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Homogeneous Charge Compression Ignition (HCCI) is among the new generation of combustion modes which can be applied to internal combustion engines. It is currently the topic of numerous studies in various fields. Due to its operating process, HCCI ensures a good efficiency, similar to that of compression ignition (CI) engines, and low particulate and nitric oxide (NOx) emissions. However, before promoting the use of this kind of engine, several challenges must be addressed, in particular controlling the combustion. Recent work showed that the combustion phasing can be controlled using low concentrations of ozone, an oxidizing chemical species. As ozone generators become increasingly compact, the integration of this kind of device in passenger cars can be considered. The present study investigates the effect of ozone on the combustion of different fuel mixtures. The engine was fuelled with various blends: a 95%methane/5%propane mixture and three different methane/hydrogen mixtures.

Homogeneous Charge Compression Ignition (HCCI) is generally considered as an efficient solution to reduce fuel consumption and meet the pollutant requirements of internal combustion engines. Furthermore, the HCCI combustion strategy delivers drastically reduced levels of NOx and particulate matter, and combined with a post treatment device, low levels of unburned hydrocarbons (HC) and carbon monoxide (CO) can be achieved. However, affordable and widely used three-way catalytic converters require the engine to be run under stoichiometric conditions. Running an HCCI engine under an increased equivalence ratio leads to advanced combustion phasing and an excessive in-cylinder pressure rate that can affect engine operation. The dilution effect of Exhaust Gas Recirculation (EGR) represents a way to delay ignition of the mixture and reduce excessive in-cylinder pressure gradients.