Comparison of flat plate and cylindrical parabolic focusing solar energy collectors for Oak Ridge

Technical Report · Wed May 22 00:00:00 EDT 1974

DOI:https://doi.org/10.2172/5477479· OSTI ID:5477479

Kronenberger, E. J.; Newman, J. S.; Demetriou, C. V.; Orlandi, R. D.

Experimental and theoretical comparisons were made of the performance of cylindrical parabolic and flat plate solar energy collectors operating under Oak Ridge weather conditions. The flat plate collector was observed to consistently out-perform the parabolic collector under the design and operating (135 to 185/sup 0/F) conditions used (parabolic cylindrical collector - one glass cover plate, refocused hourly, receiver absorptivity of 0.87; flat plate collector - two glass cover plates oriented at latitude minus declination, absorptivity 0.98). Other factors contributed to the difference including poorer insulation (1.25 in. fiberglass) for the focusing collector (versus 5 in. fiberglass for the flat plate) and a poor fin efficiency for the receiver tube of the focusing collector. Observed efficiencies were as high as 47% for the cylindrical parabolic collector operating with one glass plate at 185/sup 0/F and as high as 62% for the flat plate collector operating with two glass plates at 165/sup 0/F. Performance models were developed for both collectors and the model used for the flat plate collector was extended to predict month-to-month operation under Oak Ridge weather conditions (based on the average of 16 years of weather data). A temperature distribution model was developed for optimization of the finned tube receiver used in the cylinderical parabolic collector. Further experimentation should be conducted at higher temperatures (approx. 250/sup 0/F) with selective receiver coatings (..cap alpha../epsilon >> 1) and also runs under conditions of broken cloud cover are suggested. In addition, the performance models should be extended and the finned tube design optimization continued.

• Research Organization: Massachusetts Inst. of Tech., Oak Ridge, TN (USA). School of Chemical Engineering Practice
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5477479
• Report Number(s): ORNL-MIT-192
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
FLAT PLATE COLLECTORS
PERFORMANCE
PARABOLIC TROUGH COLLECTORS
CLOUD COVER
COMPARATIVE EVALUATIONS
DAILY VARIATIONS
FINS
MATHEMATICAL MODELS
MONTHLY VARIATIONS
OAK RIDGE
OPERATION
OPTIMIZATION
SEASONAL VARIATIONS
TEMPERATURE DISTRIBUTION
TUBES
WORKING FLUIDS
CONCENTRATING COLLECTORS
EQUIPMENT
FLUIDS
NORTH AMERICA
PARABOLIC COLLECTORS
SOLAR COLLECTORS
SOLAR EQUIPMENT
SOUTHEAST REGION
TENNESSEE
USA
VARIATIONS
141000* - Solar Collectors & Concentrators