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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 235 records · Page 13

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NASA NTRS1977

Investigation of test methods, material properties and processes for solar cell encapsulants

The potentially useful encapsulating materials for Task 3 of the Low-Cost Silicon Solar Array project were studied to identify, evaluate, and recommend encapsulant materials and processes for the production of cost-effective, long-life solar cell modules. Materials for study were chosen on the basis of existing knowledge of generic chemical types having high resistance to environmental weathering. The materials varied from rubbers to thermoplastics and presented a broad range of mechanical properties and processing requirements. Basic physical and optical properties were measured on the polymers and were redetermined after exposure to indoor artificial accelerated aging conditions covering four time periods. Strengths and weaknesses of the various materials were revealed and data was accumulated for the development of predictive methodologies. To date, silicone rubbers, fluorocarbons, and acrylic polymers appear to have the most promising combination of characteristics. The fluorocarbons may be used only as films, however, because of their high cost.

Willis, P. B.↗

NASA NTRS1976

Evaluation of a cost-effective loads approach

A shock spectra/impedance method for loads predictions is used to estimate member loads for the Viking Orbiter, a 7800-lb interplanetary spacecraft that has been designed using transient loads analysis techniques. The transient loads analysis approach leads to a lightweight structure but requires complex and costly analyses. To reduce complexity and cost, a shock spectra/impedance method is currently being used to design the Mariner Jupiter Saturn spacecraft. This method has the advantage of using low-cost in-house loads analysis techniques and typically results in more conservative structural loads. The method is evaluated by comparing the increase in Viking member loads to the loads obtained by the transient loads analysis approach. An estimate of the weight penalty incurred by using this method is presented. The paper also compares the calculated flight loads from the transient loads analyses and the shock spectra/impedance method to measured flight data.

Garba, J. A.↗

NASA NTRS1976

Alternative strategies for implementing silicon-ribbon technology for photovoltaic applications

Interactive computer models are being designed to support the development of technological and economic data required to define the potential of silicon sheet growth for large scale photovoltaic applications. Technology projection and sensitivity analysis suggest that single-ribbon growth systems offer the best potential for achieving low-cost silicon sheet material within the shortest period of time. Such systems must be highly reliable, be capable of near unattended growth, and feature automatic melt replenishment. Processing-technology improvement, such as the following, are the key elements for reducing the cost of silicon sheet material: (i) increasing ribbon width; (ii) speeding up the growth rate; and (iii) decreasing ribbon thickness. Such tasks should be pursued in that order to minimize sheet material cost. One interesting finding is that significant reductions in sheet material cost are achievable in the near future by increasing ribbon width to 5 cm.

Kran, A.↗

NASA NTRS1977

Heterojunctions in photovoltaic devices

Heterojunctions have interesting optical properties which make them attractive for solar cells. Several types of heterostructure solar cells have been investigated: heteroface, abrupt heterojunction, and graded-gap heterojunction solar cells. The primary advantage of heterostructure cells is the enhanced short-wavelength response although there is potential for low-cost cells with polycrystalline material. The improvement in solar-cell performance for heterojunctions depends upon the selection of semiconductors with useful energy gaps that are closely matched in lattice-spacing and thermal-expansion coefficients. The importance of the heterojunction interface and its dependence on material properties is discussed. Various fabrication methods are discussed and their application to the different types of heterostructures. Recent performance data for material systems representative of each type of heterostructure cell are discussed and considered in terms of maximum expected performance.

Feucht, D. L.↗

NASA NTRS1976

The Communications Technology Satellite /CTS/ Program

The purposes of the joint Canadian-U.S. Communications Technology Satellite (CTS) Program are (1) to conduct satellite communication systems experiments using the 12- and 14-GHz bands and low-cost transportable ground terminals, (2) to develop and flight test a power amplifier tube having a greater than 50% efficiency with a saturated power output of 200 W at 12 GHz, (3) to develop and flight test a lightweight extendible solar array with an initial power output greater than 1 kW, and (4) to develop and flight test a 3-axis stabilization system to maintain accurate antenna boresight positioning on a spacecraft with flexible appendages. Brief descriptions of these experiments and of the ground facilities are provided.

