We investigated the insertion of eddy promoters into a parallel-plate gas–liquid
polytetrafluoroethylene (PTFE) membrane contactor to effectively enhance carbon dioxide
absorption through aqueous amine solutions (monoethanolamide—MEA). In this study, a
theoretical model was established and experimental work was performed to predict and to compare
carbon dioxide absorption efficiency under concurrent- and countercurrent-flow operations for
various MEA feed flow rates, inlet CO2 concentrations, and channel design conditions. A Sherwood
number’s correlated expression was formulated, incorporating experimental data to estimate the
mass transfer coefficient of the CO2 absorption in MEA flowing through a PTFE membrane.
Theoretical predictions were calculated and validated through experimental data for the augmented
CO2 absorption efficiency by inserting carbon-fiber spacers as an eddy promoter to reduce the
concentration polarization effect. The study determined that a higher MEA feed rate, a lower feed
CO2 concentration, and wider carbon-fiber spacers resulted in a higher CO2 absorption rate for
concurrent- and countercurrent-flow operations. A maximum of 80% CO2 absorption efficiency
enhancement was found in the device by inserting carbon-fiber spacers, as compared to that in the
empty channel device. The overall CO2 absorption rate was higher for countercurrent operation
than that for concurrent operation. We evaluated the effectiveness of power utilization in
augmenting the CO2 absorption rate by inserting carbon-fiber spacers in the MEA feed channel and
concluded that the higher the flow rate, the lower the power utilization’s effectiveness. Therefore,
to increase the CO2 absorption flux, widening carbon-fiber spacers was determined to be more
effective than increasing the MEA feed flow rate.
