Characterization of Microfluidic CO2 Absorption in Water By Computational Fluid Dynamics

Characterization of Microfluidic CO₂ Absorption in Water by Computational Fluid Dynamics

Chongwei Xiao*, Hariganesh Bheema

Texas A&M University-Kingsville

Chongwei.Xiao@tamuk.edu

Advanced eco-friendly and efficient processed are needed to decrease post-combustion carbon dioxide (CO₂) released to the atmosphere. However, low mass transfer between gas and liquid phases hinders the development of new chemical absorption process. By a mean of process intensification, microfluidic reactors provide high surface to volume ratio and greatly increase gas-liquid mass transfer, which makes new processes for gas-liquid reactions possible. This intensified process also ensures instant thermal stability across the reactor and rapid heat transfer between the reactant, which greatly benefits reactions with strong heat effect. A few recent experimental and simulation works on CO₂-water system in micro-channels showed good potential of this new process. More studies of microfluidic CO₂-water process verified by experimental work are needed.

The characteristics of multiphase CO₂ absorption in micro-channels were numerical studied by Eulerian Volume of Fluid (VOF) approach. The hydrodynamic parameters of CO₂-H₂O in microchannel were investigated by the factors of channel dimension, inlet configuration, fluid flowrate, surface tension, and wall wettability. The reactor performance affected by design parameters was investigated. The microstructures of semi-cylinder with hydraulic diameter of 0.667 mm and various inlet configurations including T- and Y- junctions were studied. The multiphase flow in micro-channels was dominated by Taylor flow and annual flow depending on relative gas-liquid velocities. The effect of the angle at which the two inlet channels join and the influence of the static contact angle (SCA) on the flow regime was observed and found to be in a good agreement with experimental data. The parameters that influence flow patterns and corresponding transition were also found to affect Taylor bubble sizes. The two-phase flow pattern and the pressure drop through the microchannel were simulated and are compared with published experimental data. This work provides a theoretic support for the design of new CO₂ absorption processes.