Effect of hydrogen injection coupled with high-energy ignition on the combustion stability of a lean-burn gasoline engine

Abstract

The shortage of fossil energy and the aggravation of environmental pollution have led to stricter requirements for energy conservation and environmental protection of automobiles. The development of new energy vehicles still needs time and space. The internal combustion engine is still the power source that automobiles will need to rely on in the future. Lean combustion is one of the key research directions for efficient and clean combustion technology for gasoline engines. In this paper, the effects of high-energy ignition coupling hydrogen blending on the combustion stability of lean-burn gasoline engines were studied by means of multi-point high-energy ignition and gasoline/hydrogen double direct injection. Through the combination of gasoline and hydrogen injection timing, a suitable stratified mixture can be formed in the cylinder. Combined with high-energy ignition, the fire core can be formed smoothly, and the flame spreads rapidly. The introduction of hydrogen increases the concentration of H in the reaction system, enhances the activity of the reaction system, and accelerates the oxidation process of fuel molecules. Compared with a pure gasoline engine, hydrogen blending can expand the lean burn limit by 66.2% and increase ITE (Indicated Thermal Efficiency) by 6.5%. NOx emission increases first and then decreases with the increase in excess air ratio, but when λ > 1.6, NOx emission is much lower than that of the equivalence ratio condition. HC (Hydrocarbons), CO, and CO2 emissions are also lower than the equivalent ratio conditions.