Effect of heat absorbing media on thermal performance of air-type solar collectors

Abstract

In this study, effect of heat absorbing media on the thermal performance of airtype solar collector is studied experimentally. Experimental setup was built and tested by using the ASHRAE 93-1986 standard named .Methods of testing to determine the thermal performance of solar collectors.. Polyurethane foam is used as heat absorbing media with a porosity of 85%. In the analysis three air speeds 3 m/s, 3,5 m/s and 4 m/s are used. Data for similar days are compared with each other. Increment of the efficiency related to the polyurethane foam is presented and performance curves of our air-type solar collector are indicated. Factors, affect the performance of collector, are discussed. Using heat absorbing media enhances heat transfer surface area and this increases efficiency, but pressure drop should be taken into consideration to prevent extra pumping power. In conclusion, efficiency values about 55% for 3m/s for ambient temperatures between 35 and 38oC, 60% for 4 m/s and 48% for 3,5 m/s for ambient temperature between 28 and 32oC with polyurethane foam are obtained. On the other hand, pressure drops increase from 0,015 kPa to 0,215 kPa for 3 m/s, from 0,01 kPa to 0,32 kPa for 3,5 m/s and from 0,01 kPa to 0,385 kPa for 4 m/s.