A methodology has been developed by the authors, in which non-intrusive measurements (engine block vibration) are used for diagnostic purposes of combustion process in Diesel engines. A previous paper of the authors has been devoted to demonstrate the direct relationship between in-cylinder pressure and accelerometer signals, when the vibration transducer is placed in sensitive location. Moreover, in the engine block vibration a frequency band in which such a relationship is very strong has been selected. The aim of this work is to provide a deeper insight into the effects of injection parameters on engine block vibration, in order to investigate the possibility of detecting modification of the in-cylinder pressure evolution by means of the accelerometer signal with the final objective of optimizing the combustion process by means of non-intrusive transducer. In the paper, the experimental apparatus is at first described; then, the processing technique is presented and results are reported and discussed concerning different settings of injection parameters and different values of engine speed and load

The purpose of this paper is to conduct an experimental research on the impact of mixing ratio of biodiesel from waste cooking oil and an innovative diesel fuel (in which a renewable component is contained) on the emissions of an up-to-date light and compact small engine that has a leading role in city cars and urban vehicles. Two blends' mixing ratios (20% and 40% by volume) were tested and the results were compared to those obtained when the engine was operated with low sulfur diesel (ULSD) and ULSD blended with 15% by volume of renewable diesel. The results indicate that diesel+ enhances CO and HC emissions in the exhaust as regards ULSD. Blending diesel+ with WCO causes a further reduction for most of the engine operative field. Concerning particulate emission, accumulation mode dominates for all fuels. Diesel+ is always characterized by lower mean diameters as regards ULSD. The addition of WCO further reduces the court mean diameter. Particle number concentration obtained by fuelling the engine with B40 is the lowest as regards all the other tested fuels. Concerning NO , a moderate increase of the emission was observed when fuelling the engine with diesel+, net or in blends.

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This article presents a diagnostic technique in which nonintrusive measurements are used with the aim of indirect characterization of the combustion process of an internal combustion diesel engine. The developed technique is based on the vibration signal coming from a mono-axial accelerometer placed in a selected location of the engine block. Such a location is able to guarantee high sensitivity to vibration caused by forces directly linked to the combustion process and low sensitivity to all the other excitation sources. The technique is applied to the signals acquired during two series of experimental tests, carried out on the same kind of engine (multi-cylinder diesel engine, equipped with common rail injection system), in two separate engine test facilities in order to test the engine stand-alone and the engine dressed up with the integrated automatic transmission, aimed at reproducing its real operation condition (it is mainly employed in mini-car sector application). The obtained results suggest the potential applicability of the technique both in the laboratory, during the tuning between the injection parameter settings and the engine, and in the regular running condition of the engine for combustion process diagnosis.

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The employment of biofuels in blends with diesel oil proved to attain a reduced environmental impact without compromising the engine performance. Among biofuels, waste cooking oil offers the advantages of its reduced raw material cost in comparison with fresh vegetable oil cost; it also eliminates the environmental impacts caused by its disposal. Although a great number of researches has been devoted to biodiesel combustion in engines and pollutant emissions, few studies can be found on light duty diesel engine equipped with up-to-date technologies. This work aims at investigating the impact of waste cooking oil percentage in blends with diesel oil on the performance and emission characteristics of an up-to-date light and compact common rail diesel engine whose main application is in microcars and in urban vehicles. A comprehensive experimental activity was performed in the engine complete operative field. The comparison of the results with those obtained with standard ultralow-sulfur diesel highlighted that the engine performance was quite similar for B20 and diesel oil. B40 suffered for the lower caloric value in regard to diesel. A reduction in CO and HC was obtained with biodiesel blends, along with an increase in NO x . Particulate emissions were also reduced for biodiesel blends; the mean size of particles was smaller as regards diesel oil.