CO2 capturing in cross T-junction microchannel using numerical and experimental approach

Numerical and experimental studies were carried out for the analysis of hydrodynamics and volumetric mass transfer coefficient (k(L)a) in a cross-T junction microchannel for gas-liquid, two phase flow system. Initially, CO2-water hydrodynamics simulation was performed using ANSYS-FLUENT 2021 R2 and volume of fluid technique. Through the numerical simulation, fluctuation in pressure drop with variation in volume fraction was calculated for the slug flow in a 1 mm hydraulic diameter microchannel. After that mass transfer equations were coupled with the flow equations for CO2-ethyl glycol, CO2-water, and CO2-ethyl alcohol systems to understand the mass transfer mechanism using two film theory concepts. Computational fluid dynamics model was validated by comparing results with the experimental data. An empirical co-relation was also developed to measure the bubble length with its position in the direction of fluid flow. CO2 and solvents velocities were 0.21-0.424 m/s for both the phase. Effect of solvents and film thickness (0.01-0.05 mm) on volumetric mas transfer coefficient were investigated at different temperatures range i.e., T = 298.15 K and 303.15 K (experimental approach) and 298.15-318.15 K (numerical approach). The results obtained in numerical simulation and experimental work show that the total volumetric mass transfer coefficient (range 0.1-0.8 1/s) increases with the gas velocity however, it decreases with increasing film thickness (0.01-0.05 mm) and temperature (T = 298.15 K and 303.15 K). The present work gives an advantage over the conventional channel (e.g., packed bed column) and the other type of T-junction microchannel (e.g., symmetric T-junction) by providing a high mixing rate, interfacial area, and high mass transfer rate.