New drying systems for crops

Drying of agricultural products is an energy intensive operation. High prices and shortages in fossil fuels increase the emphasis on using solar energy as an alternative energy source, especially in developing countries. This paper deals with the construction of four different solar powered drying systems consisting of solar air heaters and drying chambers for small scale, natural convection, direct and indirect solar drying. Generally, solar drying systems which have two main parts, namely a solar air heater and a drying chamber, work during the day and they do not work at night and cloudy days. In this study, these drying systems were successfully tested for apple drying. The drying curves of those systems were compared with the traditional solar drying results. It is concluded that the using of the continuous drying system gave the best results with the reduction of drying time.