The Effect of Fuel-Vapor Concentration on the Process of Initial Combustion and Soot Formation in a DI Diesel Engine Using LII and LIEF

Choi, Dae; Iwamuro, Makoto; Shima, Yuta; Senda, Jiro; Fujimoto, Hajime

doi:10.4271/2001-01-1255

Cited by 14 publications

(4 citation statements)

References 32 publications

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“…Combinations of pulsed LII measurements with simultaneously performed laser diagnostics have been reported to investigate the interaction of fuel concentration and flows and to gain additional information about the soot field. The correlation of soot-volume fraction and mixture formation has been investigated with combined measurements of soot by pulsed LII and fuel concentration via laser-induced exciplex fluorescence imaging [446,447]. The influence of bulk-flow structures on soot formation has been investigated by combined pulsed LII and PIV (particle-image velocimetry) measurements in a swirl-supported, directinjection Diesel engine [448,449].…”

Section: Quantitative Imaging Of Soot-volume Fractionmentioning

confidence: 99%

Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications

Michelsen

Schulz

Smallwood

et al. 2015

Progress in Energy and Combustion Science

322

206

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The understanding of soot formation in combustion processes and the optimization of practical combustion systems require in situ measurement techniques that can provide important characteristics, such as particle concentrations and sizes, under a variety of conditions. Of equal importance are techniques suitable for characterizing soot particles produced from incomplete combustion and emitted into the environment. Additionally, the production of engineered nanoparticles, such as carbon blacks, may benefit from techniques developed. This review discusses considerations for selection of laser and detection characteristics to address application-specific needs. The benefits of using LII for measurements of a range of nanoparticles in the fields mentioned above are demonstrated with some typical examples, covering simple flames, internal-combustion engines, exhaust emissions, the ambient atmosphere, and nanoparticle production. We also remark on less well-known studies employing LII for particles suspended in liquids.An important aspect of the paper is to critically assess the improvement in the understanding of the fundamental physical mechanisms at the nanoscale and the determination of underlying parameters; we also identify further research needs in these contexts. Building on this enhanced capability in describing the underlying complex processes, LII has become a workhorse of particulate measurement in a variety of fields, and its utility continues to be expanding. When coupled with complementary methods, such as light scattering, probe-sampling, molecular-beam techniques, and other nanoparticle instrumentation, new directions for research and applications with LII continue to materialize.

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Section: Quantitative Imaging Of Soot-volume Fractionmentioning

confidence: 99%

Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications

Michelsen

Schulz

Smallwood

et al. 2015

Progress in Energy and Combustion Science

322

206

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“…As mentioned in the section on laser shadowgraphs, the luminosity of the first apparent flame appears near the initial part [13] of the spray at 4 • CA BTDC. The simultaneous measurement of the natural flame luminosity and Mie scattered light emitted from fuel droplets indicates that the ignition and the first soot formation take place in the area between the mid-plane of fuel spray and the cylinder head, where the active vortex motion is expected, as discussed in the previous papers [14]. The vortex motion promotes the increase in the mixture temperature as the motion is brought about, the surroundings are heated and they are entrained into the spray during the compression stroke.…”

Section: Spatial Dependence Of Vapour-phase Fuel On Ignition Onsetmentioning

confidence: 52%

“…From these facts, it is very clear that the diffusion state just before and/or after the ignition is much more advanced in this area. In the late crank angle, it is found that there is a great deal of fluctuation in the behaviour of the diesel flame as indicated by fluctuation in the intensities of laser-induced incandescence, related to the spatial distribution of soot particles [14,16]. With respect to these facts, it is probable that the unstable diffusion condition of vapour-phase fuel might be also responsible for the cycle-tocycle variation.…”

mentioning

confidence: 99%

Two-dimensional imaging of fuel-vapour concentration by use of LIEF technique during mixture formation process in a DI diesel engine

Fujimoto

Choi

Shima³

et al. 2002

Meas. Sci. Technol.

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The laser-induced exciplex fluorescence (LIEF) technique, which is based on spectrally resolved two-colour fluorescent emissions, has been applied to an evaporating diesel spray for the simultaneous separation of liquid and vapour phases on the two-dimensional images. The exciplex system is based on the TMPD/naphthalene system proposed by Melton. The temporal and spatial distribution of liquid and vapour phases during the mixture formation process was detected by this technique. In the LIEF technique, the vapour phase is detected by the monomer fluorescence while the liquid phase is tracked by the exciplex fluorescence. It is able to provide quantitative information on the diffusion state for applying the statistical entropy concept. This concept was put into practice in the image sets obtained through LIEF measurement in order to investigate the diffusion process of vapour phase in the evaporating diesel spray. The laser shadowgraph was taken to deduce the effect of turbulent mixing on the ignition. The experiments were conducted in a direct injection diesel engine with optical access required for the two-dimensional laser imaging. From the results, it is found that ignition occurs in the region where turbulent mixing has advanced a nearly homogeneous mixture of fuel vapour and air. Multi-sectional images obtained by LIEF indicate that there is a spatial dependence of ignition on the vapour-phase fuel in the combustion chamber.

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“…The test engine has a bore 6 stroke592 mm696 mm and a compression ratio of 18.4. The specifications of the engine are found in the literature [19]. A jerk-type injector was replaced by an electronically controlled injector in order to supply CO 2 /n-tridecane mixed fuels to the test engine.…”

Section: Experimental Set-up and Conditionsmentioning

confidence: 99%

Improvement of combustion and emissions in diesel engines by means of enhanced mixture formation based on flash boiling of mixed fuel

Senda

Wada

Kawano

et al. 2008

International Journal of Engine Research

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A novel approach to reduce diesel engine emissions at relatively low injection pressures is proposed. This approach is based on the use of a mixed fuel where an additive or a low boiling point fuel such as CO2, gas fuel, or gasoline is mixed with a higher boiling point fuel such as diesel gas oil. When producing such a fuel, the vapour—liquid equilibrium in the two-phase region where the liquid and vapour phases of both components coexist is taken into account. In designing a mixed fuel, the authors intend to control both the physical process in the spray such as fuel evaporation and vapour air mixing and the chemical processes including spontaneous ignition and with reactions with regard to NOx, particulate matter (PM), and hydrocarbon (HC) formation. In this study flash boiling of mixed fuel is particularly focused on enhancing the mixing process in the spray because it has the potential to achieve fast evaporation and relatively lean and homogeneous mixtures. Experiments were carried out using two types of mixed fuel, both of which can generate flash boiling during injection events. In an experiment using a rapid compression machine (RCM) and an optical engine, mixed fuels consisting of liquefied CO2 as an additive and n-tridecane representing gas oil were employed with the aim of simultaneously reducting soot and NOx emissions. The high-speed images acquired for sprays reacting in the RCM and the engine clearly showed a significant reduction of soot formation in the spray. Reductions of soot and NOx emissions as well as the fuel consumption were also confirmed by emission measurements and a combustion analysis respectively. In other experiments, different types of mixed fuel consisting of gas or gasoline and gas oil were tested to see the effects on both the evaporation and ignition processes. The result of an engine experiment showed marked reductions of soot and HC emissions and fuel consumption.

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The Effect of Fuel-Vapor Concentration on the Process of Initial Combustion and Soot Formation in a DI Diesel Engine Using LII and LIEF

Cited by 14 publications

References 32 publications

Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications

Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications

Two-dimensional imaging of fuel-vapour concentration by use of LIEF technique during mixture formation process in a DI diesel engine

Improvement of combustion and emissions in diesel engines by means of enhanced mixture formation based on flash boiling of mixed fuel

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