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Theoretical calculation of the thermal efficiency of an evacuated tubular collector

Journal Article · · Heat Transfer - Jpn. Res.; (United States)
OSTI ID:6562554
A formula to calculate the instantaneous efficiency of an evacuated tubular collector which has flat absorber plates in glass tubes and a white plate with diffuse reflection beneath tubes is derived, considering the dependency of the effective transmission-absorption factor (tau..cap alpha..)/sub e/ on the direction of incident solar radiation. The curve of efficiency characteristics by the theoretical calculation and that by experimental measurements have almost the same slope and the validity of the theoretical formula on heat losses from the collector is proved. The calculated efficiency eta/sub th/ and the measured efficiency eta/sub m/ show almost the same effect by the change of direction of incident solar radiation, so that dependency of the theoretically calculated (tau..cap alpha..)/sub e/ on the direction of incident radiation is similar to that of a real collector.
Research Organization:
Government Industrial Research Institute, Nagoya
OSTI ID:
6562554
Journal Information:
Heat Transfer - Jpn. Res.; (United States), Journal Name: Heat Transfer - Jpn. Res.; (United States) Vol. 15:3; ISSN HTJPA
Country of Publication:
United States
Language:
English