Investigations of advanced injection and combustion strategies on DI diesel engine performance and emissions

Mobasheri, Raouf (2012) Investigations of advanced injection and combustion strategies on DI diesel engine performance and emissions. Doctoral thesis (PhD), University of Sussex.

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The main driving force behind this research was the need for cleaner and more
efficient engines to meet the ever-increasing demands on the modern automobile’s
emissions. In recent years different studies have been carried out to analyze the
combined effects of high-pressure injection, boost pressure, multiple injections,
included spray angle and combustion chamber geometry. Though considerable research
has shown these technologies can meet the low emission regulations, the careful
optimization of the engine operating conditions is still required in order to get the full
benefit of the different strategies. With these issues as motivation, the first important
objective of this study was to gain a detailed understanding of the mechanisms through
which fuel injection interacts with other engine parameters and influences diesel
combustion and emissions, and hence to attempt to generalize the adoption of multiple
injection strategies with regards to improving diesel engine performance. For this
purpose, a modified parameter called “Homogeneity Factor of in-cylinder charge” (HF)
was introduced and proposed as a new measure in combustion theory to analyze the
combustion characteristics and air-fuel mixing process of diesel engines in more detail.
The second part of this research builds upon a detail investigation on the included spray
cone angle concept and explores further their use in conjunction with multiple-injection
strategies in diesel engines. In addition, an investigation was performed in third phase of
this research to analyze the effects of piston geometry on combustion, performance and
exhaust emission characteristics. The results showed that employing a post-injection
combined with a pilot injection results in reduced soot formation from diffusion
combustion and enhances the soot oxidation process during the expansion stroke,
resulting in decreased soot emissions, while the NOx concentration is maintained in low
levels. It was also found that spray targeting is very effective for controlling the
in-cylinder mixture distributions especially when it accompanied with advanced
injection strategies. Moreover, the results confirmed that a narrower width of piston
bowl has a higher unburned fuel air mixture region and hence results in higher soot
emissions but with slightly larger piston surface area the optimum operating point could
be obtained

Item Type: Thesis (Doctoral)
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ0751 Miscellaneous motors and engines Including gas, gasoline, diesel engines
Depositing User: Library Cataloguing
Date Deposited: 05 Dec 2012 13:05
Last Modified: 08 Sep 2015 13:24

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