Iannuzzi, Stefano Emanuele (2016) Oxygenated Fuels to Reduce Exhaust Emissions from Diesel Engines. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Lingua: English
Title: Oxygenated Fuels to Reduce Exhaust Emissions from Diesel Engines
Iannuzzi, Stefano Emanueles.iannuzzi81@gmail.com
Date: 29 March 2016
Number of Pages: 129
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:
Bozza, Fabiofabio.bozza@unina.it
Date: 29 March 2016
Number of Pages: 129
Uncontrolled Keywords: Oxygenated fuels
Settori scientifico-disciplinari del MIUR: Area 09 - Ingegneria industriale e dell'informazione > ING-IND/08 - Macchine a fluido
Date Deposited: 08 Apr 2016 08:54
Last Modified: 31 Oct 2016 11:08
URI: http://www.fedoa.unina.it/id/eprint/10792


The present dissertation aims at bringing a further scientific contribution to the knowledge on oxygenated fuels properties and their ability of reducing mainly soot emissions in diesel engine combustion. The activity comprises two different phases. The first phase has been conducted at Istituto Motori, Italian National Research Council in Naples and focused on comparing performance and engine out emissions from conventional diesel and alternative fuels. The second part of this study has been, instead, carried on at the Aerothermochemistry and Combustion Systems Laboratory, ETH Zurich, Switzerland. Different oxygenated fuels have been investigated in a constant volume chamber with large optical access. In particular Poly(oxymethylene) dimethyl ethers (POMDME) with a CH3-O-(CH2-O)n-CH3 general molecular structure have been studied both in the constant volume chamber and a single cylinder “heavy duty” diesel engine. The use of oxygenated fuels or biodiesel from renewable sources in diesel engines is of particular interest because of the low environmental impact that can be achieved. The experimental investigation performed at Istituto Motori has provided results from a light duty diesel engine fueled with biodiesel, gasoline and butanol mixed, at different volume fractions, with mineral diesel. The investigation has been performed on a turbocharged DI four cylinder diesel engine for automotive applications equipped with a common rail injection system. Engine tests have been carried out at 2500 rpm, 0.8 MPa of brake mean effective pressure selecting a single injection strategy and performing a parametric analysis on the effect of combustion phasing and oxygen concentration at intake on engine performance and exhaust emissions. The experiments demonstrated that the fuel properties have a strong impact on soot emissions. Blends composed of diesel-gasoline or diesel-butanol determined the maximum reduction in smoke emissions compared to the diesel fuel. No significant difference for NOx emissions was found between the investigated fuels highlighting that oxygen availability within the fuel may not produce an increase in NOX formation under late premixed combustion. Moreover, oxygenated fuels produced from methane-based products have been investigated at the ETH, Zurich. The different oxygenated fuels were investigated in a constant volume chamber with large optical accesses. In order to study the combustion evolution and soot formation and oxidation processes, optical techniques such as OH chemiluminescence and two dimensional two colour pyrometry (2D2CP) have been applied. Moreover, a fast particle spectrometer has been used at the chamber exhaust in order to analyse the soot emissions from the different investigated fuels. The investigation included the calculation of the kL factor, demonstrating a reduction of the soot formation dominated phase when increasing the oxygenated fraction in the blend. Moreover, fuel jet images show a reduction of the soot formation area when increasing the oxygen content in the blend. The activity even focused on the analysis of soot emissions acquired by means of the fast particle spectrometer and results highlighted nearly smokeless combustion for pure oxygenated fuels and a non-linear soot emission reduction with increasing O2 content in the blend. In order to achieve a complete overview of the impact of oxygenated fuels on engine performance and exhaust emissions, a second investigation on a single cylinder “heavy duty” direct injection diesel engine has been performed. The comparison between the POMDME-diesel blends and conventional diesel has shown a significant reduction in soot emissions, up to almost 35% reduction with the 10% POMDME in diesel blend. Moreover no significant increase in NOx emissions was found when fueling the engine with the blends, highlighting as molecular oxygen is not crucial (at least in the percentages investigated in the present dissertation) for NOX increase even in a premixed plus diffusive combustion mode. The first introductory chapter of this thesis contains an overview of the problems connected to exhaust emissions from diesel engines, describes the most promising in-cylinder emission reduction techniques and illustrates the after-treatment systems that are nowadays necessary to fulfill the increasingly stricter emission regulations. The second chapter, instead, focuses on the different adopted experimental set-up and describes the applied optical techniques while results of the different activities are presented in chapter three. Finally, conclusion and outlook are reported in chapter four.

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