Disruptive Solutions for Innovative Internal Combustion Engines and Advanced Combustion

Dear Colleagues,

The ever-more stringent emissions regulations, together with the increasing concern for environmental issues, have driven the industry to largely invest in R&D to establish innovative solutions for internal combustion engines for automotive, marine, and off-road applications.

The roadmap to decarbonization is, in fact, drawing attention to the use and exploitation of alternative fuels for the attainment of green vehicles characterized by low CO₂ and pollutant emissions.

The use of biodiesel retains the potential to reduce the net carbon footprint while still complying with the existing technical solutions and introducing the need for minor modifications to the engine chamber and control solutions. Hydrogen can potentially be enlisted among the renewable sources of fuel depending on its production, and it can be conveniently exploited as a fuel in the internal combustion engine field, leading to virtually no CO₂ and HC emissions. Notwithstanding its great advantages in terms of pollutant emissions, hydrogen requires significant modifications both to the engine design as well as to the control system. More specifically, different solutions are to be found in the literature both for the mixing process as well as for combustion ignition.  It is worth recalling that most of the solutions adopted for hydrogen are derived from those that had been developed for natural gas engines in previous decades. Finally, the high adiabatic flame temperature of hydrogen potentially generates issues in terms of thermal management and pollutant (NOx) emissions abatement. Lean-burn concepts and innovative ATS solutions should hence be considered. Last but not least, ammonia represents a sound alternative to hydrogen, mainly due to the possibility of storing it in a liquid form and its very low stoichiometric A/F ratio.

Regardless of the considered fuel, the refinement of fuels in the spray and mixture formation process, together with an accurate control of the combustion process, are mandatory to comply with the CO₂ net zero goal. As a matter of fact, spray modelling holds great relevance when different fuel characteristics and parameters are accounted for. Detailed and fuel-flexible CFD injector and combustion models, together with the data collected from transparent optical analyses, are hence required to attain a satisfactory level of readiness of engine technologies.

Finally, attention should also be devoted to refining the current state-of-the-art in after-treatment systems to further reduce engine tail-pipe emissions. Once more, advanced solutions are needed to comply with the working conditions produced by innovative combustion concepts and by different fuels, e.g., highly diluted spark ignition combustion.

This Special Issue encourages researchers working in this field to share their latest developments in the field of internal combustion engines. Specific topics of interest for publication include, but are not limited to:

• Biodiesel, ammonia, and hydrogen combustion;
• Spray analysis and mixture formation;
• Advanced combustion concepts (e.g., pre-chamber);
• CFD approaches to engine modelling;
• Data-driven engine models;
• Innovative design for consumption and emissions reduction;
• Innovative solutions for combustion control;
• Advanced ATS architectures and control systems.

Dr. Mirko Baratta
Dr. Daniela Anna Misul
Guest Editors

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• internal combustion engines
• biofuels and bioliquids
• hydrogen
• CFD analysis