Flammability, R32, Ignition, Flame, Fire
Refrigerant R32 (difluoromethane, formula CH2F2) is a working fluid with favorable environmental and performance properties. However, it can be slightly flammable under certain conditions (13 – 30% by volume in air), with a flammability classification of 2L. The risks of ignition, fire, and hazardous decomposition products are being assessed in our laboratories using experiments, risk analysis, and computational fluid dynamics simulations. R32 has entered service in Japan and is being considered for service in the US. Its adoption is being hindered by its slight flammability in air. Past research has examined the flammability of pure refrigerants without considering the effects of the presence of lubricating oil. The concentration of oil released in a refrigerant leak can vary depending on the location of the leak and the operating state of the equipment. In this study, mixtures of R32 and R410 with lubricating oil are impinged onto a hot horizontal metal surface to examine autoignition behavior. The tests simulate a leak in a cooling system that impinges on a heating element. The hypothesis of this research is that the autoignition behavior of these mixtures is dominated by the presence of lubricating oil, not by differences in the refrigerant flammability. Only preliminary results are available at the time of abstract preparation, but extensive results will be included in the presentation at Purdue.