Effect of nano cupric oxide coating on the forced convection performance of a mixed-mode flat plate solar dryer

In this study, mixed mode solar dryer of forced convection type, integrated with a CuO nanoparticle coated flat plate solar collector was developed and its effectiveness of drying maize under the meteorological conditions of Coimbatore, India was evaluated. The aforementioned setup entails a solar collector (flat plate type) with 3 drying trays and a centrifugal blower. The conventional solar absorber plate was made up of aluminium, which was coated with black paint. Another modified solar absorber plate was made up of aluminium with a coating of black paint with two different vol% of CuO nanoparticles (0.02% and 0.04%), for improving the heat transfer rate. Performance tests on the modified dryer were carried out at constant air flow rate (1.5 m(3)/min) and the results were compared with the conventional type. The efficiency of the collector got improved by 4% while using black paint with 0.04 vol% of CuO nanoparticle coated absorber. Also the drying time got reduced by 6%, when compared to conventional type dryer. Also the collector temperature recorded in the black paint with 0.04 vol% CuO nano-particle coated collector was higher compared to black paint coated and black paint with 0.02 vol% CuO nanoparticle coated collector. (C) 2020 Elsevier Ltd. All rights reserved.