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

doi:10.1016/j.cjche.2020.09.014

Abstract

Abstract: 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.

Key words: Falling film, Wavy microchannel, CFD, Mass transfer

摘要： 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.

关键词: Falling film, Wavy microchannel, CFD, Mass transfer

Siyuan Chen, Tao Zhang, Li Lv, Yanxiao Chen, Shengwei Tang. Simulation of the hydrodynamics and mass transfer in a falling film wavy microchannel[J]. Chinese Journal of Chemical Engineering, 2021, 34(6): 97-105.

Siyuan Chen, Tao Zhang, Li Lv, Yanxiao Chen, Shengwei Tang. Simulation of the hydrodynamics and mass transfer in a falling film wavy microchannel[J]. 中国化学工程学报, 2021, 34(6): 97-105.

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