Mulatu C. Gilago
Mechanical Engineering Department, National Institute of Technology Warangal, Warangal, Telangana – 506 004; Mechanical Engineering Department, Wachemo University, Post Box 667,
Hosaena City, Ethiopia,
Vishnu Vardhan Reddy Mugi
National Institute of Technology Calicut; Mechanical Engineering Department, National Institute of Technology Warangal,
Warangal, Telangana – 506 004
Mechanical Engineering Department, National Institute of Technology Warangal, Warangal, Telangana, India − 506 004
The performance investigation of natural and forced convection indirect type solar dryer (ITSD) setups was performed by drying ivy gourd. With the average solar radiation of 652.9 and 669.75 W/m2 for the successive drying days, the collector's average efficiencies were estimated to be 62.56% and 77.2% for the natural and forced convection setups, respectively. These figures indicate that the forced convection setup showed 23.4% improvement as compared to natural convection. The average drying efficiencies for natural and forced convection ITSDs were evaluated to be 6.62% and 7.8%, respectively, where almost a 17.82% improvement of drying efficiency was noticed. The moisture content (MC) of the product was reduced from an initial moisture content of 15.32 (db) to a final average MC of 0.144 (db). The forced convection setup performed well with a faster rate and saving almost 3 h of drying time. The average values of activation energy, effective diffusion coefficient, mass transfer coefficient and heat transfer coefficient were estimated to be 39.85 and 35.54 kJ/mol, 7.06 × 10-9 and 8.35×10-9 m2/s, 0.0033 and 0.0043 m/s, and 3.85 and 4.93 W/m2K, respectively, for natural and forced convection setups. The specific energy consumption and specific moisture extraction rate were evaluated where forced convection ITSD gave the best results.