Compared with the immersed coil heat exchanger, the spray coil heat exchanger has the advantages of convenient inspection and cleaning, good heat transfer effect and the like. The disadvantage is that it is bulky and has a large area; the amount of cooling water is large, and the spray is not easy to be uniform. Due to its simple structure and convenient operation, coil heat exchangers are often used in refrigeration units and small refrigeration units.
The casing type heat exchanger is composed of two straight sleeves of different diameters to form a concentric sleeve. The inner tube is connected by a U-shaped elbow, and the outer tube and the outer tube are connected to each other. The structure is as shown in the picture 4. -43 is shown. Each length of casing is called a one-pass process, and the number of passes can be increased or decreased according to the heat transfer area requirements. In the heat exchange, one fluid goes to the inner tube, and the other fluid goes to the annulus, and the wall surface of the inner tube is a heat transfer surface.
The advantage of the casing heat exchanger is that it has a simple structure; it can withstand high pressure; the heat transfer area can be increased or decreased as needed; proper selection of the inner and outer diameters of the tube can increase the flow velocity of the fluid, and the two fluids flow in a countercurrent flow, which is beneficial to Heat transfer. The disadvantage is that the metal consumption per unit heat transfer area is large; there are many pipe joints, and it is inconvenient to clean and repair. This type of heat exchanger is suitable for heat exchange between high temperature, high pressure and small flow fluids.