熱力學性質與流體相平衡對化工產業而言是相當重要的資訊，一般而言可以透過實驗量測或是熱力學模型估算來提供所需的熱力學數據。在過去的研究中，COSMO-SAC-dsp模型已被證明可以用來估算相平衡數據，如氣液相平衡、液液相平衡、無限稀釋活性係數等。COSMO-SAC-dsp模型中，分子間的作用力是利用量子化學計算所得到的分子表面電荷估算，因此不存在著參數缺失的問題。COSMO-SAC-dsp模型中活性係數的計算可分為下面三項貢獻：剩餘項(residual term)、分散項(dispersion term)和組合項(combinatorial term)。本研究目標系統性的探討COSMO-SAC-dsp使用不同分散項和組合項之效應，因此將剩餘項固定不動，比較四種組合項模型與三種分散項模型，其中分散項模型中更進一步探討不同溫度函數的作用力參數對模型精確度的效應。 本研究利用440個雙成份氣液相平衡系統與2291個雙成份無限稀釋活性係數之實驗點探討活性係數模型的準確度，結果發現組合項選用COSMO-SAC-dsp模型中所使用的Staverman-Guggenheim模型，並利用不考慮溫度影響的TCLAC模型(theoretically correct liquid activity coefficient model，一滿足配位數守恆之活性係數模型)來考慮分散項，可以在預設雙成份系統氣液相平衡與無限稀釋活性係數中獲得類似於COSMO-SAC-dsp模型的精確度。 ;Thermodynamic properties and fluid phase equilibria are important information for the design of chemical engineering processes. Such information can generally be obtained from experiment or estimated from thermodynamic models. In pervious study, COSMO-SAC-dsp has been proved to be reliable in predicting phase equilibria data, such as vapor-liquid equilibria (VLE), liquid-liquid equilibria (LLE), and infinite dilution activity coefficients (IDAC). In the COSMO-SAC-dsp model, the molecular interactions are determined from molecular surface charges obtaining from quantum mechanical calculations, and therefore the issue of missing parameter would not happen. The activity coefficient calculation in the COSMO-SAC-dsp model was obtained from the sum of three contributions: residual term, dispersion term, and combinatorial term. In this study, the effect of using different dispersion models and combinatorial models was investigated, with the residual term remains the same. We investigated the accuracy of the COSMO-SAC-dsp model with four combinatorial models and three dispersion models, including three temperature-dependence functions of interaction parameter in dispersion models. In this study, 440 binary VLE systems and 2291 binary IDAC experimental data points were used to examine the accuracy of the COSMO-SAC-dsp model with different combinations of combinatorial and dispersion terms. We found that using the Staverman-Guggenheim model as combinatorial term (the combinatorial model of the original COSMO-SAC-dsp model) together with the temperature-independent TCLAC model (theoretically correct liquid activity coefficient model, which satisfied the pair conservation) as dispersion term provides similar accuracy as the original COSMO-SAC-dsp model in both VLE and IDAC predictions.
