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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Electric power - Photovoltaic or solar dynamic?

The design of the power system for supplying the Space Station with insolation-generated electricity is the main Phase B task at NASA-Lewis Center. The advantages and limitations of two types of power systems, the photovoltaic arrays (PV) and the solar dynamic system (SD), are discussed from the points of view of cost, overall systems integration, and growth. Subsystems of each of these options are described, and a sketch of a projected SD system is shown. The PV technology is well developed and proven, but its low efficiency calls for solar arrays of large areas, which affect station dynamics, control, and drag compensation. The SD systems would be less costly to operate than VP, and are more efficient, needing less deployed area. The major drawback of the SD is its infancy. The conservative and forgiving designs for some of its components must still be created and tested, and the development risks assessed.

Thomas, R. L.↗
NASA NTRS1986

Voltage Regulators for Photovoltaic Systems

Two simple circuits developed to provide voltage regulation for highvoltage (i.e., is greater than 75 volts) and low-voltage (i.e., is less than 36 volts) photovoltaic/battery power systems. Use of these circuits results in voltage regulator small, low-cost, and reliable, with very low power dissipation. Simple oscillator circuit controls photovoltaic-array current to regulate system voltage and control battery charging. Circuit senses battery (and system) voltage and adjusts array current to keep battery voltage from exceeding maximum voltage.

Delombard, R.↗
NASA NTRS1986

Dynamic characteristics of power-tower space stations with 15-foot truss bays

A power tower space station concept which generates power with photovoltaic arrays and where the truss structure has a bay size of 15 ft is described. Rigid body and flexible body dynamic characteristics are presented for a 75-kW Initial Operating Capability (IOC) and 150-kW and 300-kW growth stations. The transient response of the IOC and 300-kW growth stations to shuttle dock, orbit reboost, and mobile remote manipulator system translation loads are studied. Displacements, accelerations, and bending moments at various locations on the IOC and 300-kW growth stations are presented.

Dorsey, J. T.↗
NASA NTRS1986

Space Station momentum control and reboost requirements for two power generation concepts

Results are presented of dynamic structural analyses of 75 and 300 kW versions of a solar dynamic (SD) power supply for the Space Station (MSS). The SD is being seriously considered as an alternative to solar panels due to lower areal and mass requirements and higher efficiencies. The functioning principle is to use parabolic concentrators to focus sunlight on a heat engine to boil liquids to drive a turbine. Potential problems are foreseen in terms of the torques which would be experienced by the MSS and the subsequent orbital stability effects. The stability would be altered by changing aerodynmaic drag, altered moment of inertia and angular momentum and the altered center of mass location. The problem is exacerbated by the need to first equip the MSS with solar panels while the SD technology is developed. The analysis shows that the attitude control system will need to be redesigned and resized to accommodate MSS growth with either power system. The effects of the rotating parts of the SD system can be minimized, but further studies are required to determine the effects on the pointing accuracy of the SD, which must be 10 times as precise as that needed by a photovoltaic array.

Farmer, J. T.↗
NASA NTRS1985

Potential civil mission applications for space nuclear power systems

It is pointed out that the energy needs of spacecraft over the last 25 years have been met by photovoltaic arrays with batteries, primary fuel cells, and radioisotope thermoelectric generators (RTG). However, it might be difficult to satisfy energy requirements for the next generation of space missions with the currently used energy sources. Applications studies have emphasized the need for a lighter, cheaper, and more compact high-energy source than the scaling up of current technologies would permit. These requirements could be satisfied by a nuclear reactor power system. The joint NASA/DOD/DOE SP-100 program is to explore and evaluate this option. Critical elements of the technology are also to be developed, taking into account space reactor systems of the 100 kW class. The present paper is concerned with some of the civil mission categories and concepts which are enabled or significantly enhanced by the performance characteristics of a nuclear reactor energy system.

Ambrus, J. H.↗
NASA NTRS1985

Thermal energy storage for a space solar dynamic power system

In the past, NASA has employed solar photovoltaic devices for long-duration missions. Thus, the Skylab system has operated with a silicon photovoltaic array and a nickel-cadmium electrochemical system energy storage system. Difficulties regarding the employment of such a system for the larger power requirements of the Space Station are related to a low orbit system efficiency and the large weight of the battery. For this reason the employment of a solar dynamic power system (SDPS) has been considered. The primary components of an SDPS include a concentrating mirror, a heat receiver, a thermal energy storage (TES) system, a thermodynamic heat engine, an alternator, and a heat rejection system. The heat-engine types under consideration are a Brayton cycle engine, an organic Rankine cycle engine, and a free-piston/linear-alternator Stirling cycle engine. Attention is given to a system description, TES integration concepts, and a TES technology assessment.

