PVT筒中气液两相非平衡过程的数值模拟

目前国内外多采用平衡后各组分逸度系数相等的平衡判据来描述两相中各个组分的分配情况，但该法无法进行两相由非平衡初始状态达到平衡状态这一非平衡热力学过程的研究。针对这一问题，提出了引入扩散方程来描述液相和气相各个组分由接触到稳定过程的方法，建立了描述两相非平衡态扩散过程的数学模型，提出了分阶段求解模型的求解算法，并运用该法对PVT筒中气液两相系统由接触到稳定过程的状态进行了分析，得出系统全程压力变化规律及平衡状态下随高度变化的甲烷浓度分布规律。计算结果与实验数据对比验证了该方法的可行性，从而为非平衡态相变问题的分析提供了新的思路。

THE NUMERICAL SIMULATION OF THE TWO PHASES NONEQUILIBRIUM THERMODYNAMIC PROCESS IN PVT CELL

The currently used methods for determining the thermodynamic equilibrium of the mixed two phases substances is to judge the equality of the coefficient of each component in two phases，and with this analysis，each component mole fraction can be got at the equilibrium state.But this method can not be used in analyzing the process from the initial two phases nonequilibrium state to the final equilibrium state.To address this issue，diffusion equation to describe various gas and liquid components from exposure to the stabilization process is introduced in this paper，a mathematical model to describe the two phases nonequilibrium diffusion process established.By using the method，a gasliquid two phases system that changes from contact to steady status in the PVTcanister is analyzed.The whole process pressure change rule of the system is obtained.The methane concentration distributing rule that changes with altitude in the balance state got，too.The results compared with the experimental data proved the feasibility of the method，thus the nonequilibrium phase transition analysis of the issue gives a new train of thought.