Sustainability and 4E analysis of novel solar photovoltaic-thermal solar dryer under forced and natural convection drying

Developing a sustainable photovoltaic-thermal (PVT) solar drying system is essential to maintain zero carbon emission in the drying process. This work represents the drying of star fruit in a novel PVT solar dryer to analyze the sustainability indicators based on the energy and exergy performance with the environmental and economic evaluation (4E) under forced convection drying (FCD) and natural convection drying (NCD). The moisture content of star fruit in the PVT solar dryer is decreased from 10.11 (d b) to 0.19 (d b.) in 12.50 h and 14.50 h under FCD and NCD, respectively. The same has been obtained in open sun conditions with a drying time of 22.00 h. The PVT energy and exergy efficiencies are 69.27% and 31.12% in FCD mode, respectively, and 43.58% and 17.89% in NCD mode. The drying efficiency of 15.27% and 13.98%, specific moisture extraction rate of 0.1786 kg/kWh and 0.6657 kg/kWh, and specific energy consumption of 12.37 kWh/kg and 3.57 kWh/kg are evaluated in FCD and NCD modes, respectively. The drying system payback time is 1.40 yr and 1.70 yr in FCD and NCD mode, respectively. (C) 2022 Elsevier Ltd. All rights reserved.