Numerical simulation of supersonic condensation flows using Eulerian-Lagrangian and Eulerian wall film models

As a clean and energy-saving natural gas purification and separation device, the supersonic separator's internal gas-liquid separation mechanism needs to be explored. However, the complex three-field (gas, droplet, liquid film) two-phase (gas, liquid) supersonic condensation flow challenges the numerical modeling. Most studies are limited to tracking the gas phase and droplets and ignore the effects of liquid film and phase change on droplets and water vapor removal. In the present study, we established a novel Eulerian-Lagrangian method coupled with the Eulerian wall film model to study the three-field behaviors and phase change for the enhancement of separation efficiency in the supersonic separator. The accuracy of the proposed model was validated by three experiments. The gas, droplet, and liquid film behaviors and three-field heat and mass transfers in the supersonic separator are studied using the proposed three-field two-phase flow model. Then, the sensitivity analysis was carried out, which showed the inlet mass flow rate qp,in of the heterogeneous droplets determines the maximum film thickness. For qp, in = 0.001 kg/s, this value is about 85.2 μm. The result also showed a significant improvement in separation efficiency with a proper inlet droplet diameter dp,in, qp,in, and gas pressure pin. For dp,in, qp,in, and pin are selected as 2.2 μm, 0.0015 kg/s, and 3 atm, better separation efficiency can be obtained with droplet removal rate, water vapor removal rate, and dew point depression being optimized to 100%, 57.4%, and 29.1% respectively.