Thermal performance improvement of an indirect solar dryer with tube-type absorber packed with aluminum wool

Abstract

In recent years, increasing energy demand and limited fossil fuel resources increased utilization of renewable and sustainable energy sources. Solar thermal systems are utilized for generating clean and environmentally friendly electricity and thermal energy. In this study, a single pass heater with tube-type absorber has been manufactured and integrated with a drying chamber. In this context, numerical simulations have been applied to verify the effect of absorber plate's shape and its placement. Then, tubular solar heaters have been fabricated considering numerical simulation results. Moreover, aluminum wool has been added into the tubes with the aim of raising the thermal efficiency of the system. Drying experiments have been performed in two different air flow rates containing 0.010 and 0.013 kg/s. The numerical simulation results of this study exhibited the successfulness of tubular absorber for solar heater. Also, the experimental results showed that using aluminum wool inside the tubes led to improve in the thermal performance and 30% reduction in drying time. Average SEC values at higher and lower mas flow rates for modified dryer were found as 1.39 and 1.82 kWh/kg respectively. Also, these values were obtained for unmodified dryer as 1.94 and 2.25 kWh/kg, respectively.