Fujian Agricultural and Forestry University successfully developed a small air-conditioning dryer

A few days ago, the College of Food Science and Technology of Fujian Agriculture and Forestry University successfully developed a small air-conditioning dryer, widely used in edible fungi, fruits and vegetables, agricultural and sideline products and other processing.

Air-conditioned dry foods are placed in the equipment, not only to adjust the gas composition in the drying room, to reduce the oxygen content of the gas during the drying process, so that it is circulated in a closed system; but also according to the food drying mechanism. , to remove water at a certain rate, reduce water activity, increase the content of soluble solids in foods, so that it is difficult for microorganisms to survive, inhibit the activity of enzymes in food, in order to preserve foods.

The small air-conditioning dryer is a box-type heat pump drying type, and the outer wall is composed of a heat-resistant and heat-insulating barrier board. The high-pressure end of the compressor is connected to two condensers that are placed in parallel in the closed box and the outside of the box through a pipeline and then stored. The tank, filter, and expansion valve are connected to two evaporators placed in parallel inside the tank and outside the tank and then returned to the low pressure side of the compressor via the main pipeline. Each condenser and evaporator pipe is equipped with a solenoid valve to control the opening and closing of the pipe.

When air-conditioning is dry, the pressure and composition of the gas in the sealed oven are regulated using a vacuum pump and a gas tank (carbon dioxide or nitrogen). The microcomputer system measures the temperature, humidity, gas composition, gas pressure, and material weight of the drying chamber through various sensors. Through the opening and closing of the corresponding evaporators and condensers of each solenoid valve, the speed of the compressor is controlled by frequency conversion, and the purpose of effectively controlling the state parameters of the gas composition, temperature and humidity in the drying process is achieved.