PERFORMANCE OF SOLAR FRUIT DRYING SYSTEM

A considerable amount of fresh fruits produced in Pakistan are wasted every year due to non-availability of basic postharvest technologies. To overcome this problem a solar fruit drying system was designed and developed at Farm Machinery Institute (FMI), Islamabad. The system consists of six flat plate solar collectors, an axial flow fan, and a drying chamber. The performance of the system was evaluated at Nalkot, Swat, where the persimmon was available in enough quantity for drying.It was observed that the solar collectors were capable to raise the average daily temperature of the ambient air from 26°C to 44°C, however, the hot air within the drying chamber was not distributed uniformly. The average daily efficiency of the solar collectors was 44%. The solar dryer was capable to process about 1 to 1.5 tonnes of fresh persimmon in one month, whereas farmers wanted to increase its drying capacity up to 4 to 5 tonnes / month. It was concluded to redesign the drying chamber, and to provide a supplement source of heat (gas or oil fired) to solar dryer in order to increase its drying capacity