Design, thermal simulation and experimental study of a hybrid solar dryer with heat storage capability

Abstract

A hybrid solar dryer equipped with heat storage unit was constructed with the aims of higher heat gain and heat storage. The dryer included a photovoltaic/thermal (PV/T) unit, a V-corrugated collector, heat storage unit and a drying chamber in a row. It was tested under forced mode of operation and was used to dry mint as a medicinal plant. The results of the thermal simulation of the dryer were in good agreement with the experimental ones. Through the experimental work, three cases of no phase change material (PCM), PCM only and nano-enhanced PCM were used to see their effects on drying parameters. Based on the results, the two PCM cases showed better results than no PCM case in terms of lowering the peak of drying air temperature inside the drying chamber which naturally led to lower heat shock applied to the product and brought about higher quality of the dried product. Furthermore, the two cases of PCM only and nano-enhanced PCM reduced the drying time period by 53 and 72 min, respectively. Besides, it was found that application of PCM led to lower mass flow rate of drying air to reach a specified moisture content. So, the consumption of electricity was reduced. Finally, the rehydration capacity of dried product, as a parameter of quality, was calculated and the nano-enhanced PCM, PCM only and no PCM cases showed a 74.06, 70.81 and 68.57% rehydration capacity on average, respectively.