Dehydration of vegetables by using indirect solar dryer

Abstract

The temperature controlled indirect solar dryer is designed in Quetta by using simple available stuffs in the market to dry the agricultural products for its longer shelf life. The dryer consists of drying cabinet, solar cell, electrical fan and collector. Inside the cabinet there are four trays at equally distance from each other, each tray receive uniformly heated air from the collector to dry the agricultural product. During the drying process temperature and relative humidity inside the cabinet is measured with help of digital hygrometer. Tomatoes, mint leaves, eggplant and onion were dried in newly low cost designed dryer. The drying time, color and quality of these products are compared with open sun drying. The result shows that the product dried in the newly dryer is good in quality and dry faster than open sun drying method. The drying occurs in falling rate period. Uniformity of the dryer in each tray was also checked by placing vegitable slices of same size and weight in each tray, the drying time for each tray was same. By increasing the size of vegitable slices increase the drying time, result also shows that increasing in drying air temperature also increase the drying time.

Keywords

• Low cost dryer,sawtooth wave absorber plate,Uniform heated air dryer,Tomatoes,Mint leaves,Eggplant,Onion

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