e air. After heated by the radiator or electric heater, the hot air delivered by the circulating fan enters into the drying room through the air duct, and transfers heat to the materials. Fresh air is replenished through the air inlet while wet air is discharged through the air outlet. By the constant replenishing of fresh air and discharging of wet air, the proper relative humidity in the drying oven is maintained.
lin: http://www.fooddryingoven.com/food_drying_equipment/vegetable-drying-oven