Research on the effect of flame retardants on the mildly flammable refrigerant ammonia

Abstract

The natural working fluid ammonia has once again attracted widespread attention due to its environmental performance. However, the flammability of ammonia will lead to some potential safety hazards in practical applications. In this paper, the flammability characteristics of ammonia mixed with R125 and R227ea were studied experimentally. Firstly, the flammability limits of the binary mixture in dry air were measured in a 12 L spherical glass flask. The results showed that when the volume ratios of R125/NH3 and R227ea/NH3 were 0.65 and 0.63, respectively, the binary mixture reached the critical flammability ratio. And the inhibition mechanism of R125 and R227ea was discussed by the density functional theory. It was found that the flame retardants are easy to produce F and CF3 inhibition radicals. Finally, the inhibitory effects of R125 and R227ea were compared by the comprehensive analysis of environmental and safety performance. Under the premise of meeting the requirements of environmental protection, R227ea has a stronger inhibitory effect on the flammability of ammonia than R125. This paper is of great significance for the safe application of ammonia in the process industries.