Gas Engine Combustion Principles and Applications 2001-01-2489
Modern commercial dual fuel engines operating in gas mode has the same level of fuel efficiency as the diesel mode. The NOx emissions level is reduced ten fold and satisfies the most stringent European 1/2 TA-Luft regulation. THC emissions can be controlled by the oxidation-catalytic process. High efficiency low NOx emissions gas engine performance is achieved by the following:
Same power cylinder components as the basic diesel.
Retarded timing together with short heat release duration by using Micropilot/Microcup designs.
Lean lambda of 2.0 to 2.2.
Minimal pilot fuel, 1% or less.
Centrally located ignition if practical.
Low air charge temperature at high load for high BMEP.
20-30% lower lambda at part load (compared to full load) achieved by compressed air bypass, skipfire, or variable geometry turbo.
This paper provides only a qualitative treatise on gas engine combustion and the effects of fuel quality and engine design on combustion. Additional research is warranted.