变阱宽方阱链流体状态方程模拟制冷剂的汽液平衡

Modeling vapor-liquid equilibrium of refrigerants using an equation of state for square-well chain fluid with variable range

应用作者先前基于二阶微扰理论和PY2近似积分方程建立的可变阱宽方阱链流体状态方程模拟了纯制冷剂及其混合体系的汽液平衡。通过关联不同温度下制冷剂的饱和蒸气压和液体体积得到了18种纯制冷剂的分子参数,新方程计算的饱和蒸气压和液体体积总的平均偏差分别为1.11%和0.92%。结合简单混合规则,将此方程扩展到混合体系。研究发现,建立的方程可满意预测制冷剂二元混合体系除临界区附近外的汽液平衡,对两个三元体系汽液平衡的预测也取得了满意的效果,当引入一个与温度无关的可调参数时,关联精度大为提高,预示着新的方程可模拟制冷剂的汽液平衡。

An equation of state developed in the authors＇ previous work by applying the second-order perturbation theory and Chiew＇s PY2 approximation of integral equation for square-well chain fluid with variable range was applied to model vapor-liquid equilibrium of pure refrigerants and their mixtures. The molecular parameters for 18 refrigerants were obtained by fitting saturated vapor pressure and liquid molar volume data. The overall average deviations of saturated vapor pressure and liquid molar volume were only 1.11% and 0.92%, respectively. Coupling with one fluid mixing rule, this model was extended to mixtures. It was found that the experimental vapor-liquid equilibrium for binary and ternary mixtures could be well predicted, except at the vicinity of critical point. When using one independent-temperature binary adjustable parameter, the correlated precisions could be greatly enhanced indicating that the new equation could be used to model vapor-liquid equilibrium of refrigerants.