Environmental legislation has pressured fuel and automotive industries to alter their technologies for compliance. Changes made to a fuel to achieve compliance can push specific fuel qualities, such as lubricity, to a level away from that required by the automotive engine, creating a fuel/engine requirement gap. Use of fuel additives offer an economical route to bridge the gap, however, their effects on stages of the diesel combustion process is not yet fully understood owing to measurement difficulty. Greater understanding of additive effects requires precision control of operational test conditions with the ability to apply high fidelity measurement techniques. To enable this a high pressure, high temperature optical facility was developed which allows for the acquisition of large data-sets of spray parameters for a more accurate study of the effect fuel additives have on the diesel combustion process. For facility commissioning, tests on diesel fuel sprays into elevated pressure and temperature environments were carried out, with data obtained from high speed backlight illuminated imaging. Macroscopic spray measurements such as penetration length and spreading areas of the sprays were performed, so that effects of ambient pressure and temperature on these parameters could be identified and discussed. From the tests, injector opening times were a main cause of variability in the observed characteristics which were taken into account in the study. Following commissioning, a systematic study was carried out using combustion improving and detergent additives for the first time, where low and high concentrations were tested. Similar behaviours in penetration lengths for each of the additives tested were seen, however no statistical confidence could be applied to the observation as the penetration lengths of the additised fuels for the tested back pressures, since these values did not shift from the base fuels' measured data by a magnitude greater than the experimental error. Penetrating spray area data variance was large, and changes due to additives were unidentifiable. To further clarify, laser droplet sizing was employed at atmospheric conditions to identify whether additives cause changes in microscopic measurements of the spray. The tests showed no change in the droplets' Sauter Mean Diameters (SMD) were observed due to additives. The study carried out clearly indicates that the additives added in the tested concentrations did not change the statistically determined transient parameters of diesel sprays.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:626246 |
| Date | January 2013 |
| Creators | Patel, P. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1398386/ |
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