X-DF Otto Cycle

The X-DF Otto cycle is the lean-burn premixed combustion mode used by WinGD two-stroke dual-fuel engines in gas operation. Low-pressure gas at about 16 bar is admitted into the cylinder and mixed with scavenge air to form a lean homogeneous charge, then ignited near top dead center by a micro pilot injection of liquid fuel, typically under 1% of energy at high load. The lean mixture keeps peak combustion temperatures down, which holds NOx within IMO Tier III without aftertreatment. The penalty is incomplete oxidation in the cylinder crevices, the source of methane slip counted well-to-wake under FuelEU Maritime.