| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 92 === Molecular dynamics simulations are used to study the phase equilibrium of the vapor-liquid coexistence system. In this study, we simulated Lennard-Jones fluid, two-center Lennard-Jones fluid and three-center Lennard-Jones fluid, and calculated the liquid density, the vapor density, and the surface tension. According to the scaling law, the critical temperature and critical density of these systems were determined. They are Tc*=1.0854 ρc*=0.3133 for the Lennard-Jones fluid, Tc*=1.4450 ρc*=0.2906 for the two-center Lennard-Jones fluid, and Tc*=1.6533ρc*=0.2719 for the three-center Lennard-Jones fluid. We checked the relationship between the surface tension and the temperature. The temperature dependence of the surface tension is well described by the scaling law. The effect of the surface area on the surface tension was investigated. It is found that the surface tension increases with the decrease in the surface area. However, this effect is pronounced only in small surface areas. When the vapor-liquid equilibrium system is under high gravity, the liquid density increases, the vapor density decreases, and the surface tension increases.
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