Recent Advances in Ozone-Assisted Combustion for Sustainable Thermal Engines

Recent advances in ozone-assisted combustion for both compression ignition and spark ignition engines are discussed. Ozone, which can be produced by an electrical discharge in air or pure oxygen, decomposes at high temperature to yield highly oxidizing oxygen atoms, which enhance fuel/air reactions. As a result, flames are faster and more stable, ignition is enhanced and low-temperature chemistry is promoted. In the literature, the beneficial influence of ozone on standard and innovative fuels, including low-carbon (syngas) and zero-carbon (hydrogen and ammonia) fuels, has been assessed. In addition, the impact of ozone seeding on new combustion strategies has also been discussed. Ozone enables better control of ignition in Homogeneous Charge Compression Ignition (HCCI) engines, and improves the combustion stability in low-load Gasoline Compression Ignition (GCI) engines, as well as in lean Spark-Assisted Compression Ignition (SACI) and spark ignition (SI) engines, thus broadening the operating range of these engines.