Pool boiling heat transfer of low GWP refrigerants R1234ze(E), R1234ze(Z) and R1233zd(E) on a horizontal plane tube.

The low GWP refrigerant of R1234ze(E) is considered to be the prospective candidate alternative to conventional R134a for car air conditioners, while the isomer R1234ze(Z) and R1233zd(E) are anticipated to be the low GWP alternative to R245fa used in high-temperature heat pumps and organic Rankine cycles. The pool boiling heat transfer coefficients (HTCs) of these refrigerants on a horizontal smooth tube made of a copper with an outer diameter of 19.12 mm are quantitatively assessed in this study. The data on surface tension are also presented for R1234ze(E), R1234ze(Z) and R1233zd(E). The observed bubble behaviour and surface tension data support the relativity in HTC. It was confirmed that the experimental HTC closely agrees with the calculated HTC of Stephan-Abdelsalam (1980), Ribatski-Jabardo (2003), and Gorenflo et al. (2010).

全球变暖潜能值（Global Warming Potential, GWP）较低的制冷剂R1234ze(E)被认为是车用空调领域传统制冷剂R134a的理想替代候选者；其同分异构体R1234ze(Z)与R1233zd(E)则被预期可作为高温热泵与有机朗肯循环中所用R245fa的低GWP替代制冷剂。本研究针对上述制冷剂在外径为19.12 mm的水平光滑铜管表面的池沸腾传热系数（Heat Transfer Coefficients, HTCs）开展了定量评估，同时还给出了R1234ze(E)、R1234ze(Z)与R1233zd(E)的表面张力数据。观测得到的气泡行为与表面张力数据可为传热系数的变化相关性提供佐证。研究证实，实验测得的传热系数与Stephan-Abdelsalam（1980）、Ribatski-Jabardo（2003）以及Gorenflo等人（2010）提出的传热系数计算结果高度吻合。