Potential for twin spark plug configurations to improve emissions and fuel economy

From 2020, Euro 5 emission standards have required CO, NO_x, and THC to be reduced by 12%, 14.29%, and 73.68%, respectively. The cost-effective twin spark plug (TSP) configuration seems to be a promising solution to reduce HC. In this study, the experimental and numerical work were both tested for a 125 c.c. engine adopting either single spark plug (SSP) or TSP configuration. Compared to the SSP engine, the TSP reduced the ignition delay and burn duration by an average of 10%–12.26% and 10.89%–15.20%, respectively. TSP can operate with a 13.60% leaner mixture without facing knock or compromising performance. Therefore, 12.73% lower fuel economy, 47.07% lower ISCO and 29.14% lower ISHC achieved for a compromise of ISNO_x of 2 times at WOT. According to the numerical work, simultaneous ignition under TSP helps shorten the ignition delay, while the interaction between turbulence and flame propagation of two flames reduces the burn duration.