Performance Studies on Solar Air Heater with Staggered Open Channel Aluminium Turbulators

Solar air heaters (SAH) are widely used in industries where hot air at low and medium temperatures satisfies the demand for drying process. The effectiveness of SAH is measured by its multi-tasking capability and operational parameters. Generally, the heating performance of SAH is under average due to poor convective coefficient between absorber plate and the air passing through the duct. In order to boost the thermal performance, artificial roughness is provided on upper and lower facets of the absorber plate and thereby turbulence is induced within the heat transfer zone. The performance of a two pass solar air heater with staggered open channel aluminium turbulators was investigated experimentally. Experiments were conducted under varying solar radiation, and the average thermal efficiency was observed to be around 66%. The peak heat transfer coefficient was found to be 66 W/m2 K for solar radiation 1070 W/m2. There is a 10% additional improvement in mean efficiency when compared with similar solar air heater with staggered full aluminium can turbulators.