VG公式预测汽液平衡与多解问题

就十三个体系研究了色谱斜率法VG公式的适用条件.结果表明,除该公式本身要求实验柱温在溶质沸点附近外,汽液平衡预测结果还取决于过量自由焓模型的选择.对于UNIQUAC方程,在溶质沸点以下0—5.5℃的范围内可获得满意的预测汽液平衡结果;对于Wilson方程,如在求解Wilson参数的过程中不出现多解,则在溶质沸点以下3—5℃可得到满意的结果.不论UNIQUAC还是Wilson方程,一旦在求解方程参数的过程中出现多解,则应用本文所提出的“最小解原则”可很好地预测汽液平衡.

Prediction of Binary Vapor Liquid Equilibria by Valentin-Guiochon Equation and its Multiple Solutions

The employment of Valentin-Guiochon equation in the chromatographic slope method has been studied. Results of the thirteen binary systems studied show that predictions of vapor-liquid equilibria depend not only on whether the experimental temperature is around the boiling point of the solute or not, but also on the selection of excess Gibbs energy model. Satisfactory prediction results can be obtained at 0-5.5℃ below the boiling point of the solute for UNIQUAC, while, for the Wilson equation, it will be 3-5℃ below the boiling point of the solute if multiple roots do not show up. When multiple roots do appear, the least root will be one of the pair of parameters which can give the satisfactory vapor-liquid equilibr ium prediction.