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运用Tang等提出的Lennard-Jones(L-J)流体两参数的一阶平均球形近似(FMSA)状态方程,计算了流体的汽液共存相图和饱和蒸汽压曲线,以及非饱和区的PVT性质,并与文献数据进行比较.L-J参数由Tr<0.95的汽液相共存数据回归得到.计算结果表明,对于分子较接近球形的流体,除临界点附近外,该方程可以在较大的温度和压力范围内计算真实流体的PVT性质,结果满意.对于球形分子,该方程的精确度随分子尺寸的变大基本保持稳定.该方程不适用于强极性物质.在高密度区,该方程的计算结果明显优于P-R方程.对于分子偏离球形较远的流体,该方程的适用性变差,此时要考虑分子形状的影响,可采用三参数的FMSA状态方程进行计算.
Based on the first-order spherical approximation (FMSA) equation of two-parameter Lennard-Jones (LJ) fluid proposed by Tang et al., The vapor-liquid coexistence phase diagram and the saturated vapor pressure curve of the fluid and the PVT properties of the unsaturated zone Compared with the literature data.LJ parameters are obtained from the coexistence of vapor-liquid phase data with Tr <0.95.The calculated results show that for the fluid with a relatively spherical shape, except for the vicinity of the critical point, the equation can be used in a wide range of temperature and pressure The calculation of the PVT property of the real fluid is satisfactory. For the spherical molecule, the accuracy of the equation is basically stable with the increasing of the molecular size. This equation is not suitable for the highly polar material. Which is obviously better than the PR equation.The applicability of this equation is worsened when the fluid is far away from the sphere. In this case, the influence of the molecular shape is taken into account and the three-parameter FMSA equation of state can be used to calculate the equation.