Gasoline Direct Injection (GDI) engines have been considered to be the key enabler for reducing the CO2 emission from gasoline-powered vehicles. Compared to Port Fuel Injection (PFI) engines, GDI engines realize a higher compression ratio, a lower intake temperature and the absence of throttling which will deliver higher volumetric efficiency and lower fuel consumption. However, due to the reduced time for fuel atomization and the possibility of fuel impingement, GDI engines will inherently generate more Particulate Matter (PM) emissions than PFI engines. Previous research demonstrated that GDI engines typically emit one order of magnitude more PM than PFIs. Therefore, the number-based measurement of PM emissions from GDI engines is essential, for engine researchers and manufacturers to meet the number-based PM regulations in the near future. This thesis undertakes to investigate: a) the effects of the after-treatment (Three-Way Catalyst) and various engine operational parameters, such as injection and ignition timing, injection strategy and valve timing on the PM emissions; b) the characteristics of GDI PM emissions using a range of gasoline/ethanol blends; c) The compositional information for GDI-generated PM emissions, i.e. the PM mass fractions in different volatility ranges. The first objective was achieved by using a Cambustion Ltd Differential Mobility Spectrometer 500 (DMS500) to simultaneously derive the PM size-resolved number concentrations and mass concentrations in the range of 5-1000 nm. The second objective was addressed by using the DMS500 together with other instruments such as a Photron high-speed camera, a Cambustion Ltd fast Flame Ionization Detector (FID). The third objective was realized by using Thermo-Gravimetric Analysis (TGA). These experiments are amongst the first of their kind and may well provide vehicle manufacturers and the fuel industry with useful data for PM control and abatement. Data acquisition (DAQ) systems for two test engines, namely, a V8 GDI engine and a single-cylinder optical access engine, have been developed in LabVIEW to facilitate recording various experimental data at different sampling rates (1Hz to 300 kHz). The DAQ system in the single-cylinder engine is also capable for communicating with the engine controlling system to enable automatic data logging. A controlled automatic dilution system has been developed for taking filter samples in a way that is consistent with emissions legislation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:531964 |
| Date | January 2010 |
| Creators | Chen, Longfei |
| Contributors | Stone, Richard |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:19e8dc75-9873-4b76-831d-3878fd048169 |
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