Experimental Study of Apricot Drying Using Direct and Indirect Solar Dryers with Natural Convection

Abstract

This study investigated the drying performance of apricots using direct and indirect solar dryers operating under natural convection. Experimental trials were conducted under field conditions to compare drying time, product surface temperature, moisture reduction, and quality indicators. For reference, openair sun-drying was used as a control. The results showed that apricots dried in the indirect dryer reached equilibrium moisture content in 6 d, compared to 8 d in the direct dryer and 10 d in open-air drying. The product surface temperature in the indirect system was, on average, 12 °C lower than in the direct dryer, thereby preserving the structural integrity of the product. Chemical analysis revealed lower concentrations of toxic elements (0.13 mg/kg vs. 0.22 mg/kg) and nitrate ions (8.5 mg/kg vs. 9.3 mg/kg) in apricots dried in the indirect system compared with open-air drying, resulting in a 10 12% improvement in quality. The findings confirm that indirect solar dryers provide better quality retention and shorter drying times than traditional methods.