PERFORMANCE EVALUATION OF A SIMPLE SOLAR DRAYER(GREENHOUSE-TYPE)

Abstract

Drying is simply the process of moisture removal from a product. It can be performed by various methods. In these methods, thermal drying is most commonly used for drying agricultural products. These drying systems are usually classified into low and high temperature dryers according to their operating temperature ranges. In low temperature drying systems, natural-circulation greenhouse-type dryers appear the most attractive option for use in rural locations. They are superior operationally and competitive economically to natural open sun drying. An experimental of natural solar drying system was constructed at Sharkia Governorate in order to study the drying behavior of some vegetables. Two agricultural crops were used in this experiment, fresh melokhia and red pepper. The obtained data showed that, the highest removal rate of moisture content was obtained at open holes number of 9 for the products at any product mass. The lowest mass of melokhia (0.3 kg/tray) was dried within 6 hours to an average moisture content of 4.9 and 34.7% wet basis in solar dryer and the open sun drying system respectively. For red pepper the lowest mass (0.5 kg/tray) was dried within 18 hours to an average moisture content of 9 and 21 % wet basis in solar dryer and the open sun drying system respectively. The higher thermal efficiencies of the dryer were 24.3 and 24.6% for melokhia and pepper respectively campared to the open sun drying which were 17.5 and 20.7% for melokhia and pepper respectively. The production costs for drying one ton of melokhia and pepper were 970 and 1280 LE/ Mg compared to the open sun drying system for both melokhia and pepper which were1680 and 1820 LE/ Mg.