Evans, W. M.↗

NASA NTRS1976

Hydrogen production from coal using a nuclear heat source

A strong candidate for hydrogen production in the intermediate time frame of 1985 to 1995 is a coal-based process using a high-temperature gas-cooled reactor (HTGR) as a heat source. Expected process efficiencies in the range of 60 to 70% are considerably higher than all other hydrogen production processes except steam reforming of a natural gas. The process involves the preparation of a coal liquid, hydrogasification of that liquid, and steam reforming of the resulting gaseous or light liquid product. A study showing process efficiency and cost of hydrogen vs nuclear reactor core outlet temperature has been completed, and shows diminishing returns at process temperatures above about 1500 F. A possible scenario combining the relatively abundant and low-cost Western coal deposits with the Gulf Coast hydrogen users is presented which provides high-energy density transportation utilizing coal liquids and uranium.

Quade, R. N.↗

NASA NTRS1976

An analytical and experimental evaluation of the plano-cylindrical Fresnel lens solar concentrator

Plastic Fresnel lenses for solar concentration are attractive because of potential for low-cost mass production. An analytical and experimental evaluation of line-focusing Fresnel lenses with application potential in the 200 to 370 C range is reported. Analytical techniques were formulated to assess the solar transmission and imaging properties of a grooves-down lens. Experimentation was based primarily on a 56 cm-wide lens with f-number 1.0. A sun-tracking heliostat provided a non-moving solar source. Measured data indicated more spreading at the profile base than analytically predicted. The measured and computed transmittances were 85 and 87% respectively. Preliminary testing with a second lens (1.85 m) indicated that modified manufacturing techniques corrected the profile spreading problem.

Hastings, L. J.↗

NASA NTRS1976

Producibility aspects of advanced composites for an L-1011 Aileron

The design of advanced composite aileron suitable for long-term service on transport aircraft includes Kevlar 49 fabric skins on honeycomb sandwich covers, hybrid graphite/Kevlar 49 ribs and spars, and graphite/epoxy fittings. Weight and cost savings of 28 and 20 percent, respectively, are predicted by comparison with the production metallic aileron. The structural integrity of the design has been substantiated by analysis and static tests of subcomponents. The producibility considerations played a key role in the selection of design concepts with potential for low-cost production. Simplicity in fabrication is a major factor in achieving low cost using advanced tooling and manufacturing methods such as net molding to size, draping, forming broadgoods, and cocuring components. A broadgoods dispensing machine capable of handling unidirectional and bidirectional prepreg materials in widths ranging from 12 to 42 inches is used for rapid layup of component kits and covers. Existing large autoclaves, platen presses, and shop facilities are fully exploited.

Van Hamersveld, J.↗

NASA NTRS1977

Distress detection, location, and communications using advanced space technology

This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

Sivertson, W. E., Jr.↗

NASA NTRS1977

Spraylon fluorocarbon encapsulation for silicon solar cell arrays

A development program was performed for evaluating, modifying, and optimizing the Lockheed formulated liquid transparent filmforming Spraylon fluorocarbon protective coating for silicon solar cells and modules. The program objectives were designed to meet the requirements of the low-cost automated solar cell array fabrication process. As part of the study, a computer program was used to establish the limits of the safe working stress in the coated silicon solar cell array system under severe thermal shock.

Source record↗

NASA NTRS1976

Application of thick-film technology to solar cell fabrication

Several uses of thick-film technology in solar cell fabrication are discussed. Wrap-around contacts are obtained by first printing and firing a dielectric over the edge and subsequently applying a low-firing temperature conductor. Interconnection of cells into arrays can be achieved by printing and co-firing thick-film pastes, soldering, or with heat-curing conductive epoxies on low-cost substrates. Despite ongoing research, printed (thick) film vitreous protective coatings do not yet offer sufficient optical uniformity and transparency for use on silicon. Ohmic contacts on n- and p-type silicon are considered.

