Open adsorption system for atmospheric CO2 capture: Scaling and sensitivity analysis

Open adsorption process of gas mixtures involves complex heat and mass transfer mechanisms. Understanding of the physical mechanisms and their impacts on the adsorption process from gas mixtures is vital. In this study, a detailed analysis of an open CO2 adsorption from CO2/N2 mixtures using zeolite 13X-APG was investigated. Key physical mechanisms (unsteady, diffusive, convective, and component source, etc.) involved were scrutinized, and their order of magnitudes relative to the system energy complex were determined. The influences of these physical mechanisms on the equilibrium and dynamic nature throughout the capture were quantified. The validated computational fluid dynamics (CFD) simulations for the same adsorption domain were carried out to verify the rationality of the scaling method. The adsorption time, tad; the maximum average temperature, T‾max; CO2 removal rate, Rre,CO2; equilibrium pressure drop, ΔPeq on different scale parameters and their sensitivity were investigated. The maximum relative sensitivity to porosity was found to be −0.945, 0.0235, −0.357, and −5.33 for tad, T‾max, Rre,CO2 and ΔPeq, respectively. It is observed that heat transfer by the conduction mechanism inside the bed significantly influences all scale parameters, except for ΔPeq. This work will contribute to a better understanding of the atmospheric CO2 adsorption and provide guidance for the design optimization.