| The characteristics of three ignition systems, such as inductive ignition, capacitor discharge ignition, and railplug ignition system, are investigated. Based on the characteristics, the railplug is a very promising ignition system for lean burn natural gas engines with its high-energy deposition and high velocity plasma arc. Parallel railplugs are designed, fabricated and tested on an operating natural gas fueled engine. The engine tests shows that the lean-stability-limit (LSL) can be extended from a fuel/air equivalence ratio of ϕ = 0.62 for spark plugs down to ϕ = 0.535 using a railplug. Thus, engine-out NOx emission is also reduced using railplugs. A heat transfer model is proposed to aid the railplug design. A parameter study is performed both in a constant volume bomb and in an operating natural gas engine to improve and optimize the railplug designs. |
