Vibration-induced enhanced mass transfer within membrane contactors for efficient CO2 capture

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Membrane gas-solvent contactors are a hybrid separation technology that has significant potential to replace conventional solvent columns in a range of industrial applications. One industry application where the technology has shown promise is for carbon dioxide capture. The performance of membrane gas-solvent contactors is limited by the mass transfer resistance on chemical species traversing from the gas to the solvent phases, with the boundary layer of the solvent phase representing the rate limiting stage. Here, enhancements to mass transfer were achieved by applying vibration to the membrane module. An increase in the overall liquid phase mass transfer coefficient (KL) was associated with both the frequency and amplitude of the vibration. A vibration amplitude displacement between 0 and 16% resulted in overall mass transfer being 10 to 21% higher than the non-vibrational case. Similarly, a vibrational frequency of 2.3 Hz corresponded to mass transfer enhancement of up to 20% higher than the non-vibrational case. This represents a significant improvement in the membrane contactor’s mass transfer performance for carbon dioxide separation. To quantify vibration improvement in membrane contactors, a mass transfer correlation for the solvent phase of the membrane contactor system was established, based on a vibrational dimensionless number. This correlation enabled the performance of membrane contactors under vibration conditions to be model and provide insight into the vibrational conditions that will enhance mass transfer. Subsequently, an analysis of the power requirement for module vibration was undertaken to demonstrate the most effective applications of vibrations.