Simulation of the hydrodynamics and mass transfer in a falling film wavy microchannel

The flow in a liquid falling film is predominantly laminar, and the liquid-side mass transfer is limited by molecular diffusion. The effective way to enhance the mass transfer is to improve the liquid film flow behavior. The falling film behaviors of water, ethanol and ethylene glycol in nine different wavy microchannels were simulated by Computational Fluid Dynamics. The simulation results show that the falling film thickness exhibits a waveform distribution resulting in a resonance phenomenon along the wavy microchannel. The fluctuation of liquid film surface increases the gas–liquid interface area, and the internal eddy flow inside the liquid film also improves the turbulence of liquid film, the gas–liquid mass transfer in falling film microchannels is intensified. Compared with flat microchannel, the CO2 absorption efficiency in water in the wavy microchannel is improved over 41%. Prediction models of liquid film amplitude and average liquid film thickness were established respectively.