Advanced characterisation of deposits in diesel fuel filters
Publication Date
July 21, 2023
Creator
Abstract
The fuel filtration system is an integral part of the internal combustion engine. With the ever more stringent emission limits and desire for performance from vehicles, resultant changes to the FIE have meant that they are less tolerant of contaminant particulates and deposit build up. The fuel filter is situated between the fuel tank and the FIE and is used to remove as much of the contaminant as possible to minimise damage to the FIE.
As with FIE, blocking of the fuel filters can lead to reduction in performance, increase in emissions, increase in fuel contamination seen by the FIE, and in extreme cases, engine malfunction. In order to mitigate deposit build up, additives such as DCA are commonly employed, but first an understanding of the deposit is necessary in order to design effective additives.
SEM-EDX, XPS and SIMS have played a vital part in identifying a variety of different deposits that can be present on fuel filters from laboratory and engine test rigs as well as fuel filters from the field. Tandem MSMS has also been employed to unambiguously identify some of the chemical species. Depth profiling of the deposit is now commonly used to describe the deposit on FIE, and in this thesis we will employ similar techniques to describe the layering of deposits in diesel fuel filters for the first time.
As the data from SIMS can be large, a purpose-built script “compound\_finder” was design to be able to assign possible formula to large amounts of SIMS peaks. The user can change a variety of settings including elements and isotopes to consider, deviation and intensity limits to customise their search.
As the fuel saturated filters were all analysed in-situ, this thesis characterised common SIMS peaks that are present in dual phase melt blown fibres to enable the differentiation between deposit and filtration media. The compound_finder script was used to assign a series of PAH ions which saturated the reference filter spectra.
A custom multi-pass filtration rig was designed to test the effects of different combinations of FAME, HVO and petroleum diesel on filters. The initial flow rates of the seven combination of fuels ranged from 55 to 110 L/h. Whilst all fuel combinations reduced in flowrate after 40 hours of running, after 27 hours a B100 fuel blend blocked the filter. Using 3D OrbiSIMS, it was possible to unambiguously assign the presence of sterol glucoside in the deposit to less than 0.1 ppm deviation.
Eight filters from different DW10 engine tests using combinations of DCA, corrosion inhibitor and detergents alongside different sodium sources were analysed. SEM-EDX revealed that the morphology of the deposits varied between filters from particle like features trapped in the filter pores to film like layers covering the fibres. 3D OrbiSIMS data showed the presence of dodecyl succinic sodium salts in filters that had a film like layer. Depth profiles of the deposit were explored for the first time and showed the presence of multiple layers in the film like deposit. The first layer which generally appeared to reduce in intensity within 100 s of sputtering contained sodium chloride, organonitrogen and sodium carbonate species, although the latter was seen in the bulk deposit in other filters. The second layer, the bulk of the deposit contained sodium salts and carbonates, as well as other acid species. In some of the engine test filters that did not have a layer like film, alkylbenzene sulfonate (ABS) ions were present on the surface of the filters.
Three field filters from different geographical locations were analysed. The deposit morphology and chemistry varied between them with the presence of inorganic film like deposit in between the fibres as well as complex organic structures and iron oxide particles. As with the engine test filters, depth profiling of the deposit on these field filters was applied for the first time to show multiple layers. A large contingent of the SIMS data of a European and North American filters can be attributed to the presence of calcium associated ions found in the bulk of the deposit. The North American filter also showed a presence of sodium associated salts and carbonates on the surface and in the bulk of the deposit. In both the European and North American filters, the surface and initial part of the bulk deposit had a presence of ABS. In a filter from the Asian region, iron oxide particles were seen alongside the presence of a polyisobutylene succinimide fragmentation ion series.
Item Type
ethesis
Thesis Type
EngD
Supervisors
Subjects (LC)
Associated Schools / Departments
Department of Chemical and Environmental Engineering (UK)
eprints ID
69814
UoN Repository URI
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Examined. Thesis after corrections from viva
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