Performance evaluation of solar air heater having V-down perforated baffles on the absorber plate

Abstract

The roughened solar air heater performs thermally better than the conventional smooth solar air heater but is associated with a high pumping power requirement. The effective efficiency based criteria is suitable to design roughened solar air heater duct, as it takes both in accounts the useful heat gain from the system and the pumping power requirement. The thermal and effective efficiency of V down perforated baffled roughened solar air heater is studied analytically and the results obtained are compared with the conventional system. Flow Reynolds number and roughness parameters have combined effect on the heat transfer and fluid flow characteristics. The effective efficiency based criteria to predict the performance suggests using the V down perforated baffled roughened solar air heater in the range of flow Reynolds number 10 000–20 000, which corresponds to the range of solar air heater. It was found that there exists an optimum set of roughness parameters for a given Reynolds number or temperature rise parameter at which effective efficiency is maximum. Designs plots are prepared to predict the optimum set of roughness parameters.