H_2O-CH_4-H_2-CO_2-CO-O_2在高温、高压和高密度条件下的状态方程

Equation of state for H_2O-CH_4-H_2-CO_2-CO-O_2 at high temperatures, pressures and densities

为了计算高温、高压和高密度流体的热力学性质,提出了一个具有19个参数的维里型状态方程,其中参数与温度间的函数关系采用由Sutherland位能函数导出的维里系数近似式。除临界点附近以外,在已报道的pVT数据所覆盖的大部分超临界区域内,该方程均可适用。用该方程对H2O、CH4、H2、CO2、CO和O2等流体pVT关系的计算结果令人满意,其中pVT上限分别为:91～610GPa、1.6～11.0cm3/mol、4000～5000K,计算体积的平均偏差小于0.8%,最大偏差小于5.4%。

A virial equation of state (EOS) with 19 parameters for fluids is developed to calculate the thermodynamic properties of pure fluids at high temperatures, pressures and densities, where the approximate virial coefficient expression derived from Sutherland potential energy model is employed as the temperature function of the parameters. The parameters in the EOS are fitting to the experimental pVT data and those from molecular dynamics and Monte Carlo simulation. The EOS is valid in most of the supercritical area covered by the reported pVT data, except for the vicinity of the critical point. The pVT properties of H2O, CH4, H2, CO2, CO, O2, etc. are calculated with the EOS, and the results are very satisfactory. The up limits of the calculated pVT data are: 91～610 GPa, 1.6～11.0 cm3/mol, 4 000～5 000 K, respectively. The average deviation of the calculated volumes is less than 0.80%, and the maximum deviation is less than 5.4%. Additionally, comparisons of precisions indicate that the EOS in this work is much more accurate than Belonoshko Saxena (1991) equation, and slightly better than Duan Mller Weare (1992) equation except for the area near the critical point.