Thermal properties and heat transfer characteristics of ternary alternative refrigerant mixtures for HCFC22.

本研究的目的是阐明HFC 32/125/134a三元混合物的热性能和换热特性，HFC 32/125/134a被认为是一种很有前途的HCFC22.1的替代制冷剂。为了确定Peng-Robinson状态方程中的二元相互作用参数，用应变式压力传感器和气相色谱分别测量了混合物的蒸汽压和蒸气中的组成。气温从零下10度到50度不等。通过比较HFC134a的测量饱和压力和公布的饱和压力，验证了压力测量的准确性，准确度在0.25%以内。根据得到的数据，确定了Peng-Robinson状态方程中的二元相互作用参数，并编制了三元混合物的程序代码。在水平光滑管内测量了HFC32、HFC125、HFC134a、HFC32/134a和HFC32/125/134a等工质的蒸发和冷凝换热系数。考察了热流密度、质量流量、质量和温度滑移对换热特性的影响。蒸发和冷凝温度分别为20度和40度。与热物性相近的单组分流体相比，混合物的换热系数降低了约30%。建立了HFC32/125/134a的蒸发换热预测模型。结果表明，三元混合物的主要传热降解机理与二元混合物相同。

The purpose of this study is to clarify the thermal properties and heat transfer characteristics of ternary mixture of HFC 32/125/134a, which is assumed a promising alternative refrigerant for HCFC22.1. In order to determine the binary interaction parameters in the Peng-Robinson equation of states, vapor pressure of the mixtures and composition in vapor were measured using a strain gauge type of pressure transducer and a gas chromatography, respectively. The temperature ranged from-10 to 50 degrees. Accuracy of the pressure measurement was checked by comparing measured and published saturation pressures of HFC134a, and was within 0.25%. Based on the obtained data, the binary interaction parameters in the Peng-Robinson equation of states were determined, and a program code for the ternary mixtures was developed.2. Evaporation and condensation heat transfer coefficients of various kinds of refrigerant including HFC32, HFC125, HFC134a, HFC32/134a and HFC32/125/134a, were measured inside a horizontal smooth tube. Effects of heat flux, mass flux, quality and temperature glide of the mixture on the heat transfer characteristics were examined. Evaporating and condensing temperature were 20 and 40 degrees, respectively. The heat transfer coefficients of mixtures were about, 30% lower than the single component fluids with similar thermopysical properties to the mixtures. A predictive model of evaporation heat transfer for HFC32/125/134a was presented. It was concluded that the principal mechanism of heat transfer degradation of the ternary mixtures was the same with the binary mixtures.