Low emission Lean-Burn engines

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Lean-burn natural gas engines offer higher efficiency and lower exhaust emissions compared to conventional stoichiometric homogeneous charge engines. However, as the mixture is leaned out beyond the lean limit of combustion, the stability of engine operation is reduced, and emissions increase sharply. To extend the lean-limit of natural gas combustion, a unique partially stratified-charge (PSC) engine control concept has been developed. This new system provides enhanced ignition and combustion in lean-burn engines, resulting in reduced exhaust emissions and increased thermal efficiency. Initial "proof-of-concept" testing has shown that the PSC system provides increased engine stability and lower exhaust emissions compared to conventional homogeneous charge engine operation. The overall objective of the research being proposed is to develop a better understanding of how the PSC ignition technique can be used to improve the performance of low-emission natural gas engines. The proposed research will include fundamental experimental work as well as numerical studies to develop a more complete understanding of the fuel-air mixing, ignition, and combustion processes that take place in an engine equipped with a PSC ignition system. The results of these fundamental studies will guide further development of the PSC technique for commercial application in large lean-burn stationary engines used to drive natural gas compressors.