The entire mobility industry currently faces enormous regulatory demands due to the Paris agreement and its corresponding initiatives to eliminate the business sector-related greenhouse gas emissions (GHG) emissions. A major focus is hereby set on wide-spread electrification of all kinds of applications, but from current perspective it is obvious that a quick and complete shift is highly unlikely, especially with view on heavy and challenging industrial and commercial applications. In line with this, it’s apparent that internal combustion engines (ICEs) maintain to play an important role in the overall propulsion system line-up. For compliance with the engaged CO2 reduction policies and efficiency improvement demands, a fast and broad replacement of fossil fuels needs to be realized. Due to the specific properties of carbon-neutral fuels and as well the variety of the range of industrial applications, different types of alternative fuels are considered. These novel fuels can be subdivided into preferred solutions for smaller or on-highway applications vs heavy off-highway and marine applications, or simply according to local or national preferences or policies. As of now, Hydrogen as well as Methanol/Ethanol is highly attractive for on-highway applications as well as construction/agricultural applications, the heavier and larger applications tend to more energy-dense energy carriers like NH3 and partially Methanol/Ethanol. In addition, to support a smooth transition to fully carbon-neutral operation, intermediate dual-fuel layouts are requested, partially requiring a full redundancy between classical Diesel operation and powering with new fuels. This complexity and variety in customer demands provide a major challenge for globally operating OEMs as future engines designs and definitions need to be developed under extreme cost pressure.
The paper at hand delivers an interesting approach to design and develop modern ICE platforms for the anticipated multi-fuel case, aiming at superior key performance indicators concerning power output and efficiency, while maximizing the degree of commonality between the individual engine versions and variants. This flexibility and modularity needs to be incorporated in the base engine design, especially in the top end of the assembly, as it implicates different demands in air delivery and as well the transition from a diffusive combustion system to a pre-mixed combustion principle. This affects on one hand the installation of key sub-systems like fuel injection and ignition, but as well also the decision about an appropriate compression ratio and the definition of an adjusted in-cylinder charge motion. The article closes with recommendations for a future multi-fuel engine definition and an assessment concerning the major design changes in contrast to a refined and optimized Diesel engine layout.