基于MATLAB的双液系汽液平衡模型构建及其相图绘制

Vapor-liquid equilibrium modeling and its phase diagram drawing for the ethanol-cyclohexane system based on MATLAB

汽液相平衡数据的测量及热力学模型的研究是化学工程中的重要内容之一。本文借助MATLAB软件计算平台,将在乙醇-环已烷互溶双液系中测定的汽液相平衡实验数据,代入选定的汽液相平衡数学模型Wilson方程,通过程序设计自动完成该关联方程的最小二乘求解,得到其配偶参数;随后,借由回归的Wilson方程计算各实验观测点汽相组成的热力学模型预测值,并与实验值协同统计学方法执行热力学一致性检验。应用结果表明构建的Wilson汽液相平衡模型通过热力学一致性检验,且恒沸点温度及组成数据的预测精度高,整个MATLAB操作过程直观、方便与快捷,绘制的相图美观,符合实验要求。

The measurement of vapor-liquid equilibrium （VLE） data and its suitable thermodynamic model constructing is one of the important works in the chemical engineering field. In this paper, several pairs of the compositions data and their corresponding boiling points in the ethanol-cyclohexane system were firstly measured at a constant pressure 100.91 kilopascals. Then these VLE data were correlated by the Wilson equations and the Wilson model parameters of the liquid activity coefficient were determined by the least square method. After these steps, the thermodynamic consistencies of the obtained experimental data were examined with the model calculated results. The results showed that not only did the experimental data satisfy the examination of the thermodynamic consistencies, but the Wilson model was suitable for correlation and prediction on the system of ethanol-cyclohexane. In order to make the data calculation and the phase diagram drawing more feasible, a procedure software based on MATLAB platform had been developed and put into practice. Its calculated and experimental results were in good agreement and the phase diagram in appearance was in line with the experimental requirements.