The shell-and-tube evaporator is made by expanding two-layer metal plates with high-pressure gas or mechanically pressing nine. It can also be made of aluminum alloy die-casting.
This type of evaporator is widely used in small refrigeration equipment such as refrigerators, merchandise display cabinets, and popsicle storage boxes.
Flat shell and tube evaporators made of aluminum alloy die-casting are widely used for contact freezing and are generally called flat shell and tube quick freezers. Now, let's take a look at its principle and structural characteristics together!
The working principle of shell and tube evaporator:
Shell and tube evaporator has a wide range of applications due to its better heat transfer effect, compact structure, small footprint, and convenient 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 evaporator and the end cover, forming a multi-pass 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 law is discharged from the upper part.
The heat transfer coefficient of a shell and tube evaporator is larger in liquid than in gas and larger in a flowing state than in a static state.
When the shell and tube evaporator 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 way the liquid exchanges heat to the 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, there will be liquid back in the chiller.
Structural features 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 refrigerant flows in the tube and the refrigerant flows in the tube in the evaporator.
Whether it is a shell and tube condenser or a shell and tube evaporator, the main manufacturing process and the materials used are the same.
They all use a large steel tube, and then weld and install different numbers of low-ribbed copper pipes (according to requirements) inside and isolate them into two independent channels.
Over time, due to material fatigue or quality problems of the material itself, some low-rib copper pipes will have cracks and leaks; and the welding of low-rib copper pipes and simplified tube sheets will also be caused by fatigue of welding materials or welding quality problems. Leakage occurs due to cracks or blisters.