Field, M. B.↗

NASA NTRS1976

Materials for encapsulation systems for terrestrial photovoltaic arrays

The paper is concerned with glass and polymeric candidate materials and processes for potential encapsulation systems that could be used in low-cost long-life terrestrial photovoltaic arrays. The characteristics of encapsulation systems in use are reviewed, and the properties of proposed materials are examined. These materials include acrylics, epoxies, fluorocarbons, polycarbonates, polyesters, polyimides, polyxylylenes, and silicones. Properties of glass types are also considered. The prospects for glass and polymeric systems are analyzed, and the knowledge gained from a study of existing systems is discussed with attention to weather/aging effects, failures, environments, hazards, costs, development efforts, and materials choices.

Carmichael, D. C.↗

NASA NTRS1976

SAMIS - A simulation of the solar array manufacturing industry

SAMIS is a continuing activity of the Project Analysis and Integration Task of the Low-cost Silicon Solar Array Project (LSSA). It provides a standardized procedure for producing reliable estimates of the cost of manufacturing solar arrays or their components. These estimates are based on descriptions of the manufacturing processes which are being studied and developed by LSSA subcontractors and will be used to assess the commercial viability of those processes and to set research priorities.

Chamberlain, R. G.↗

NASA NTRS1976

Single crystal and polycrystalline GaAs solar cells using AMOS technology

A description is given of current technology for fabricating single AMOS (antireflection-coated metal oxide semiconductor) solar cells, with attention given to thermal, plasma, and anodic oxidation, native oxide stripping, and X-ray photoelectron spectroscopy results. Some preliminary results are presented on the chemistry and electrical characterization of such cells, and the characteristics of cells fabricated on sliced polycrystalline GaAs wafers are examined. Consideration is also given to the recrystallization of evaporated Ge films for use as low-cost substrates for polycrystalline GaAs solar cells.

Stirn, R. J.↗

NASA NTRS1977

Long Duration Exposure Facility - A unique mode of Shuttle utilization

The Long Duration Exposure Facility (LDEF) is a Shuttle-transported, reusable, essentially passive facility with accommodations for a wide variety of experiments which require a free-flying carrier for exposure in space. Specifically, the LDEF is tailored to provide low-cost accommodations for experiments which have modest requirements for electrical power and data systems, and for experiments which benefit from postflight laboratory investigations with the retrieved experiment hardware. Each experiment for LDEF will be totally self-contained in a tray. As the interface with the facility has been minimized, the LDEF experimenters will be freed from many of the requirements which have complicated development of space experiments in the past.

Kinard, W. H.↗

NASA NTRS1977

Distress detection, location, and communications using advanced space technology

Sivertson, W. E., Jr.↗

NASA NTRS1976

Firefighters' Radios

Public Technology Inc. asked for NASA assistance to devise the original firefighter's radio. Good short-range radio communications are essential during a fire to coordinate hose lines, rescue victims, and otherwise increase efficiency. Useful firefighting tool is lower cost, more rugged short range two-way radio. Inductorless electronic circuit replaced inductances and coils in radio circuits with combination of transistors and other low-cost components. Substitution promises reduced circuit size and cost. Enhanced electrical performance made radio more durable and improved maintainability by incorporating modular construction.

Source record↗

NASA NTRS2020

An Ultra-long Life, High-performance, Flexible Li-CO2Battery Based on Multifunctional Carbon Electrocatalysts

Integrating CO2 utilization and renewable energy delivery/storage, the rechargeable Li–CO2 battery has been considered as a promising candidate for next-generation secondary batteries. However, high-performance catalyst(s) for efficient formation and decomposition of the discharge product, Li2CO3, are an imperative part of a Li–CO2 battery. The development of flexible Li–CO2 batteries extends their applications into compliant and wearable devices/systems, but at the same time imposes a big challenge for battery fabrication and lifetime enhancement. In this study, a rechargeable quasi-solidus flexible Li–CO2 battery was designed and fabricated using highly active N,S-doped carbon nanotubes (N,S-doped CNTs) as the cathode catalyst, and a smart polymer gel as the flexible electrolyte. This newly-developed flexible Li–CO2 battery exhibited a capacity as high as 23560 mAh g−1 based on the catalyst mass and an ultra-long lifetime of up to 538 cycles with excellent mechanical flexibility. This work provides a platform for the design and development of high-performance flexible Li–CO2 batteries from low-cost, earth-abundant, carbon-based multifunctional cathode catalysts.

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