Flammability assessment of CH sub(2) CFCF sub(3): Comparison with fluoroalkenes and fluoroalkanes

The burning velocity, flammability limits, and heat of combustion of CH sub(2) CFCF sub(3) (1234yf) have been studied to elucidate the fundamental flammability properties of this new alternative refrigerant with low global-warming potential. The burning velocity of 1234yf was measured independently by schlieren photography and the spherical vessel method. In the spherical vessel method, the burning velocities of 1234yf and its analogues CH sub(2) CFCHF sub(2) (1243yf) and CH sub(2) CHCF sub(3) (1243zf) as well as those of typical fluoroalkanes CH sub(2)F sub(2) (HFC-32) and CH sub(3)CHF sub(2) (HFC-152a) were measured in mixtures of air at various O sub(2)/(N sub(2)+O sub(2)) ratios. The maximum burning velocity of 1234yf was found to be 1.2+ /-0.3cms super(-) super(1), which was approximately one-fifth that of HFC-32 (6.7cms super(-) super(1)) and one order of magnitude less than those of 1243yf (19.8cms super(-) super(1)) and 1243zf (14.1cms super(-) super(1)). The flame propagation of 1234yf was highly sensitive to flame temperature compared to that of the other compounds. The measured flammability limits and calculated heat of combustion of 1234yf were also determined.