Testing of the performance of a fruit and vegetable solar drying system in Iraq

Abstract

In this work a drying system was constructed, consisting of three parts (solar collector, solar drying cabinent, and air blower). Two identical air solar collectors having V-corrugated absorption plates of two air passes, a single glass cover was used. The total area of the collectors is 2.4 m 2. The dimensions of the drying cabinet are 1 × 0.33 × 2 m (width, depth, and height). The cabinet is divided into six divisions separated by five shelves. The distance between the shelves is 0.3 m except the upper one, which is 0.5 m from the roof. Each shelf is 0.95 × 0.3 m and is made of metallic mesh. The drying chamber walls are made of aluminum plate except the southern side, which was fixed with glass plate having the dimensions 1 × 2 × 0.002 m. Two types of fruit and one type of vegetables were dried during the present work. These were grapes, apricots, and beans. The moisture content of apricot was reduced from 80 to 13% within one day and a half of drying. Moisture content of grapes was reduced from 80 to 18% in two and a half days of drying, while that of beans was reduced from 65 to 18% in one day only. The results show that the most effective factor on the drying rate is the temperature of the air inside the cabinet. The effect variation of speed of air inside the drying cabinet is small and can be neglected. The relative humidity of air exit from the cabinet was small between (25–30%) and therefore there is no need for high velocity air inside the cabinet.