Investigation of argon oxy combustion with low molecular weight fuels: Improving thermodynamic efficiency

Utilizing fuel and oxidizing mixtures of oxygen and argon in spark ignition (SI) engines have been shown to increase thermal efficiency relative to standard fuel and air oxidizing mixtures due to the increased ratio of specific heats [1], [2] et. al. Motivated by these results, stoichiometric methane mixtures with various oxidizing volumetric ratios of argon and oxygen (90/10, 85/15, 80/20) are explored and studied in a simulated research engine in a fuel port injection configuration. Computational fluid dynamics (CFD) and combustion simulations using reduced chemical kinetic mechanisms were performed to investigate overall combustion performance and thermodynamic efficiencies. A successive approach of increasingly higher dimensional models (zero dimensional, quasi one dimensional, and three dimensional CFD) with adiabatic, Angelberger, and Woschni heat loss models are compared in the context of thermodynamic theory. Significantly higher efficiency gains on the order of 10% relative to standard fuel and air oxidizing mixtures are predicted.