Development of Drying Using Hot Air – Microwave Technique

Abstract

In southern Thailand, consisting of Yala, Pattani, and Narathiwat provinces; The agricultural products are conventionally dried using heat from the sun or heat from burning woods. These drying methods have problems such as low efficiency and environmental problems. Exploiting the strong electric dipole of the water molecules in the agricultural products, which allows the agricultural products to the absorb microwave energy effectively; we have developed a novel hot air-microwave heating system for the efficient drying of agricultural products. The experimental result reveal that heat produced by the hot air-microwave system causes evaporation of moisture from the agricultural products making it possible to produce high quality dried agricultural products. The situations are tested; the temperature of heater and air velocity is supervised in rang of 30-180^๐C and 1.0-7.0 m/s respectively. The result from this study indicates that the heater temperature increases according to the rising temperature in the dryer. The air velocity is affected by the temperature within the dryer chamber, and it was found that whenever the air velocity increases the temperature in the dryer chamber decreases accordingly. This designed and constructed dryer is, therefore, able to use for drying kinetic of food and agricultural products.