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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 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Use of glow discharge in fluidized beds

Static charges and agglomerization of particles in a fluidized bed systems are minimized by maintaining in at least part of the bed a radio frequency glow discharge. This approach is eminently suitable for processes in which the conventional charge removing agents, i.e., moisture or conductive particle coatings, cannot be used. The technique is applied here to the disproportionation of calcium peroxide diperoxyhydrate to yield calcium superoxide, an exceptionally water and heat sensitive reaction.

Wydeven, T.↗
NASA NTRS1982

Physiological responses to prolonged bed rest and fluid immersion in man: A compendium of research (1974 - 1980)

Water immersion and prolonged bed rest reproduce nearly all the physiological responses observed in astronauts in the weightless state. Related to actual weightlessness, given responses tend to occur sooner in immersion and later in bed rest. Much research was conducted on humans using these two techniques, especially by Russian scientists. Abstracts and annotations of reports that appeared in the literature from January 1974 through December 1980 are compiled and discussed.

Greenleaf, J. E.↗
NASA NTRS1981

Steam reforming of n-hexane on pellet and monolithic catalyst beds. A comparative study on improvements due to heat transfer

Monolithic catalysts with higher available active surface areas and better thermal conductivity than conventional pellets beds, making possible the steam reforming of fuels heavier than naphtha, were examined. Performance comparisons were made between conventional pellet beds and honeycomb monolith catalysts using n-hexane as the fuel. Metal-supported monoliths were examined. These offer higher structural stability and higher thermal conductivity than ceramic supports. Data from two metal monoliths of different nickel catalyst loadings were compared to pellets under the same operating conditions. Improved heat transfer and better conversion efficiencies were obtained with the monolith having higher catalyst loading. Surface-gas interaction was observed throughout the length of the monoliths.

Source record↗
NASA NTRS1983

Fluidized bed coal desulfurization

Laboratory scale experiments were conducted on two high volatile bituminous coals in a bench scale batch fluidized bed reactor. Chemical pretreatment and posttreatment of coals were tried as a means of enhancing desulfurization. Sequential chlorination and dechlorination cum hydrodesulfurization under modest conditions relative to the water slurry process were found to result in substantial sulfur reductions of about 80%. Sulfur forms as well as proximate and ultimate analyses of the processed coals are included. These studies indicate that a fluidized bed reactor process has considerable potential for being developed into a simple and economic process for coal desulfurization.

Ravindram, M.↗
NASA NTRS1983

Correlating downward flame spread rates for thick fuel beds

Flame spread rates are presented for polymethylmethacrylate fuel beds as a function of gravitational acceleration and ambient pressure and oxygen concentration. The data are correlated by plotting a dimensionless spread rate that is a measure of the heat transferred forward of the flame, required to sustain the flame, compared to the maximum possible forward heat transfer against a Damkoehler number. The latter parameter indicates the approach of the flame to its maximum temperature, where the maximum possible forward heat transfer occurs, such that the dimensionless spread rate approaches unity at large Damkoehler number. Surface regression effects on the flame spread process are incorporated into the dimensionless spread rate, and the final correlation is independent of bed thickness.

Altenkirch, R. A.↗
NASA NTRS1983

Preliminary study of a radiantly heated fluidized bed for the production of high purity silicon

The preparation of very pure silicon from silane (SIH4) using radiant heating of the hot silicon particles of a fluidized bed is discussed. The fraction of electrical energy supplied to the heater which is actually absorbed by the particles and the heat transfer coefficient between the hot bed and the cool distributor plate were investigated. The experimental design is presented and the results of the study are summarized.

Levenspiel, O.↗
NASA NTRS1984

Fines in fluidized bed silane pyrolysis

Silicon deposition on silicon seed particles by silane pyrolysis in a fluidized-bed reactor is investigated as a low-cost, high-throughput method to produce high-purity polysilicon for solar-cell applications. Studies of fines, particles 0.1-10 microns diam, initiated from homogeneous decomposition in the reactor were conducted using 2 and 6-in-diam fluidized beds. The studies show functional dependences of fines elutriation on silane feed concentration, temperature, gas velocity, and bubble size. The observation that the fines elutriation is generally below 10 percent of the silicon-in-silane feed is attributed to scavenging by large particles in an environment of less free space for homogeneous nucleation. Preliminary results suggest that, with proper conditions and distributor design, high-silane-concentration (over 50 percent SiH4 in H2) feed may be used.

Hsu, G.↗
NASA NTRS1984

A fluidized-bed reactor for silane pyrolysis

The silane decomposition in a fluidized bed reactor was studied. The process feasibility and operating windows were determined. Long duration tests were conducted and silicon purity was demonstrated. A high purity linear was installed in the fluid bed reactor; the FBR product was melted and single crystallized. Product purity improvements are noted.

Iya, S.↗
NASA NTRS1986

Fluidized-bed development at JPL

Silicon deposition on silicon seed particles by silane pyrolysis in a fluidized bed reactor (FBR) was investigated as a low cost, high throughput method to produce high purity polysilicon for solar cell applications. The emphasis of the research is fundamental understanding of fluidized bed silicon deposition. The mechanisms involved were modeled as a six-path process: heterogeneous deposition; homogeneous decomposition; coalescence; coagulation; scavenging; and chemical vapor deposition growth on fines.

