Thermal Analysis of a Hybrid Solar Tunnel –Microwave, Dryer for Drying Cultivated Banana

This research aims to design and develop a hybrid dryer between solar energy and microwave for drying cultivated banana. The solar collector uses black painted steel sheets to absorb the sun's radiation covered with a clear acrylic sheet to prevent heat loss from convection and hot air is sent to the drying cabinet equipped with a 6 inch diameter electric fan. The size of solar collector is 0.56 meters width and 1.2 meters length. The drying cabinet is made of stainless steel with a volume of 0.2035 cubic meters. There is a set of electrical control cabinets for adjusting and controlling the inside temperature of the cabinet. A magnetron head set for microwave generator was installed at the back of the cabinet. Dried samples were evaluated for rehydration ratio, drying time and drying rate when the dryer is completely fabricated, the banana drying experiment was conducted for comparing the drying rate in 2 cases. The results showed that when drying banana with microwave mode the average drying rate was 29.167 g water/kg d.s/min m2 and when using the solar collector mode, drying can be achieved by convection heat transfer. The average drying rate was 13.778 g water /kg d.s/min m2 . Therefore, this hybrid dryer should be used in the proper conditions and gain the most energy efficient and suitable. In case of using solar and microwave, mix-mode, should be used for continuous dehumidification and can be used as an auxiliary mode during the night time without sunlight or assist in increasing the temperature in the cabinet to reduce the duration time of drying products.