Measurement of the Flame Lift-Off Location on DI Diesel Sprays Using OH Chemiluminescence

Higgins, Brian; Siebers, Dennis L.

doi:10.4271/2001-01-0918

Cited by 221 publications

(146 citation statements)

References 12 publications

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“…The AHRR curves are similar for all of the fuels. 9 end of the premixed burn (EOPMB) [40]. OH chemiluminescence at 310 nm is a reliable marker of the flame lift-off location because the predominant light emission from the stabilization region of a diesel spray is from this band of OH chemiluminescence.…”

Section: Diagnosticsmentioning

confidence: 99%

An Experimental Investigation of the Origin of Increased NO_xEmissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel

Mueller¹,

Boehman²,

Martin³

2009

SAE Int. J. Fuels Lubr.

323

233

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The Engineering Meetings Board has approved this paper for publication. It has successfully completed SAE's peer review process under the supervision of the session organizer. This process requires a minimum of three (3) reviews by industry experts. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. ISSN 0148-7191 Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. SAE ABSTRACTIt is generally accepted that emissions of nitrogen oxides (NO x ) increase as the volume fraction of biodiesel increases in blends with conventional diesel fuel. While many mechanisms based on biodiesel effects on incylinder processes have been proposed to explain this observation, a clear understanding of the relative importance of each has remained elusive.To gain further insight into the cause(s) of the biodiesel NO x increase, experiments were conducted in a singlecylinder version of a heavy-duty diesel engine with extensive optical access to the combustion chamber. The engine was operated using two biodiesel fuels and two hydrocarbon reference fuels, over a wide range of loads, and using undiluted air as well as air diluted with simulated exhaust gas recirculation. Measurements were made of cylinder pressure, spatially integrated natural luminosity (a measure of radiative heat transfer), engine-out emissions of NO x and smoke, flame lift-off length, actual start of injection, ignition delay, and efficiency. Adiabatic flame temperatures for the test fuels and a surrogate #2 diesel fuel also were computed at representative diesel-engine conditions.Results suggest that the biodiesel NO x increase is not quantitatively determined by a change in a single fuel property, but rather is the result of a number of coupled mechanisms whose effects may tend to reinforce or cancel one another under different conditions, depending on specific combustion and fuel characteristics. Nevertheless, charge-gas mixtures that are closer to stoichiometric at ignition and in the standing premixed autoignition zone near the flame liftoff length appear to be key factors in helping to explain the biodiesel NO x increase under all conditions. These differences are expected to lead to higher local and average in-cylinder temperatures, lower radiative heat losses, and a shorter, more-advanced combustion event, all of which would be expected to increase thermal NO x emissions. Differences in prompt NO formation and species concentrations resulting from fuel and jet-structure changes also may play important roles.

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Section: Diagnosticsmentioning

confidence: 99%

An Experimental Investigation of the Origin of Increased NO_xEmissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel

Mueller¹,

Boehman²,

Martin³

2009

SAE Int. J. Fuels Lubr.

323

233

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“…OH* is a good indicator for actual combustion activity [62] and can be measured by two dimensional OH* chemiluminescence. The UV light emitted by the OH radical in the reaction zones of the flame is reflected and separated by the dichroic mirror and filtered with a narrow band bass filter (313 nm).…”

Section: Optical Methodsmentioning

confidence: 99%

Spray Combustion Analysis of Humins

Feijen¹,

Klink

Jong

et al. 2017

SAE Technical Paper Series

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Second generation biomass is an attractive renewable feedstock for transport fuels. Its sulfur content is generally negligible and the carbon cycle is reduced from millions to tens of years. One hitherto non-valorized feedstock are so-called humins, a residual product formed in the conversion of sugars to platform chemicals, such as hydroxymethylfurfural and methoxymethylfurfural, intermediates in the production of FDCA, a building block used to produce the polyethylene furanoate (PEF) bottle by Avantium.The focus of this study is to investigate the spray combustion behavior of humins as a renewable alternative for heavy fuel oil (HFO) under large two-stroke engine-like conditions in an optically accessible constant volume chamber. To reduce the viscosity to HFO levels of the otherwise crystalline humins, methyl levulinate (ML), another side-stream from the same sugar dehydration process, is blended to the former compound at 25 wt.-%; a ratio comparable to that actually produced in many dehydration processes.Various fuel properties of interest, including elemental composition, heating value, density, ignition quality, acid number, flash point, pour point, carbon residue, sediment, water and ash content are measured for the resulting humins-ML blend.The blend is injected into an optically accessible constant volume chamber, the dimensions, injector characteristics and prevailing ambient conditions of which are representative of those found in large two-stroke marine engines. Commercial HFO is used as a benchmark.The combustion process is evaluated by means of shadow imaging and OH*-chemiluminescence. The former and latter optical techniques are used to determine the phasing and overall magnitude of the heat release event, and ignition delay/location and flame lift off length, respectively.From the results becomes clear that the average ignition delay is comparable to that of HFO, albeit at a higher cycle-to-cycle variation. Notwithstanding a longer lift off length and more downstream ignition kernels, the overall results suggest that the proposed bioblend is a feasible renewable alternative for HFO in terms of technical feasibility.

