Encapsulated PCM based double pass solar air heater: A comparative experimental study

An experimental investigation on thermal performance of a solar air heater with and without the usage of spherically encapsulated phase change medium (PCM) is presented in this paper. The PCM, paraffin wax, is filled in spherical balls mounted on the holes of the absorber plate so that heat transfer area is slightly extended. A comparative study of three different configurations of the absorber plate is made. Parameters that influence the collector efficiency are recorded and discussed. The results obtained are compared with a conventional absorber plate without PCM for similar conditions. The mean efficiency obtained for conventional absorber plate without PCM is 31%, for flat absorber plate with PCM is 39%, and for inclined absorber plate with PCM is 43%. The encapsulation efficiency is 40% for flat plate absorber with PCM and 42.2% for inclined plate absorber with PCM and the approximate cost of heating 1?kg of air is INR 0.95/$0.014.