CFD Investigation of a Burner-base Heating Strategy to Speed up the cold Start Transient of ICEs

Abstract

The upcoming emission legislations are expected to introduce further restrictions on the admittable level of pollutants from vehicles measured on homologation cycles and real drive tests, requiring the implementation of novel strategies to speed-up the light-off of the reactions occurring in the after-treatment system to comply with the new limits. This paper focuses on the evaluation of the potential of a burner system, which is activated before the engine start to generate a high temperature gas stream to promote a fast heating of the substrate. A CFD model has been developed to investigate the light-off of the reactions during the initial operation of the burner and the subsequent start of the engine. The model, developed on the basis of the OpenFOAM code, resorts to a multi-region approach, where different meshes are employed to describe the fluid domain and the solid regions, namely the catalytic porous substrates and the metallic walls constituting pipes and canning. Specific submodels are implemented to consider flow resistance, heat transfer, mass transfer and catalytic reactions occurring in the catalyst region. The CFD framework has been initially validated on the experimental data acquired on the test bench. The methodology has been then applied to the preliminary analysis of the catalyst light-off at engine cold start, considering a full exhaust line equipped with burner-like system.