熔融盐膜法脱除航天舱中CO2传质模型

基于电化学理论、膜分离与传质理论，采用非平衡态热力学，建立了熔融盐(43．5％ Li2CO2 25％K2CO3 31.5?Na2CO3)(mol.?膜法脱除C02数学模型。首先，根据熔盐体系离子的Hittorf迁移数、比电导、扩散系数等独立实验参数，计算得到体系的Onsager系数和模型参数，然后用计算机求得该模型的数值解。解的结果表明：影响CO2传质通量的因素主要有电流密度及C02在膜两侧的浓度差。在低电流密度下，浓差推动力起主导作用：在较高电流密度下，膜两侧浓差推动力对C02传质影响甚微，电流密度对C02的传质则起着决定性作用。为了进一步验证数学模型，在823K及常压条件下，模拟航天舱中的气体成分，进行了熔融盐膜法脱除CO2的实验研究。实验结果与模型理论解吻合较好。

The Mathematical Model for Carbon Dioxide Removal from Cabin Gas of Spacecraft Using a Molten Salt Membrane

Based on the theory of electro-chemistry, membrane separation and mass transfer, non-equilibrium thermodynamics was used to establish the mathematical model for CO2 removal using a molten salt membrane (43.5% Li2CO3 + 25% K2CO3 +31.5% Na2CO3) (mol. %). Onsager coefficients and parameters in the model were calculated on the basis of some independent experimental quantities, such as the specific conductance, Hittorf transference numbers and diffusion coefficients. Using Runge-Kutta method the mathematical model was solved on an electronic computer. The results show that CO2 transfer rate increases with increasing electrical current density and CO2 concentration difference across the membrane. When electrical current density (ECD) is very low, CO2 concentration difference has a greater effect on CO2 transfer rate. However, if ECD is high, it will dominantly control CO2 transfer rate. In order to further examine and certify the model, some experiments, using the molten salt membrane to remove CO2 from the imitated atmosphere of spacecraft cabin, were carried out at 823 K and under atmospheric pressure. The experimental results are in good agreement with the solution of the model.