汽液相变系统的平衡稳定性分析

以非平衡热力学理论为基础，通过引入可用能这个汽液相变换热过程的一个重要的功势函数，对汽液相变系统的可用能进行了分析，得到了汽液相变系统的可用能变化的计算式，并以此为判据来分析汽液相变系统的稳定性，得到了汽液相变系统的相平衡条件、力学稳定性条件和热稳定性条件。并给出了有关物理意义；定义了汽液相变时的汽、液相的力稳边际曲线。结果表明，汽液相变系统的力稳条件不同于简单可压缩单相系统的力稳条件，相变力稳边际曲线是相变时不可逾越的界限。

Equilibrium Stability Analysis of a Liquid-vapor Phase Transition System

On the basis of the theory of non-equilibrium thermodynamics and through the introduction of an important work/potential function in the heat exchange process of a liquid-vapor phase transition,the so-called available energy,an analysis was conducted of the available energy of the liquid-vapor phase transition system.As a result,a calculation formula for the available energy variation of the liquid-vapor phase transition system was obtained,and using this as criteria an analysis was performed of the stability of the liquid-vapor phase transition system.Thus,obtained were the phase equilibrium conditions of the above-mentioned system,mechanics stability conditions and thermal stability conditions with relevant physical meanings being also given.Furthermore,a definition is provided for the liquid and vapor phase force-stable marginal curves during the liquid-vapor phase transition.It can be shown that the force-stable condition of the liquid-vapor phase transition system is different from that of a simple compressible single-phase system.The phase transition force-stable marginal curves constitute a limit or boundary which cannot be overstepped during a phase transition.