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A SOLAR TEST COLLECTOR FOR EVALUATION OF BOTH SELECTIVE AND NON-SELECTIVE ABSORBERS

Description: A solar test collector was designed for the testing of thermally absorbing coatings under controlled conditions. The design consisted of a collector fed by a controlled temperature fluid within the range of 25-90 C (77-194 F). This temperature was maintained by a custom electronic controller. A small variable flow pump circulated water through three collector pipes at selected flow rates. Strip heaters coupled with a differential temperature controller compensated for edge losses associated with small collectors. Detailed design and operation data were presented and three black chrome and one nonselective absorber were analyzed in detail by test collector measurements. Results showed efficiencies as high as 77% and 75% ({Delta}T = 0) were obtained respectively for 1.0 {micro}m black chrome on copper and nickel plated steel. The lowest loss coefficients were about 3.8 w/m{sup 2} C for all black chrome/metal surfaces with the highest being 8.4 w/m{sup 2} C for the black paint/metal sample. Also, a collector model was presented for comparison.
Date: June 1, 1978
Creator: Lampert, Carl M. & Washburn, Jack
Partner: UNT Libraries Government Documents Department

Black chrome outgassing study

Description: This report covers why black chrome is of interest, why its outgassing is relevant, how the study was conducted, examples of resultant data, and a conclusion. Black chrome is of interest in several areas of activity. Vacuum outgassing characteristics must be known to establish the pumping speed requirements. How much gas is evolved determines the pump speed required. The species of gas evolved determines the type of pump. The outgassing characteristics must be known to determine needed precleaning steps.
Date: January 1, 1979
Creator: Beat, T.
Partner: UNT Libraries Government Documents Department

Test results, Industrial Solar Technology parabolic trough solar collector

Description: Sandia National Laboratories and Industrial Solar Technology are cost-sharing development of advanced parabolic trough technology. As part of this effort, several configurations of an IST solar collector were tested to determine the collector efficiency and thermal losses with black chrome and black nickel receiver selective coatings, combined with aluminized film and silver film reflectors, using standard Pyrex{reg_sign} and anti-reflective coated Pyrex{reg_sign} glass receiver envelopes. The development effort has been successful, producing an advanced collector with 77% optical efficiency, using silver-film reflectors, a black nickel receiver coating, and a solgel anti-reflective glass receiver envelope. For each receiver configuration, performance equations were empirically derived relating collector efficiency and thermal losses to the operating temperature. Finally, equations were derived showing collector performance as a function of input insolation value, incident angle, and operating temperature.
Date: November 1, 1995
Creator: Dudley, V.E.; Evans, L.R. & Matthews, C.W.
Partner: UNT Libraries Government Documents Department

Absorber coatings' degradation

Description: This report is intended to document some of the Los Alamos efforts that have been carried out under the Department of Energy (DOE) Active Heating and Cooling Materials Reliability, Maintainability, and Exposure Testing program. Funding for these activities is obtained directly from DOE although they represent a variety of projects and coordination with other agencies. Major limitations to the use of solar energy are the uncertain reliability and lifetimes of solar systems. This program is aimed at determining material operating limitations, durabilities, and failure modes such that materials improvements can be made and lifetimes can be extended. Although many active and passive materials and systems are being studied at Los Alamos, this paper will concentrate on absorber coatings and degradation of these coatings.
Date: January 1, 1984
Creator: Moore, S.W.
Partner: UNT Libraries Government Documents Department

Long-term weathering effects on the thermal performance of the Lennox/Honeywell (liquid) solar collector

Description: The test procedures used and the results obtained during the evaluation test program of the Lennox/Honeywell double covered liquid solar collector are presented. The tests were performed under simulated conditions, following long-term exposure to natural weathering conditions. The Lennox/Honeywell collector is a flat-plate solar collector. The absorber plate is steel with copper tubes bonded on the upper surface, and is coated with black chrome with an absorptivity factor of .95 and emissivity factor of .12. It has a double glass cover of 1/8-inch tempered glass and weighs about 153 pounds. The overall dimensions of the collector are 3' x 6' x 6-1/2''.
Date: November 1, 1978
Partner: UNT Libraries Government Documents Department

Black germanium selective absorber surfaces. Semi-annual progress report, September 1, 1978-March 1, 1979

Description: It was shown that by controlling the sputtering preparation conditions of noncrystalline Ge films the surface microstructure can be drastically altered by simply etching in 30% H/sub 2/O/sub 2/. The resulting surface has a total reflectance of less than 3% in the solar spectrum. This flat-black surface appearance is shown to be due to a dense array of aligned, needle-like protrusions which have an extremely high aspect ratio and both a cross-sectional area and a separation between needles on the order of the wavelength of solar radiation. A systematic series of thin films were prepared by rf-sputtering with rf-power and Ar gas pressure as the primary preparation parameters and characterizing the various films.
Date: April 23, 1979
Creator: Messier, R F & Vedam, K
Partner: UNT Libraries Government Documents Department

