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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Comparative evaluation of distributed-collector solar thermal electric power plants

Distributed-collector solar thermal-electric power plants are compared by projecting power plant economics of selected systems to the 1990-2000 timeframe. The approach taken is to evaluate the performance of the selected systems under the same weather conditions. Capital and operational costs are estimated for each system. Energy costs are calculated for different plant sizes based on the plant performance and the corresponding capital and maintenance costs. Optimum systems are then determined as the systems with the minimum energy costs for a given load factor. The optimum system is comprised of the best combination of subsystems which give the minimum energy cost for every plant size. Sensitivity analysis is done around the optimum point for various plant parameters.

Fujita, T.↗
NASA NTRS1978

Magnetically confined plasma solar collector

The possibility of using a plasma medium for collecting solar energy in space is examined on the basis of a concept involving an orbiting magnetic bottle in which a solar-energy-absorbing plasma is confined. A basic system uses monatomic cesium as working fluid. Cesium evaporates from a source and flows into the useful volume of a magnetic bottle where it is photoionized by solar radiation. Ions and electrons lost through the loss cones are processed by a recovery system, which might be a combination of electromagnetic devices and heat engines. This study concentrates on the plasma production processes and size requirements, estimates of the magnetic field required to confine the plasma, and an estimate of the system parameters for a 10 GW solar collector using cesium.

Walters, C. T.↗
NASA NTRS1978

Efficiency degradation due to tracking errors for point focusing solar collectors

An important parameter in the design of point focusing solar collectors is the intercept factor which is a measure of efficiency and of energy available for use in the receiver. Using statistical methods, an expression of the expected value of the intercept factor is derived for various configurations and control law implementations. The analysis assumes that a radially symmetric flux distribution (not necessarily Gaussian) is generated at the focal plane due to the sun's finite image and various reflector errors. The time-varying tracking errors are assumed to be uniformly distributed within the threshold limits and allows the expected value calculation.

Hughes, R. O.↗
NASA NTRS1978

Protection of solar collector materials from UV

Certain plastic films, such as KAPTON, are known to be stable with excellent long-term aging characteristics under intense uv radiation. Our recent measurements of the optical transmission spectra of KAPTON films show an absorption edge in the blue and are interpreted in terms of an electronic excitation mechanism. The application of this type of film as covering for solar collectors is discussed in regard to the protection this strong uv absorption offers to the materials underneath.

Castle, J. G., Jr.↗
NASA NTRS1980

Indoor tests of the concentric-tube solar collector

Report describes performance tests on 12-tube, liquid-filled collector. Thermal efficiency, change in efficiency with sun position, and time constant for temperature drop after solar flux is cut are described.

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NASA NTRS1980

Evacuated-tube solar collector--performance evaluation

Report gives thermal performance test procedures and results for commercially produced, water-filled, 8-tube collectors. Tests include efficiency, time constant for temperature drop after solar flux is cut, change in efficiency as function of sun angle, and test to see if tubes break when filled with hot water.

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NASA NTRS1980

Glycol/water evacuated-tube solar collector

Report describes performance of 8 tube and 10 tube commercially produced solar collectors. Tests include thermal efficiency, time constant for temperature drop after solar flux is cut, change in efficiency with Sun angle, and temperature rise if circulation is stopped.

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NASA NTRS1980

Fresnel lens tracking solar collector

Commercial tracking collector that uses acrylic Fresnel lenses to focus Sunlight on copper absorber tubes was evaluated. Tests are documented in 16 page report.

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NASA NTRS1980

Outdoor tests of the concentric-tube collector

Seventy two element, air-filled version of concentric-tube solar collector recently underwent 2 month performance evaluation at Marshall Space Flight Center solar house. Summary of results, along with other relevant data, is presented in 27 page report.

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NASA NTRS1980

Selective optical coatings for solar collectors

For best performance, energy-absorbing surface of solar collector should be characterized by high ratio of solar absorptance to thermal emitance. Report on optical characteristics of several chemical treatments and electrodeposited coatings for metal solar-absorbing surfaces should interest designers and users of solar-energy systems. Moisture resistance of some coatings is also reported.

Lowery, J. R.↗
NASA NTRS1980

A test program for solar collectors

Rigorous environmental and performance tests qualify solar collector for use in residential solar-energy systems. Testing over 7 month period examined pressurized effects, wind and snow loading, hail damage, solar and thermal degradation, effects of pollutants, efficiency, and outgassing. Test procedures and results are summarized in tables, graphs, and text.

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NASA NTRS1981

Evaluation of an evacuated-tube liquid solar collector

Indoor and outdoor thermal performances of collectors are compared in report. Tests conducted on indoor solar simulator with data from both diffuse and specular reflectors are presented graphically and in tables. Comparisons with previous data for prototype show effects of improved mainfold.

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NASA NTRS1980

Heat and electricity from the Sun using parabolic dish collector systems

Point focus distributed receiver solar thermal technology for the production of electric power and of industrial process heat is addressed. The thermal power systems project which emphasizes the development of cost effective systems which will accelerate the commercialization and industrialization of plants up to 10 MWe, using parabolic dish collectors is described. The projected size of the isolated load market in the 1990-2000 time period is 300 to 1000 MW/year. Although this market is small in comparison to the grid connected utility market, it is indicated that by assuming only a 20 percent market penetration, up to 10,000 power modules per year would be required to meet this need. At a production rate of 25,000 units/year and assuming no energy storage, levelized bus bar energy costs of 75 mills/kWeh are projected. These numbers are based on what is believed to be a conservative estimate regarding engine-generator conversion efficiency (40 percent) for the 1990 time period. With a more optimistic estimate of efficiency (i.e., 45 percent), the bus bar cost decreases to about 67 mills/kWeh. At very large production rates (400,000 modules/years), the costs decrease to 58 mills/kWeh. Finally, the present status of the technology development effort is discussed.

Truscello, V. C.↗
NASA NTRS1980

Line-focus concentrating collector program

The Line-Focus Concentrating Collector Program has emphasized the development and dissemination of concentrating solar technology in which the reflected sunlight is focused onto a linear or line receiver. Although a number of different types of line-focus concentrators were developed, the parabolic trough has gained the widest acceptance and utilization within the industrial and applications sectors. The trough is best applied for application scenarios which require temperatures between 140 and 600 F. Another concept, the bowl, is investigated for applications which may require temperatures in the range between 600 and 1200 F. Current technology emphases are upon the reduction of system installation cost and the implementation of production oriented engineering.

Dugan, V. L.↗
NASA NTRS1979

Heat and electricity from the sun using parabolic dish collector systems

The paper investigates point focus distributed receiver (PFDR) solar thermal technology for the production of electric power and of industrial process heat. Attention is given to a thermal systems project conducted by JPL under DOE sponsorship. It is reported that project emphasis is on the development of cost-effective systems which will accelerate the commercialization and industrialization of plants up to 10 MWe, using parabolic dish collectors. Also discussed are the characteristics of PFDR systems, the cost targets for major systems hardware, and markets for this technology. Finally, the present system status of the technology development effort is discussed.

Truscello, V. C.↗
NASA NTRS1979

Analysis and two years of testing of the vee-trough concentrator/evacuated tube solar collector

The paper summarizes the mathematical analysis and presents the experimental results for a vee-trough/evacuated tube collector (VTETC). Test results reported represent the performance of the VTETC based on an aperture area. The effectiveness of vee-trough reflectors is demonstrated by comparing the useful heat collected by a receiver tube with and without concentrators.

Selcuk, M. K.↗