Natural Gas is an energy carrier with multiple applications in several energy sectors. Electricity generation, transportation and heating are expected to employ Natural Gas in increasing amounts in the future, due to the most favourable CO2-output among all fossil fuels but also to the capability of reduced NOx, soot and higher hydrocarbon emissions.
In particular Reciprocating Combustion Engines both for decentralized cogeneration (up to 15 MWel unit size) and transportation (passenger cars, buses, trucks, construction machines and even ships) are in need of intensified research related to the combustion not only of conventional NG/LNG but also of a variety of gaseous fuels.
Advancement in conversion efficiency and environmental performance of IC gas engines refer to higher supercharging Miller/Atkinson cycles, avoidance of self-ignition/knock, abatement of CH4-emissions and extension of operation to even leaner and/or more dilute mixtures. Improved ignition systems, flame propagation and turbulence-thermochemistry interactions also in the vicinity of the combustion chamber walls are important fundamental research questions. An additional need for research in this context deals with the emergence of renewable gaseous fuels as potential admixtures to natural gas for IC engines. Such fuels may be biogas (with high CO2 content), synthesis gas (from wood pyrolysis) or H2 from electrolysis based on wind/solar primary energy. Such fuels of varying composition ask for tailored combustion systems in IC Engines, as different physical and chemical properties (density, propensity to self-ignition, calorific value, laminar and turbulent flame speeds) affect ignition, heat-release, knock, near-wall flame termination etc. Interfaces of gas engine combustion with dual-fuel engines (incl. varying composition of liquid-gaseous fuels) can also be conceived of as emerging, very interesting research topics.