Impact of collector aspect ratio on the energy and exergy efficiency of a louvered fin solar air heater

Solar air heaters have huge applications in renewable energy utilization segments concerning the issues of space heating, drying, and ventilation systems. Performance prediction of such systems largely depends upon the design of the collector itself. The present study has highlighted the influence of various aspect ratios of the collector on the thermal and exergy performance of louvered finned solar or air heaters. In this context, an experimental analysis has been carried out to compare the performance of LFSAH with conventional PSAH. These results show that an increase in aspect ratios enhances thermal efficiencies of heat transfer and the systems. An aspect ratio of 4:1 showed the maximum thermal efficiencies as 81.63 % for LFSAH and 68.13 % for PSAH. On the other hand, at larger mass flow rates, the exergetic efficiency of LFSAH becomes lower owing to the larger friction and exergy losses and sometimes even lower than that of PSAH. The novelties of the present study are in emphasizing the importance of aspect ratio in optimizing solar air heater design and providing relevant insight for better energy use.