Essay On Solar Dryers

Abstract-

Solar drying is one of the most ancient and simplest forms of drying known to mankind. Even today, most of the agricultural produce such as grains, spices, fruits and vegetables are dried under the sun. However, drying these products in open sun drying has many drawbacks. The debris, rain, blowing wind, insect infestation, human and animal interference etc. leads to contamination of the products. By the use of solar dryers, such problems can be easily overcome. Thus, there is a need to make the solar dryers more efficient and cheaper. There are various types of solar dryers developed and are classified based on the mode of air circulation, such as, natural circulation and forced circulation solar dryers; based on the type of drying, like, direct solar drying, indirect solar

SOLAR DRYER CLASSIFICATION:

Solar dryers are classified depending upon the mode of air circulation, such as natural circulation and forced circulation dryers; or based on type of drying, like, direct solar drying, indirect solar drying and mixed mode solar drying. Following figure indicates the classification of solar dryers and drying modes [

Fig.1: Classification of solar dryers drying modes.

III. INDIRECT TYPE FORCED CIRCULATION SOLAR DRYERS

Indirect solar drying is the new and more effective technique of product drying. In this type of drying, the products are not directly exposed to the sun but, the solar radiation is used to heat the air which then flows through the product to be dried. Thus, moisture from the product may lost by convection and diffusion.

When this heated air is forced into the drying cabinet by means of an external device, (eg. blower, fan, etc.) the solar dryer is called a forced circulation solar dryer. They are normally referred to as active dryers.

The basic schematic of an indirect type forced circulation solar dryer is shown in the fig. below.

Fig.2: Indirect type forced convection solar dryer.

IV. SOLAR DRYER EVALUATION

V. LITERATURE