Performance comparison between refrigerant R290 and refrigerant R22
Refrigerant R290, propane, is a natural hydrocarbon refrigerant that can be obtained directly from liquefied gases. Compared with the synthetic refrigerant such as Freon, the natural working fluid R290 does not contain chlorine atoms in the molecule, so the ODP value is zero, and it does not have a destructive effect on the ozone layer. In addition, the GWP value of R290 is close to zero compared to the HFC material which also has no destructive effect on the ozone layer, and has no effect on the greenhouse effect. Currently in Germany R290 has been used in domestic water heaters and air conditioning systems.
At present, China's air-conditioning industry uses more refrigerant R22. The basic physical properties of R290 and R22, such as the standard boiling point, freezing point and critical point, are very close, and have the basic conditions for replacing R22. In saturated liquid state, the density of R290 is smaller than R22, so the amount of R290 perfusion is smaller under the same volume. The test proves that the amount of R290 perfusion in the same system volume is about 43% of R22. In addition, since the latent heat of vaporization of R290 is about twice that of R22, the refrigerant circulation rate of the refrigeration system using R290 is smaller. R290 has good material compatibility and is compatible with copper, steel, cast iron and lubricating oil.
However, the refrigerant R290 cannot be applied on a large scale because its flammability and explosiveness has not been effectively solved, which is the biggest obstacle to its popularity. In order to reduce safety hazards, the IEC standard limits the maximum safe perfusion of R290 refrigerant: when the installation height is 2.2m in a room of 10 square meters, the filling amount must be less than 290g. Reducing the amount of perfusion can reduce the leakage of the refrigerant to a certain extent, thereby improving the safety of the use of R290. Whether the reduction in refrigerant perfusion will bring about a decline in refrigeration capacity? In this regard, the industry said that the latent heat of vaporization of R290 is about twice that of R22, which means that the refrigeration capacity per unit mass R290 is higher. And the current test has confirmed that in the case of reducing the amount of R290 refrigerant perfusion, the cooling effect of R22 can be achieved or exceeded by the structural modification of the refrigeration system. Reducing the amount of leakage and improving the ability to detect and respond to leaks is an important measure to improve the safety of R290. It is understood that most manufacturers currently have high requirements for air conditioning seal testing standards. The annual air leakage of normal air conditioners can be controlled below 5g without any danger. The refrigerant leakage that occurs nowadays is mostly concentrated in the installation, use and maintenance of air conditioners. However, there are many uncontrollable factors such as environment and usage methods in these processes. Therefore, the safety control measures in these processes still need further research and improvement.