Performance analysis of a mixed mode forced convection solar dryer with and without thermal energy storage heat exchanger

Abstract

A mixed mode forced convection solar dryer with and without thermal energy storage is developed for drying of different agricultural products. The drying kinetics of bitter gourd has been investigated under open sun drying and using solar dryer. The average drying efficiency of mixed mode solar dryer with thermal energy storage system was 32 % and without thermal energy storage, it was found to be 24.5%. The bitter gourd slices were dried from initial moisture content of 90% (wb) to the final moisture content of 9 % (wb) within 6 hr, 8 hr and 11 hr in solar dryer with thermal energy storage system, solar dryer without thermal storage and open sun drying conditions. The drying kinetics studies were performed for the three conditions and found that Midilli –Kucuk model was suited for the product dried in solar dryer and logarithmic model was found to fit for the open sun dried product. The color change values of the fresh, solar dried and open sun dried samples were 65.4, 56.8 and 46.8 respectively.