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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 343 records · Page 19

Feasibility Study of Solar Dome Encapsulation of Photovoltaic Arrays

The technical and economic advantages of using air-supported plastic enclosures to protect flat plate photovoltaic arrays are described. Conceptual designs for a fixed, latitude-tilt array and a fully tracking array were defined. Detailed wind loads and strength analyses were performed for the fixed array. Detailed thermal and power output analyses provided array performance for typical seasonal and extreme temperature conditions. Costs of each design as used in a 200 MWe central power station were defined from manufacturing and material cost estimates. The capital cost and cost of energy for the enclosed fixed-tilt array were lower than for the enclosed tracking array. The enclosed fixed-tilt array capital investment was 38% less, and the levelized bus bar energy cost was 26% less than costs for a conventional, glass-encapsulated array design. The predicted energy cost for the enclosed fixed array was 79 mills/kW-h for direct current delivered to the power conditioning units.

Source record↗

Bayonet plug with ramp-activated lock

Matched pair of washers with broad surface ramps is locking mechanism in bayonet plug. It can be used where threaded springs and fasteners are impractical because of extreme temperatures or other environmental incompatibility. Matched pair of ramped washers is placed on plug and bayonet inserted. Inner slot of one washer matches contour of plug; this washer is stationary. Inner slot of second washer is circular. When second washer is rotated, washers push against bayonet plug, locking it in place. Retaining wire secures plug.

Wood, K. E.↗

Testing panels in tension and flexure

Simple jig adapts tensile test machine for simulataneous application of tension and flexure, for evaluating panel composition, processing, and design. Environmental test chamber can be added so that panel properties can be measured at extreme temperatures.

Jing, G. K.↗

Self-lubricating gearset

Gearset fabricated from molybdenum sulfide filled polyimide allows attention-free operation in vacuum and at extreme temperatures. Ring gear drives pinion gear on shaft in skewed-axis arrangement. Because loads are shared among multiple meshing teeth, self-lubricating material is strong enough to accomodate high gear ratio.

Binge, D. S.↗

Life and stability testing of packaged low-cost energy storage materials

Thermal cycling and performance tests, performed to verify the package integrity, life, and stability of the chub packaged materials system for storage coolness with application to residential air conditioning, are described. The moisture vapor retention characteristics of the laminate film for long term chub performance was determined. The stability, mechanical integrity, and thermal performance of chubs following mechanical shock, vibration, and temperature extremes is reported.

Frysinger, G. R.↗

Prolonging the Life of Refractory Fillers

Useful life of refractory glass-cloth gap filler is increased by coating it with a suspension of silicon carbide in butanol and polyethylene. Coating is applied to refractory-fiber cloth filler that seals gaps between insulating tiles on Space Shuttle orbiter. Tests showed that cloth fibers would be embrittled by extreme temperatures encountered on reentry into Earth's atmosphere and that only 25 percent of the thousands of fillers would be reusable after a mission. With coating, 85 percent of fillers would be reusable.

Schomburg, C.↗

An active alignment scheme for the MPTS array

In order to achieve and maintain required flatness of the antenna array, a rotating laser beam used for leveling applications on earth was utilized as a reference system. A photoconductive sensor with a reflective collecting surface determines the displacement and polarity of any misalignment and automatically engages a stepping motor to drive a variable-length mechanism to make the necessary corrections. Once aligned, little power is dissipated since a nulling bridge circuit that centers on the beam is used. A three-point subarray alignment arrangement is described which independently adjusts, in the three orthogonal directions, the height and tilt of subarrays within the MPTS array and readily adapts to any physical distortions of the secondary structure (such as that resulting from severe temperature extremes caused by an eclipse of the Sun). It is shown that only one rotating laser system is required since optical blockage is minimal on the array surface and that it is possible to incorporate a number of redundant laser systems for reliability without affecting the overall performance.

Iwasaki, R.↗

Design allowables for T300/5208 graphite/epoxy composite materials

Material coupon tests were conducted to formulate design allowables for T300/5208 graphite/epoxy unidirectional tape and bidirectional fabric composites. This paper gives a description of the tests conducted, representative ply level and laminate test data, and results of the statistical analysis. The design allowables for tension and compression strength are given and include the effect of notches, impact damage, temperature extremes and moisture absorption.

Ekvall, J. C.↗

A corundum-rich inclusion in the Murchison carbonaceous chondrite

Although thermodynamic calculations predict corundum to be the first condensate from a cooling gas of solar composition, a corundum-hibonite inclusion, BB-5, has for the first time been found in the Murchison carbonaceous chondrite. Ion microprobe measurements of Mg isotopic compositions yield the result, unexpected in such an early condensate, that Mg-26 excesses are small despite large Al-27/Mg-24 ratios. The extreme temperature required to melt this inclusion makes a liquid origin unlikely, except by the hypervelocity impact of refractory bodies. Alternatively, B-5 is a direct gas-solid condensate, and its uniform Mg-26 enrichment must be a characteristic of the reservoir from which it condensed. Nebular heterogeneity in magnesium isotopic composition is the preferred explanation for the formation of such a reservoir.

