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In this work, an ozone/air/gasoline mixture has been used as an alternative strategy to achieve a stable combustion in a spark ignition (SI) single cylinder PFI research engine. The air intake manifold has been modified to include four cells to produce ozone with different concentrations. In the research engine, various operating parameters have been monitored such as the in-cylinder pressure, temperature and composition of the exhaust gases, pressure and temperature of the mixture in the intake manifold, engine power and torque and specific fuel consumption. Experimental tests have been carried out under stoichiometric mixture conditions to observe the influence of ozone addition on the combustion process. The results show an advance and an increase of the in-cylinder pressure compared to the reference test-case, where a gasoline/air mixture is used. It is worth noting that, especially under stoichiometric condition, ozone concentration induces auto-ignition and knock.

With the aim of decarbonizing the vehicles fleet, the use of hydrogen is promising solution. Hydrogen is an energy carrier, carbon-free, with high calorific value and with no CO2 and HC emissions burning in ICE. Hydrogen use in spark ignition engines has already been extensively investigated and optimized. On the other hand, its use in compression ignition engines has been little developed and, therefore, there is a lack of information regarding the combustion in ultra-lean conditions, typical of diesel engines. Several applications employ dual fuel combustion for the easy management of the PFI injection system to be applied in addition to the DI Common Rail system. However, this mode suffers from several problems regarding the management of the maximum flow rate of hydrogen into the intake. In particular, to avoid throwing hydrogen into the exhaust, injection must be started after the valve crossing.