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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Performance correlations of five solar collectors tested simultaneously outdoors

Collector thermal efficiency, and efficiency degradation with time were measured for 5 flat-plate solar collectors tested simultaneously in an outdoor solar collector test facility. Results indicate that by using collector performance parameters which account for diffuse insolation, outdoor data recorded on 'cloudy' days can be used as a measure of performance, as long as the ratio of direct to total insolation exceeds approximately 0.6. These outdoor results also show good agreement with thermal efficiency data obtained indoors in a solar simulator. Significant efficiency degradation occurred on only one of the five collectors exposed to outdoor conditions for a period of one to two years.

Miller, D. R.↗
NASA NTRS1977

Performance evaluation of two black nickel and two black chrome solar collectors

The test program was based on the evaluation of four unique solar collectors described below: (1) black nickel collector surface with a desiccant drying bed, (2) black nickel collector surface without a desiccant drying bed, (3) black chrome collector surface with a dessicant drying bed, and (4) black chrome collector surface without a desiccant drying bed. The test program included three distinct phases: Initial performance evaluation, natural environmental aging, and post-aging performance evaluation. Results of Phase III testing conclusively indicated a higher normalized efficiency for Black Chrome surfaces when compared to Black Nickel.

Losey, R.↗
NASA NTRS1977

Thermal performance of honeywell double covered liquid solar collector

The test procedures and results obtained during an evaluation test program to determine the outdoor performance characteristics of the Honeywell liquid solar collector are presented. The program was based on the thermal evaluation of a Honeywell double covered liquid solar collection. Initial plans included the simultaneous testing of a single covered Honeywell collector. During the initial testing, the single covered collector failed due to leakage; thus, testing continued on the double covered collector only. To better define the operating characteristics of the collector, several additional data points were obtained beyond those requested.

Losey, R.↗
NASA NTRS1978

Design package for concentrating solar collector panels

Information used to evaluate the design of the Northrup concentrating collector is presented. Included are the system performance specifications, the applications manual, and the detailed design drawings of the collector. The collector is a water/glycol/working fluid type, with a dipped galvanized steel housing, transparent acrylic Fresnel lens cover, copper absorber tube, and fiber glass insulation. It weights 98 pounds. A collector assembly includes four collector units within a tracking mount array.

Source record↗
NASA NTRS1978

MSFC hot air collectors

A description of the hot air collector is given that includes a history of development, a history of the materials development, and a program summary. The major portion of the solar energy system cost is the collector. Since the collector is the heart of the system and the most costly subsystem, reducing the cost of producing collectors in large quantities is a major goal. This solar collector is designed to heat air and/or water cheaply and efficiently through the use of solar energy.

Anthony, K.↗
NASA NTRS1978

Analysis and Experimental Tests of a High-Performance Evacuated Tubular Collector

A high-performance collector based on the use of all-glass, evacuated tubular collector elements is described and analyzed, and supporting experimental data presented. The collector operated with excellent efficiency at temperatures high enough to drive existing air conditioning units, and showed good performance under diffuse light and low insolation conditions. Collector efficiency was insensitive to operating temperature, ambient temperature, and wind speed. In addition, air, as well as liquid, can be used as the heat transfer fluid, with no significant performance penalty. While the equations governing the useful energy produced can be cast in a form similar to that for flat plate collectors, several important parameters were unique in a number of respects. The loss coefficient was unusually low, while the flow factor and effective insolation were unusually high.

Beekley, D. C.↗
NASA NTRS1979

The parabolic concentrating collector: A tutorial

A tutorial overview of point-focusing parabolic collectors is presented. Optical and thermal characteristics are discussed. Data representing typical achievable collector efficiencies are presented and the importance of balancing collector cost with concentrator quality is argued through the development of a figure of merit. Various types of two-axis tracking collectors are described. The Department of Energy program to develop these devices is briefly discussed, as are present and projected costs for these collectors.

Truscello, V. C.↗
NASA NTRS1979

An analytical investigation of the performance of solar collectors as nighttime heat radiators in airconditioning cycles

It was found that if the upper and lower ends of a collector were opened, large free convention currents may be set up between the collector surface and the cover glass(es) which can result in appreciable heat rejection. If the collector is so designed that both plates surfaces are exposed to convection currents when the upper and lower ends of the collector enclosure are opened, the heat rejection rate is 300 watts sq m when the plate is 13 C above ambient. This is sufficient to permit a collector array designed to provide 100 percent of the heating needs of a home to reject the accumulated daily air conditioning load during the course of a summer night. This also permits the overall energy requirements for cooling to be reduced by at least 15 percent and shift the load on the utility entirely to the nighttime hours.

