Performance Characterization of Alternative Ignition Systems Using Optical Tools in Natural Gas Engines

Lean-burn combustion dominates the current reciprocating engine R&D efforts due to its inherent benefits of high BTE and low emissions. The ever-increasing push for high power densities necessitates high boost pressures. Therefore, the reliability and durability of ignition systems face greater challenges. In this study, four ignition systems, namely, stock Capacitive discharge ignition (CDI), Laser ignition, Flame jet ignition (FJI), and Nano-pulse delivery (NPD) ignition were tested using a single cylinder natural gas engine. Engine performance and emissions characteristics are presented highlighting the benefits and limitations of respective ignition systems. Optical tools enabled delving into the ignition delay period and assisted with some characterization of the spark and its impact on subsequent processes. It is evident that advanced ignition systems such as Lasers, Flame-jets and Nano-pulse delivery enable extension of the lean ignition limits of fuel/air mixtures compared to base CDI system.