2025 AIChE Annual Meeting

(38f) The Impact of Turbulence on Adsorption in Packed Bed Reactors

Authors

Jesse Capecelatro, Dept of Mechanical Engineering
As atmospheric CO2 levels continue to rise, considerable attention has been focused on developing effective removal technologies. Among these, adsorption via solid sorbents shows great promise, although its full potential has yet to be realized due to a limited understanding of the multiphase interactions within reactors. Key factors influencing mass transfer include adsorption reactions, turbulent mixing, wall effects, diffusion, and advection. Reaction rates obtained from experiments may lump contributions from these effects into a single mass transfer coefficient. Turbulence induced by particle wakes, known as “pseudo-turbulence,” is often unresolved in numerical simulations. Although closure models have been proposed for pseudo-turbulence, it isn’t clear whether explicitly accounting for turbulent scalar mixing is double counting the effects of turbulence. This work aims to answer that question.

We plan to conduct particle-resolved simulations of CO2 adsorption in a packed bed reactor, explicitly resolving wake-induced turbulence and surface reactions. The mass transfer rate will be accounted for using a linear driving force model with a known mass transfer coefficient. By filtering the simulation results, we aim to quantify the mass transfer contributions from various factors, including particle reactions, pseudo-turbulence, diffusion, and advection. The actual mass transfer coefficient will be compared with the apparent mass transfer coefficient derived from fitting a traditional 1D plug-flow model. This comparison will help determine if and to what extent the apparent mass transfer coefficient includes turbulent effects. The same case will then be run in a coarse-grain CFD-DEM framework both with the actual mass transfer coefficient and the apparent mass transfer coefficient. Pseudo-turbulent closure models will be used to account for turbulent scalar mixing. We hypothesize that using the apparent mass transfer coefficient may lead to overcompensation for mass transfer within the reactor, due to double counting of turbulent effects.