Thermal performance evaluation of the Calmac (liquid) solar collector

Description: The procedures used and the results obtained during the evaluation test program on the Calmac Manufacturing Company, S.N.1, (Liquid) Solar Collector are presented. The flat-plate collector uses water as the working fluid. The absorber plate is aluminum with plastic tubes coated with Urethane black. The glazing consists of a single .040'' Fiberglas reinforced polyester (Kalwall). The collector weight is 78.5 pounds with overall external dimensions of approximately 50.3'' x 98.3'' x 3.8''. The test program was conducted to obtain the following information: Thermal performance data under simulated conditions, structural behavior under static loading and the effects of long-term exposure to natural weathering. These tests were conducted using the MSFC Solar Simulator.
Date: June 23, 1978
Creator: Usher, H.
Partner: UNT Libraries Government Documents Department

Long term weathering effects on the thermal performance of the Solaron (air) solar collector

Description: The test procedures and the results obtained during the evaluation test program on the Solaron Corporation air-type solar collector are presented. The tests were performed under simulated conditions, following long-term exposure to natural weathering conditions. The Solaron Model 2001, air-type solar collector has a gross area of 19 square feet (35.25'' x 77.63'') and the weight is 160 pounds. The absorber plate is made of 24-gage steel, the coating is baked-on black paint, the cover consists of two sheets of 1/8-inch low-iron tempered glass, and the insulation is one thickness of 3 5/8-inch fiberglass batting.
Date: March 1, 1979
Partner: UNT Libraries Government Documents Department

Microstructure and optical properties of black chrome befor and after exposure to high temperatures

Description: the chemical and microstructural stability of the CHROM-ONYX type of black chrome solar coating was investigated at different temperatures and atmospheres. This was done to give a better understanding of the mechanism of solar energy selectivity and its variability when subjected to short term heat treatments. The as-plated structure was found to consist of a suspension of metallic chromium particles within the size range of 100A in a amorphous oxide matrix. this assembly was in turn formed into larger particles within the size range of 0.05 to 0.30 microns. Short term high temperature heat treatments were used to simulate stagnation conditions. Samples were annealed in both air and vacuum, which resulted in similar characteristics. Annealing in air appeared to mildly accelerate optical degradation at high temperatures. For short term heat treatments below 300/sup 0/C the reflective and microstructural properties appeared to be unchanged. By in situ vacuum annealing of the coating above 400/sup 0/C microscrystalline Cr/sub 2/O/sub 3/ was identified. By observation of diffraction patterns it was concluded that a-Cr/sub 2/O/sub 3/ was transformed into crystalline Cr/sub 2/O/sub 3/. The Cr/sub 2/O/sub 3/ phase continued to grow at higher temperatures at the expense of chromium content. At temperatures above 500/sup 0/C in vacuum, a new phase identified as Cr/sub 3/O/sub 4/ formed. It was found that black chrome failed optically between 500 to 600/sup 0/C for 1 hour heat treatments in both air and vacuum; also the coating heated in air failed mechanically by peeling at 600/sup 0/C.
Date: January 1, 1979
Creator: Lampert, C.M. & Washburn, J.
Partner: UNT Libraries Government Documents Department

Selective paint and black chrome coatings development. Semiannual report, June 5-December 5, 1978

Description: Solar selective black chrome and paint coatings were investigated to improve their performance and to develop techniques for large-scale applications. Formulations and processing conditions for thickness sensitive paint coatings were defined which consistently provide solar absorptance (..cap alpha..) of 0.90 and emittance (epsilon) of 0.10 on low emittance substrates. A significant improvement in abrasion resistance was achieved by decreasing the pigment volume concentration. Addition of aluminum flake to these formulations has resulted in a thickness insensitive coating with ..cap alpha.. = 0.90 and epsilon = 0.30. The critical bath components of a commercial black chrome plating process have been identified as hexavalent chromium, trivalent chromium, acetic acid and ferric ion. These components were varied and their effect on coating optical properties and durability at temperatures of 350-400/sup 0/C were studied. Coating thermal stability was significantly improved by reducing the trivalent chromium concentration from the normal 16 g/l to 12 g/l or less. Initial efforts have begun to optimize black chrome systems on aluminum substrates in terms of cost and durability.
Date: December 1, 1978
Creator: Lin, R J.H. & Zimmer, P B
Partner: UNT Libraries Government Documents Department

