What is a chiller secondary cold? Why is it too cold twice?
Our heat pump jets solve the problem of air-conditioning low-temperature heat, and the second-class overcold is to improve refrigeration efficiency and increase refrigeration capacity.
First, the change in refrigerant in the refrigeration cycle:
The refrigerant compressor compresses the gaseous refrigerant to a high-temperature high pressure gaseous refrigerant, and the condenser is condensed into a high-temperature high-pressure refrigerant liquid, and the liquid refrigerant turns a low temperature and low pressure refrigerant liquid, low temperature and low pressure. The refrigerant liquid enters the evaporator to evaporate heat, becoming a low temperature and low pressure refrigerant gas into the refrigeration compressor, so that reciprocates.
During the refrigeration process, the better the condenser cooling effect, the better the cooling effect, the lower the temperature of the condenser, the lower the cooling effect, the better the cooling effect.
It is assumed that the normally discharged from the compressor is 85 ° C, these high temperature and high pressure steams are generally cooled to 40 ° C liquid refrigerant (35 ° C in an outdoor ambient temperature of 35 ° C) after the condenser. Cold cooling, [Source of this article: Refrigeration encyclopedia], if you want to continue cooling to 37 ° C, you can implement the area of the heat exchanger, but due to the ambient temperature, according to the Carno formula, even if it is infinite Large heat exchanger cooling temperatures are not possible to reduce to the ambient temperature, and the two temperatures will not be transferred to each other.
However, it is found that in the entire refrigeration cycle, the temperature of the refrigerant gas from the evaporator is very low, only about 15 ° C, so it is thought that the gas difference of the cold media from the condenser is large, let They have been in contact, it is possible to reduce liquid refrigerants at 40 ° C below 35 ° C, which is the so-called “secondary overcold” technology.
The principle of “secondary cooling” is very easy to implement, but in the actual process, if the temperature cooling of the liquid refrigerant temperature can result in the temperature of the heated gas-refrigerant being heated, it is equivalent to from the evaporator. The temperature of the gaseous refrigerant temperature will increase, which will cause the compressor’s return temperature, and the compressor has overheated protection. Excessive refrigerant steam temperatures will destroy the lubricant lubrication performance, and make the valve channel and valve sheets , Make the compressor cannot work.
In the process of running, if it is too cold, it will reduce the traffic of the main circulation of refrigerant, affect the stability of the system oil return and electronic expansion valve; if the cooling degree is too low, it will result in a decrease in cooling effect. Therefore, it is generally controlled to match the performance of the system within a suitable range (5-8 ° C) to ensure the system is stable.