Reduced chemical kinetics mechanism for modelling of n-Heptane/syngas combustion with NOx formation in a micro-pilot ignited dual fuel engine

Abstract

A reduced chemical kinetics model was developed to simulate the combined combustion of n-Heptane with syngas, as well as the standalone syngas combustion and NOx formation in a pilot-ignited dual fuel engine. This simplified model comprises 75 different species and 276 reactions. Its accuracy was confirmed by comparing it with experimental data from existing literature and numerical results from established models. The comparison encompassed key factors such as ignition delay, the speed of combustion in a laminar flame, and the concentration profiles of NOx. The reduced model closely aligned with both experimental and simulated outcomes, particularly under conditions relevant to engine combustion.This reduced mechanism was then employed in a comprehensive computational fluid dynamics computations to predict syngas combustion in a dual-fuel engine that employs the injection of reduced amount of liquid n-Heptane fuel with subsequent micro-pilot ignition. The model accurately captured the necessary conditions for n-Heptane injection and the co-oxidation of syngas with n-Heptane. Moreover, it exhibited strong agreement with experimental measurements of the heat release rate (ROHR) and cylinder pressures. The study's results highlight that the reduced mechanism can precisely simulate combustion of syngas-based fuels in engine cylinder containing up to 57% hydrogen (H2) content. As a result, this simplified model is highly suitable for simulating engine conditions involving fuels derived from syngas.