Abstract
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).
