Exergy efficiency and sustainability indicators of forced convection mixed mode solar dryer system for drying process

The study investigates the effectiveness of a mixed-mode solar dryer (MSD) featuring two double-pass solar air collectors in series, with a focus on dehydrating cluster figs characterized by high moisture content and rapid deterioration. Exergy analysis is a powerful tool to assess the efficiency and sustainability of drying systems. The study involves experimental data obtained from the drying process under different air mass flow rates (0.018-0.062 kg/s). The solar radiation intensity ranged from 120 W/m2 to 750 W/m2 during these experiments. The solar air collectors and mixed mode dryer exergy efficiency is found to be dependent on solar radiation intensity, showing increased efficiency with higher air mass flow rates due to enhanced heat removal and reduced losses to the surroundings. The findings reveal that the optimal air mass flow rate of 0.062 kg/s yields the highest exergy efficiency in the solar air collectors. The overall exergy efficiency of the mixed-mode solar drying chamber increases with higher air mass flow rates, ranging from 18.8 % to 41.4 %. Improvement potential (IP) analysis indicates that, as the air mass flow rate increases, the potential for reducing exergy losses decreases. The sustainability index (SI), measures the environmental impact, and it ranges from 1.26 to 1.71, with higher values associated with higher exergy efficiency.