Experimental investigation and economic evaluation of a new mixed-mode solar greenhouse dryer for drying of red pepper and grape

This paper presents an experimental analysis to investigate the performance of a novel mixed mode solar greenhouse dryer with forced convection which was used to dry red pepper and sultana grape. The drier consisted of a flat plate solar collector and a chapel-shaped greenhouse. The drying rate in the solar greenhouse dryer could be much higher than that for the open air sun drying. The present drying system practically shortens the drying time of red pepper and grape by 7 and 17 h respectively. The experimental drying curves show only the falling rate period. The payback period of the dryer was found to be 1.6 years, much less than the estimated life of the system (20 years).