Jones, C. B.↗
NASA NTRS1979

Efficiency enhancement of dual-mode traveling wave tubes at saturation and in the linear range by use of spent-beam refocusing and multistage depressed collectors

An axisymmetric, multistage depressed collector of fixed geometric design was evaluated in conjunction with an octave-bandwidth, dual-mode TWT. The TWT was operated over a wide range of conditions to simulate different applications. The collector was operated in three-, four-, and five-stage configurations, and its performance was optimized (within the constraint of fixed geometric design) over the range of TWT operating conditions covered. For operation of the dual-mode TWT at and near saturation, the collectors increased the TWT overall efficiency by a factor of 2 1/2 to 3 1/2. Collector performance was relatively constant for both the high and low TWT modes and for operation of the TWT across an octave bandwidth. For operation of the TWT in the linear, low-distortion range, collector efficiencies of 90 percent and greater were obtained, leading to a five- to twelvefold increase in the TWT overall efficiency for the range of operating conditions covered and reasonably high (greater than 25 percent) overall efficiencies well below saturation.

Ramins, P.↗
NASA NTRS1980

Thermionic converter output as a function of collector temperature

Surprisingly few data are available on the variation of thermionic converter output with collector temperature. In this study the output power density has been measured as a function of collector temperature (at a fixed emitter temperature of 1650 K) for six converters with different electrode combinations. Collector temperatures ranged from 750 to 1100 K. For collector temperatures below 900 K, converters built with sublimed molybdenum oxide collectors gave the best performance.

Stark, G.↗
NASA NTRS1981

Analytical prediction and experimental verification of performance at various operating conditions of a dual-mode traveling wave tube with multistage depressed collectors

A comparison of analytical and experimental results is presented for a high performance dual-mode traveling wave tube (TWT) operated over a wide range conditions. The computations are carried out with advanced multidimensional computer programs. These programs model the electron beam as a series of disks or rings of charge and follow their trajectories from the rf input of the TWT through the slow-wave structure refocusing system to their points of impacts in the depressed collector. TWT performance, collector efficiency, and collector current distribution are computed and compared with measurements. Very good agreement was obtained between computed and measured TWT performance and collector efficiencies, and the computer design of a highly efficient collector was demonstrated.

Dayton, J. A., Jr.↗
NASA NTRS1981

Performance of computer-designed small-sized four-stage depressed collector for operation of dual-mode traveling wave tube

A computer-designed axisymmetric 2.4-cm-diameter four-stage depressed collectors was evaluated in conjunction with an octave bandwidth, dual-mode traveling wave tube (TWT). The TWT was operated over a wide range of conditions to simulate different applications. The collector performance was optimized (within the constraint of fixed collector geometry which was designed for operation of the TWT at saturation) over the range of TWT operating conditons covered. For operation of the dual-mode TWT at saturation, average collector efficiencies of 81 1/2 and 82 percent for the high and low modes, respectively, were obtained across an octave bandwidth, leading to a three-fold increase in the TWT overall efficiency. For operation of the TWT in the linear, low distortion range, collector efficiencies of 87 to 92 percent were obtained, leading to TWT overall efficiencies as high as 35 percent. For operation of the dual-mode TWT over a 10 to 1 range in output power, overall efficiencies of 14 to 41 percent were obtained.

Ramins, P.↗
NASA NTRS1990

Wide acceptance angle, high concentration ratio, optical collector

The invention is directed to an optical collector requiring a wide acceptance angle, and a high concentration ratio. The invention is particularly adapted for use in solar collectors of cassegrain design. The optical collector system includes a parabolic circular concave primary mirror and a hyperbolic circular convex secondary mirror. The primary mirror includes a circular hole located at its center wherein a solar collector is located. The mirrored surface of the secondary mirror has three distinct zones: a center circle, an on-axis annulus, and an off-axis section. The parabolic shape of the primary mirror is chosen so that the primary mirror reflects light entering the system on-axis onto the on-axis annulus. A substantial amount of light entering the system off-axis is reflected by the primary mirror onto either the off-axis section or onto the center circle. Subsequently, the off-axis sections reflect the off-axis light toward the solar collector. Thus, off-axis light is captured which would otherwise be lost to the system. The novelty of the system appears to lie in the configuration of the primary mirror which focuses off-axis light onto an annular portion of the secondary mirror to enable capture thereof. This feature results in wide acceptance angle and a high concentration ratio, and also compensates for the effects of non-specular reflection, and enables a cassegrain configuration to be used where such characteristics are required.

