Equation Of State,Gas-liquid Coexistent System And Critical Properties Of Simple Fluid

It has been more than one hundred years since the investigation on state of equation (EOS) and phase transition theory of fluid, and this is still an active field in present. Kinds of theories come into existence one after another with the development of experimental technology and enhancement of cognition, this leads to the stepwise increase of apprehending on these projects. But there is still many problems, for example, a reasonable experiential EOS according to experimental result appeared long ago, but similar ending can not be obtained via statistical mechanics; The produce mechanism and the concomitant properties of first-order and second-order phase transitions haven't a satisfied explain. To solve these problems needs much more exploration.In this dissertation the problems in this field are discussed in three chapters, development and complementarity to the existent theory are presented. Chapter 1 is the review of state of equation theories from the experience and statistical mechanics, then a new EOS is obtained in statistical mechanics on the basis of it. This EOS possesses of vdW EOS's strong suits such as simplicity and possession of reduced form, and can predict better phase diagram and saturated vapor pressure, indicating its theoretical and practical value. In chapter 2, a familiar system -gas-liquid coexistent system which is concomitant of first-order gas-liquid phase transition is discussed. The descriptions of it, i.e. Maxwell construction from thermodynamics and Yang-Lee 's theory from statistical mechanics are summarized, then the limitation of Yang-Lee theory which can only applied to the system satisfying thermodynamics limit is pointed out. A new way dealing with real physical system is put forth, this make theory describing first-order phase transition with statistical mechanics self-contained. The last chapter is the argumentation of second-order phase transition. The rules occurred here and kinds of technique expounding it are listed. Combined with analysis of experimental results, the method deriving the scaling laws (i.e. scaling equality) from thermodynamics is found, it is a progress of existent ending which is the derivation of inequality. This outcome represents the profound foundation of physics of scaling relations, and foreshows the possibility of explaining critical phenomena with thermodynamics.