Microstructure and optical properties of black chrome before and after exposure to high temperatures

Description: The chemical and microstructural stability of the CHROM-ONYX type of black chrome solar coating was investigated at different temperatures and atmospheres. This was done to give a better understanding of the mechanism of solar energy selectivity and its variability when subjected to short term heat treatments. The as-plated structure was found to consist of a suspension of metallic chromium particles within the size range of 100A in an amorphous oxide matrix. This assembly was in turn formed into larger particles within the size range of 0.05-0.30 microns. Short term high temperature heat treatments were used to simulate stagnation conditions. Samples were annealed in both air and vacuum, which resulted in similar characteristics. Annealing in air appeared to mildly accelerate optical degradation at high temperatures. For short term heat treatments below 300/sup 0/C the reflective and microstructural properties appeared to be unchanged. By in situ vacuum annealing of the coating above 400/sup 0/C microcrystalline Cr/sub 2/O/sub 3/ was identified. By observation of diffraction patterns it was concluded that a-Cr/sub 2/O/sub 3/ was transformed into crystalline Cr/sub 2/O/sub 3/. The Cr/sub 2/O/sub 3/ phase continued to grow at higher temperatures at the expense of chromium content. At temperatures above 500/sup 0/C in vacuum, a new phase identified as NiCr/sub 2/O/sub 4/ formed. It was found that black chrome failed optically between 500-600/sup 0/C for 1 hour heat treatments in both air and vacuum; also the coating heated in air failed mechanically by peeling at 600/sup 0/C.
Date: January 1, 1979
Creator: Lampert, C.M. & Washburn, J.
Partner: UNT Libraries Government Documents Department

Legal aspects of coatings for solar collectors

Description: A number of legal issues are presented by the application and marketing of coatings for solar collectors. Those issues which may be the most relevant to the solar coating industry are addressed with emphasis on the electroplating community. Those issues are: whether coatings are a good or a service; if a service, what liabilities are involved; if a good, what are the warranties involved; and could the consumer recover damages from the electroplater. (MHR)
Date: October 1, 1979
Creator: Noun, R.J.
Partner: UNT Libraries Government Documents Department

Black-chrome solar-selective coatings electrodeposited on metallized-glass tubes

Description: Glass tubes, initially metallized with thin layers of chromium and copper, were electroplated with copper and black chrome. The optical properties of the black-chrome-plated tubes were excellent with ..cap alpha../sub s/ approx. = 0.94 and epsilon/sub TH/ (25/sup 0/C) approx. = 0.08. Thermal-cycling tests of the tubes revealed relatively stable optical properties until temperatures around 400/sup 0/C in vacuum were reached.
Date: unknown
Creator: Grimmer, D.P. & Collier, R.K.
Partner: UNT Libraries Government Documents Department

Passive test-cell experiments during the winter of 1979-1980

Description: During the winter of 1979-80 the performance of a variety of passive solar heating configurations in 14 passive test cells were monitored. The cells included attached greenhouses, masonry and water walls with black-chrome absorber surfaces, night insulation, and phase-change thermal storage walls. The results of these side-by-side tests were used to make quantitative comparisons of the delivered performance of these configurations for the conditions under which they were tested.
Date: November 1, 1981
Creator: Hyde, J.C.
Partner: UNT Libraries Government Documents Department

Dynamic measurement of heat loss coefficients through Trombe wall glazing systems

Description: A Trombe wall presents a unique opportunity to measure the heat-loss coefficient through the glazing system because the wall itself can be used as a heat meter. Since the instantaneous heat flux through the outer wall surface can be determined, the heat loss coefficient at night can be calculated by dividing by the wall surface-to-ambient temperature difference. This technique has been used to determine heat-loss coefficients for Los Alamos test rooms during the winter of 1980-1981. Glazing systems studied include single and double glazing both with and without night insulation used in conjunction with a flat black paint, and both single and double glazing used in conjunction with a selective surface.
Date: January 1, 1981
Creator: Balcomb, J.D.
Partner: UNT Libraries Government Documents Department

Microstructure of a black chrome solar selective absorber

Description: The structure of Harshaw Chemicals' CHROM-ONYX type of black chrome/metal selective absorber was studied to gain a better understanding of its influence upon the mechanism of wavelength selectivity. Spectral reflectance measurements were performed on seven samples. In this study, the best selectivity was found by these measurements to be 1.0 micron of black chrome on copper and 0.7 micron of black chrome on nickel. Both transmission and scanning electron microscopy were employed to study microstructure and chemical composition. As a result of the combined studies, some effects of black chrome thickness and the metallic substrate were determined. It was found that black chrome consisted of a very fine metallic distribution of particles of chromium, possibly suspended within a matrix of an oxide of chromium. This combination was, in turn, agglomerated into larger particles within the 0.05--0.3 micron size range. These larger particles formed a network which constituted the surface coating.
Date: August 1, 1978
Creator: Lampert, C.M.
Partner: UNT Libraries Government Documents Department

