Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.789944
Title: Co-combustion of diesel and gaseous fuels with exhaust emissions analysis and in-cylinder gas sampling
Author: Talibi, M.
ISNI:       0000 0004 8502 5652
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2015
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Abstract:
The development of novel strategies for improved efficiency and 'cleaner' emissions from internal combustion engines requires new insights into the processes of energy release and in-cylinder species formation from future sustainable fuels. This work presents an experimental investigation carried out on a compression-ignition engine to study the co-combustion of diesel fuel with various gaseous fuels, including hydrogen, methane-hydrogen mixtures, biogas and biogas-hydrogen mixtures. In addition, a novel in-cylinder gas sampling and analysis system, developed during the project, was used to extract samples from the engine cylinder during combustion of these gaseous fuels at various stages of the engine cycle, with two sampling location arrangements relative to the diesel fuel spray. Furthermore, the co-combustion of hydrogen and diesel fuel was investigated with the engine intake air boosted and simulated EGR applied. It was found that exhaust NOx emissions were minimal at low engine loads when in-cylinder gaseous fuel-air stoichiometry was quite lean, but increased rapidly when the combined temperatures from gaseous fuel and diesel fuel co-combustion exceeded the threshold of NOx formation temperatures. The eventual level of exhaust particulate mass emissions was observed to be dependent on two competing factors; the aspirated gaseous fuel reduced the intake oxygen concentration resulting in increased soot formation rate, while thermal soot oxidation rates increased due to higher gaseous fuel combustion temperatures. During the early stages of combustion (10 CAD ATDC), the in-cylinder NOx concentration was observed to be higher in the region between two sprays, relative to that within the spray core. This is attributable to a higher proportion of the aspirated gaseous fuel mixture being located between two sprays, resulting in higher gas temperatures from combustion, and hence elevated NOx formation rates. In the later stages of combustion there was much less distinction in the concentration of species between the two sampling locations.
Supervisor: Balachandran, R. ; Ladommatos, N. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.789944  DOI: Not available
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