局部面积搜索法在高压相平衡中的应用

The Application of Local Search for Maximum Area to High Pressure Phase Equilibrium

用最小Gibbs能曲线积分的正面积最大方法 (AM)进行相平衡的计算和预测 ,可以比传统的闪蒸计算法更好地计算高压下和近临界区的相平衡组成。但是这一方法由于使用了在全组成范围的“穷举”方法搜索最大正面积对应的相平衡组成 ,使得收敛速度慢 ,计算和搜索时间过长 ;将其修改成多次局部面积搜索法(LSAM ) ,极大提高了收敛速度和减少了计算时间 。

The area method (AM) that minimizes the Gibbs energy by integrating, instead of differentiating, the Gibbs energy curve provides a sufficient condition for global Gibbs energy minimization rather than only a necessary condition provided by the flash equilibrium calculation method. However, it uses the method of exhaustion to search the positive maximum area, therefore requires a long calculation time. Here this method is modified as LSAM (local search area method), which is a repeated search shrinking vicinities of the liquid and gas equilibrium composition points located by previous rough search. The calculation time decreases to one over several thousands of AM's or less. The experimental equilibrium data of benzene and propylene are used to demonstrate the merit of this method.