Thesis-2007-Williams.pdf (27.61 MB)
Autoselective regeneration of gelcast ceramic foam
thesis
posted on 2013-06-17, 12:42 authored by Andrew M. WilliamsThis thesis describes the development and application of an electric discharge for
regenerating gelcast ceramic foam diesel particulate filters (DPF) for effective and
efficient reduction of particulate matter (PM) emissions from diesel fuelled IC
engines.
The combustion in diesel compression ignition engines generates a number of
unwanted by-products including PM. The PM from diesel engines is believed to be
potentially carcinogenic when inhaled into the lungs and, therefore, needs to be
controlled. Emission legislation has made it increasingly difficult for engineers to
reduce PM emissions whilst meeting NOx targets by combustion optimisation alone,
leading to the requirement for exhaust gas aftertreatment, most notably exhaust gas
filtration. Filtration and regeneration (filter cleaning) technology must be robust, filter
high amounts of PM, be compact, energy efficient and cost effective. A large number
of published solutions do not meet all of these criteria. This research has developed a
compact, efficient, robust and cost effective solution: The Autoselective regeneration
of gelcast ceramic foam DPFs.
Gelcast ceramic foam geometry can be optimised on a microscopic and macroscopic
scale with a large number of material characteristics. This thesis develops and applies
new methodology for rapid optimisation of gelcast ceramic foam DPFs. The optimum
foam geometry is found to be highly application-dependent. Filters with >95%
filtration efficiency and a low filtration volume have been demonstrated, although are
limited in their PM mass holding capacity. It was found that filters with higher PM
mass holding capacity require larger pore sizes and filtration volume. Design maps
were produced to allow rapid optimisation of gel cast ceramic foams with a novel
methodology that can be applied to all forms of deep bed filtration, saving both time
and cost in future filter development.
Investigation and optimisation of Autoselective regeneration demonstrated that the
regeneration system is most effective when the electric discharge is active within the
filter volume. Using modelling and novel methods for measuring heat flux from
electrical discharges, thermal optimisation of the heat flows in the system were
achieved. Rig tests increased the robustness of the regeneration system and developed
profiled mesh electrodes to maximise the effective regeneration volume. An engine
test programme demonstrated regeneration effectiveness of -12 g kW·1 h-I which is
equivalent to -333 W for a typical 56 kW heavy duty diesel engine. Alternatives such
as fuel burners and electrical resistance heaters typically consume between I and
5 kW of fuel energy for filter regeneration. Multiple electrode prototypes are
presented and evaluated for efficient and effective on-engine and on-vehicle PM
control.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Publisher
© A. M. WilliamsPublication date
2007Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.574190Language
- en