Investigation of a Photovoltaic–Thermal Solar Dryer System with Double-Pass Solar Air Collectors and Absorber Surfaces Enhanced with Graphene Nanoparticles

Abstract

AbstractAs a result of increasing energy demand, seeking eco-friendly and sustainable energy resources increases the interest in renewable energy, specifically solar energy. In this study, a novel photovoltaic–thermal solar dryer system with double-pass solar air collectors and nano-enhanced absorber surface was developed, and its performance was experimentally investigated. Initially, a double-pass solar dryer (DPSD) with an absorber surface of flexible aluminum ducts coated with black matte paint was produced. Then, a double-pass solar dryer (NDPSD) consisting of flexible aluminum ducts coated with graphene and black paint was designed. These two systems were experimentally and simultaneously examined, and parameters such as energy and exergy efficiency, drying rate, and moisture ratio, which are the performance indicators of solar air collectors and the drying process, were analyzed. The sustainability parameters were also considered as a part of the analysis. The mean thermal efficiency of the solar air collectors for DPSD and NDPSD was calculated as 57.23 and 73.36%, respectively, where the airflow rates were measured as 0.024 and 0.017 kg/s. Furthermore, under the same airflow rate conditions, while the mean exergy efficiency of the collector was 27.77% for NDPSD, it was calculated as 16.64% for DPSD. Moreover, exergy efficiencies of the drying chamber varied between 27.35% and 82.20% for NDPSD and between 21.03 and 81.25% for DPSD, under the airflow rates of 0.012–0.016 kg/s conditions, respectively.