Abstract: Considering the contribution of association and the density fluctuations，an equation of state (EOS)based on the original cubic-plus-association (CPA)EOS and the renormalization group theory (RG)was extended to binary mixtures.The binary interaction parameters were obtained by fitting the vapor-liquid equilibrium(VLE)data at one temperature，and then were used to predict the VLE data at other temperatures.The RG-CPA EOS was used to predict the VLE and the critical line of the supercritical CO₂-1-alkanol (n=1—8)binary mixtures，which are nonideal systems with association.Using temperature independent binary interaction parameters，satisfactory results for composition and density of both vapor and liquid phases were obtained by the RG-CPA EOS.The overall average absolute derivations of composition in liquid and vapor were 0.032 and 0.019 respectively.In addition，the RG-CPA EOS can successfully reproduce the vapor liquid critical line of these binary mixtures，which is much better than the original CPA EOS.

Key words: vapor-liquid equilibrium, supercritical CO₂, association, renormalization group

摘要： 综合考虑缔合作用和密度涨落的影响，将经重整化群修正的CPA方程（RG-CPA方程）扩展到二元体系汽液相平衡的计算。通过一个温度下的汽液相平衡数据回归得到二元交互作用参数，预测其他温度下的相平衡。采用这种方法计算了超临界CO₂与醇二元体系的汽液相平衡性质和临界曲线。结果表明，RG-CPA方程预测超临界CO₂与醇二元体系的气液相组成和密度具有较高的精度，液相组分平均绝对偏差为0.032，气相组分平均绝对偏差为0.019。与原始CPA方程相比，RG-CPA方程能更好地预测气液临界曲线。

关键词: 汽液相平衡, 超临界CO₂, 缔合, 重整化群