吸收过程自然对流非稳态数值模拟

Numerical simulation of natural convection in the transient gas-liquid unsteady absorption process

传质过程中液相密度变化导致的自然对流,改变了液相流动状态,对传质有着较大的影响。利用纹影仪光学方法,获得了乙醇吸收CO2过程中自然对流的纹影图像;并通过吸收传质流体CFD模型,应用有限元方法对气液吸收过程中出现的自然对流发生过程进行了数值计算,得到了液相自然对流发生时的非稳态流场分布和浓度分布信息。分析结果表明传质过程中当自然对流发生后,促进了液相表面更新,加强了传质效果,在考察相际传质过程时,应充分考虑自然对流对传质速率的影响。

The natural convection occurred in mass transfer process due to change of liquid-phase density gradient usually induces a higher mass transfer rate. By means of the Schlieren technique, Schlieren images of the natural convection were taken in CO2-ethanol absorption system. Unsteady flow and concentration fields in the liquid phase of a gas-liquid contacting system were simulated to show the natural convection by utilizing the finite-element CFD method. According to the simulated and the experimental results, the influence of the natural convection on mass transfer was analyzed qualitatively. The result shows that the natural convection can facilitate the renewal of the surface and the mass transfer process. So the influence of natural convection on mass transfer should be fully considered in the investigation of interracial mass transfer.