What are the factors that affect the heat transfer of the evaporator of the cold water machine
2016-05-25 08:06:16 admin
Whether the cold water machine evaporator can be very good heat transfer effect on the effect of the cold water machine, we have to talk about the main factors that can affect the cooling effect of the cooling water machine. Cold water machine in the temperature control is divided into low temperature and normal temperature cold water machine, the temperature of the temperature control in the range of 0 degrees -35 degrees.
The evaporator of the cold water machine is a heat exchange device, and the refrigerant liquid is boiled at a lower temperature in the evaporator, which is changed into vapor to absorb the heat of the cooled object or medium. According to the characteristics of the cooling medium, it is generally divided into the cooling air and the cooling liquid refrigerant in two categories.
First, there is a lubricating oil into the evaporator:
Every cold water machine filling amount of lubricating oil, once the lubricating oil into the evaporator heat transfer surface, directly reduce the refrigerant liquid wetting surface heat transfer ability, and accelerate the formation of film, and produce great thermal resistance lead to reduce heat transfer efficiency and reduces the cooling capacity.
Two, the structure of the evaporator design:
To ensure that the steam will soon leave the heat transfer surface, and maintain a reasonable level of liquid height, then the structure design of the evaporator is the most important point, that is, to ensure that the steam from the heat transfer surface as soon as possible.
To make full use of the water chiller evaporator heat transfer surface, can be produced by throttling after flash gas before entering the evaporator to separate, so in some of the larger refrigeration system, usually a gas-liquid separator is arranged in front of the evaporator.
Three, the evaporator under the bubble boiling operation:
Bubble boiling is refers to the refrigerant in the heating surface to form a lot of bubbles, and gradually increase in the liquid inside and up, and then break down, to reach the boiling state. If more and more bubbles to leave the heating surface to sink into a gas film, it will increase the heat transfer resistance, reduce the heat transfer coefficient, so to control the evaporator in bubble boiling operation. Only in full contact with the refrigerant in the case of cold water machine can have a better cooling effect.