One of the main purposes of drying of the agricultural products is increasing the shelf life of such products. Solar powered systems as a proper choice in drying process has received less attention due to low thermal performance and non-homogeneous drying condition are less. In the presented project the thermal properties of a solar rotary dryer with phase change material (PCM) in the drum was evaluated. The evaluations were carried out at the air velocities of 0.4, 0.9 and 1.6 m/s with Sumac as medicinal plant. According to the obtained results it can be stated that using recirculation and storage mechanism improved the dehydration performance at least 37.26 %. The thermal efficiency of the system increased about 58.68 %. By economical optimization of the rotary dryer the payback period reduced 4 months. Moreover, computational fluid dynamic method applied to evaluate and analysis the thermal performance of the dryer at various conditions. The findings of the modeling process implied that the applied CFD model can predict the thermal behavior of the rotary system with a suitable accuracy (relative error < 3.25 ± 0.68). Based on the results the best condition for the structure of the storage system and drying air velocity was introduced.
