Numerical Modelling of Radiative Heat Transfer in Heavy-Duty Engines for Improved Emission Predictions

Computer Fluid Dynamics (CFD) coupling with experimental research is widely utilised in improving internal combustion engines in terms of pollutant formation and energy efficiency. Recent studies showed that including radiative heat transfer in participating media for more accurate internal combustion emission predictions is necessary. Especially in heavy-duty engines due to their more significant dimensions than automotive engines. In this work, the discrete ordinates method (DOM) is employed with the finite volume method in AVL FIRE™ CFD software. The absorptivity and emissivity are described with Weighted Sum of Gray Gases Method (WSGGM), which calculates the overall absorption coefficient using carbon dioxide, water vapour, and soot absorption coefficient. This paper aims to evaluate the impact of radiative heat transfer on the thermal state of the media and the formation prediction of pollutants. The radiative heat transfer model is validated against mean pressure results inside an engine cylinder. Finally, pollutant formation curves are compared and analysed, where approximately 15% NO mass fraction is obtained for the calculations with included radiative heat transfer.