关键词: 传质理论, Rayleigh对流, 格子Boltzmann方法, 传质系数

Abstract: In an interfacial mass transfer process, the concentration gradient of the transferred component near the interface may generate Rayleigh instability if the concentration gradient leads to a density gradient that directs oppositely to the direction of the gravity, and Rayleigh convection may occur if disturbance exists at the interface. The convection has an important effect on the interfacial mass transfer. In the present study, a 2D time-dependent lattice Boltzmann method (LBM) with a random perturbation model is used to simulate the liquid-phase Rayleigh convection in the CO₂ absorption into solvents process. Gas-liquid mass transfer theory accompanied by Rayleigh convection was analyzed by LBM. The width of plume convection pattern at the interfacial vicinity is considered as characteristic scale, which was used to calculate the surface renewal time for surface renewal theory. The results show that liquid film thickness in two-film theory can be effectively reduced by Rayleigh convection, and the mass transfer coefficients are calculated by the surface renewal theory and agree well with the LBM simulation results.

Key words: mass transfer theory, Rayleigh convection, lattice Boltzmann method, mass transfer coefficient