Performance Analysis of a Solar Dryer Equipped with a Recycling Air System and Desiccant Chamber

Drying is a high energy consuming process. Solar drying is one of the most popular methods for dehydration of agricultural products. In the present study، the performance of a forced convection solar dryer equipped with recycling air system and desiccant chamber was investigated. The solar dryer is comprised of solar collector، drying chamber، silica jell desiccant chamber، air ducts، fan and measuring and controlling system. Drying rate and energy consumption in three levels of air temperature (40، 45 and 50 oC) and two modes of drying (with recycling air and no-recycling with open duct system) were measured and compared. The results showed that increasing the drying air temperature decreased the drying time and increased the energy consumption in the mode of non-recycling air system. The dryer efficiency and drying rate were better in the mode of recycling air system than open duct system. The highest dryer efficiency was obtained from drying air temperature of 50 oC and the mode of recycling air system. In general، the efficiency of solar collector and the highest efficiency of the dryer were 0. 34 and 0. 41، respectively.