Multidimensional Modeling of Fuel Composition Effects on Combustion and Cold-Starting in Diesel Engines

Ayoub, Nabil S.; Reitz, Rolf D.

doi:10.4271/952425

Cited by 15 publications

(4 citation statements)

References 21 publications

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“…They reported that the first injection creates an ignitable atmosphere due to the cool flame reaction, before the main injection takes place, producing a significative reduction of the ignition delay. Ayoub and Reitz [14] also found a positive effect by using split injections, but they assumed that it was due to the fact that the first injection ignites at the moment when the second injection starts. This important effect that enhances the ignition process has been only seen on pressure traces, which does not allow us to identify or quantify clearly the cool flame effect.…”

Section: State Of the Artmentioning

confidence: 99%

Experimental facility and methodology for systematic studies of cold startability in direct injection Diesel engines

Pastor¹,

García-Oliver²,

Pastor³

et al. 2009

Meas. Sci. Technol.

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Cold start at low temperatures in current direct injection (DI) Diesel engines is a problem which has not yet been properly solved and it becomes particularly critical with the current trend to reduce the engine compression ratio. Although it is clear that there are some key factors whose control leads to a proper cold start process, their individual relevance and relationships are not clearly understood. Thus, efforts on optimization of the cold start process are mainly based on a trial-and-error procedure in climatic chambers at low ambient temperature, with serious limitations in terms of measurement reliability during such a transient process, low repeatability and experimental cost. This paper presents a novel approach for an experimental facility capable of simulating real engine cold start, at room temperature and under well-controlled low speed and low temperature conditions. It is based on an optical single cylinder engine adapted to reproduce in-cylinder conditions representative of those of a real engine during start at cold ambient temperatures (of the order of −20 °C). Such conditions must be realistic, controlled and repeatable in order to perform systematic studies in the borderline between ignition success and misfiring. An analysis methodology, combining optical techniques and heat release analysis of individual cycles, has been applied.

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Section: State Of the Artmentioning

confidence: 99%

Experimental facility and methodology for systematic studies of cold startability in direct injection Diesel engines

Pastor¹,

García-Oliver²,

Pastor³

et al. 2009

Meas. Sci. Technol.

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“…Hardenberg et al [17] showed that the activation energy of the ignition process depends on the fuel cetane number. Thus, Ayoub et al [18] suggested that the reaction parameter Ef4 should be corrected by using eq. (13).…”

Section: The Shell Modelmentioning

confidence: 99%

A Preliminary Study on the Effect of Low Temperature Kinetics on Engine Modeling

Risi

Laforgia

Donateo³

2001

SAE Technical Paper Series

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Modeling autoignition in diesel engines is a challenging task because of the wide range of equivalence ratios over which it takes place. A variety of detailed autoignition models has been proposed in literature for different fuels. Since these models include about one thousand chemical reactions and more than one hundred species, their application to CFD engines simulations requires a very high computational time, so that they are of no practical interest. In order to lower the computational time, a number of reduced models has been developed including the shell model, which is one of the most used. This model does not take into account low temperature kinetics and consists of seven reactions and three radicals. The use of this model in engine simulations shows its limits when applied to delayed injections because of the predominant influence of the low temperature kinetics. A modified version of the shell model is proposed in the present study. It includes the effect of low temperature kinetics by the addition of two more radicals and three new kinetics reactions. The model has been implemented in a modified version of the KIVA3V code. The performance of the new kinetic scheme has been investigated by computing the ignition delay at different operating conditions in bomb like simulations. The investigated operating conditions were obtained by changing gas temperature and pressure, air to fuel ratio (i.e., oxygen concentration). The effect of the pre-exponential factor in the rate of production of the intermediate agent has also been investigated. The model has also been applied to predict autoignition of a commercial small bore direct injection diesel engine for different injection timings. Results showed that, for delayed injections, the new model was able to better predict the heat released and the pressure traces. The influence of the modified shell model on engine emissions has also been analyzed.

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“…During the last 15 years, diesel cold starting study was accomplished at the University of Wisconsin-Madison via multidimensional analysis [e.g. 127,128], which allowed more insight into the complicated in-cylinder phenomena without, however, coupling with a dynamic sub-model.…”

Section: Commentsmentioning

confidence: 99%

Review of Thermodynamic Diesel Engine Simulations under Transient Operating Conditions

Rakopoulos¹,

Giakoumis²

2006

SAE Technical Paper Series

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Study and modeling of transient operation is an important scientific objective. This is due to the fact that the majority of daily vehicle driving conditions involve transient operation, with non-linear situations experienced during engine transients. Thus, proper interconnection is needed between engine, governor, fuel pump, turbocharger and load. This paper surveys the publications available in the open literature concerning diesel engine simulations under transient operating conditions. Only those models that include both full engine thermodynamic calculations and dynamic powertrain modeling are taken into account, excluding those that focus on control design and optimization. Most of the attention is concentrated to the simulations that follow the filling and emptying modeling approach. A historical overview is given covering, in more detail, research groups with continuous and consistent study of transient operation. One of the main purposes of this paper is to summarize basic equations and modeling aspects concerning in-cylinder calculations, friction, turbocharger, engine dynamics, governor, fuel pump operation, and exhaust emissions during transients. The various limitations of the models are discussed together with the main aspects of transient operation (e.g. turbocharger lag, combustion and friction deterioration), which diversify it from the steady-state. Some of the most important findings in the field during the last 30 years are presented and discussed. The survey extends to special cases of transient diesel engine simulation, such as second-law analysis, response when the turbocharger compressor experiences surge, and whole vehicle performance. Several methods of improving transient response are also mentioned, based on the various simulations. An easy-to-read tabulation of all research groups dealing with the subject, that includes details about each model developed and engines/parameters studied, is also provided at the end of the paper.

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Multidimensional Modeling of Fuel Composition Effects on Combustion and Cold-Starting in Diesel Engines

Cited by 15 publications

References 21 publications

Experimental facility and methodology for systematic studies of cold startability in direct injection Diesel engines

Experimental facility and methodology for systematic studies of cold startability in direct injection Diesel engines

A Preliminary Study on the Effect of Low Temperature Kinetics on Engine Modeling

Review of Thermodynamic Diesel Engine Simulations under Transient Operating Conditions

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