Effect of gas partial pressure on Rayleigh convection mass transfer characteristics during CO2 absorption
Rayleigh convection phenomenon caused by interfacial concentration gradient can significantly improve the mass transfer rate of CO2 absorption process,but the mechanism of mass transfer enhancement in this process is not clear at present.In order to explore the enhancement mechanism of Rayleigh convection mass transfer process,water absorbing CO2 process was selected as the research object,and realized the visualization and quantitative measurement of interfacial convection based on particle image velocimetry(PIV)and laser induced fluorescence(LIF)technology under different CO2 partial pressure conditions.It was found that the average interface concentration would drop instantaneously at the critical time of the convection and would rise after the formation of the ordered self-organization structure,the final average interface concentration would descend with the decrease of CO2 partial pressure in gas phase.After convection,the mass transfer capacity enhancement of the system was divided into two stages,vorticity field played a leading role before the formation of the ordered self-organization structure,but after the formation of the ordered self-organization structure,the mass transfer capacity enhancement was the result of the joint action of vorticity field and interface concentration.After the formation of the ordered self-organization structure,the average instantaneous mass transfer coefficients of different systems had a strong correlation with the corresponding average vorticity,indicating that the vorticity field formed by the interaction of concentration field and velocity field played an important role in the process of convective mass transfer enhancement.
CO2 captureRayleigh convectionmass transferlaser induced fluorescenceparticle image velocimetry
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