement fusion targets. The results obtained support the selection of appropriate crucible materials and oxygen partial pressure-temperature combinations that avoid phase separation from PbO reduction and/or crucible reactions.

Schilling, Christopher H.↗
NASA NTRS1988

Preparation for microgravity - The role of the Microgravity Material Science Laboratory

Experiments at the NASA Lewis Research Center's Microgravity Material Science Laboratory using physical and mathematical models to delineate the effects of gravity on processes of scientific and commercial interest are discussed. Where possible, transparent model systems are used to visually track convection, settling, crystal growth, phase separation, agglomeration, vapor transport, diffusive flow, and polymer reactions. Materials studied include metals, alloys, salts, glasses, ceramics, and polymers. Specific technologies discussed include the General Purpose furnace used in the study of metals and crystal growth, the isothermal dendrite growth apparatus, the electromagnetic levitator/instrumented drop tube, the high temperature directional solidification furnace, the ceramics and polymer laboratories and the center's computing facilities.

Johnston, J. Christopher↗
NASA NTRS1986

The materials processing research base of the Materials Processing Center

An annual report of the research activities of the Materials Processing Center of the Massachusetts Institute of Technology is given. Research on dielectrophoresis in the microgravity environment, phase separation kinetics in immiscible liquids, transport properties of droplet clusters in gravity-free fields, probes and monitors for the study of solidification of molten semiconductors, fluid mechanics and mass transfer in melt crystal growth, and heat flow control and segregation in directional solidification are discussed.

Latanision, R. M.↗
NASA NTRS1988

The soils of Mars

A mineralogical model for the Mars fine soil that includes as major components smectite clays absorbed and coated with amorphous iron oxyhydroxides and perhaps mixed with small amounts of better-crystalized iron oxides as separate phases is proposed. Also present as accessory minerals are sulfate minerals such as kieserite (MgSO4.H2O) and/or anhydrite (CaSO4), rutile (TiO2), and maghemite (Fe2O3) or magnetite (Fe3O4), the last two as magnetic components. Carbonates may be present at low concentrations only (less than 1 to 2 pct). However, a prime question to be addressed by a Mars Sample Return Mission shall be related to the mineralogical composition of the soil, and its spatial variability.

Banin, A.↗
NASA NTRS1988

Space Cryogenics Workshop, University of Wisconsin, Madison, June 22, 23, 1987

Papers are presented on liquid helium servicing from the Space Station, performance estimates in the Superfluid Helium On-Orbit Transfer Flight Experiment, an analytical study of He II flow characteristics in the SHOOT transfer line, a Dewar to Dewar model for superfluid helium transfer, and mechanical pumps for superfluid helium transfer in space. Attention is also given to the cavitation characteristics of a small centrifugal pump in He I and He II, turbulent flow pressure drop in various He II transfer system components, slip effects associated with Knudsen transport phenomena in porous media, and an integrated fountain effect pump device for fluid management at low gravity. Other papers are on liquid/vapor phase separation in He-4 using electric fields, an enclosed capillary device for low-gravity management of He II, cavitation in flowing superfluid helium, the long-term performance of the passive thermal control systems of the IRAS spacecraft, and a novel approach to supercritical helium flight cryostat support structures.

Source record↗
NASA NTRS1988

Slip effects associated with Knudsen transport phenomena in porous media

Porous media used in phase separators and thermomechanical pumps have been the subject of characterization efforts based on the Darcy permeability of laminar continuum flow. The latter is not always observed at low speed, in particular at permeabilities below 10 to the -9th/squared cm. The present experimental and theoretical studies address questions of slip effects associated with long mean free paths of gas flow at room temperature. Data obtained are in good agreement, within data uncertainty, with a simplified asymptotic Knudsen equation proposed for porous plugs on the basis of Knudsen's classical flow equation for long mean free paths.

Frederking, T. H. K.↗
NASA NTRS1988

Integrated fountain effect pump device for fluid management at low gravity

A new device for fluid management at low gravity is described. The system is basically the same as the enclosed capillary device using screens, in which the screens along the gallery channels are replaced by porous plugs which are responsible for both the fluid retention and pumping of He II; in this device, no downstream pump is needed. The plugs in contact with liquid He on both sides act as a fountain-effect pumps (FEPs), while plugs exposed to vapor on one side behave as vapor-liquid phase separators (VLPSs). The total net rate of He II transfer into the receiving tank equals the mass flow rate through the FEP plugs minus the liquid loss from the VLPS plugs. The results of the performance analysis of this integrated FEP device are presented together with its schematic diagram.

Yuan, S. W. K.↗
NASA NTRS1989

Fermentation and oxygen transfer in microgravity

The need for high rate oxygen transfer in microgravity for a Controlled Ecological Life Support System (CELSS) environment offers a number of difficulties and challenges. The use of a phase separated bioreactor appears to provide a way of overcoming these problems resulting in a system capable of providing high cell densities with rapid fermentation rates. Some of the key design elements are discussed.

Dunlop, Eric H.↗
NASA NTRS1989

Mechano-caloric cooling device

The mechano-caloric effect is potentially useful in the He II temperature range. Aside from demonstration work, little quantification effort appears to have been known since other refrigeration possibilities have been available for some time. Successful He II use-related system examples are as follows: in space, the utilization of the latent heat of vaporization has been quite successful in vapor-liquid phase separation (VLPS) in conjunction with thermomechanical force application in plugs. In magnet cooling systems, the possibility of using the mechano-caloric cooling effect in conjunction with thermo-mechanical circulation pump schemes, has been assessed (but not quantified yet to the extent desirable). A third example is quoted in conjunction with superfluid wind tunnel studies and liquid helium tow tank for surface vessels respectively. In all of these (partially future) R and D areas, the question of refrigerator effectiveness using the mechano-caloric effect appears to be relevant, possibly in conjunction with questions of reliability and simplicity. The present work is concerned with quantification of phenomena including simplified thermodynamic cycle calculations.

Frederking, T. H. K.↗
NASA NTRS1989

Morphological control of inter-penetrating polymer networks

Synthetic organic polymer chemistry has been successful in producing composition of matter with thermal oxidation stability and progressively higher glass transition temperatures. In part, this was done by increasing the steric-hindrance of moieties in the chain of a macromolecule. The resulting polymers are usually quite insoluble and produce molten polymers of very high viscosities. These types of polymers are not easily processed into graphite fiber prepregs by melt or solution impregnation methods. Hence, a technological need exists to produce new knowledge of how to produce polymer-fiber composites from this class of polymers. The concept of freeze drying amic-acid prepolymers with reactive thermoplastic was proposed as a research topic for the ASEE/NASA Summer Faculty Program of 1989 as a means of producing polymer-fiber composites. This process scheme has the thermodynamic attribute that the magnitude of phase separation due to differences in solubility of two organic constituents in solution will be greatly reduced by removing a solvent not by evaporation but by sublimation. Progress to date on evaluating this polymer processing concept is briefly outlined.

Hansen, Marion↗