Bar-Matthews, M.↗

Fiber optic experiment for the Shuttle long-duration exposure facility

The present investigation is concerned with an active fiber-optic data transmission experiment which has been under development for a planned orbital exposure on the Shuttle Long Duration Exposure Facility (LDEF) and subsequent recovery for laboratory evaluation. The LDEF is a space shuttle payload which is designed to carry a large number of independent tray-mounted experiments into low earth orbit for exposure to the space environment. The LDEF is then to be recovered by a later shuttle flight for postflight examination. Data is stored on a tape recorder within the experiment tray; no telemetry is provided. A description is given of two independent experiment trays which are being prepared. The experiments are to be conducted to gain experience in the design of a complete fiber link for the space environment and to confirm that the effects of the critical environments in space, in particular particle radiation and temperature extremes, are not detrimental to satisfactory link operation.

Johnston, A. R.↗

Tribological systems as applied to aircraft engines

Tribological systems as applied to aircraft are reviewed. The importance of understanding the fundamental concepts involved in such systems is discussed. Basic properties of materials which can be related to adhesion, friction and wear are presented and correlated with tribology. Surface processes including deposition and treatment are addressed in relation to their present and future application to aircraft components such as bearings, gears and seals. Lubrication of components with both liquids and solids is discussed. Advances in both new liquid molecular structures and additives for those structures are reviewed and related to the needs of advanced engines. Solids and polymer composites are suggested for increasing use and ceramic coatings containing fluoride compounds are offered for the extreme temperatures encountered in such components as advanced bearings and seals.

Buckley, D. H.↗

Reciprocating magnetic refrigerator employing tandem porous matrices within a reciprocating displacer

Disclosed is a method and apparatus for a magnetic refrigeration system. A continuously reciprocating displacer houses at least a pair of paramagnetic substances each of which is alternately driven into and out of a magnetic field. Two separate bidirectional pumping systems flow helium gas through the displacer and through both paramagnetic substances to create heat exchange conditions at two separate temperature extremes.

Johnson, D. L.↗

Reciprocating magnetic refrigerator

A 4 to 15 K magnetic refrigerator to test as an alternative to the Joule-Thomson circuit as the low temperature stage of a 4 to 300 K closed-cycle refrigerator was developed. The reciprocating magnetic refrigerator consists of two matrices of gadolinium gallium garnet spheres located in tandem on a single piston which alternately moves each matrix into a 7 telsa magnetic field. A separate helium gas circuit is used as the heat exchange mechanism for the low and the high temperature extremes of the magnetic refrigerator. Details of the design and results of the initial refrigerator component tests are presented.

Johnson, D. L.↗

Thermal analysis of the ACCESS space truss

This paper introduces the Assembly Concept for the Construction of Erectable Space Structure (ACCESS) experiment and describes the thermal requirements in detail. The experiment, an erectable truss beam to be flown and assembled aboard the Space Shuttle, was thermally modeled using the TRASYS and SINDA computer codes. Results from the thermal analysis are presented. Development tests dictate the application of a metallized film insulation on the aluminum beam struts to control transient orbital temperature extremes.

Foss, R. A.↗

The MC and LFC cameras

The characteristics of the shuttle-borne Large Format Camera are listed. The LFC focal plane format was 23 by 46 cm, double the usual size, thereby acquiring approximately double the ground area. Forward motion compensation was employed. With the stable platform (shuttle) it was possible to use the slow exposure, high resolution, Kodak aerial films; 3414 and 3412 black and white, SO-242 color, and SO-131 aerochrome infrared. The camera was designed to maintain stability during varying temperature extremes of space.

Norton, Clarice L.↗

Design considerations for a Martian Balloon Rover

The present NASA-sponsored design feasibility study for a balloon-borne sensor platform that is to be used over environmentally dissimilar sites on Mars gives attention to specific environmental and configurational parameters of a baseline balloon design, with a view to day/night altitude variations in response to temperature extremes. It is concluded that a Martian Balloon Rover can be developed using current technology; projected reductions in high-strength fabric density and radiation-resistant coatings will further enhance mission effectiveness, permitting either balloon size reductions or payload capacity increases.

Redd, F.↗

Applications of heat pipes to cool PWBS and hybrid microcircuits

Some of the advanced thermal management techniques used to reduce operating junction temperature under extreme environmental temperature conditions are discussed. Heat pipes in actual electronic packaging applications, and those under development, are discussed. Performance characteristics of heat pipes are given, and examples are described of how thermal problems in electronic packaging are solved through the use of heat pipes.

Sekhon, K. S.↗