机载制氮系统中空纤维膜分离特性

采用微元方法建立了机载制氮系统中空纤维膜数学模型，并使用龙格-库塔法对其进行了数值计算，与实验数据进行对比后显示，误差不超过10%。然后分析了单位膜面积进料量、膜丝(membrane fiber)内外压比和氧氮渗透比其对产品气氧摩尔浓度和制氮效率的影响。结果表明，增加单位膜面积进料量虽然可提高制氮效率的增加，但是会显著降低产品气中氮的摩尔浓度，因此需要采用合适的流程设计以克服此缺点。压比和氧气渗透系数的增加均会使氧浓度与制氮效率减小，但是提高渗透比(penetration ratio)对制氮效率影响不大，因此对于气体分离过程是有利的。通过计算模型及实验数据，分析了中空纤维膜分离理想度随压比和温度的变化关系，结果显示压力对理想度影响较大，随着压力增加，实际分离过程与理论值偏差趋大，而温度对理想度影响较小。

Separation performance of hollow fiber membrane for on-board inerting gas generating system

The mathematical model of the hollow fiber membrane of OBIGGS is set up in term of the differential method, and solved by the Runge-Kutta method. The comparison between calculating results and experimental data published in literature reveals that the deviation is within 10%. Furthermore, this theoretical model is employed to analyze the influence of the specific feed flux of membrane area, pressure ratio of membrane fiber, the separation factor and the permeability coefficient to the molar concentration of oxygen in production gas and the production efficiency of nitrogen. The study shows that though the increase of the specific feed flux of membrane area could positively promote the production efficiency of nitrogen, the molar concentration of oxygen reduces sharply. Hence, an appropriate process of OBIGGS should be designed to overcome the disadvantage mentioned above. The increase of the pressure ratio and the permeability coefficient of oxygen will decrease the production efficiency of nitrogen and the molar concentration of oxygen, but the influence of the permeability coefficient is slight. Therefore, the increase of the permeability coefficient of oxygen is beneficial to the separation performance. Based on the experimental data and the model, the change of the separation ideal level related to the temperature and pressure is analyzed, the result shows that the pressure ratio will make greater effect on the separation ideal level. When the pressure ratio increases, the actual separation process will deviate from the theoretical one gradually.