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The strategies adopted to control the combustion in Diesel applications play a key role when dealing with current and future requirements of automotive market for Diesel powertrain systems. The traditional “open loop” control approach aims to achieve a desired combustion behaviour by indirect manipulation of the system boundary conditions (e.g. fresh air mass, fuel injection). On the contrary, the direct measurement of the combustion process, e.g. by means of in-cylinder pressure sensor, offers the possibility to achieve the same target “quasi” automatically all over the vehicle lifetime in widely different operating conditions. Beside the traditional combustion control in closed loop (i.e. based on inner torque and/or combustion timing), the exploitation of in-cylinder pressure signal offers a variety of possible further applications, e.g. smart detection of Diesel fuel quality variation, control of combustion noise, modeling engine exhaust emission (e.g. NOx).

In order to study the effects of air bulk motion and methane injection strategies on the development and pollutant levels of dual-fuel combustion, an intense experimental campaign was performed on a diesel common rail research engine with variable inlet configurations. Activating only the swirl or the tumble inlet valve of the engine, or both of them, it was possible to obtain, inside the cylinder, three different bulk flow structures. The air-methane mixture was obtained injecting the gaseous fuel into the inlet manifold varying its pressure and the injector position, either very close to the inlet valves, in order to obtain a stratified-like mixture, or more upstream, to obtain a homogeneous-like mixture. By combining the two different positions of the injector and the three air bulk flow structures, seven different inlet setup have been tested, at different values of engine speed and load.

The maintenance on condition is gaining more and more importance in the field of vehicle pool management. A crucial role in the vehicle maintenance is covered by the changing of the lubricating oil of the gearbox, the differential and the engine. In the lubricating oil different substances dissolve: metal traces from the mechanical parts as well as soot and fuel traces from the leakages unavoidably present in the moving parts of the engine. As well known, the oil loses its lubricating characteristics according to the content of the above contaminants. The aim of the present work is therefore to test a new sensors array whose function is to reveal the diesel fuel content in the lubricating oil. The array consists of different gas microsensors based on different metal oxide thin films deposited by sol-gel technique on silicon substrates.

It is well established that the combustion development and the consequent pollutant emissions in a Diesel engine depend on the fuel spray characteristics. Nowadays, many new injection strategies are being tested, in order to improve the diesel combustion efficiency and so to reduce its environmental impact in terms of pollutant emissions and fuel consumption. Many works have proved that NOx, THC, CO and particulate levels emitted from a Diesel engine, as well as specific fuel consumption, depend, for a given engine speed and load, upon the parameters characterizing any particular injection strategy. Despite the extensive experimental activity analyzing the effects of the previous control parameters on the engine emission and fuel consumption levels, very few are the works dealing with the effect of the same parameters on the fuel spray, and in particular on the droplet dimension distribution. The aim of this work is therefore to study these effect.