Collector Efficiency in Downward-Type Double-Pass Solar Air Heaters with Attached Fins and Operated by External Recycle

Energies

Ho-Ming Yeh¹ 

[1] Energy and Opto-Electronic Materials Research Center, Department of Chemical and Materials Engineering, Tamkang University, Tamsui, New Taipei 251, Taiwan; E-Mail

关键词: solar air heater;    collector efficiency;    downward type;    double pass;    external recycle;    fins;   

DOI  :  10.3390/en5082692

来源: mdpi

【 摘 要 】

The collector efficiency in a downward-type double-pass external-recycle solar air heater with fins attached on the absorbing plate has been investigated theoretically. Considerable improvement in collector efficiency is obtainable if the collector is equipped with fins and the operation is carried out with an external recycle. Due to the recycling, the desirable effect of increasing the heat transfer coefficient compensates for the undesirable effect of decreasing the driving force (temperature difference) of heat transfer, while the attached fins provide an enlarged heat transfer area. The order of performances in the devices of same size is: double pass with recycle and fins > double pass with recycle but without fins > single pass without recycle and fins.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.