混合工质R447A在水平管内的流动沸腾换热特性

R447A是一种三元非共沸混合工质,已成为高温室效应工质R410A潜在的替代品之一。本文通过研究R447A在内径为10.6mm的水平光滑管内的流动沸腾传热特性,获得了R447A在水平光滑管内的流动沸腾传热数据以及传热现象,并分析了不同因素对R447A传热效果的影响。实验条件为:热流密度5～20kW/m2,质量流速100～300kg/(m2·s),蒸发温度5～25℃。实验结果表明:R447A的传热系数在0.8～4kW/(m2·K)之间。同时对R410A进行了相同工况下传热系数测试,发现热流密度对R410A传热系数的影响要大于对R447A的影响,而干度和质量流速则对R447A的传热影响更为显著。本文基于实验数据及实验现象发展了一种分干度区预测传热系数的新模型,新模型对R447A换热系数预测的平均偏差为+6.21%,绝对偏差为+12.96%。此研究结果可为这种工质的换热器设计提供帮助。

Flow boiling heat transfer of the refrigerant mixture R447A in a horizontal smooth tube

The object of this study, R447A, is a ternary non-azeotropic refrigerant mixture as a potential substitute of R410A with high GWP(Global Warming Potential). Flow boiling heat transfer characteristics of R447A were investigated in the horizontal smooth tube with inner diameter (I.D.) of 10.6mm. The heat flux ranged in 5—20kW/m², the evaporating temperature ranged in 5—25℃, and the mass flux ranged in 100—300kg/(m²·s). This study shows that under the conditions of this experiment, the heat transfer coefficients of R447A are between 0.8—4kW/(m²·K). In addition, the heat transfer coefficients of R410A were also tested under the same conditions. It was found that the influence of heat flux on the heat transfer coefficients of R410A was greater than those of R447A, while the influence of vapor quality and mass flow rate on the heat transfer coefficient of R447A was more significant. This paper proposed a new method that divides vapor quality into two part to predict heat transfer coefficients. A new prediction correlation was developed with a mean deviation of +6.21%, an absolute deviation of +12.96%. The results of this study can be helpful to design heat exchangers for R447A.