Technical Paper
The Ultra Lean Burn Partially Stratified Charge Natural Gas Engine
2009-09-13
2009-24-0115
It is well known that lean operation of homogeneous- charge spark-ignited engines is effective in increasing thermal efficiency and reducing exhaust emissions. In particular, the lower combustion temperatures provided by a lean air-fuel mixture result in a significant reduction in NOx emissions. Lean operation is normally restricted, however, by the “lean-limit” of combustion, as measured by the air-fuel ratio above which ignition is impossible, or combustion is incomplete. In order to extend the lean limit of operation a new “partially-stratified charge” combustion concept has been developed. This technique relies on the fact that a stronger initial flame kernel produced following the spark event should also be effective in igniting a very lean mixture which may not otherwise ignite, or which may result in incomplete combustion.