CIESC Journal ›› 2012, Vol. 63 ›› Issue (5): 1331-1337.DOI: 10.3969/j.issn.0438-1157.2012.05.001

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Modelling VLE of supercritical CO2 + alkanol mixtures using RG-CPA EOS

XU Xinhao,DUAN Yuanyuan,YANG Zhen   

  1. Department of Thermal Engineering,Tsinghua University
  • Received:2011-09-11 Revised:2012-01-13 Online:2012-05-05 Published:2012-05-05

RG-CPA方程计算超临界CO2-醇体系汽液相平衡

许心皓,段远源,杨震   

  1. 清华大学热能工程系
  • 通讯作者: 段远源

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

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