Mass transfer characteristics for CO₂ absorption in nanoabsorbents

In this work, an improved VOF-PLIC model is developed to simulate 3D bubble behavior and to analyze the mass transfer characteristics for CO₂ absorption in pure methanol and methanol with Al₂O₃ nanoparticles. The lower bound boundary value of CO₂ volume fraction(α_g) is redefined according to the influence of α_g on bubble shape and diameter as well as the interfacial area between gas and liquid. In addition, a reasonable drag force is added into the momentum equation using UDF code based on the assumption that the drag force only exists in liquid phase. It is found that the level lines of bubbles with the α_g value of 0.05 agree well with the real case, and the drag force has significant influence on the bubble behavior and mass transfer characteristics. The velocity contours and pressure gradients around the bubble are proposed to analyze the influence of drag force on the mass transfer characteristics. Also, the influence of the Al₂O₃ nanoparticles on the mass transfer enhancement is studied, and the results show that the dispersed particles can significantly enhance the mass transfer by increasing the gas–liquid interfacial surface renewal frequency.