Evaluating Dying Efficiency and Energy Performance of a Hybrid Solar Dryer with Natural, Forced, and Hybrid Convection Modes for Tomatoes

This research focuses on developing innovative hybrid solar dryers that combine solar Photovoltaic (PV) and solar thermal systems for sustainable food preservation in Pakistan, addressing the country’s pressing issues of high post-harvest losses and unreliable energy sources. The proposed active hybrid solar dryer features a drying cabinet, two Direct Current (DC) fans for forced convection, and a resistive heating element powered by a 180 W solar PV panel. An energy-storing battery ensures continuous supply to the auxiliaries during periods of low solar irradiance, poor weather conditions, or nighttime. Tomatoes, a delicate and in-demand crop, were selected for experimentation due to their high perishability. Three experiments were conducted on the same prototype: natural convection direct solar dryer (NCDSD), forced convection direct solar dryer (FCDSD), and forced convection hybrid solar dryer (FCHSD). Each experiment began with 0.2 kg of tomatoes at 94% moisture content, achieving significant reductions: 28.57% with NCDSD, 16.667% with FCDSD, and 16.667% with FCHSD. The observed drying rates varied: 1.161 kg/h for NCDSD, 2.062 kg/h for FCDSD, and 2.8642 kg/h for FCHSD. This study presents a comparative analysis of efficiency, drying rate, and cost-effectiveness, alongside the system’s economic and environmental feasibility.