Research On Heat Pump Type Pasteurization System

Pasteurization is one kind of sterilizations to kill bacteria by using low temperature while keeping the nutrition and flavor in the material be constant, it can be maximized to keep the color, fragrance, taste, nutritional composition and texture of food and it has been widely used in the dairy, food, pharmaceutical, beverage and other industrial sectors. At present, it is applied widely in the production of pasteurized milk.The thesis is a research on the heat pump type pasteurization system, the whole process of production of pasteurized milk need heating, when the pasteurization is finished the milk need to be cooled. Heat pump is a device which can transfer heat energy from low temperature heat source to the high temperature heat source, it can complete both heating and cooling.So we can combine the heat pump device and pasteurization equipment, which can be very good to improve energy efficiency and decrease operation cost.Fisrtly, comparing the heat pump type pasteurization system and electric heating type pasteurization system which is widely used in the market ar present in technology and economy aspects, we can find initial investment of heat pump type pasteurization system is relatively low, running cost is lower than the electric heating type pasteurization equipment. Additional, the life of the heat pump type pasteurization system is long, heat pump type pasteurization system is more safety than electric heating type pasteurization system, so it has broad market prospect.Secondly, in order to improve the performance of heat pump type pasteurization system and considering the practical production, it is necessary to optimize system components.matchment and process parameters. Optimization of parts mainly for pasteurizing cans, including tank length diameter ratio, full coefficient of cans,selection of tank jacket, stirring impeller diameter and so on. Matchment of system mainly includes selection of the ratio of the tank capacity and milk capacity. To make the cold and heat energy produced by heat pump is fully utilized, it is necessary to optimize the operating parameters, including the initial temperature of cold and hot water tanks, heating and cooling amplitude of milk at different stages.At last, the experimental device of heat pump type pasteurization system is established. Making the water simulates milk, using heat and cold capacity of the heat pump to achieve heating and cooling of milk in simulated sterilization tank.Then we can obtain change regulation of heating and cooling of milk at different stages and performance change regulation of heat pump device while it is running. The experimental results indicate that, to match the pasteurized milk’s demand of heating and cooling energy, we can only use heat and cold capacity in water tanks at first-then use heat and cold capacity which is produced by heat pump to continue heating and cooling of milk. Demand of heat and cold capacity of pasteurization system can be matched verifies the feasibility of heat pump type pasterilization system.