Flammability assessment of CH2=CFCF3: Comparison with fluoroalkenes and fluoroalkanes

The burning velocity, flammability limits, and heat of combustion of CH2=CFCF3 (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 CH2=CFCHF2 (1243yf) and CH2=CHCF3 (1243zf) as well as those of typical fluoroalkanes CH2F2 (HFC-32) and CH3CHF2 (HFC-152a) were measured in mixtures of air at various O-2/(N-2 + O-2) ratios. The maximum burning velocity of 1234yf was found to be 1.2 +/- 0.3 cm s(-1),which was approximately one-fifth that of HFC-32 (6.7 cm s(-1))and one order of magnitude less than those of 1243yf (19.8 cm s(-1)) and 1243zf (14.1 cm s(-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. (C) 2009 Elsevier B.V. All rights reserved.