DRYING CHARACTERISTICS OF OKRA BY DIFFERENT SOLAR DRYERS

Abstract

Drying of agricultural products is the great importance for preservation of food by human beings. Solar drying refers to a technique that utilizes incident solar radiation to convert it into thermal heat energy for drying purposes. The drying operation is mainly affected by variation of the air drying temperature, air flow rate and air relative humidity. The research was carried out to study the drying characteristics of okra to achieve highly drying rates and good quality. Three similar drying units were designed and manufactured in the Faculty of Agricultural., Menoufiya University and installed on the roof of Agricultural Engineering building. Each unit consists of solar collector, drying chamber, drying trays, chimney, and suction fan. Drying characteristics of okra treated by 1.0%sodium carbonates at boiling point for three minuets under different drying systems and flow rates of air 0.075 m 3 /sec, 0.149 m 3 /sec, and 0.249 m 3 /sec at the same time. Computer program used to define the fit mathematical model described the dying curves of okra in different conditions. The obtained results showed that, indirect dryer for drying okra at air flow rate of 0.075 m 3 /sec achieved the best quality. The drying efficiency was decreased as, the moisture content of okra crop reduced.