Theoretical and experimental study of the inhibition and inert effect of HFC125, HFC227ea and HFC13I1 on the flammability of HFC32

HFC32 is a potential alternative refrigerant with excellent thermal performance, but the flammability is a main obstacle for its applications. The group contribution method is utilized to analyze the inhibition efficiency of nonflammable refrigerants in binary mixtures. Furthermore, a novel equation of predicting the minimum inerting concentration of nonflammable refrigerants has been proposed by analyzing the variation of the flame propagation velocity and the flammable refrigerant concentration. Experimental studies of the explosion limits of HFC125/HFC32, HFC227ea/HFC32 and HFC13I1/HFC32 were carried out and the ranges of explosion limits were obtained. At the same time, the relationship between the maximum charge of the flammable refrigerants and lower flammability limit (LFL) was analyzed. The result demonstrates that the proposed novel theoretical equation can effectively predict the minimum inerting concentration of nonflammable refrigerants to flammable refrigerants, and the theoretical results have significance on the security application of the binary mixtures.

► A novel equation of predicting the minimum inerting concentration of nonflammable refrigerant has been proposed.
► Explosion limits of HFC125/HFC32, HFC227ea/HFC32 and HFC13I1/HFC32 were experimented and ranges of explosive limits were obtained.
► The relationship between maximum charge of the flammable refrigerants and lower flammability limit was analyzed.
► The proposed novel theoretical equation can effectively predict the minimum inerting concentration of nonflammable refrigerants.