Search Results

In the last ten year the mechanical power output of car engine increased significantly. This result has been possible especially through new injection systems that brought to an optimization of the combustion (direct injection, common rail) and to an improvement of the turbocharging. Moreover, these technical devices brought a reduction of the exhaust emissions and an increasing of the engine efficiency. In particular, the specific power is increased from 34 kW/liter of 1992 to the 63 kW/liter of 2010. Furthermore, the pressure peaks into the combustion chamber and the fuel injection pressure have been increased to the aim of emission reduction and higher engine efficiency. In this scenario, car manufacturers are following the direction of the engine downsizing that means to have the same engine power by a lower engine displacement.

The aim of this study is to investigate the effect of ethanol-gasoline mixtures on cold emissive behavior of commercial motorcycles. For the newly sold motorcycles, equipped with a three-way catalyst and electronic mixture control, CO and HC cold additional emissions, if compared with those exhausted in hot conditions, represent an important proportion of total emissions. On the other hand, ethanol is known as potential alcohol alternative fuel for spark ignition engines, which can be blended with gasoline to increase oxygen content and then to decrease emissions. From this explanations, a research on cold start emissions of motorcycles using ethanol-gasoline mixtures was conducted.

Nowadays, due to catalyst improvements and electronic mixture control of last generation vehicles equipped with internal combustion engine, the most significant part of the total emissions of carbon monoxide and unburned hydrocarbons takes place during the cold phase, if compared with those exhausted in hot conditions, with a clear consequence on air quality of urban contexts. The purpose of this research, developed by the Department of Industrial Engineering of the University of Naples Federico II with reference to an European background, is a deeper analysis of the engine and after-treatment system behaviour within the cold start transient and the evaluation of cold start additional emissions: a methodology was developed and optimized to evaluate the cold transient duration, the emitted quantities during the cold phase and the relevant time-dependence function.

In recent years, in order to optimize performance and exhaust emissions of internal combustion engines, the design of auxiliary systems assumed a particular importance especially due to the need to obtain higher efficiency and reduce power losses required by these components. In this sense, looking at the lubrication circuit, it appears important to use solutions that allow to optimize the fluid dynamics of both the ducts and the pump. In this paper a tridimensional CFD analysis of a lubrication circuit oil pump of a modern high-performance engine will be shown. In this particular application there is a variable displacement pump used to optimize the operative conditions of the lubricant circuit in all engine running conditions. This variable displacement pump changes the positions of the ring as a function of the boundary conditions.