Detailed simulations of heterogeneous reactions in porous media using the Lattice Boltzmann Method

Other conference contribution, 2018

Flows though porous media are commonly found in many systems, both natural
and manmade. A few examples from nature include petroleum reservoirs, soil and
solid biomass where industrial applications include fuel cells, foams and packed beds.
Most of these areas are still subject to both scientific and engineering challenges
ranging from basic understanding to detailed optimization. A non-trivial part of
the remaining challenges includes the interaction between macro-scale performance
and micro-scale characteristics. For some systems, it is possible to control and tune
micro-scale properties to optimize the overall performance of the application. This
scenario typically manifests in the design of packed beds, especially when reactions
occur within the bed. In such situations, particle shape and size distribution will
affect not only the pressure drop (and hence the preferential flow paths), but also
local reaction rates and thereby efficiency and selectivity.
This work aims to understand and identify key design parameters that influences
reactions within a packed bed, and ultimately, the overall performance of the pack-
ing. Representative microstructures of packed beds are generated with a Discrete
Element Method. Flow, temperature and concentration fields (cf. Figure 1) are then
fully resolved using the Lattice Boltzmann Method with a first order reaction scheme
at the boundaries. Residence time, flow structures and permeability of the systems
are correlated to conversion and selectivity of the chemical reactions in the system.
Comparisons between packings of different particle shapes and spacing serve to eluci-
date phenomena involved in the process and implies design directions for macro-scale
optimization.