Abstract : Dilute combustion is an effective way to increase part-load efficiencies in a Spark Ignition (SI) engine. However, dilute combustion leads to a slower combustion rate and longer burn durations, which results in higher heat transfer loss. To overcome this, some degree of charge flow enhancement exists in modern engines that improves combustion rate and shortens burn durations. This flow enhancement has an adverse effect on performance of the modern Transistorized Coil Ignition (TCI) system and hence presents a limitation on improving combustion rates. Additionally, dilute combustion has a detrimental effect on combustion stability, wherein a larger variation in engine cycle work is observed from cycle to cycle which degrades engine performance. Improving combustion stability under dilution poses a challenge for the modern single coil ignition system, which is where the motivation lies in this research. This research details the development and instrumentation of a Configurable Dual Coil Ignition (CDCI) system that is later tested on a single cylinder metal engine. The effectiveness of different ignition profiles developed with the CDCI system in extending the dilution limit while maintaining combustion performance and lower cycle-cycle variations, thereby improving fuel conversion efficiency, is investigated. Effects of dilution by excess air and internal (exhaust) residuals on the performance of these ignition profiles are investigated under different operating conditions. In-cylinder flow is enhanced by means of tumble planks installed in the intake port of the engine. The impact of enhanced in-cylinder flow on the capabilities of the developed ignition profiles is also investigated under different conditions. Moreover, effects of different spark plug gap sizes and orientations are also investigated. Although majority of the tests are done with Direct Injection (DI) gasoline, some tests are performed with Port Fuel Injection (PFI) methane to compare the effects of fuel delivery and charge preparation.

The volume includes selected and reviewed papers from the 3rd Conference on Ignition Systems for Gasoline Engines in Berlin in November 2016. Experts from industry and universities discuss in their papers the challenges to ignition systems in providing reliable, precise ignition in the light of a wide spread in mixture quality, high exhaust gas recirculation rates and high cylinder pressures. Classic spark plug ignition as well as alternative ignition systems are assessed, the ignition system being one of the key technologies to further optimizing the gasoline engine.

The present manuscript discusses the performance and emission benefits due to two diesel injections in diesel-ignited methane dual fuel Low Temperature Combustion (LTC). A Single Cylinder Research Engine (SCRE) adapted for diesel-ignited methane dual fuelling was operated at 1500 rev/min and 5 bar BMEP with 1.5 bar intake manifold pressure. The first injection was fixed at 310 CAD. A 2nd injection sweep timing was performed to determine the best 2nd injection timing (as 375 CAD) at a fixed Percentage Energy Substitution (PES 75%). The motivation to use a second late injection ATDC was to oxidize Unburnt Hydrocarbons (HC) generated from the dual fuel combustion of first injection. Finally, an injection pressure sweep (550-1300 bar) helped achieve simultaneous reduction of HC (56%) and CO (43%) emissions accompanied with increased IFCE (10%) and combustion efficiency (12%) w.r.t. the baseline single injection (at 310 CAD) of dual fuel LTC.