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通过建立单孔狭缝模型,采用非平衡分子动力学方法研究CH_4/CO_2二元气体混合物通过管状炭膜的传递和分离特性,考察了系统温度、气体组成和膜孔径对通量的影响。模拟过程中将膜低势,区压力取为更符合实际情况的非零值(大于零)。研究结果表明,在温度为20℃～160℃范围内,随温度升高,CH_4的通量增加,CO_2的通量则先降低后升高(80℃出现最低值);随混合气中CH_4组成的增加,CO_2通量下降、CH_4通量升高;随膜孔径增大,CH_4通量先增后减(9.77 (?)时出现最大值)、CO_2通量则呈下降趋势。以上模拟结果与实验数据相比较,吻合良好。在此基础上,本文还考察了跨膜压差对过程的影响,发现CH_4和CO_2的通量均随跨膜压差的增大而增大,膜的分离性能则随之降低。本研究结果充分表明,所建模型能够正确地描述CH_4/CO_2气体混合物的炭膜分离过程。
The influence of temperature, gas composition and membrane pore size on the fluxes was investigated by establishing a single-hole slit model and using the non-equilibrium molecular dynamics method to study the transfer and separation characteristics of CH 4 / CO 2 binary gas mixtures through tubular carbon membranes. During the simulation, the membrane potential and zone pressure are taken as non-zero values (greater than zero) which are more in line with the actual situation. The results show that the flux of CH_4 increases with the increase of temperature and the flux of CO_2 decreases firstly and then increases with the increase of temperature (the lowest value occurs at 80 ℃) with the increase of temperature at 20 ℃ ~ 160 ℃. With the increase of temperature, The flux of CO_2 decreased and the flux of CH_4 increased. With the increase of membrane pore size, the flux of CH_4 first increased and then decreased (maximum value appeared at 9.77 (?)), While the flux of CO_2 showed a downward trend. The above simulation results compared with the experimental data, good agreement. On this basis, the paper also investigated the influence of transmembrane pressure difference on the process. It was found that the fluxes of CH 4 and CO 2 increased with the increase of transmembrane pressure difference, and the membrane separation performance decreased accordingly. The results of this study show that the model can correctly describe the carbon separation of CH_4 / CO_2 gas mixture.