1. What are the refrigeration cycle forms of carbon dioxide?
Generally speaking, there are three types of carbon dioxide refrigeration cycle, namely supercritical carbon dioxide refrigeration cycle, transcritical carbon dioxide refrigeration cycle and subcritical carbon dioxide refrigeration cycle.
Supercritical carbon dioxide refrigeration cycle: That is to say, all the circulation state is above the critical point. In the process of circulation, carbon dioxide can not become liquid, and is always in the form of gas. This method is generally used in the nuclear electric power generation, not used in the field of refrigeration and air conditioning.
Transcritical carbon dioxide refrigeration cycle: That is, the suction pressure is lower than the critical pressure, the evaporation temperature is lower than the critical temperature, but the exhaust pressure is higher than the critical pressure. The heat absorption process in this cycle is carried out under subcritical conditions, and the heat transfer is mainly realized by latent heat. This form of refrigeration cycle is currently the most used and most active.
Subcritical carbon dioxide refrigeration cycle: That is, the suction pressure and exhaust pressure are both lower than the critical pressure, and the evaporation temperature is lower than the critical temperature, so the heat absorption and heat release process in this cycle are carried out under subcritical conditions. This form of refrigeration cycle is mainly used in the overlapping refrigeration cycle.
2. What are the main areas carbon dioxide refrigerants are used in?
There are three main areas, including heat pump water heater, vehicle air conditioning and refrigeration system.
(1)Heat pump water heater
Carbon dioxide heat pump water heaters generally have higher exhaust temperature and larger temperature glide, which can be matched with the temperature rise process of cooling medium, so that the water heater has unique advantages in application.
(2)Vehicle air conditioning
If carbon dioxide is used as the refrigerant, the loss caused by irreversible heat transfer on the high-pressure side can be reduced. The compression ratio of the carbon dioxide is low, so that the carbon dioxide is completely environment - friendly.
It is mainly used as low temperature refrigerant. Because when the carbon dioxide is at low temperature, its viscosity is small, heat transfer is good, the chemical property is stable, and the refrigeration effect is good, it is very suitable.http://www.wxytgas.com/