Instationary heat and mass transfer phenomena in additive manufactured open cell polyhedral structures for automotive catalysis

Additive Manufactured (AM) Open Cell Polyhedral lattices are novel substrates for automotive catalytic converters due to promising properties. The present investigation focuses on heat and mass transfer with chemical reactions during cold starts, based on numerical simulations in OpenFOAM and dimensionless analytical analysis. The numerical model consists of a multi-region approach with overlapping meshes for fluid and solid regions, in order to simulate the presence of porous substrates. Experimental results from first vehicle-size AM catalysts are used as a basis. The catalyst heat-up is characterized by two distinguished phases: the initial phase where heat is convected from the inflowing gases to the catalyst and the following phase which is governed by the heat released by the chemical reactions. The impact of different operating parameters, lattice and converter geometries has been quantified. The introduction of dimensionless temperature, time and space, evidences the similarity of the initial warm-up phase.