There are two types of cooling methods: direct cooling and indirect cooling. Direct cooling is to install the evaporator of the refrigerator in the box or building of the refrigeration device, use the evaporation of the refrigerant to directly cool the air in it, and rely on the cold air to cool the objects that need to be cooled. The advantages of this cooling method are that the cooling speed is fast, the heat transfer temperature difference is small, and the system is relatively simple, so it is widely used. Indirect cooling relies on the evaporation of the refrigerant in the evaporator of the refrigerator, thereby cooling the refrigerant (such as brine), and then feeding the refrigerant into the box or building of the refrigeration device, and cooling the air through the heat exchanger. This cooling method has a slow cooling rate, a large total heat transfer temperature difference, and a complex system, so it is only used in less occasions, such as brine ice making and cold storage with constant temperature requirements.
According to the different cooling purposes and cooling capacity utilization methods, refrigeration devices can be roughly divided into four categories: refrigeration devices for refrigeration, refrigeration devices for testing, refrigeration devices for production, and refrigeration devices for air conditioning.
Refrigeration devices for refrigeration are mainly used to store or transport food and other goods under low temperature conditions, including various refrigerators, cold stores, refrigerated trucks, refrigerated ships and refrigerated containers.