Renewable fuel and blend properties for the reduction of GHG emissions under different spark-ignited engine architectures

Abstract

Despite the increasing efforts to electrify the transport sector, discussions remain on the interest of renewable and low-carbon fuels as an alternative solution to mitigate the impact on GHG. This work assesses the influence of liquid fuels’ properties on engine-out GHG emissions through the optimisation of both thermal efficiency and fuel’s carbon index, combined with highly efficient turbulent combustion chamber architecture, in an aim to maximise gains. The study helps underline the limitations and advantages associated to high efficiency fuels for spark-ignited combustion systems when applied to advance architectures. Limitations to the combination of such strategies have been observed, not commonly presented in previous studies. Indeed, the beneficial impact of optimised fuel properties on peak efficiency could be compromised when applied to high efficiency turbulent engines as their combination can aggravate heat transfer losses. Moreover, the fuel’s capacity to increase the maximal dilution rate could depend on the engine’s architecture. Despite these results, low-carbon fuels remain relevant to accelerate the decarbonisation of the transport sector due to benefits at higher load and a fuel’s lower carbon emissions. However, the importance of the synergetic optimisation of low carbon fuel formulation’s and combustion system’s design is underlined for more advanced technologies.