Review on Heat Transfer Through Absorber Plate of a Solar Air Heater with Artificial Roughness

Solar air heaters are being used to heat the air with the use of renewable energy source and thus preventing the environment. Artificial roughness when developed on the surface of the absorber plate, the heat transfer through the absorber plate in air flowing over it improves. Several experimental and numerical studies have been performed by the researchers to improve the performance of the solar air heaters by this artificial roughness. The objective of this paper is review the previously done work in this field so that further scope of work in the enhancement of heat transfer through absorber plate could be found. The review results show that the researchers have mainly worked upon the type of the roughness element, their arrangement and the physical dimensions of the absorber plate and the roughness elements. Several studies reveals the heat transfer enhancement and shown the variation in Nusselt number with the change in Reynolds number. It is found that the CFD technique is being mostly used for the analysis and simulation purpose. The CFD results have also been validated by the experimental results.