Hsu, G.↗
NASA NTRS1986

Space Station propulsion test bed - A complete system

A test bed was fabricated under NASA/MSFC (Marshall Space Flight Center) Contract NAS8-36418 to demonstrate hydrogen/oxygen propulsion technology readiness for the Initial Operating Conditions Space Station application and for use as a means to test evolving technology for the growth station. This paper describes the test bed and its function.

Briley, G. L.↗
NASA NTRS1986

Space station experiment definition: Advanced power system test bed

A conceptual design for an advanced photovoltaic power system test bed was provided and the requirements for advanced photovoltaic power system experiments better defined. Results of this study will be used in the design efforts conducted in phase B and phase C/D of the space station program so that the test bed capabilities will be responsive to user needs. Critical PV and energy storage technologies were identified and inputs were received from the idustry (government and commercial, U.S. and international) which identified experimental requirements. These inputs were used to develop a number of different conceptual designs. Pros and cons of each were discussed and a strawman candidate identified. A preliminary evolutionary plan, which included necessary precursor activities, was established and cost estimates presented which would allow for a successful implementation to the space station in the 1994 time frame.

Pollard, H. E.↗
NASA NTRS1986

Space station propulsion test bed: A complete system

A test bed was fabricated to demonstrate hydrogen/oxygen propulsion technology readiness for the Initial Operating Capabilities (IOC) space station application and for use as a means to test evolving technology for the growth station. The test bed, its function, and plans for future testing are discussed.

Briley, G. L.↗
NASA NTRS1988

Fluidized-Bed Deposition Of Single-Crystal Silicon

Uniformly thin single-crystal films of silicon produced by modification of fluidized-bed-reactor technique producing polysilicon by chemical vapor deposition. Proposed for silicon wafers for flat-plate solar arrays and results in different structural and electronic properties in deposition layer desirable for specific microelectronic or solar-cell processing. In process deposition occurs on silicon wafers, kept individually at temperatures above 1,000 degree C. Heated wafers held in unheated and minimally-agitated-fluidized bed of silicon particles and in low concentration of silane.

Hsu, George C.↗
NASA NTRS1986

Space station propulsion technology: Space station propulsion system test bed test plan

Testing of the hydrogen/oxygen Space Station Propulsion System will demonstrate the technology readiness for the IOC application. To facilitate early demonstration of this technology and to allow demonstration of maturing technology, this testing will be performed with the components installed on a test bed which simulated the Space Station Structure. The test plan contains a description of the test bed, test objective, instrumentation plan, and controls plan. Each of these is discussed in detail.

Briley, G. L.↗
NASA NTRS1988

Simulation test beds for the space station electrical power system

NASA Lewis Research Center and its prime contractor are responsible for developing the electrical power system on the space station. The power system will be controlled by a network of distributed processors. Control software will be verified, validated, and tested in hardware and software test beds. Current plans for the software test bed involve using real time and nonreal time simulations of the power system. This paper will discuss the general simulation objectives and configurations, control architecture, interfaces between simulator and controls, types of tests, and facility configurations.

Sadler, Gerald G.↗
NASA NTRS1988

Physiology of prolonged bed rest

Bed rest has been a normal procedure used by physicians for centuries in the treatment of injury and disease. Exposure of patients to prolonged bed rest in the horizontal position induces adaptive deconditioning responses. While deconditioning responses are appropriate for patients or test subjects in the horizontal position, they usually result in adverse physiological responses (fainting, muscular weakness) when the patient assume the upright posture. These deconditioning responses result from reduction in hydrostatic pressure within the cardiovascular system, virtual elimination of longitudinal pressure on the long bones, some decrease in total body metabolism, changes in diet, and perhaps psychological impact from the different environment. Almost every system in the body is affected. An early stimulus is the cephalic shift of fluid from the legs which increases atrial pressure and induces compensatory responses for fluid and electrolyte redistribution. Without countermeasures, deterioration in strength and muscle function occurs within 1 wk while increased calcium loss may continue for months. Research should also focus on drug and carbohydrate metabolism.

Greenleaf, J. E.↗
NASA NTRS1988

The WCSAR telerobotics test bed

Component technologies for use in telerobotic systems for space are being developed. As part of this effort, a test bed was established in which these technologies can be verified and integrated into telerobotic systems. The facility consists of two slave industrial robots, an articulated master arm controller, a cartesian coordinate master arm controller, and a variety of sensors, displays and stimulators for feedback to human operators. The controller of one of the slave robots remains in its commercial state, while the controller of the other robot has been replaced with a new controller that achieves high-performance in telerobotic operating modes. A dexterous slave hand which consists of two fingers and a thumb is being developed, along with a number of force-reflecting and non-force reflecting master hands, wrists and arms. A tactile sensing finger tip based on piezo-film technology has been developed, along with tactile stimulators and CAD-based displays for sensory feedback and sensory substitution. The telerobotics test bed and its component technologies are described, as well as the integration of these component technologies into telerobotic systems, and their performance in conjunction with human operators.

Duffie, N.↗
NASA NTRS1988

Simulation test beds for the Space Station electrical power system

NASA Lewis Research Center and its prime contractor are respnsible for developing the electrical power system on the Space Station. The power system will be controlled by a network of distributed processors. Control software will be verified, validated, and tested in hardware and software test beds. Current plans for the software test bed involve using real time and nonreal time simulations of the power system. This paper will discuss the general simulation objectives and configurations, control architecture, interfaces between simulator and controls, types of tests, and facility configurations.

Sadler, Gerald G.↗