[Objective] At present

the greenhouse effect is becoming increasingly severe

making it crucial to control CO2 emissions from fossil fuel combustion. Carbon dioxide capture technology represents both the primary step and the critical pathway

serving as a vital means for reducing carbon emissions in the future. [Methods] Based on a novel double-contact carbon capture gas-liquid two-phase absorption bed

and to investigate its enhanced mass transfer performance for ammonia-based carbon capture

this study employs an Eulerian-Lagrangian CFD framework. By integrating dual-film theory into a secondary development of Fluent

a mass transfer model for ammonia-based carbon capture is constructed. [Results] The droplet load exhibits a unimodal distribution along the tower height

being low near the walls and high towards the center. As the liquid-to-gas ratio decreases

the net CO2 flux increases

leading to a higher droplet load. Significant flow deviation exists at the flue gas inlet

with its severity diminishing as the liquid-to-gas ratio decreases. The uneven droplet distribution causes non-uniformity in CO2 absorption and concentration field distribution. When the liquid-to-gas ratio decreases from 0.40 m3/m3 to 0.17 m3/m3

the CO2 capture efficiency drops from 89.19% to 77.29%

a reduction of 13.34%

while the outlet CO2 molar fraction rises from 1.45% to 3.00%. The overall gas-phase mass transfer coefficient(KG) remains relatively high below three-quarters of the bed height. A banded region of low KG forms beneath the nozzle manifold. In the region above the nozzles

KG gradually decreases with increasing bed height due to insufficient mass transfer driving force and the influence of mass transfer resistance from the gas film side. As the liquid-to-gas ratio decreases

the high KG zone contracts

and the banded low KG zone exhibits a parabolic upward trajectory. Regarding the flow field

two high-velocity zones and vortices form within the bed due to the inlet and Venturi effect. The average gas phase velocity in the Z-direction exhibits a bimodal distribution along the bed height

a symmetrical three-segment oscillation along the X-cross section

and a non-monotonic distribution along the Y-cross section. As the liquid-togas ratio decreases

the disturbance between the gas and liquid phases intensifies

causing the average gas phase velocity along the Y=0 cross section and the X-cross section to gradually increase. [Conclusion] The double-contact carbon capture gas-liquid two-phase absorption bed exhibits favourable mass transfer characteristics

with the liquid-to-gas ratio exerting a significant regulatory effect on both flow and mass transfer. These findings provide a theoretical basis for optimizing carbon capture equipment.