Insights on postinjection-associated soot emissions in direct injection diesel engines

Arrégle, Jean; Pastor, Javier; López, J. Javier; García, Antonio

doi:10.1016/j.combustflame.2008.04.021

Cited by 63 publications

(40 citation statements)

References 9 publications

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“…The maximum peak of the optical thickness traces almost coincided with the end of injection. After the end of injection, the oxidation process governs soot emissions and therefore the soot formation reaches at its maximum value [40]. Thus, when the load was increased the soot formation also increased.…”

Section: Operating Conditionsmentioning

confidence: 99%

In-cylinder soot radiation heat transfer in direct-injection diesel engines

Benajes

Martín

García

et al. 2015

Energy Conversion and Management

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HIGHLIGHTSOptoelectronic pyrometer provides similar results compared with a conventional method Lower injection pressure results in higher radiation Higher ambient temperature and higher in-cylinder gas density produce higher radiation Larger lift-off length reduces the soot volume fraction and the spectral intensity An increase on swirl number, load and CA50 provide a lower total radiation Lower values of EGR implies a decreased on radiation intensity KEYWORDSSoot; in-cylinder heat transfer; radiation; Optical pyrometer; ABSTRACTThe efficiency and CO 2 are one of the main concerns of automotive manufacturers.There are several strategies under investigation to solve this problem. In the present work, the research effort has been focused on improving knowledge of in-cylinder heat transfer and its impact on engine efficiency. In particular, soot radiation was studied since it can be considered a significant source of the efficiency losses in modern diesel engines. Considering previous studies, the portion of total chemical energy released during combustion lost due to radiation heat transfer varies widely from 0.5 up to 10%, depending on engine parameters and combustion process. Thus, the main objective of this work was to evaluate the amount of energy lost to soot radiation relative to the input fuel chemical energy during the combustion event under different operating conditions in a completely controlled environment provided by an optical engine. Under these simplified conditions, two-color method was applied by using high speed imaging pyrometer with cameras (two dimensional results) and optoelectronic pyrometer (zero dimensional results). Once a detailed comparison between both diagnostics was performed, optoelectronic pyrometer was used to characterize radiant energy losses in a fully instrumented 4-cylinder direct-injection light-duty diesel engine. In particular swirl ratio, EGR and combustion phasing effects on radiation heat transfer were evaluated.

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Section: Operating Conditionsmentioning

confidence: 99%

In-cylinder soot radiation heat transfer in direct-injection diesel engines

Benajes

Martín

García

et al. 2015

Energy Conversion and Management

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“…The maximum peak of the optical thickness traces almost coincides with the end of injection. After the end of injection, the oxidation process governs soot emissions and therefore the soot formation has arrived at its maximum value [36] The 2 bar BMEP case, doesn't follow this behavior.…”

Section: In-cylinder Radiation Intensity and Rate Of Heat Releasedmentioning

confidence: 99%

“…Nevertheless, considering literature [10,38] seems that values obtained are completely reasonable although more effort should be done to better characterize the flame area. To provide general vision of how energy is split, the global energy balance (GEB) methodology developed by Payri et al has been applied [36] to the studied engine operating conditions. With the instantaneous in-cylinder pressure as the main input, the methodology is able to detail the energy distribution in the engine, describing the different paths thanks to specific sub-models, accounting for all the relevant subsystems.…”

Section: Energy Balance Considering Radiant Fractionmentioning

confidence: 99%

An Investigation of Radiation Heat Transfer in a Light-Duty Diesel Engine

Benajes¹,

Martín²,

García³

et al. 2015

SAE Int. J. Engines

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In the last two decades engine research has been mainly focused on reducing pollutant emissions. This fact together with growing awareness about the impacts of climate change are leading to an increase in the importance of thermal efficiency over other criteria in the design of internal combustion engines (ICE). In this framework, the heat transfer to the combustion chamber walls can be considered as one of the main sources of indicated efficiency diminution. In particular, in modern direct-injection diesel engines, the radiation emission from soot particles can constitute a significant component of the efficiency losses. Thus, the main of objective of the current research was to evaluate the amount of energy lost to soot radiation relative to the input fuel chemical energy during the combustion event under several representative engine loads and speeds. Moreover, the current research characterized the impact of different engine operating conditions on radiation heat transfer. For this purpose, a combination of theoretical and experimental tools were used. In particular, soot radiation was quantified with a sensor that uses two-color thermometry along with its corresponding simplified radiation model. Experiments were conducted using a 4-cylinder direct-injection light-duty diesel engine fully instrumented with thermocouples. The goal was to calculate the energy balance of the input fuel chemical energy.Results provide a characterization of radiation heat transfer for different engine loads and speeds as well as radiation trends for different engine operating conditions.

