Characteristics Of Gas-Liquid Interface Using Molecular Dynamics Simulation

In the past decades, with the rapid development of steel and chemicalindustries, the demands for different pure gases kept on increasing. As a result, theair separation systems gradually turn to be ultra-large and low-energy. To realize it,one of the key factors is to predict the thermal physical properties of multicomponentand multiphase fluid precisely. Among them, the characteristics of the gas-liquidinterface are one of the basic problems. In present work, according to the truncatedand shifted Lennard-Jones12-6potential model, molecular dynamics simulationmethod was adopted to investigate the gas-liquid interface characteristics of diatomicoxygen and nitrogen, the thermodynamic property of droplets of argon and kryptonmixture, and the transport properties of argon.Taking the resonance effects of bonds in the molecules into consideration, thediatomic model was used to investigate the gas-liquid interface characteristics fordiatomic oxygen and nitrogen. According to the experimental results of gas-liquidphase densities and saturation pressures of oxygen and nitrogen, the appropriateparameters of oxygen and nitrogen atoms were first obtained, and the reliability ofthese parameters and the correctness of procedure were verified. Some characteristicsof atomic molecules with temperature were then calculated, such as the tangentialand normal components of pressure tensor and surface tension. The droplet of argonand krypton mixture was then studied. The number of argon and krypton decreasesrapidly at the beginning of the simulation. Then a relative equilibrium state in dropletsystem can be achieved and the concentration of argon and krypton will not changewith time. The higher the temperature is, the lower the concentration of argon will be.The transport properties of argon were investigated at last. The viscosity coefficientwith temperature and pressure are obtained, and the thermal conductivity coefficientwith temperature is achieved. These results agree very well with experimental data.In a word, the molecular dynamics simulation method is appropriate to study thethermal physical properties of multiphase and multicomponent mixtures.