SI Engines for Alternative Fuels - Combustion Phase and the Tradeoff Between Ignitability and Spark Plug Wear

Abstract

Electrification of vehicles is important to reduce greenhouse gas (CO2) emissions and stop global warming, but electrification will not be enough. Use of alternative and renewable fuels in SI-ICE will be an important complement to electrification in the heavy-duty segment, motivated by their ability to efficiently use the large potential of renewable fuels with low cetane numbers which are not suitable for diesel-like combustion. However, the property of alternative and renewable fuels may vary considerably, with a significant decrease in engine performance and total cost of ownership (TCO) as result. There is a need to compensate for a varying combustion phase and assure robust ignition while keeping the spark plug wear to a minimum, despite such variations.

The peak pressure location (PPL) can accurately be estimated using ion sense and the ignition timing adapted in a closed loop to compensate for variations in the fuel combustion property. The spark design and requirements are discussed when using different and/or varying fuel. Preliminary results on ignitability and electrode wear indicate that the electrode wear can be reduced considerably. The TCO can be reduced by approximately $1100 per year for fuel and spark plugs alone, hereby making SI-ICE fueled by alternative and renewable fuels an even more attractive solution to reduce the GHG-emissions.