Experimental investigation on flow boiling heat transfer characteristics of R1234ze(E)/R152a in 6-mm ID horizontal smooth tube

The near-azeotropic refrigerant mixture R1234ze(E)/R152a (40/60 by mass%) was an excellent alternative refrigerant with outstanding environmental protection and thermophysical properties as well as good cycle performance. The flow boiling heat transfer characteristics of R1234ze(E)/R152a (40/60 by mass%) in horizontal smooth copper tube with inner diameter (ID) of 6 mm were investigated experimentally. The effects of mass flux (100-200 kg center dot m(-2)center dot s(-1)), saturation temperature (285.15-291.15 K), heat flux (5-20 kW center dot m(-2)), and vapor quality (0.02-0.98) on the boiling heat transfer coefficient (HTC) and critical vapor quality were analyzed. It was found that the boiling HTCs increased with increasing heat flux or saturation temperature, and decreased at first but then increased with rising mass flux. The boiling HTCs almost kept constant firstly but then decreased with increasing vapor quality. Besides, the critical vapor quality decreased with increasing heat flux or decreasing mass flux. Finally, the experimental results were compared with several correlations which predict boiling heat transfer characteristics, it could be concluded that the correlations proposed by Jung et al. and Choi et al., respectively, had high prediction accuracy.