Shell-and-tube evaporator is made of two-layer metal plates by high-pressure gas expansion molding or mechanical compression molding. It can also be made by aluminum alloy die-casting. This hair dryer is widely used in refrigerators, commodity display cases, popsicle storage boxes and other small refrigeration equipment. The flat shell tube type hair dryer made of aluminum alloy die-casting is widely used for contact freezing, and is generally called a flat shell tube quick freeze. Now, let's take a look at its principle and structural characteristics with the editor of Xianji.com!
Working principle of shell and tube evaporator:
Shell and tube evaporators are widely used due to their good heat transfer effect, compact structure, small footprint, and easy installation. The structure of the chiller shell and tube evaporator is the same as that of the horizontal shell and tube condenser. In order to control the proper flow rate, the refrigerant enters from the lower part of the end cap, flows out from the upper part, and flows back and forth in the Yanfa tube and the end cap to become a multi-path flow. The refrigerant flows outside the tube. The throttled refrigerant liquid enters from the bottom or side of the evaporator, and the gas after the hair is discharged from the upper part.
The heat transfer coefficient of shell-and-tube evaporator is larger in liquid than in gas, and larger in flowing state than in stationary state.
When the shell-and-tube type 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 ball valve. The height of its hydrostatic surface should be about the diameter of the cylinder. Heat exchange is performed liquid-to-liquid. Therefore, the heat transfer effect is better, and the heat transfer coefficient is larger. But the liquid level should not be too high, otherwise the liquid return phenomenon of the chiller will occur.
Structural characteristics of shell and tube evaporator:
The structure of the shell-and-tube evaporator is basically the same as that of the shell-and-tube condenser. The difference is that the evaporator flows the refrigerant in the tube and the refrigerant flows in the cylinder.
Whether it is a shell and tube condenser or a shell and tube evaporator, the main manufacturing process and materials used are the same. A large steel cylinder is used, and then a variety of (as required) low-rib copper pipes are welded and installed in it and separated into two independent channels. Over time, due to material fatigue or the quality of the material itself, some low-rib copper pipes will crack and leak; there is also the welding of low-rib copper pipes and simplified tube sheets due to welding material fatigue or welding quality problems. A crack or trachoma occurs and leakage occurs.