A Theoretical Study on the Equation of State of Liquid Methane at High Temperature and High Densities
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摘要: 采用热力学统计理论研究了液态甲烷在高温高压下分子分解反应特点及该体系的物态方程。着重讨论了体系中CH4-H2分子间有效势对体系化学反应平衡及物态方程的影响，并根据实验Hugoniot点(pH, V)优化确定出其exp-6势函数中的参数值。该势函数的排斥部分值比理想混合条件下Lorentz-Berthelot规则给出的势函数值低约50%，预示着高压下CH4和H2之间存在着某种亲合性。用该势函数计算得到的p-T线与现有的两个实验点符合很好。还讨论了CH4-H2之间的有效作用势参数对CH4分子冲击离解度（x）的影响。Abstract: Equation of state and molecular dissociation reactions of liquid methane at high-temperature and high-pressure are investigated by Statistical Mechanics and Chemical Equilibrium method, with focus on the interactions between CH4 and H2, which apparently would affect the equilibrium of chemical reactions and EOS of shock compressed liquid methane. By using a set of optimized exp-6 potential parameters obtained from experimental Hugoniot data (pH, V), our theoretical calculation results agree satisfactorily with published experimental data. The repulsive part of our potential, however, is softer than that determined by ideal mixture rule, which implies attractive interaction between CH4 and H2 may exist under high pressure. The effect of the effective potential between CH4-H2 on the dissociation of CH4 molecules under shock compression is also discussed in this paper.
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Key words:
- liquid methane /
- interaction potential /
- EOS /
- dissociative reaction
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