Drying of Grapes in Cabinet Solar Dryer. Preliminary Results

Abstract

A pilot scale cabinet solar tray dryer was constructed of 500 Kg capacity of fresh product. An array of air-cooled flat plate solar collectors, of area 5.2 m2, was installed to heat the drying air stream3Currants were dried in the first drying experiments during autumn’83. Parallel experiments were performed with a similar solar dryer, of 10 Kg capacity, to investigate the effect of the flow rate of the, drying agent on the drying time of currants. Currants dried at mean operating temperatures 30° to 40° C and low to moderate flow rates. The process completed in 20 and 13 days of intermittent operation, 180 and 117 hr of real drying time, respectively for the two experiments. No auxiliary heating was used. The drying experiments led to the following conclusions: To reduce the drying time the flow rate and distribution in the drying chamber must improve, and the operating temperatures to increase. Drying time will be more reduced dipping currants before drying. The dried product will be more uniform when thinner layers of currants are dried The ratio of the total area of the collectors per kilogram of evaporated moisture must increase The thermal performance of the dryer and the collectors was satisfactory.