Abstract
In the present work, membrane resistance was estimated and analyzed, and the results showed that total membrane resistance increased sharply when membrane pores were wetted. For further study, a two-dimensional (2D) mathematical model was developed to predict the chemical absorption of CO2 in aqueous methyldiethanolamine (MDEA)-based carbon nanotubes (CNTs) in a hollow fiber membrane (HFM) contactor. The membrane was divided into wet and dry regions, and equations were developed and solved using finite element method in COSMOL. The results revealed that the existence of solid nanoparticles enhanced CO2 removal rate. The variables with more significant influence were liquid flow rate and concentration of nanoparticles. Furthermore, there was a good match between experimental and modeling results, with the modeling estimates almost coinciding with experimental data. Solvent enhanced by solid nanoparticles significantly improved the separation performance of the membrane contactor. There was around 20% increase in CO2 removal when 0.5 wt% CNT was added to 5 wt% aqueous MDEA.
Highlights
Gas–liquid hollow fiber membrane (HFM) contactors have attracted the attention of many researchers due to their high interfacial area per unit volume compared to conventional absorption processes
The mathematical model developed in the present work describes the CO2 concentration profile in a partially wetted HFM contactor, where CO2 is absorbed in aqueous MDEA-based carbon nanotubes (CNTs)
Analysis of the mass transfer resistance in the HFM contactor revealed that wetting of membrane pores by the absorbent liquid led to a high increase in the total membrane resistance and decreased the percentage removal of CO2
Summary
Gas–liquid hollow fiber membrane (HFM) contactors have attracted the attention of many researchers due to their high interfacial area per unit volume compared to conventional absorption processes. In [15], a numerical model was established to represent the process of capturing CO2 from a gas mixture using HMC in distilled water enhanced by carbon nanotubes and nanosilica, mainly at high nanofluid absorbent flow rate. In the area of modeling and simulation of nanofluids, a 2D numerical model was developed for the study of CO2 gas capture from a gas mixture in a HFM contactor, with water-based nanofluids used as the liquid absorbent [13,18]. Absorption of CO2 from the gas mixture of air/CO2 in gas–liquid HFM contactors via nanofluids comprising silica nanoparticles and carbon nanotubes were experimental investigated in [27]. A comprehensive 2D mathematical model was developed and solved to study the chemical absorption of CO2 from CO2 /N2 gas mixture in aqueous MDEA-based CNT inside a HFM contactor, with the model considering partial wetting. The effect of operating conditions, such as gas flow rate, liquid flow rate, absorbent size, and concentration, on percentage removal of CO2 was studied
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