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“…Although OH chemiluminescence is the dominant source of UV emission near 310 nm [7,23], other sources of interference can be significant, especially visible light that is scattered off the liquid fuel spray [8,13]. To remove this scattering interference, a second camera was used to acquire a simultaneous image of long-wavelength light emitted by the flame.…”

Section: Diagnosticsmentioning

confidence: 99%

“…The fast, high temperature reactions occurring in the lifted, stoichiometric diesel diffusion flame have been shown to produce significant quantities of excited state OH (OH*) [7]. Accordingly, the presence of chemiluminescence emission from OH* is an indicator of the location of the diffusion flame.…”

Section: Introductionmentioning

confidence: 99%

“…Accordingly, the presence of chemiluminescence emission from OH* is an indicator of the location of the diffusion flame. To measure the flame lift-off length, a technique used by Siebers and Higgins [2,7] to image OH* chemiluminescence from the reacting diesel fuel jets has been adapted and used in the facility of the current study [8]. The flame lift-off length was determined through analysis of the diffusion flame images using an intensity thresholding technique, with a mask to remove interference from liquid fuel scattering [8].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of diesel fuel combustion-modifier additives on In-cylinder soot formation in a heavy-duty Dl diesel engine.

Musculus

Dietz²

2005

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Based on a phenomenological model of diesel combustion and pollutant-formation processes, a number of fuel additives that could potentially reduce in-cylinder soot formation by altering combustion chemistry have been identified. These fuel additives, or "combustion modifiers," included ethanol and ethylene glycol dimethyl ether, polyethylene glycol dinitrate (a cetane improver), succinimide (a dispersant), as well as nitromethane and another nitro-compound mixture. To better understand the chemical and physical mechanisms by which these combustion modifiers may affect soot formation in diesel engines, in-cylinder soot and diffusion flame lift-off were measured, using an optically-accessible, heavy-duty, direct-injection diesel engine.A line-of-sight laser extinction diagnostic was employed to measure the relative soot concentration within the diesel jets ("jetsoot") as well as the rates of deposition of soot on the piston bowl-rim ("wall-soot"). An OH chemiluminescence imaging technique was utilized to measure the lift-off lengths of the diesel diffusion flames so that fresh oxygen entrainment rates could be compared among the fuels. Measurements were obtained at two operating conditions, using blends of a base commercial diesel fuel with various combinations of the fuel additives.The ethanol additive, at 10 % by mass, reduced jet-soot by up to 15%, and reduced wall-soot by 30-40%. The other fuel additives also affected in-cylinder soot, but unlike the ethanol blends, changes in in-cylinder soot could be attributed solely to differences in the ignition delay. No statistically-significant differences in the diesel flame lift-off lengths were observed among any of the fuel additive formulations at the operating conditions examined in this study. Accordingly, the observed differences in in-cylinder soot among the fuel formulations cannot be attributed to differences in fresh oxygen entrainment upstream of the soot-formation zones after ignition.

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Measurement of the Flame Lift-Off Location on DI Diesel Sprays Using OH Chemiluminescence

Cited by 221 publications

References 12 publications

An Experimental Investigation of the Origin of Increased NO_xEmissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel

An Experimental Investigation of the Origin of Increased NO_xEmissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel

Spray Combustion Analysis of Humins

Effects of diesel fuel combustion-modifier additives on In-cylinder soot formation in a heavy-duty Dl diesel engine.

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Measurement of the Flame Lift-Off Location on DI Diesel Sprays Using OH Chemiluminescence

Cited by 221 publications

References 12 publications

An Experimental Investigation of the Origin of Increased NOxEmissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel

An Experimental Investigation of the Origin of Increased NOxEmissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel

Spray Combustion Analysis of Humins

Effects of diesel fuel combustion-modifier additives on In-cylinder soot formation in a heavy-duty Dl diesel engine.

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Product

Resources

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An Experimental Investigation of the Origin of Increased NO_xEmissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel

An Experimental Investigation of the Origin of Increased NO_xEmissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel