2D Axisymmetric Coupled Computational Fluid Dynamics–Kinetics Modeling of a Nonthermal Arc Plasma Torch for Diesel Fuel Reforming

The present study is dedicated to the 2D axisymmetric coupled computational fluid dynamics–kinetics modeling of a plasma-assisted diesel fuel reformer developed for two different applications: (i) onboard H2 production for fuel-cell feeding and (ii) NO x trap regeneration. These cases correspond to very different reaction conditions. In the first case, diesel fuel reacts with air, while in the second case, it reacts with diesel engine exhaust gas. The plasma is modeled with a simple power source domain. n-Heptane has been chosen as a surrogate molecule for diesel fuel. A reduced kinetic mechanism is used for the study. Both cases have been studied under adiabatic and nonadiabatic postreactor conditions. We can distinguish four zones in the torch: a reactant heating zone, a plasma zone, a mixing zone, and a postdischarge zone. The main precursors of the reforming reactions are H, O, and OH radicals. The oxygen rate is a key point of the application. The thermal losses make the reforming reaction difficult to ignite and beget a lower syngas production and a lower postdischarge temperature. For the nonadiabatic reactor, the results have been compared to experimental data. The model predicts relevant gas fractions.