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Due to the increasingly stringent emissions standards in the world and, on the other hand, the foreseen shortage of fossil fuels, the application of low viscosity engine oils (LVO) is considered one of the most interesting options for counter these threats. In parallel to a fuel consumption fleet test, the aim of this study was to assess the performance of commercial low viscosity oils regarding their degradation and engine wear, since the use of LVO could imply an increase in wear rate. Potential higher engine wear could result in a reduction in the expected engine life cycle, obviously is a non-desired effect. In addition, currently limited data are available regarding “real-world” performance of LVO in a real service fleet.

This paper shows the results of a fuel consumption in-use comparison test where the effect of Low Viscosity Oils (LVO) was evaluated over a sample of 39 urban buses powered by Diesel and CNG engines. The aim of the test was to verify the fuel consumption benefits of LVO in Heavy Duty Vehicles (HDV) found in previous works, which were obtained mainly in engine test bench, when engines are working on “on-Road” conditions. In order to achieve this goal, a sample of 39 urban buses was studied over an Oil Drain Interval or 30.000 km (approximately an 11 month period), measuring daily mileage and fuel consumed to calculate each bus fuel consumption. Mileage was measured by GPS and fuel consumed was measured from refueling system. The sample was divided into two groups; a control group of buses using reference oils (SAE grade viscosities of 15W-40 and 10W-40) and a candidate group using LVO oils (SAE grade viscosities 5W-30).

The goal of this paper is to obtain a simple fast model that provides information about the spray tip penetration (for free and wall jet), droplets velocity distribution and fuel concentration distribution. This model would be an important first step in the construction of a simple model capable to provide online information about the spray behaviour in engine conditions, although for the moment, the model only concerns cold sprays. As this model is based in momentum and mass flux conservation, and the patterns observed in gaseous turbulent jets, its agreement with experimental Diesel results will help to improve understanding of the spray structure in terms of the similarities and differences with a gas jet, as well as of the importance of the spray front structure in its penetration.

The objective of the work presented here is to evaluate the potential of rape oil methyl ester (RME) to improve the combustion process in a high-speed direct injection (HSDI) Diesel engine equipped with high-pressure common-rail injection system. The study, based on the comparison of three different fuels (standard gas-oil, RME and 30% RME/gas-oil mixture), takes into account the main aspects that control Diesel combustion, from the injection rate characteristics to the spray behaviour characterised using an optical pressurised chamber. This global study of the whole injection-combustion process allows identifying some causes of the decrease in pollutant emissions observed when the engine operates with RME.

This paper has the objective of characterising the macro and microscopic behaviour of Diesel sprays generated by a common-rail system and quantifying the influence of injection parameters and boundary conditions through a broad experimental study. The main purpose of this research is to validate and extend the different correlations available in the literature to the case of sprays generated by common-rail systems, i.e. at high injection pressures with small nozzle holes. The sprays are characterised in an environment which simulates the in-cylinder air density existing in the real engine when the injection starts. However, it should be pointed out that isothermal conditions at room temperature are considered and very little evaporation occurs.