Performance Study of Solar Air Heater with Smooth and Baffled Ducts

A detailed mathematical model for performance prediction of a smooth duct solar air heater has been presented. The predicted values from the model are in good agreement with the experimental results. The paper also presents results of an experimental study on a solar air heater having absorber plate with half perforated baffles on the air flow side. The thermal efficiency of the baffled duct solar air heater is found to be about 28–45% higher than that of the smooth duct solar air heater. The improvement is attributed to the heat transfer enhancement (of the order of 180–235%) due to the perforated baffles attached to the absorber plate and reduction in the mean temperature of the absorber plate, which is found to be lower by 20–25°C than that of the smooth duct air heater.