Effect of dual-core spark discharge on ignition probability and engine power

This report presents the experimental study of developing a dual-core spark discharge (2C-SD) model for clean combustion. We first studied ignition probability (Pig) of lean methane/air at an equivalence ratio of 0.5 using 2C-SD with different spark-gaps (dgap = 1.0mm and 2.0mm) in a constant volume combustion chamber. We then applied 2C-SD to the engine driving a 2.5-kW generator. The results indicated that Pig is 30% and 45% at dgap=1.0mm and 2.0mm, respectively, while Pig is 0 when using conventional single spark discharge (CSSD). Compared to CSSD, when using 2C-SD the engine power could be improved by 4%-9.7%, depending on the throttle openings. We expect the larger volume of the initial flame kernel by 2C-SD could enhance Pig and quickly reach the critical flame radius before self-sustained propagating. The faster initial flame speed is essential for achieving the optimal combustion phasing, resulting in a higher power.