Evaluation of a jet plate solar air heater

To achieve higher heat transfer from the absorber plate to the flowing air stream with an intention to increase the amount of the collected energy, and hence, to improve the efficiency of an air-based solar collector, a unique jet impingement concept has been advanced for evaluation in the present study. To investigate the effects of various geometrical parameters such as the ‘hole’ or ‘nozzle’ diameter on the jet plate, their interspacings, the nozzle height, the distance between the absorber and the jet plate and the operational parameter such as the velocity of air impinging out of the holes/nozzles on to the back side of the absorber surface on the performance parameters of the jet impingement concept air heater, a detailed theoretical parametric analysis has been made on the design for different mass flow rates of air and different lengths of air channel. A parallel study has also been carried out on a conventional parallel plate air heater in order to compare its air temperature increment and performance efficiency with those of the jet plate air heater. The gain in air temperature increment and performance efficiency of the jet-concept air heater over that of the parallel plate air heater with duct depth 10 cm and length 2 m is 15.5°C to 2.5°C and 26.5% to 19%, respectively, for air flow rates in the range 50 to 250 kg/hm 2.