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Proposed all tempered glass solar collector uses black collection fluid and mirrored bottom to reduce energy loss and overall costs associated with conventional collectors. Collector is more efficient and practically maintenance-free.
The test procedures used to obtain the thermal performance data for a solar collector under simulated conditions are presented. Tests included a stagnation test, a time constant test, a thermal efficiency test, an incident angle modifier test, and a hot fill test. All tests were performed at ambient conditions and the transient effect and the incident angle effect on the collector were determined. The solar collector is a water working fluid type.
State-of-the-art of solar collectors which concentrate low-level solar energy to a usable density for the particular energy-conversion method
Additional verification data to support the utilization of the MSFC Solar Simulator for testing solar collectors was obtained. The Honeywell double-covered liquid solar collector number 2 for which thermal performance data under natural outdoor conditions had been previously obtained was installed on the Solar Simulator and subjected to a series of eight tests under various conditions of wind flow rate. Although these test conditions were not absolutely identical to those of the outdoor tests, they are considered to be sufficiently representative to provide a basis for an accurate comparative analysis of the data recorded for both test programs.
Maximum collection efficiency prediction method for paraboloid solar collector
The design, construction, and operation of a mobile apparatus for solar collector testing (MASCOT) is described. The MASCOT is a self-contained test unit costing about $10,000 whose only external requirement for operation is electrical power and which is capable of testing two water-cooled flat-plate solar collectors simultaneously. The MASCOT is small enough and light enough to be transported to any geographical site for outdoor tests at the location of collector usage. It has been used in both indoor solar simulator tests and outdoor tests.
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.
Wavelength selective coatings for solar collectors are considered. Substrates with good infrared reflectivity were examined along with their susceptibility to physical and environmental damage. Improvements of reflective surfaces were accomplished through buffing, chemical polishing and other surface processing methods.
Optically selective coatings for solar collectors are produced by thermally treating stainless steel in furnace after series of cleaning and soaking operations. Coatings have withstood 18-month exposure tests at 100 percent relative humidity and temperatures of 95 F. Room temperature coatings are valuable as they are inexpensive to produce, highly production oriented, and environmentally stable.
Results from retesting of liquid solar collector described in "Performance evaluation of liquid collector" (M-FS-23931), after long term exposure to natural weathering indicate no detectable degradation in collector performance and no visable deterioration in appearance of collector. Supporting data and pretest/post test efficiency comparison are included.
A performance evaluation of the solar kinetics T-700 line concentrating solar collector is reported. Collector descriptions, summary, test conditions, test equipment, test requirements and procedures, and an analysis of the various tests performed are described.
Methods for optimizing parabolic dish solar collectors and the consequent effects of various optical, thermal, mechanical, and cost variables are examined. The most important performance optimization is adjusting the receiver aperture to maximize collector efficiency. Other parameters that can be adjusted to optimize efficiency include focal length, and, if a heat engine is used, the receiver temperature. The efficiency maxima associated with focal length and receiver temperature are relatively broad; it may, accordingly, be desirable to design somewhat away from the maxima. Performance optimization is sensitive to the slope and specularity errors of the concentrator. Other optical and thermal variables affecting optimization are the reflectance and blocking factor of the concentrator, the absorptance and losses of the receiver, and, if a heat engine is used, the shape of the engine efficiency versus temperature curve. Performance may sometimes be improved by use of an additional optical element (a secondary concentrator) or a receiver window if the errors of the primary concentrator are large or the receiver temperature is high. Previously announced in STAR as N83-19224
This article analyzes the thermal performance of a new vacuum tube solar collector. The assumptions and mathematical modeling are presented. The problem is reduced to the formulation of two simultaneous linear differential equations characterizing the collector thermal behavior. After applying the boundary conditions, a general solution is obtained which is found similar to the general Hottel, Whillier and Bliss form, but with a complex flow factor. The details of the two-dimensional thermal model of the solar collector at steady state is also presented to include the computer simulation and the performance parameterization. Comparison of the simulated performance with the manufacturer's test data showed good agreement at wide ranges of operating conditions.
The procedures used and the results obtained during the evaluation test program on the Solar Unlimited, Inc., Suncatcher SH-11 (liquid) solar collector are presented. The flat-plate collector case assembly is made of .08 inch aluminum 3003 H14 riveted with fiberglass board insulation. The absorber consists of collared aluminum fins mechanically bonded to 3/8 inch copper tubing and coated with 3M Nextel black. Water is used as the working fluid. The glazing is made of a single glass, 1/8 inch water white, tempered and antireflective. The collector weight is 85 pounds with overall external dimensions of about 35.4 in x 82.0 in x 4.0 in. Thermal performance data on the Solar Unlimited Suncatcher SH-11 solar collector under simulated conditions were conducted using the MSFC Solar Simulator.
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 isolation, outdoor data recorded on cloud 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.
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.
The test procedures used and the results obtained during the evaluation test program of the Lennox/Honeywell double covered liquid solar collector. 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. Visual inspection of the collector indicated slight discoloration of the absorber plate. Results indicate that performance degradation had occurred. Absorptivity and/or transmissivity decreased as a result of the weathering.
The test procedures used and the results obtained during the evaluation test program of the Sunworks single-covered liquid solar collector are presented. The tests were performed under simulated conditions, following long-term exposure to natural weathering conditions. The sunworks collector is a flat-plate solar collector. The absorber plate is copper with copper tubes bonded by soft solder, and is coated with Enthon selective black with an absorptivity factor of .87 similar to .92 and an emissivity factor of .10 similar to .20. It has a single glass cover of 3/16 inches tempered glass and weighs about 115 pounds. The overall dimensions of the collector are 36 x 84 x 4 inches.