Equation of state of initially liquid carbon monoxide and nitrogen mixture

The modified liquid perturbation variational theory and the improved vdW-1f model were applied to calculating the equation of the state of liquid CO-N2 mixture with the ratio of 1:1, 4:1 and 1:4, respectively, in the shock pressure range of 9-49 GPa. It was shown that the calculated result for CO-N2 mixture with the ratio of 1:1 is well consistent with the earlier experimental data. The thermodynamics equilibrium, chemical equilibrium and phase equilibrium were all considered in detail. It was found that Hugoniot of liquid CO-N2 mixture is moderately softened in the pressure range of 20-30 GPa and 30-49 GPa for different initial proportions, and that the Hugoniot is more softened in the latter pressure range, which means that the structural phase transition occurs near 20 GPa and 30 GPa. Since the shock pro-ductions may absorb a plenty of systematic energy, the shock temperature and pressure decline compared with the case of no chemical reaction. Pressures and temperatures increase gradually with the increase in the mole fraction of nitrogen composition. The results for the 1:1 CO-N2 mixture lie in the middle of two others. Therefore, it was shown that the modified Lorentz-Berthelor rule used in the scheme is effective to study shock-compression properties of liquid CO-N2 mixture under high temperatures and high pressures.

液态一氧化碳与液氮混合物的物态方程

采用改进的液体微扰变分统计理论和van der Waals分子混合物的等效单组分流体模型，计算了压力在9～49GPa范围内1：1，4：1和1：4摩尔比的液态CO-N2混合物的高压物态方程．在计算过程中考虑了体系的热力学平衡，化学平衡以及相平衡．结果表明，CO：N2为1：1的理论计算结果与实验数据吻合较好；不同比例的混合体系在压力区间为20～30和30—49GPa范围内，Hugoniot曲线逐渐趋于软化，这意味着该混合体系在20和30GPa压力点附近分别经历了结构性相变．在极端条件下该混合体系中液态CO与N2发生了复杂的化学反应．冲击压缩产物形成时吸收了部分系统能量，导致了体系的冲击温度和冲击压力有所降低．随着N2初始组分的增加，Hugoniot曲线向上平移，其中CO：N2为1：1摩尔比时其Hugoniot曲线居于1：4和4：1两者之间，表明Lorentz-Berthelor组合规则在计算液态CO—N2混合物的高压物态方程时是有效的．