The importance of double bond position and cis–trans isomerisation in diesel combustion and emissions

Hellier, Paul; Ladommatos, Nicos; Allan, Robert; Filip, Sorin V.; Rogerson, John

doi:10.1016/j.fuel.2012.08.007

Cited by 27 publications

(36 citation statements)

References 31 publications

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“…An influence of the adiabatic flame temperature on NO x emissions in the combustion of fatty acid esters, which is secondary to that of the duration of ignition delay, has been observed where the ignition delays of esters with various degrees of alkyl chain saturation have been equalised by the use of ignition-improving additives. 36,44 Similar results have been observed when cocombusting CH 4 -H 2 mixtures with pilot diesel fuel in compression ignition engines. Increasing the proportion of hydrogen in the aspirated CH 4 -H 2 mixture increased heat release rates during the premixed burn fraction and reduced the cycle-to-cycle variability.…”

Section: No Xsupporting

confidence: 73%

“…Movement of a single double bond within isomers of octene towards the centre of the alkyl chain was found to result in an increase in PM mass engine exhaust emissions by Hellier et al 44 at all injection timings, and at constant ignition delay timing trans-2-octene was found to produce more nucleation-mode particles (D p \ 50 nm) than 1-octene. This observation is in agreement with the shock tube study of decene isomers by Fridlyand et al 48 who found an increasing yield of benzene (an important precursor to particulate formation) in the speciation of reaction intermediates by gas chromatography with movement of the decene double bond from position 1 to positions 2 and 5.…”

Section: Particulate Mattermentioning

confidence: 88%

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An overview of the effects of fuel molecular structure on the combustion and emissions characteristics of compression ignition engines

Hellier

Talibi

Eveleigh

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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Future fuels for compression ignition engines will be required both to reduce the anthropogenic carbon dioxide emissions from fossil sources and to contribute to the reductions in the exhaust levels of pollutants, such as nitrogen oxides and particulate matter. Via various processes of biological, chemical and physical conversion, feedstocks such as lignocellulosic biomass and photosynthetic micro-organisms will yield a wide variety of potential fuel molecules. Furthermore, modification of the production processes may allow the targeted manufacture of fuels of specific molecular structure. This paper therefore presents an overview of the effects of fuel molecular structure on the combustion and emissions characteristics of compression ignition engines, highlighting in particular the submolecular features common to a variety of potential fuels. An increase in the straight-chain length of the alkyl moiety reduces the duration of ignition delay, and the introduction of double bonds or branching to an alkyl moiety both increase ignition delay. The movement of a double bond towards the centre of an alkyl chain, or the addition of oxygen to a molecule, can both increase and decrease the duration of ignition delay dependent on the overall fuel structure. Nitrogen oxide emissions are primarily influenced by the duration of fuel ignition delay, but in the case of hydrogen and methane pilot-ignited premixed combustion arise only at flame temperatures sufficiently high for thermal production. An increase in aromatic ring number and physical properties such as the fuel boiling point increase particulate matter emissions at constant combustion phasing.

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Section: No Xsupporting

confidence: 73%

Section: Particulate Mattermentioning

confidence: 88%

An overview of the effects of fuel molecular structure on the combustion and emissions characteristics of compression ignition engines

Hellier

Talibi

Eveleigh

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Differences in molecular structure and DBE between paraffins and aromatic hydrocarbons contribute to greater particulate emissions for aromatics. 46,48,49 For example, the DBEs of paraffins is 0, whereas the DBEs of aromatic hydrocarbons, depending on the molecular structure, are approximately 4 to 7. In addition, components with higher boiling points and lower corresponding vapor pressures evaporate more slowly, resulting in a greater tendency for diffusion combustion instead of premixed combustion.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Evaluating the Effects of Aromatics Content in Gasoline on Gaseous and Particulate Matter Emissions from SI-PFI and SIDI Vehicles

Karavalakis

Short

et al. 2015

Environ. Sci. Technol.

101

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We assessed the emissions response of a fleet of seven light-duty gasoline vehicles for gasoline fuel aromatic content while operating over the LA92 driving cycle. The test fleet consisted of model year 2012 vehicles equipped with spark-ignition (SI) and either port fuel injection (PFI) or direct injection (DI) technology. Three gasoline fuels were blended to meet a range of total aromatics targets (15%, 25%, and 35% by volume) while holding other fuel properties relatively constant within specified ranges, and a fourth fuel was formulated to meet a 35% by volume total aromatics target but with a higher octane number. Our results showed statistically significant increases in carbon monoxide, nonmethane hydrocarbon, particulate matter (PM) mass, particle number, and black carbon emissions with increasing aromatics content for all seven vehicles tested. Only one vehicle showed a statistically significant increase in total hydrocarbon emissions. The monoaromatic hydrocarbon species that were evaluated showed increases with increasing aromatic content in the fuel. Changes in fuel composition had no statistically significant effect on the emissions of nitrogen oxides (NOx), formaldehyde, or acetaldehyde. A good correlation was also found between the PM index and PM mass and number emissions for all vehicle/fuel combinations with the total aromatics group being a significant contributor to the total PM index followed by naphthalenes and indenes.

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“…In a test by Hellier, et al., four different isomers of octene (1‐octene, trans ‐2‐octene, trans ‐3‐octene, and cis ‐3‐octene) were engine tested in a single‐cylinder direct‐injection diesel engine, and the ignition delay was found to be (shortest first) 1‐octene< cis ‐3‐octene< trans ‐3‐octene< tran s‐2‐octene. This was explained by the reactivity differences between the alkenes . It should be noted that alkenes also have lower reactivity, longer ignition times, and therefore lower cetane numbers than their saturated alkane counterparts …”

Section: Carbon Effectsmentioning

confidence: 99%

The Effect of Functional Groups in Bio‐Derived Fuel Candidates

et al. 2016

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Interest in developing renewable fuels is continuing to grow and biomass represents a viable source of renewable carbon with which to replace fossil-based components in transportation fuels. During our own work, we noticed that chemists think in terms of functional groups whereas fuel engineers think in terms of physical fuel properties. In this Concept article, we discuss the effect of carbon and oxygen functional groups on potential fuel properties. This serves as a way of informing our own thinking and provides us with a basis with which to design and synthesize molecules from biomass that could provide useful transportation fuels.

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The importance of double bond position and cis–trans isomerisation in diesel combustion and emissions

Cited by 27 publications

References 31 publications

An overview of the effects of fuel molecular structure on the combustion and emissions characteristics of compression ignition engines

An overview of the effects of fuel molecular structure on the combustion and emissions characteristics of compression ignition engines

Evaluating the Effects of Aromatics Content in Gasoline on Gaseous and Particulate Matter Emissions from SI-PFI and SIDI Vehicles

The Effect of Functional Groups in Bio‐Derived Fuel Candidates

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