Thermal performance of a dual function air-water heater with a cover cum reflector mirror

ABSTRACT In the present work a dual function integrated solar air-water heater which contains reflector cover has been proposed. The reflector can be reversed back over the glass cover to serve as an insulated cover for heater during no sunshine hours. The proposed heater’s mathematical model has been formed and experimentally verified. The average monthly optimum tilt angle of reflector has been determined for climate of Raipur, Chhattisgarh. The average optimum tilt angle is maximum 54.5° for the month of June and minimum 23.4° for the month of December. The average optimum angle of tilt for winters is 26.1° whereas for summer the average optimum tilt angle is 48.5o. The use of reflector enhances the output, by using reflector the maximum water and air temperature achieved is 16.4% and 12% more than without reflector. The performance of the heater is influenced by the flow rate of air flowing in the upper compartment. Less heating of the water and air occurs with higher mass flow rates. For a typical winter day in Raipur, the maximum air and water temperatures reached are 45.5°C and 70.2°C at a flow rate of 0.010 kg/s, respectively. At a flow rate of 0.030 kg/s it is 34.6°C and 61.8°C. The maximum air temperature reached is 12% more without reflector. For three consecutive days of operation the maximum water and air temperature achieved on the third day is 92.4°C and 54.1°C, respectively.