Evaluation of a Roof-integrated Solar Air Heating System for Drying Foodstuffs

The paper describes the detailed techno-commercial analysis done on a 46 m2 solar air heating system developed in a food processing industry. The solar air heating system was connected to an indoor drier through a duct. A detailed performance analysis was undertaken on the system by loading with 75 kg of ripe mango flake. The product loaded was uniform in size having a thickness of 4mm. On a clear sunny day, the maximum temperature recorded at the outlet of the solar air heater was 66.9C. The moisture content of the product loaded in the solar drier reduced from an initial moisture content of 75.0% to 6.46 % in a drying duration of 8 hours. Detailed technical analysis was done on the system by four methods namely annualized cost, present worth of annual savings, present worth of cumulative savings, and payback period. The cost of drying 1 kg mango worked out to be Rs. 11 which was roughly half of that of an electric dryer. The payback period worked out to 0.54 year, much less than the estimated life of the system (20 years).