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在统计缔合流体理论(statistical associating fluid theory,SAFT)的基础上,将二氧化碳(CO2)处理为似缔合分子,考虑醇羟基之间的自缔合作用,以及CO2分子与醇羟基之间的交叉缔合作用,提出了适用于CO2-醇类体系的交叉缔合模型.应用该模型研究了CO2-甲醇和CO2-乙醇体系从低温低压到高温高压的相平衡性质.p-x和p-ρ相图的计算值与实验值吻合良好.研究表明,考虑CO2与甲醇和乙醇分子之间的交叉缔合对Helmholtz自由能的贡献,可显著改善相平衡性质的计算结果,并避免模型对低温区间中三相平衡和三相点的错误预测.
Based on statistical associating fluid theory (SAFT), carbon dioxide (CO2) is treated as an associative molecule to consider the self-association between alcoholic hydroxyl groups and between CO2 molecules and alcoholic hydroxyl groups Cross-association effect, a cross-association model for CO2-alcohol system was proposed.The phase equilibrium property of CO2-methanol and CO2-ethanol system from low temperature to high temperature and high pressure was studied by using this model.px and p-ρ phase The calculated values agree well with the experimental data. The results show that considering the contribution of cross-association between CO2 and methanol and ethanol molecules to the Helmholtz free energy can significantly improve the calculation of the phase equilibrium property and avoid the effect of the model on the low- Three-phase equilibrium and three-phase error prediction.