DEVELOPMENT AND PERFORMANCE EVALUATION OF FORCED CONVECTION POTATO SOLAR DRYER

This research paper deals with the design development and testing of a forced convection solar dryer, for drying and converting to flour of high moisture content vegetables like potatoes. the angle of solar collector was made adjustable for the absorption of maximum solar radiation by the absorber plate. the air flow rate was controlled by adjustable gate valve to find the optimum flow rate for dehydration of the product. the penetration of solar radiation raised the temperature of the absorber plate of the dryer to 110°c during the operation under stagnation or no load conditions. the maximum air temperature attained in the solar air heater, under this condition was 80°c. the dryer was loaded with 12 kg of blanched potato chips having an initial moisture content of 89.75%, and the final desired moisture content of 6.95% was achieved within five hours without losing the color of potato chips, while the moisture contents reduction was from 89.75% to 33.75% for five hours in open sun drying under shade. the drying cost for 1 kg of potatoes flour was calculated as rs. 245 and it was rs. 329 in the case of an electric dryer. the life span of the solar dryer was assumed to be 20 years. the cumulative present worth of annual savings over the life of the solar dryer was calculated for blanched potato chips drying, and it turned out be rs.163177.67/- which was much higher than the capital cost of the dryer (rs. 25000). the payback period was calculated as 0.89 years, which was also very small considering the life of the system (20 years).