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Keywords
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air pollution, carbon capture, carbon nanotube, membrane technology, nanoparticles
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Abstract
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A numerical parametric analysis of CO2 removal from the air using silica (SiO2) and
carbon nanotube (CNT) nanofluids (NFs) in a gas–liquid hollow fiber membrane contactor
in the non-wetted condition is investigated in this work. Diffusion in radial and
axial directions is considered in the tube, the shell compartments, and the membrane
regarding the convection mechanism. Different significant factors, including liquid
and gas flow rates, membrane porosity, inlet concentration of CO2, liquid temperature,
number of fibers, and nanoparticle diameters, are investigated in viable ranges.
The finite element method is implemented to solve governing equations. The model
output is validated against the experimental data of CO2 absorption with NFs, and an
acceptable agreement is obtained. The results of the simulation indicate the CNT
NFs outperform SiO2 NFs in CO2 absorption. Also, the performance of CO2 removal
improves with the nanoparticle diameter reduction in the base fluid, inlet CO2 concentration,
gas flow rate, and temperature. In the tube, by adding 0.5 wt % CNT and
silica nanoparticles, the absorption rate improves by 47.6% and 39.6%, respectively.
Finally, three correlations among significant parameters to predict CO2 removal is
presented due to the lack of specific correlations for this model in the literature.
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