Faget, N. M.↗
NASA NTRS1987

High-Strength Glass for Solar Applications

Technology for strengthening thin sections reviewed. Report reviews technology of high-strength glass for such solar applications as heat collectors, reflectors, and photovoltaic arrays. Discusses most feasible methods - heat strengthening and chemical strengthening of increasing strength of glass for solar-energy use. Also estimates cost and availability of high-strength glass and considers physical characteristics, amenability to back-silvering, and effects of atmospheric contamination.

Bouquet, F. L.↗
NASA NTRS1987

Assessment Of Advanced Concentrator Photovoltaic Modules

Computer program developed to estimate probabilistically total and component costs to end users of concentrating photovoltaic arrays in 1990's. Based on modified version of SIMRAND program, Simulation of Research and Development projects, -to estimate total cost of system for large number of module designs. Module design that yields minimum cost for total system then chosen as preferred design. To obtain distribution of expected module costs, simulation performed. Component estimates made by SIMRAND include efficiency of module and costs of cell, assembly of cells, lenses, and modules. Written in FORTRAN 77.

Borden, C. S.↗
NASA NTRS1986

Characterization of 2.5 microns HgCdTe detectors for low-background applications

A program of testing aimed at the evaluation of systems that have the potential to provide the level of performance required for use in space-based instruments was undertaken and their usefulness appraised for astronomy. The results of the first phase of the program to characterize selected pixels of a HgCdTe photovoltaic array detector were reported.

Depoy, D. L.↗
NASA NTRS1987

Air Force and DOD solar power requirements

It is noted that future power requirements are increasing for some expanded and new missions within the Air Force and Department of Defense. New requirements are needed in terms of lifetime, survivability, power level and performance. The photovoltaic arrays have a demonstrated record of reliable performance, life, affordable cost, and utility. It is argued that there is a need to push for the research and development resources needed to develop the technology base for these future power system needs.

Wise, Joseph F.↗
NASA NTRS1987

Electrodynamic tether

Electrodynamic tethers hold promise for a variety of space applications. Electrodynamic tethers depend upon the interactions between a moving insulated conductor and the Earth's magnetic field. An electric field is generated along the tether as in a conductor moving in the magnetic field of a generator. If the circuit is closed to the ambient space plasma via a plasma gun or other equivalent device, a current is enabled to flow in the tether, and electric power is generated at the expense of orbital mechanical energy. The net effect is a decrease in the altitude of the orbiting tethered system. The situation can be reversed by driving current against the electric field via an external power supply such as a photovoltaic array.

Patterson, Michael↗
NASA NTRS1988

Analyzing Solar-Power Options For Spacecraft

Solar Space Power Analysis Code, SOSPAC, developed to examine solar-thermal and photovoltaic power-generation options available for satellite or spacecraft in low orbit around Earth. Is software tool for preliminary analysis of systems and enables engineer to compare areas, weights, and costs of several candidate electric- and thermal-power systems. Configurations studied include photovoltaic arrays and paraboloidal-dish systems to produce electricity only and in various combinations to provide both thermal and electric power. Written in FORTRAN IV.

Selcuk, M. K.↗
NASA NTRS1988

Space station power system requirements

Presented is an overview of the requirements on which the Space Station Electric Power System is based as well as a summary of the design itself. The current design, which is based on silicon photovoltaic arrays, NiH2 batteries, and 20 kHz distribution technology, meets all of the requirements.

Dunning, John W., Jr.↗
NASA NTRS1987

Past, present, and future activities in space power technology in the United States of America

Space power technology research in the U.S. is examined. The objectives for advanced power systems are long life, safety, flexibility, modularity, growth capability, and autonomy. Research in the areas of photovoltaic arrays, electrical energy storage, and the development of solar dynamic power systems and radio thermal generators is described. The applications of advances in power generation, energy storage, and power management and distribution to the Space Station are discussed.

