Performance analysis of parallel flow flat plate solar air heater having arc shaped wire roughened absorber plate

Abstract This paper deals with the theoretical analysis of a parallel flow solar air heater having an absorber plate roughened with arc shaped wires. The absorber plate that forms the upper and lower ducts is roughened on its upper side only. A mathematical model describing the fluid flow and heat transfer characteristics of such a parallel flow roughened absorber plate solar air heater has been developed to study the effects of various operating and systems parameters on thermal performance of the solar air heater. The governing energy equations have been solved by iterative method using computer codes in MATLAB. A comparison between the theoretical results obtained and experimental results available in the literature has been made which shows a good agreement between the results. The thermal efficiency of parallel flow roughened solar air heater has been found nearly 8–10% higher than the smooth parallel flow solar air heater operating under similar conditions. It has been found that based on the thermohydraulic efficiency criteria, parallel flow roughened solar air heater is not beneficial for higher Reynolds number (Re > 29000) as compared to solar air heater having smooth absorber plate and this fact can be considered for designing roughened parallel flow solar air heaters.