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Proceedings Paper

A Comparison Of Solar Thermal Energy Collection Using Fixed And Tracking Collectors
Author(s): John D. Garrison; George T. Craig; Charles Morgan
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Paper Abstract

Solar thermal energy collection at seven sites is calculated for air and vacuum flat plate collectors and a vacuum collector using cylindrical Winston concentration. The hourly intensity and angular distribution of solar radiation is predicted for the calculations using insolation measurements and an insolation model. Tracking configurations include two-axis, vertical axis, polar axis and east-west axis tracking. Fixed collector arrays are all tilted towards the equator at the latitude angle. These calculations indicate energy collection varies linearly with cloudiness index KT. Diffuse radiation is ≈ 15% of energy collected by concentrating collector arrays at low operating temperatures where large acceptance angles maximize energy collection. Smaller acceptance angles, required to maximize collection at higher operating temperatures, eliminate the advantage of Winston concentration for tracking arrays. Absorbers with high selectivity are necessary for high efficiency of fixed evacuated collectors at higher operating temperatures. Ratios of tracking to fixed collector energy collection increase rapidly between ≈ 200°C and ≈ 300°C making it likely that tracking becomes economically viable in this temperature range. These results are easily extended to other cylindrical concentrating collectors.

Paper Details

Date Published: 17 November 1978
PDF: 9 pages
Proc. SPIE 0161, Optics Applied to Solar Energy IV, (17 November 1978); doi: 10.1117/12.956871
Show Author Affiliations
John D. Garrison, San Diego State University (United States)
George T. Craig, San Diego State University (United States)
Charles Morgan, San Diego State University (United States)

Published in SPIE Proceedings Vol. 0161:
Optics Applied to Solar Energy IV
Keith D. Masterson, Editor(s)

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