When the Freon liquid of the refrigeration system enters the expansion valve and is throttled and sent to the evaporator, it is a vaporization process. At this time, a large amount of heat needs to be absorbed to gradually reduce the temperature of the cooled product to achieve the effect of cooling. Then, according to the type of the medium to be cooled, it can be divided into two categories: an evaporator for cooling liquid (water) (dry evaporator) and an evaporator for cooling air (surface-cooled evaporator).
Here mainly introduced is the evaporator used in the chiller refrigeration system, generally a dry shell and tube evaporator. As shown in the figure, the refrigerant evaporates in the heat exchange tube, and water flows on the shell and tube side. In order to increase the heat exchange efficiency, a 2mm thick baffle plate is set on the shell and tube side to allow water to flow back and forth to achieve the purpose of generating ice brine. Made of steel pipe with a thickness of more than 6mm, it can withstand pressure of 10 Kg / cm2, and the outside is insulated by PE foam board. The heat exchange tube adopts high-efficiency seamless copper tube, which is processed into internally threaded ribbed tube through embossing process, which increases the heat transfer area and improves the heat transfer efficiency. The pressure resistance is 20 Kg / cm2. The heat exchange tube and the end plate are expanded tube type, and a partition is added in the end cover to separate the refrigerant into multiple flows to keep the refrigerated oil flowing back. Both the refrigerant liquid tube and the low pressure tube are connected by a working valve. The total heat transfer coefficient should be It can tolerate 0.086 M2 ℃ / KW scale factor, and the water pressure drop through the evaporator does not exceed 6.5mAq.