Applications of solar energy for drying of agricultural commodities

Drying is a simultaneous heat and mass transfer energy intensive operation, widely used as a food preservation technique. In view of improper postharvest methods, energy constraint and environmental impact of conventional drying methods, solar drying could be a practical, economical and environmentally reliable alternative. Open air solar drying method is used frequently to dry the agricultural products. But this method has some disadvantages. Therefore, to avoid disadvantages it is necessary to use the other solar drying methods. Different solar drying methods are direct solar drying, indirect solar drying and mixed mode solar drying. The device used for drying process with application of solar energy called the solar dryer. Solar dryer are also classified with mode of air circulation. In this paper, we studied the various modes of solar drying and classification of solar drying techniques.