S. Prem Kumar - Department of Mechanical Engineering, Sri Dhrmasthala Manjunatheshwara Institute of Technology, Ujire, Karnataka, India
G. Kumar - Department of Mechanical Engineering, Sri Dhrmasthala Manjunatheshwara Institute of Technology, Ujire, Karnataka, India

In solar drying, the moisture content of a product is reduced through the use of sunlight. Solar drying is practiced since civilization for the drying of crops. The dried crop has a longer shelf life and requires less storage space. For crop drying, hot air is required in the moderate temperature range of ۴۰ to ۷۵℃. Solar dryer makes it possible to obtain better product quality. Over the past ۲۰ years, numerous experimental projects have been carried out in the field of solar dryers. Most conventional dryers are not able to operate continuously during the off sunshine time. However, attempts were made to develop uninterrupted solar drying systems by incorporating an energy storage facility and a hybrid mode of operation.  Sensible and latent heat storage methods are widely used to store solar energy. Heat storage materials store energy in the form of heat during sunshine and release it whenever it is required. Biogas backup, Chemical heat pump, Photo Voltaic, and Fluidized bed methods were integrated with solar dryers for uninterrupted operation. In this article, the discussion is made about different dryers. Also, the challenges and scope in the area of the solar dryer are highlighted.

Crop drying, heat storage, Solar dryer, Solar energy, Solar thermal