A solar test collector for evaluation of both selective and non-selective absorbers

Description: A solar test collector was designed for the testing of thermally absorbing coatings under controlled conditions. The design consisted of a collector fed by a controlled temperature fluid within the range of 25 to 90/sup 0/C (77 to 194/sup 0/F). This temperature was maintained by a custom electronic controller. A small variable flow pump circulated water through three collector pipes at selected flow rates. Strip heaters coupled with a differential temperature controller compensated for edge losses associated with small collectors. Detailed design and operation data were presented and three black chrome and one non-selective absorber were analyzed in detail by test collector measurements. Results showed Efficiencies as high as 77% and 75% (..delta..T = 0) were obtained respectively for 1.0 ..mu..m black chrome on copper and nickel plated steel. The lowest loss coefficients were about 3.8 W/m/sup 2/ /sup 0/C for all black chrome/metal surfaces with the highest being 8.4 W/m/sup 2/ /sup 0/C for the black paint/metal sample.
Date: August 1, 1978
Creator: Lampert, C.M. & Washburn, J.
Partner: UNT Libraries Government Documents Department

Solar collectors. Part II. Recent developments and future performance data and economic analysis

Description: The concepts, materials, and collector types indicative of recent developments in solar collector research for increasing thermal performance are listed by category. The categories are: selective surfaces, honeycombs, all-glass evacuated tube collectors, non-tracking concentrating collectors, tracking concentrating collectors, and heat pipe collectors. (MHR)
Date: January 1, 1978
Creator: Collier, R.K.
Partner: UNT Libraries Government Documents Department

Solar-collector materials exposure to the IPH site environment. Final report

Description: In-situ environmental exposure tests were conducted at nine proposed intermediate-temperature Industrial Process Heat (IPH) sites. Three types of reflector materials were evaluated for survivability at the nine sites: second-surface silvered glass, aluminized acrylic FEK-244 film on aluminum substrate, and Alzak (electropolished aluminum) on aluminum substrate. Black chrome absorber material and low-iron float glass were evaluated for thermal, photochemical, and environmental degradation. The reflector specimens were monitored for decreases in specular and hemispherical reflectance due to soil buildup. The absorber material was evaluated for changes in solar absorptivity and emissivity, and the float glass was monitored for changes in transmissivity. Surface and subsurface defects on all materials were examined microscopically and, where deemed of note, were documented photographically.
Date: January 1, 1982
Creator: Morris, V.L.
Partner: UNT Libraries Government Documents Department

Solar-collector-materials exposure to the IPH site environment. Volume 1. Final report

Description: In-situ environmental exposure tests were conducted at nine proposed intermediate-temperature Industrial Process Heat (IPH) sites. Three types of reflector materials were evaluated for survivability at the nine sites: second-surface silvered glass, aluminized acrylic FEK-244 film on aluminumsubstrate and Alzak (electropolished aluminum) on aluminium substrate. Black chrome absorber material and low-iron float glass were evaluated for thermal, photochemical, and environmental degradation. The reflector specimens were monitored for decreases in specular and hemispherical reflectance due to soil buildup. The absorber material was evaluated for changes in solar absorptivity and emissivity, and the float glass was monitored for changes in transmissivity. Surface and subsurface defects on all materials were examined microscopically and, where deemed of note, were documented photographically.
Date: January 1, 1982
Creator: Morris, V.L.
Partner: UNT Libraries Government Documents Department

SERI Materials Branch semiannual report, January 1, 1978--June 30, 1978

Description: Comprehensive program planning, laboratory development, and cooperative research programs with subcontractors are reported. Initial planning has given direction to the materials research activated by SERI. The program planning activities have been consolidated so that the plans for reflector, absorber, and polymer materials research are complementary to each other and support the Branch effort to assess materials limitations in solar energy conversion systems. New equipment and General Services Administration (GSA) surplus equipment have been obtained or ordered. Laboratories for housing the equipment have been specified, laid out, and are under construction. Cooperative research contracts have been placed with Clarkson College (black chrome degradation) and the Colorado School of Mines (corrosion electrode development, black cobalt preparation and properties, sorption by desiccants). Negotiations are nearly complete for contracts to survey the properties of new thermoelectric materials, to study more corrosion resistant silver alloys for second-surface plastic mirrors, and to study the UV degradation of selected polymers.
Date: August 1, 1978
Creator: Butler, B. L.
Partner: UNT Libraries Government Documents Department