A review of thermohydraulic performance of artificially roughened solar air heaters

Solar air heaters form the major component of solar energy utilization system which absorbs the incoming solar radiation, converting it into thermal energy at the absorbing surface, and transferring the energy to a fluid flowing through the collector. The efficiency of flat plate solar air heater has been found to be low because of low convective heat transfer coefficient between absorber plate and the flowing air which increases the absorber plate temperature, leading to higher heat losses to the environment resulting in low thermal efficiency of such collectors. Artificial roughness in the form of repeated ribs is the most effective and economic way of improving the thermal performance of solar air heater. This paper presents an extensive review on the research carried out on artificial roughened solar air heater ducts. The objective of this paper is to review various studies, carried out on thermal as well as hydraulic performance of artificial roughened solar air heater ducts. The review presented in this paper will be useful for the researchers working in this area.