Leakage analysis and concentration distribution of flammable refrigerant R290 in the automobile air conditioner system

The natural refrigerant R290 has been gradually investigated as an alternative refrigerant of R134a in the automobile air conditioning (MAC) systems at present. As an A3 class refrigerant, the application of R290 is associated with the greatest challenge of its flammable and explosive characteristics. This paper aimed to describe the distribution of R290 gas under different leakage conditions through experiments in the engine compartment and the passenger compartment. Our results showed that, evaporator leakage was the most risky situation of the system. In this case, R290 gas leaked to the passenger compartment, as a result, the R290 concentration in the environment was above the lower flammable limit (LFL). In the case of leakage in the engine compartment, the leak pressure, leak hole size, and wind speed were recognized as the three main parameters affecting R290 distribution. Moreover, increasing the hole size and decreasing the wind speed would raise the maximum R290 concentration as well as the duration in which the R290 gas concentration was above the LFL level. Additionally, a lower pressure suggested that the R290 concentration rose slower but it was maintained for a longer time above the LFL than that under high pressure situation.