What is the principle of the chiller shell and tube evaporator

What is the principle of the chiller shell and tube evaporator

The cold water shell and tube evaporator is made by expanding two-layer metal plates with high-pressure gas or by mechanical pressing. It can also be made of aluminum alloy die-casting. This kind of bird's nest is widely used in small refrigeration equipment such as refrigerators, merchandise display cabinets, and popsicle storage boxes. The flat-shell and tube-style hair dryer made of aluminum alloy die-casting is widely used for contact freezing, and is generally called the flat-shell and tube quick-freezer.

　　The heat transfer coefficient of the cold water shell and tube evaporator is larger in liquid than in gas, and larger in flow state than in static state.

　　 water chiller shell-and-tube evaporator has a wide range of applications due to its better heat transfer effect, compact structure, small footprint and easy installation. The structure of the chiller shell and tube evaporator is the same as the horizontal shell and tube condenser. In order to control the proper flow rate, the refrigerant enters from the lower part of the end cover, flows out from the upper part, and flows back and forth between the Yanfa tube and the end cover, forming a multi-pass flow. The refrigerant flows outside the tube, and the throttled refrigerant liquid enters from the bottom or side of the evaporator, and the gas after the blowout is discharged from the upper part.

　　 The upper part of the cylinder of the evaporator is generally equipped with a few rows of cooling pipes or a gas bag is welded to the shell, so that the gas separates the liquid droplets before leaving the hair dryer. Large-scale yan-hair devices are generally made as a special separating device.

When the shell-and-tube type bird hair dryer is working, a certain amount of liquid refrigerant should be retained in the shell, and the liquid level should be controlled by a float valve. The height of the static liquid level should be about the diameter of the cylinder. Exchange heat in a liquid-to-liquid manner. Therefore, the heat transfer effect is better and the heat transfer coefficient is larger. But the liquid level should not be too high, otherwise liquid back of the refrigerator will occur.

　　 Although this type of evaporator is common to both nitrogen and slave, the pipe materials used are different. Generally, the ammonia evaporator is made of 4025x2.5-438x3 steel pipes, and the Hylion Swallow Hair Apparatus is made of copper or brass pipes. When the refrigerant is corrosive, the tube sheet generally uses a corrosion-resistant composite metal plate, and the cooling tube uses a high-strength aluminum-arsenic brass tube. In order to enhance the heat transfer effect, finned tubes are often used in Nurion evaporators.

　　 In general, the heat transfer coefficient of the evaporator is smaller than that of the condenser, which is mainly due to the small heat transfer temperature difference.