Ambrus, Judith H.↗
NASA NTRS1987

Development of 8 cm x 8 cm silicon gridded back solar cell for space station

The 8-cm x 8-cm gridded back cell being developed for the space station photovoltaic array is described. Modeling studies show that the beginning of life power output of 1.039 W per cell may be met by several different configurations, the most promising being either a fielded or nonfielded 2 ohm-cm planar 8-mil cell. Experimental data are presented which show that a thermal alpha of 0.63 is achievable on a planar cell but at the expense of some Isc. Planar cells are found to possess short-circuit currents which are 9 percent lower than on textured cells due to the loss of near-IR radiation by transmission through the cell. Preliminary modeling shows that the efficiency of the textured cell exceeds the planar cell by approximately 9 percent at 25 C but the situation is reversed in orbit due to the high thermal alpha of textured cells (0.82). Experimental data show that the IR absorption in textured cells can be reduced by about 3 alpha points without loss of efficiency by controlling the doping concentration in the diffused layers, thus increasing the efficiency in orbit.

Lillington, D. R.↗
NASA NTRS1988

NASA photovoltaic research and technology

NASA photovoltaic R and D efforts address future Agency space mission needs through a comprehensive, integrated program. Activities range from fundamental studies of materials and devices to technology demonstrations of prototype hardware. The program aims to develop and apply an improved understanding of photovoltaic energy conversion devices and systems that will increase the performance, reduce the mass, and extend the lifetime of photovoltaic arrays for use in space. To that end, there are efforts aimed at improving cell efficiency, reducing the effects of space particulate radiation damage (primarily electrons and protons), developing ultralightweight cells, and developing advanced ray component technology for high efficiency concentrator arrays and high performance, ultralightweight arrays. Current goals that have been quantified for the program are to develop cell and array technology capable of achieving 300 watts/kg for future missions for which mass is a critical factor, or 300 watts/sq m for future missions for which array size is a major driver (i.e., Space Station). A third important goal is to develop cell and array technology which will survive the GEO space radiation environment for at least 10 years.

Flood, Dennis J.↗
NASA NTRS1989

Advances in thin-film solar cells for lightweight space photovoltaic power

The present stature and current research directions of photovoltaic arrays as primary power systems for space are reviewed. There have recently been great advances in the technology of thin-film solar cells for terrestrial applications. In a thin-film solar cell the thickness of the active element is only a few microns; transfer of this technology to space arrays could result in ultralow-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper-indium selenide (CuInSe2) and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon:hydrogen and alloys. The best experimental efficiency on thin-film solar cells to date is 12 percent AMO for CuIn Se2. This efficiency is likely to be increased in the next few years. The radiation tolerance of thin-film materials is far greater than that of single-crystal materials. CuIn Se2 shows no degradation when exposed to 1 MeV electrons. Experimental evidence also suggests that most of all of the radiation damage on thin-films can be removed by a low temperature anneal. The possibility of thin-film multibandgap cascade solar cells is discussed, including the tradeoffs between monolithic and mechanically stacked cells. The best current efficiency for a cascade is 12.5 percent AMO for an amorphous silicon on CuInSe2 multibandgap combination. Higher efficiencies are expected in the future. For several missions, including solar-electric propulsion, a manned Mars mission, and lunar exploration and manufacturing, thin-film photovolatic arrays may be a mission-enabling technology.

Landis, Geoffrey A.↗
NASA NTRS1989

Evolutionary growth for Space Station Freedom electrical power system

Over an operational lifetime of at least 30 yr, Space Station Freedom will encounter increased space station user requirements and advancing technologies. The space station electrical power system is designed with the flexibility to accommodate these emerging technologies and expert systems and is being designed with the necessary software hooks and hardware scars to accommodate increased growth demand. The electrical power system is planned to grow from the initial 75 kW up to 300 kW. The Phase 1 station will utilize photovoltaic arrays to produce the electrical power; however, for growth to 300 kW, solar dynamic power modules will be utilized. Pairs of 25 kW solar dynamic power modules will be added to the station to reach the power growth level. The addition of solar dynamic power in the growth phase places constraints in the initial space station systems such as guidance navigation and control, external thermal, truss structural stiffness, computational capabilities and storage which must be planned-in in order to facilitate the addition of the solar dynamic modules.

Marshall, Matthew F.↗