Experimental analysis of wavy mesh assisted solar drying system with a survey of common drying technologies employed by farmers

Abstract

Solar drying is a promising post-harvest drying process to increase the shelf life of agricultural products. The current paper reviews conventional drying practices including traditional farmers’ practices. It also reports experimental results using a single-pass solar dryer with rolls of wavy porous mesh for the drying of coriander leaves in the meteorological conditions of Calicut, Kerala. The objective of the work is to investigate the improvement in performance and drying rate of mesh-assisted drying system over the bare plate collector drying system. The experiments compared the drying performance of a wavy porous mesh-integrated plate collector and bare-plate collector, respectively, at a mass flow rate of 0.03 kg/s. The novel design of the porous-mesh-integrated solar air heater improves heat transfer to the air, enhancing the drying performance. Coriander leaves were dried to equilibrium moisture content in 3 h. The mean thermal efficiency of the wavy mesh system was 50.3 % compared to 22.7 % for the bare plate solar collector. The wavy mesh improved the heat gain by 57.3 %, enhancing the drying rate with a time saving of 45.4 %. This demonstrates the advantage of wavy-mesh forced-convection solar drying over conventional solar drying and open sun drying.