Solar Drying System Integrated with Phase Change Material (PCM)

The post-harvest losses for agricultural products are around 30%-40% [1]. Drying is a one of the necessary processes for the preservation of agricultural products. Agricultural products require hot air of temperature above 40 ºC for drying. Open sun drying takes more time for drying of products due to slower drying rates. Also, various factors hamper the quality of the dried product. Due to the moisture content in the products bacterial attack is possible. India being the tropical region has good solar radiation. It is advisable to use the solar dryer to avoid spoilage of quality of products [2]. In this work, the compact and portable forced convection solar dryer designed and developed for drying chilies with thermal energy storage. Solar dryer is having capacity of 15 kg and it consists of the flat plate collector based air heating system with thermal energy storage. Paraffin wax used as phase change material (PCM). The CFD simulations carried out for the solar dryer to study the temperature distribution over the surfaces of the flat plate collector and inside the drying chamber, velocity of air and phase change behavior of paraffin wax inside the trays. The energy stored in the paraffin wax and time required for charging and discharging of paraffin wax is found out. The time for which temperature in the drying chamber is maintained above 40 oC is also found out. Results of CFD simulations validated with the experimental results.