Effect of channel depth ratio and absorber plate configuration on performance of a solar air heater

Abstract

An experimental evaluation of the effect of channel depth ratio and absorber plate configuration on the performance of a baffled counter flow double-pass solar air heater (BCDSAH) is main objective of current work. The BCDSAH was constructed so as to permit adjustments of channel depth ratio (CDR) to 2, 3 and 4. During experimentation, the lower channel depth was kept at 50 mm while the upper channel depth was adjusted to 100 mm, 150 mm and 200 mm, yielding various channel depth ratios. The assessments were conducted for three configurations of absorber plate: (i) flat absorber plate, (ii) baffled absorber plate and (iii) baffled absorber plate with phase change material (PCM). The performance of the BCDSAH was evaluated at an air mass flow rate of 0.07 kg/s for temperature rise, useful heat gain (UHG), energy efficiency, and exergy efficiency. For CDR = 2 and a baffled absorber plate with PCM, the obtained average values of temperature rise, UHG, energy efficiency and exergy efficiency were 15.3 °C, 1075.2 W, 76.2 % and 2.7 % respectively. For the baffled absorber plate with PCM, increases of 8.5 %, 9.4 %, 10.1 % and 10.9 % were obtained in temperature rise, UHG, energy efficiency and exergy efficiency respectively for CDR = 2 compared to CDR = 4. Finally, a value of CDR = 2 and a baffled absorber plate with PCM are suitable for applications like drying of agricultural products and space heating.