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Adaptation of both oil based fuel and engine technologies are key enablers to reduce CO2 footprint as well as pollutant emissions. Recent work has demonstrated the potential of gasoline-like fuels to reduce NOX and particulate emissions when used in compression ignition engines. In addition, properties of naphtha produced directly from the atmospheric crude oil distillation process in a refinery offer significant CO2 benefits. When introducing such innovative fuel and engine, after-treatment investigations are mandatory to meet pollutant regulations. In that respect, this work focuses on investigating structure and properties of the particulates produced with naphtha fuel to validate Diesel Particulate Filter (DPF) design requirements. First, soot mass measurement techniques are detailed. Then, characterization of soot is performed through DPF pressure drop, soot oxidation rates with and without Fuel Borne Catalyst (FBC), composition & structure analysis.

Increasing global efficiency of direct injection spark ignition (DISI) engine is nowadays one of the main concerns in automotive research. A conventional way to reduce DISI engine fuel consumption is through downsizing. This approach is well suited to the current homologation cycle as NEDC, but has the drawback to induce over-consumptions in customer real driving usage. Moreover, the driving cycles dedicated to EURO 6d and future regulations will evolve towards higher load operating conditions with higher particulate emissions. Therefore, efficiency of current DISI has to be strongly increased, for homologation cycle and real driving conditions. This implies to deeply understand and improve injection, mixing and flame propagation processes.

Compared to Spark Ignition (SI) engines, Compression Ignition (CI) engines are more efficient because of the higher compression ratios and leaner operation. However, thanks to stoichiometric air fuel ratio, SI engines allow efficient pollutants after treatment, particularly for NOx emissions. In this context, IFP Energies nouvelles (IFPEN) has developed the concept of diesel-gasoline combustion in order to combine the advantages of both fuels and both combustion processes. Focusing on a passenger car application, experiments have been performed using a modified DI turbocharged small diesel engine (the combustion chamber has been redesigned and port fuel injectors have been added). In-Cylinder Fuel Blending (ICFB) using port-fuel-injection of gasoline and optimized direct injection of diesel was used to control combustion phasing and duration. This modified engine can still run on diesel alone.

Among the existing concepts that help to improve the efficiency of spark-ignition engines at part load, Controlled Auto-Ignition™ (CAI™) is an effective way to lower both fuel consumption and pollutant emissions. This combustion concept is based on the auto-ignition of an air-fuel-mixture highly diluted with hot burnt gases to achieve high indicated efficiency and low pollutant emissions through low temperature combustion. To minimize the costs of conversion of a standard spark-ignition engine into a CAI engine, the present study is restricted to a Port Fuel Injection engine with a cam-profile switching system and a cam phaser on both intake and exhaust sides. In a 4-stroke engine, a large amount of burnt gases can be trapped in the cylinder via early closure of the exhaust valves. This so-called Negative Valve Overlap (NVO) strategy has a key parameter to control the amount of trapped burnt gases and consequently the combustion: the exhaust valve-lift profile.

Among the existing concepts that help to improve the efficiency of spark ignition engines at part load, Controlled Auto-Ignition™ (CAI™) is an effective way to lower both fuel consumption and pollutant emissions without major modifications of the engine design. The CAI™ concept is based on the auto-ignition of a fuel mixture highly diluted with burnt gases in order to achieve high indicated efficiency and low pollutant emissions through low temperature combustion. Large amounts of burnt gases can be trapped in the cylinder by re-breathing them through the exhaust ports during the intake stroke. For that, a 2-step exhaust valve-lift profile is used. The interaction between the intake and exhaust flows during the intake stroke was identified as a key parameter to control the subsequent combustion in a CAI™ port fuel injected (PFI) engine.

Among the existing concepts that help to improve the efficiency of spark ignition engines at part load, Controlled Auto-Ignition™ (CAI™) is an effective way to lower both fuel consumption and pollutant emissions without major modifications of the engine design. The CAI™ concept is based on the auto-ignition of a fuel mixture highly diluted with burnt gases in order to achieve high indicated efficiency and low pollutant emissions through low temperature combustion. In a 4-stroke engine, large amounts of burnt gases can be trapped in the cylinder by re-breathing them through the exhaust ports during the intake stroke using a 2-step exhaust valve-lift profile. The interaction between the intake and exhaust flows during the intake stroke was identified as a key parameter to control the subsequent combustion in a CAI™ PFI engine. Consequently, the intake valve-lift profile as well as the exhaust re-opening profile can potentially be used as control parameters for this combustion mode.