CO2/N2 separation by glycerol aqueous solution in a hollow fiber membrane contactor module: CFD simulation and experimental validation

Abstract

In this paper, CO2 separation from CO2/N2 mixed gas was experimentally and theoretically investigated inside a gas–liquid hollow fiber membrane contactor (HFMC) module along with developing and validation of a comprehensive computational fluid dynamic (CFD) model. An aqueous solution of glycerol (10 wt%) (C3H8O3), a green and cost-effective physical solvent, was employed as the liquid absorbent, flowing in the shell side of the hollow fibers. To attain a better insight into the membrane wetting effects on separation performance, all non-wetting, partially-wetting, and completely-wetting conditions were investigated. Moreover, a correlation for CO2 Henry’s law constant was developed to estimate the CO2 solubility in aqueous solutions of glycerol via adopting the literature data. The CFD simulation results revealed that the gas to absorbent flow rate ratio (Fg/Fa) is a dominant parameter in controlling the CO2 removal efficiency. CO2 separation performance was augmented via decreasing the gas flow rate, absorption temperature and increasing the membrane porosity to tortuosity ratio as well as glycerol concentration. In contrast, by increment of the membrane wettability from non-wetting to completely-wetting condition, the CO2 removal percentage was dramatically reduced from 72.5 to 18.5%. A fair agreement between the CFD simulation results and experimental data with an absolute average relative error percentage (AARE%) of 2.7% was achieved, confirming the validity of the developed model.