Sequino, Luigi (2016) Diagnostiche non convenzionali per l’analisi del processo di iniezione in un motore monocilindrico ad accensione per compressione - Non conventional diagnostics of injection process in single cylinder compression ignition engine. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Lingua: English
Title: Diagnostiche non convenzionali per l’analisi del processo di iniezione in un motore monocilindrico ad accensione per compressione - Non conventional diagnostics of injection process in single cylinder compression ignition engine
Date: 31 March 2016
Number of Pages: 111
Institution: Università degli Studi di Napoli Federico II
Department: Ingegneria Industriale
Scuola di dottorato: Ingegneria industriale
Dottorato: Ingegneria dei sistemi meccanici
Ciclo di dottorato: 28
Coordinatore del Corso di dottorato:
Mancaruso, EzioUNSPECIFIED
Vaglieco, Bianca MariaUNSPECIFIED
Date: 31 March 2016
Number of Pages: 111
Uncontrolled Keywords: Iniezione diesel; Diagnostica ottica infrarossa; Modello iniezione 1d
Settori scientifico-disciplinari del MIUR: Area 09 - Ingegneria industriale e dell'informazione > ING-IND/08 - Macchine a fluido
Date Deposited: 08 Apr 2016 08:55
Last Modified: 31 Oct 2016 11:10


This thesis has been carried out in the Istituto Motori – CNR of Napoli. The mission of the institute is the research on engines and other kinds of propellers for the development of the future transport systems. The main targets of the research activities concern the reduction of pollutant emissions and fuel consumption of modern engines. A variety of experimental and numerical activities are carried out in the institute with the aim to understand the entire functioning chain of internal combustion engines. The research activities of the present doctoral thesis have been run in the optical diagnostics laboratory. In particular, the present work focuses on the analysis of the injection process in a single-cylinder compression ignition engine via direct imaging with high speed cameras. The research engine is derived from a light duty production engine and is fed with commercial Italian diesel fuel. The engine performances have been analyzed in seven operating conditions that are representative of the engine behavior during the homologation cycle New European Driving Cycle (NEDC) when installed on a D-class vehicle. The approach used in this work for the investigation of in-cylinder processes is based on the combination of experimental activities and numerical simulations. A mono-dimensional (1d) model developed by the Sandia National Laboratories to simulate the fuel injection in a control volume combustion vessel has been implemented and adjusted to fit in-cylinder thermodynamic conditions and geometrical limitations. The model has been set up using experimental data collected on the single-cylinder optical engine. The thermodynamic parameters have been collected in conjunction to images of the injection process in the visible range. A sensitivity analysis to the model input values has been made and by comparing the model result to injection images it has been possible to understand the model limitations and potentialities. It has revealed to work well for the simulation of the injection process inside the engine and could provide additional information to the investigated phenomena. For example, the jet/wall interaction has been investigated and the fuel mass impinging on the combustion chamber wall has been correlated to the exhaust emissions of particulate matter (PM). Moreover, the model has been able to provide both the penetrations of the liquid and vapor fuel. Whereas visible imaging of the injection process could provide only images of the fuel liquid phase, it could be very useful to get information about the vapor phase too. The 1d model has revealed to be a valid support for the development of a novel optical technique for the visualization of the vapor fuel using infrared imaging. As aforementioned, visible imaging is able to detect only the fuel liquid phase; for the visualization of the fuel vapor phase there exist several optical techniques characterized by complex set up and high sensitivity to fuel impurities and geometrical limitations. On the contrary, infrared imaging is able to overcome the limitations of the previous diagnostics. For this reason, this technique has been setup and applied for the optical diagnostics in the single-cylinder research engine. The spectral analysis in the range 1.5-5 μm allowed to identify two wavelengths to investigate: at 3.4 μm and at 3.9 μm. The penetration curves obtained from the infrared images have been compared to the ones from visible images and from the model (liquid and vapor penetrations). The two selected wavelength, 3.4 μm and 3.9 μm, demonstrated to be good for the visualization in the infrared of the vapor and liquid phase, respectively. According to these observations, a more accurate analysis of the infrared radiation of the fuel jets and the modeled fuel evaporation rate allowed to understand better the fuel vaporization process. The results reported in this doctoral thesis, the description of the 1d model of fuel injection inside the engine, and the presentation of an innovative optical technique in the infrared for the detection of the fuel vapor phase could contribute to the present scientific context for the development of sustainable transport systems with low environmental impact.

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