Energy and Exergy Investigation of a Solar Air Heater for Different Absorber Plate Configurations

In this paper, the effect of using different configurations of absorber plate, including one line finned flat absorber and two lines finned absorber plate, on the thermal performance of a flat plate – double passing solar air heater was investigated experimentally. L- shape fins are soldered on the absorber plate to roughen the absorber plate and generate vortices to enhance the heat transfer between the working fluid (air) and absorber plate to improve the thermal efficiency. The outdoor experimental test was carried out during February and May under the weather conditions of Baghdad city (Longitude 33.3 N and Latitude 44.44 E). The results show that the air temperature is 48 ℃, 47.5 ℃, and 58.5 ℃ at an air velocity of 1.7 m/s for a single line of fins which increased to 52 ℃, 57.5 ℃, and 66 ℃ at air velocity of 0.9 m/s for two lines of fins. The efficiency is increased by 28% for one line of fins and 66% for two lines of fins at an air velocity of 0.9 m/s while increased by 27% for one line of fins and 51% for two lines of fins at an air velocity of 1.7 m/s. The average exergy destruction rate increases by 37.6%, 60.6%, and 68.66% for the absorber plate, working fluid, and glass cover, respectively, for velocity increase from 0.9 m/s to 1.9 m/s. The exergy efficiency increased by 24.1% when the velocity increased from 0.9 m/s to 1.9 m/s.