Thermal performance of the double-pass solar collector with and without porous media

This paper presents the thermal performance of a double-pass solar collecto r with and without porous media in the second or lower channel of the colle ctor. The experimental setup has been designed to study the thermal perform ance over a range of design and operating conditions. Several important rel ationships between the design and operating conditions have been obtained. These relationships effect the thermal performance of the double-pass solar collector. The relationships include the effect of changes in upper and lo wer channel depth on the thermal efficiency with and without porous media. Moreover, the effects of mass flow rate, solar radiation, and temperature r ises on the thermal efficiency of the double-pass solar collector have been studied. The study concluded that the presence of porous media in the seco nd channel increases the outlet temperature, therefore increases the therma l efficiency of the systems. (C) 1999 Published by Elsevier Science Ltd. Al l rights reserved.