Research on characteristics of refrigerant R290 and its lubricating oil mixture for small heat pump air-conditioning

Abstract

Freon (CFCs, BCFCs) refrigerants are widely used in refrigeration equipment and air-conditioning, but because of its destructive effect on the ozone layer, and it is a greenhouse gas, it has certain Developed countries have completely banned the production and use of CFCs since 1996, and the banning period of HCFCs has also been advanced from 2030 to 2020 in the Montreal Amendment. Based on the analysis of the history, current situation and domestic and foreign situations of refrigerant substitution (especially HCFCs substitution), this paper demonstrates the feasibility of replacing R22 with R290 in small heat pump air-conditioning, including physical and chemical properties, theoretical refrigeration cycle, economic efficiency and Security and many other aspects.

The basic thermophysical properties of R290 are similar to R22, the chemical properties are also relatively stable, the price is easy to obtain, and the compatibility with materials is good. Its thermophysical properties are even better than R22 in many aspects. Moreover, its ODP and GWP values u200bu200bare both zero, and there is no problem of damaging the environment. Therefore, replacing R22 with R290 has broad prospects in small refrigeration devices.

Propane is a hydrocarbon, and its flammability as a refrigerant is a problem that needs serious consideration. For the safe operation of the refrigerator, under the premise of ensuring the COP, the amount of propane filling should be reduced as much as possible. The solubility of refrigerant in lubricating oil will have a significant impact on refrigerant charge and refrigeration performance. In order to explore the properties of the mixture of propane and lubricating oil, an experimental device was designed, and the experimental methods and testing methods were optimized. Through the comparison experiment of miscibility between propane and the three selected lubricating oils, the performance of the refrigeration cycle under the corresponding conditions is analyzed, and the z* best refrigerating oil and its matching ratio that can be used in the propane refrigeration and air conditioning system are sought. The experimental results show that for the mixture of R290 and insoluble oil, the refrigerating oil has no effect on the cycle performance of the system, but it will cause the compressor to return to the oil difficult. For the mixture of R290 and soluble oil, in order to ensure the COP of the system, the amount of lubricating oil must be controlled, preferably not more than 5%, and z* should not exceed 20%. Moreover, in the propane refrigeration system, the use of PAG lubricant is a better choice, because it takes into account the requirements of safety, system refrigeration performance and compressor oil return. On the basis of summarizing the theoretical analysis and experimental research, suggestions for further improvement, improvement and in-depth research are put forward for the promotion and application of R290 in the future.

Keywords: heat pump air conditioner, refrigerant substitution, R290, lubricating oil miscibility, refrigeration performance