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“…Nozzle geometry has been studied for the influence on the internal flow and spray characteristics with respect to: atomization [4,5], mixing processes [6,7], emission [9,10] and cavitation [8,13]. Different injection strategies have been investigated to show the effect on pollutant emissions [2,3]. Specific studies have also been conducted with conical and cylindrical nozzles [11,12], and to develop more understanding on the effects of nozzle holes [14][15][16] on spray characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…For diesel engines, spray characteristics (liquid/vapour penetration and distribution) significantly affect the combustion and emission processes. By optimizing these characteristics, the tailpipe emissions, mainly oxides of Nitrogen (NOx) and partciculate matter (PM), can be minimized [2]. Spray penetration, which is usually analysed macroscopically, considers the development of the liquid and vapour components.…”

Section: Introductionmentioning

confidence: 99%

Fuel spray vapour distribution correlations for a high pressure diesel fuel spray cases for different injector nozzle geometries.

Njere

Emekwuru

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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The evolution of diesel fuel injection technology, to facilitate strong correlations of in-cylinder spray propagation with injection conditions and injector geometry, is crucial in facing emission challenges. More observations of spray propagation are, therefore, required to provide valuable information on how to ensure that all the injected fuel has maximum contact with the available air, to promote complete combustion and reduce emissions. In this study, high pressure diesel fuel sprays are injected into a constant-volume chamber at injection and ambient pressure values typical of current diesel engines. For these types of sprays the maximum fuel liquid phase penetration is different and reached sooner than the maximum fuel vapour phase penetration. Thus, the vapour fuel could reach the combustion chamber wall and could be convected and deflected by swirling air. In hot combustion chambers this impingement can be acceptable but this might be less so in larger combustion chambers with cold walls. The fuel-ambient mixture in vapourized fuel spray jets is essential to the efficient performance of these engines. For this work, the fuel vapour penetration values are presented for fuel injectors of different k-factors. The results indicate that the geometry of fuel injectors based on the k-factors appear to affect the vapour phase penetration more than the liquid phase penetration. This is a consequence of the effects of the injector types on the exit velocity of the fuel droplets. KeywordVapour, spray, k-factor, shadowgraph. IntroductionSpray formation occurs with the introduction of liquid into a gaseous environment through an orifice such that the liquid breaks-up into droplets by interacting with the surrounding gases and causing its own unsteadiness [3]. For diesel engines, spray characteristics (liquid/vapour penetration and distribution) significantly affect the combustion and emission processes. By optimizing these characteristics, the tailpipe emissions, mainly oxides of Nitrogen (NOx) and partciculate matter (PM), can be minimized [2]. Spray penetration, which is usually analysed macroscopically, considers the development of the liquid and vapour components. It is desirable to achieve optimal travel of these spray components to avoid the adverse effects of impingement caused by under/overpenetration of liquid spray [19,20]. Advances in fuel injection system, with the introduction of the common rail technology, have provided increased controllability of the injection event. The analyses of injection system development have been presented from several viewpoints. Nozzle geometry has been studied for the influence on the internal flow and spray characteristics with respect to: atomization [4,5], mixing processes [6,7], emission [9,10] and cavitation [8,13]. Different injection strategies have been investigated to show the effect on pollutant emissions [2,3]. Specific studies have also been conducted with conical and cylindrical nozzles [11,12], and to develop more understanding on the effects of nozzl...

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Insights on postinjection-associated soot emissions in direct injection diesel engines

Cited by 63 publications

References 9 publications

In-cylinder soot radiation heat transfer in direct-injection diesel engines

In-cylinder soot radiation heat transfer in direct-injection diesel engines

An Investigation of Radiation Heat Transfer in a Light-Duty Diesel Engine

Fuel spray vapour distribution correlations for a high pressure diesel fuel spray cases for different injector nozzle geometries.

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