Nowadays, diesel fueled compresson ignition engines are widely used in heavy-duty transportation vehicles such as trucks, buses, tractors, construction equipment, and diesel generators because of their many advantages including higher thermal efficiency, fuel economy, and power characteristics compared to spark ignition gasoline engines (SI). Futhermore the precise scale of oil reserves left and the ultimate availability of fossil fuels worldwide are hard to determine and therefore depletion of fuel reserves and energy saving are important global concerns in all industrial fields. With increasing concerns about environmental protection and exhaustion of energy resources, studies for reducing exhaust emissions from automotive vehicles and improving the thermal efficiency of combustion engines have become an important area of research for the internal combustion engine. Dimethyl ether (DME) is an organic compound that can be produced using indirect or direct synthetic methods and is an interesting alternative to Diesel for many reasons. In this study, an improved thermal efficiency and a reduction of pollutant emissions have been observed in the present work. Moreover the properties of this fuel makes it an optimal solution to be used as cleaner fuel for Internal Combustion Engines (ICEs). The work presented in this thesis consists in studying the capabilities of the DME in different types of conditions in terms of workload, geometry and type of combustion. The properties of DME combustions in different engine configurations will be analyzed: Sandia optical research engine, three different bowl geometries of a Cummins N-series direct-injection (DI) extensively modified for optical access, and an heavy-duty FPT engine. In the mentioned cases, DME will be compared against Diesel and with experimental data to validate the numerical setup. The investigation can be split in into two main parts: at first, fuel properties and engine system will be compared with Diesel ones, then the combustion process in a compression ignition engine will be investigated.
Al giorno d'oggi, il motore Diesel ad accensione per compressione è ampiamente utilizzato nei mezzi pesanti come camion, autobus, trattori, macchine edili e generatori per via dei suoi numerosi vantaggi tra cui una maggiore efficienza termica, risparmio di carburante e caratteristiche migliori in termini di potenza rispetto a motori ad accensione comandata (SI). Purtroppo, l'entità precisa delle riserve di petrolio rimaste e la disponibilità finale di combustibili fossili in tutto il mondo sono difficili da determinare e quindi l'esaurimento delle riserve di carburante ed il risparmio energetico sono divenuti dei concetti molto importanti a livello globale in tutti i settori industriali. Con le crescenti preoccupazioni per la salvaguardia dell'ambiente e l'esaurimento di tali risorse energetiche, sono divenuti fondamentali studi di ricerca per la riduzione delle emissioni inquinanti ed il miglioramento dell'efficienza termica. Il DME è un composto organico che può essere prodotto con metodi sintetici indiretti o diretti ed è un'interessante alternativa al Diesel per molte ragioni. Migliore efficienza termica e riduzione delle emissioni inquinanti rispetto al Diesel, come dimostrato in questo studio. Il lavoro presentato in questa tesi consiste nello studio delle capacità del DME in diversi tipi di condizioni in termini di carico di lavoro, geometria e tipo di combustione. Verranno, infatti, analizzate le proprietà della combustione del DME in tre diversi studi: Motore Ottico Sandia, Motore con variazione del diametro della tazza e Motore FPT. In tutti questi casi verrà studiato il DME in modo da confrontarlo con il Diesel e con i dati sperimentali per poter validare prima di tutto il setup numerico. L'indagine di questo elaborato può essere suddivisa in due parti principali: in primo luogo lo studio delle proprietà fisiche e chimiche, la progettazione del sistema di iniezione ed i vari tool usati per i vari setup delle simulazioni; infine la seconda parte sarà dedicata ai risultati delle simulazioni relative al processo di combustione DME con l'utilizzo di simulazioni CFD tridimensionali.
Multi-dimensional numerical investigation of the combustion process for DME powered CI engines
COSTANZO, PIERANGELO
2020/2021
Abstract
Nowadays, diesel fueled compresson ignition engines are widely used in heavy-duty transportation vehicles such as trucks, buses, tractors, construction equipment, and diesel generators because of their many advantages including higher thermal efficiency, fuel economy, and power characteristics compared to spark ignition gasoline engines (SI). Futhermore the precise scale of oil reserves left and the ultimate availability of fossil fuels worldwide are hard to determine and therefore depletion of fuel reserves and energy saving are important global concerns in all industrial fields. With increasing concerns about environmental protection and exhaustion of energy resources, studies for reducing exhaust emissions from automotive vehicles and improving the thermal efficiency of combustion engines have become an important area of research for the internal combustion engine. Dimethyl ether (DME) is an organic compound that can be produced using indirect or direct synthetic methods and is an interesting alternative to Diesel for many reasons. In this study, an improved thermal efficiency and a reduction of pollutant emissions have been observed in the present work. Moreover the properties of this fuel makes it an optimal solution to be used as cleaner fuel for Internal Combustion Engines (ICEs). The work presented in this thesis consists in studying the capabilities of the DME in different types of conditions in terms of workload, geometry and type of combustion. The properties of DME combustions in different engine configurations will be analyzed: Sandia optical research engine, three different bowl geometries of a Cummins N-series direct-injection (DI) extensively modified for optical access, and an heavy-duty FPT engine. In the mentioned cases, DME will be compared against Diesel and with experimental data to validate the numerical setup. The investigation can be split in into two main parts: at first, fuel properties and engine system will be compared with Diesel ones, then the combustion process in a compression ignition engine will be investigated.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/181964