Kruer, Mark Arthur↗
NASA NTRS1992

Solar radiation on a catenary collector

A tent-shaped structure with a flexible photovoltaic blanket acting as a catenary collector is presented. The shadow cast by one side of the collector produces a shadow on the other side of the collector. This self-shading effect is analyzed. The direct beam, the diffuse, and the albedo radiation on the collector are determined. An example is given for the insolation on the collector operating on Viking Lander 1 (VL1).

Crutchik, M.↗
NASA NTRS2019

Metallized Plastic Current Collectors

Metallized plastic current collectors are an innovation patented by the Soteria Battery Innovation Group with the promise of isolating active material involved in an internal short by vaporizing and isolating the short from the rest of the cell electrode jellyroll or stack. Partnering with NREL, UCL, Coulometrics, and Soteria, NASA is leading a research effort into demonstrating the merits and understanding the phenomena of this safety innovation using prototype 18650 cylindrical cells vs control cells with standard metal foil current collectors. Cells with and without the plastic collector, with and without the on-demand internal short circuit device, and with polymer or cellulose separators were made. Safety evaluations were done with driving cells into thermal runaway (TR) with thermal and nail penetration triggers while inside our TR calorimeter and with ultra high speed X-ray videography provided at Synchrotrons. Preliminary results suggests that the thermally unstable plastic current collector innovation has great promise for preventing TR or reducing the severity of the TR output.

Li-ion cell↗
NASA NTRS2024

Removing Contamination From Genesis Sapphire Collectors By Polishing

The Array Collectors of the Genesis spacecraft collected bulk solar wind (SW), as well as three subsets of SW (fast, slow, and coronal mass ejection) in a variety of materials. In all cases the SW implant peaked within < 0.2 microns of the surface. So, when the sample return capsule crashed on landing, cleaning the surfaces for analysis became an extremely difficult, but imperative, task. One collector material was “sapphire”, commercial single crystal corundum. Only ~7.7% of the Genesis Array collectors were sapphire (SAP) but a much higher percentage survived the crash. In fact, surviving bulk SW sapphire collectors have an average area ~10x that of their silicon counterparts since SAP is physically tough, and hard (MOHS 9, by definition) as well as is chemically inert. So, SAP is a good candidate for analytical techniques for measuring SW that require clean areas larger than a millimeter; e.g., synchrotron TXRF and INAA. It is also possible to measure SW in SAP using laser ablation and secondary ion mass spectrometry (SIMS) and, recently, more researchers are choosing to analyze sapphire. Thus, removing surface contamination from SAP could enable many research projects. This report extends the task presented in Schmeling et al. ([4]) that used polishing compounds to remove contamination from Genesis sapphire. It focuses on how polishing with their two top candidates (colloidal silica and cerium oxide) affects the SW layer in SAP.

Genesis solar wind↗
NASA NTRS1973

Flat-plate collector performance evaluation. The case for a solar simulation approach

A method is proposed for determining the performance of flat-plate solar collector using a simulated sun. Collector test variables that will help establish the basis for the indoor test facility at the Lewis Research Center are discussed. The use of the indoor testing should permit a standard test for the convenient and accurate determination of collector performance. Preliminary test results are reported as an example of the type of collector performance data to be expected from the simulation approach.

Simon, F. F.↗
NASA NTRS1974

Flat plate collector performance determined experimentally with a solar simulator

The NASA is constructing a new office building at Langley Research Center that will utilize solar energy for heating and cooling. A collector technology program being conducted at Lewis will provide the basis for selecting collectors for use at Langley. The technology program includes testing collectors in an indoor facility under simulated solar radiation. Tests have been conducted on five collectors to date and performance data are presented herein.

Vernon, R. W.↗