Particulate matter emissions from premixed diesel low temperature combustion
- Autores: Christopher Paul Kolodziej
- Directores de la Tesis: Jesús Benajes Calvo (dir. tes.)
- Lectura: En la Universitat Politècnica de València ( España ) en 2012
- Idioma: inglés
- Tribunal Calificador de la Tesis: José María Desantes Fernández (presid.), Raúl Payri Marín (secret.), Andrea Strzelec (voc.), Hongming Xu (voc.), Magín Lapuerta Amigo (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TESEO
- Resumen
Premixed diesel Low Temperature Combustion (LTC) strategies, as defined in this research by peak combustion temperatures below 2200 K, have been developed to simultaneously achieve very low emissions of particulate matter (PM) mass and oxides of nitrogen (NOx). Some studies have identified differences of the exhaust chemical and physical characteristics between engine operating conditions of the premixed diesel LTC and conventional diesel combustion regimes. But better understanding of how these exhaust chemical and physical characteristics change throughout the premixed diesel LTC regime was still needed.
Beyond common opacity-based PM mass measurement techniques, this work has employed instruments to measure the particle size distribution, filter-based PM mass and chemical composition, and select gaseous hydrocarbon (HC) components while sweeping the engine fuel injection timing, intake pressure, and intake oxygen concentration within the premixed diesel LTC regime. After choosing five representative premixed diesel LTC points, and one of premixed diesel non-LTC, with similar levels of opacity-based PM mass emissions (to reduce the effects of changes to the number of the larger particles and their available surface area for volatile material condensation in the exhaust), a highly detailed characterization of the exhaust gaseous and PM emissions was performed with the discussed measurement techniques.
It was observed that key factors to consider for reducing PM mass emissions within the premixed diesel LTC regime included: reduced fuel spray liquid length interaction with the combustion chamber to decrease HC emissions and the potential for particle-forming pool fires, increased fuel and air premixing time before ignition to reduce local fuel richness during combustion, reduced peak flame temperature to decrease particle formation, and increased flame temperature towards the end of the combustion process to increase late-cycle particle oxidation (and of other pollutants). After overcoming liquid fuel impingement effects through increased in-cylinder charge air density during the fuel injection event, it was determined that very low PM mass emissions could be achieved in the premixed diesel LTC regime at relatively early or late fuel injection timings, relatively higher or lower intake oxygen concentrations, and with increases to intake pressure. But between these premixed diesel LTC engine operating conditions with very low PM mass emissions, total particle number concentrations (especially for particles smaller than 50-55 nm) and masses of PM soluble organic fraction and insoluble fraction increased for the later injection timings and lower intake oxygen concentrations.
In general this work shows that, though very low PM mass emissions can be achieved in the premixed diesel LTC regime, changes to in-cylinder combustion can have important effects on the chemical and physical characteristics of the particle emissions.
