Evaporator in refrigerated cold room according to the t […]
Evaporator in refrigerated cold room according to the type of medium to be cooled can be divided into cooling liquid evaporator and cooling air evaporator (table evaporator) these two categories. Surface-cooled evaporator and more for air-conditioning installations, dry water evaporator refrigerant.
Horizontal evaporator and horizontal shell and tube condenser structure is basically similar. By the way for the liquid can be divided into shell and tube evaporator and dry evaporator two. Horizontal shell and tube evaporators are widely used in closed salt water circulation system. Its main features are: compact structure, liquid and heat transfer surface contact, heat transfer coefficient. However, it needs to be filled with a large amount of refrigerant, and the liquid column will have an influence on the evaporation temperature. And when the brine concentration decreases or the salt pump is shut down for some reason, the brine may freeze in the tube. If the refrigerant is freon, the freon dissolved lubricating oil is difficult to return to the compressor. In addition, the need to stop working when cleaning.
Dry freon evaporator. The main difference is that the refrigerant flows inside the tube while the refrigerant flows outside the tube. The throttled Freon liquid enters the evaporator from the lower part of one end cap and is led out from the upper part of the end cap through several processes. As the refrigerant continuously evaporates in the tube as it flows, a part of the wall is occupied by the vapor, therefore , Its heat transfer effect is less than full liquid type. However, it has no effect of liquid column on the evaporation temperature and is better due to the higher freon flow rate (≥4 m / s). In addition, the risk of freezing is slowed down due to the large amount of refrigerant contained in the tubes. The charge of refrigerant in this evaporator is only 1/2 ~ l / 3 or less full liquid, so it is called "dry evaporator."
The common feature of the riser and coil evaporator is that the refrigerant evaporates in the tube and the entire evaporator tube is immersed in a tank filled with refrigerant (or in a tank or tank). In order to ensure that the refrigerant A certain speed cycle, the tank is welded with longitudinal partitions and equipped with a spiral mixer. The carrier fluid flow rate is generally 0.3 ~ 0.7m / s, in order to enhance heat transfer.