Performance evaluation of sand coated absorber based solar air collector

Abstract

An experimental investigation into solar air collectors (SACs) was done in the atmospheric conditions at RLJIT- Bangalore, Southern part of India. Three novel SACs were developed by incorporating locally available sand on the surface of the absorber to enhance outlet temperature and the respective thermal efficiency. The sand diameters used were 0.075, 0.150, and 0.250 mm, and tests were performed at four different mass flow rates of air (0.010, 0.015, 0.020, and 0.025 kg/s). The results showed that the novel SACs had higher efficiency and provided higher outlet air temperature than the SAC without sand coating. The energy efficiencies improved for sand-coated SACs were up to 13%, 8.7%, and 2.8% for Type-II (0.075 mm), Type-III (0.150 mm), and Type-IV (0.250 mm) SACs, respectively compared to Type-I (without sand coated) SAC. The temperature rises were enhanced by 8.21%, 4.69%, and 3.12% for Type-II, Type-III, and Type-IV SACs, respectively, compared with the reference Type-I SAC. Hence, the energy efficiency and outlet temperature of sand-coated SACs were increased.