Porous media are widely used in several energy-related industrial applications. Their specific features, such as versatile microstructure, high specific surface area and compact size, make them an optimal candidate for flow-controlled reaction systems. A classical example is packed bed reactors which, owing to their capability of spreading active species carried by the fluid which flows through and to the high fluid-solid interfacial area, can ensure high reaction rates and conversion efficiencies.
Nevertheless, the mechanisms of mass and momentum transport though a porous microstructure that determine the system performances, i.e. the flow and dispersion mechanism at the pore-scale, are very complex, interdependent phenomena and their physical behaviour and comprehension is still under investigation [1,2]. The presence of a reaction mechanism at the fluid-solid boundary further complicates the physics.
The Lattice-Boltzmann Method (LBM) is a powerful tool able to solve flows in complex geometries at the microscale . The LBM is therefore a perfect candidate in order to study the effects of the porous microstructure on the fluid-dynamics aspects of such systems.
In the present work, we will focus on two flow-controlled reaction systems: (i) a Redox Flow Battery (RFB) and (ii) an Activated Carbon Adsorption System (ACAS) for exhaust gas cleaning. Even though their practical applications are different, both their efficiencies depend on the flow, dispersion and reaction mechanisms in a porous microstructure.
RFBs are a promising technology for stationary energy storage and conversion . The system performance can be increased by enhancing the dispersion mechanisms provided by the porous microstructure. Therefore, simulations of flow, dispersion and reaction in different real porous materials (reconstructed via X-Ray tomography) will be performed with the LBM in order to identify the optimal material.
ACAS are nowadays used in state-of-the-art biomass gasification plants in order provide a high quality gas . The activated carbons, which are able to promote the adsorption of gas impurities, are randomly packed in a container, forming a porous medium. The efficiency of the cleaning system is determined by the gas flow behaviour and geometrical traits of the porous microstructure. Using LBM simulations, we will investigate the efficiency of different packing beds, with varying the geometrical shape of the carbons and the gas flow rate (Reynolds and Peclet numbers).