Multidimensional Modeling of Fuel Composition Effects on Combustion and Cold-starting in Diesel Engines PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages : 12
Book Description
A computer model developed for describing multicomponent fuel vaporization, and ignition in diesel engines has been applied in this study to understand cold-starting and the parameters that are of significant influence on this phenomena. This research utilizes recent improvements in spray vaporization and combustion models that have been implemented in the KIVA-II CFD code. Typical engine fuels are blends of various fuels species, i.e., multicomponent. Thus, the original single component fuel vaporization model in KIVA-II was replaced by a multicomponent fuel vaporization model (based on the model suggested by Jin and Borman). The model has been extended to model diesel sprays under typical diesel conditions, including the effect of fuel cetane number variation. Necessary modifications were carried out in the atomization and collision sub-models. The ignition model was also modified to account for fuel composition effects by modifying the Shell ignition model. The improved model was applied to simulate diesel engine cold-starting. The effect of fuel residual from previous cycles was studied and was found to be important. Other injection parameters, such as injection timing and duration were also studied. Another factor that was investigated was engine geometry and how it can be modified to improve on cold-starting in diesel engines. Cold-starting was found to be enhanced by the presence of a small fuel vapor residual and by a shorter injection duration, while engine geometry modifications were found to be helpful in selecting an optimum location on the cylinder head for an ignition aid.
Author: Publisher: ISBN: Category : Languages : en Pages : 12
Book Description
A computer model developed for describing multicomponent fuel vaporization, and ignition in diesel engines has been applied in this study to understand cold-starting and the parameters that are of significant influence on this phenomena. This research utilizes recent improvements in spray vaporization and combustion models that have been implemented in the KIVA-II CFD code. Typical engine fuels are blends of various fuels species, i.e., multicomponent. Thus, the original single component fuel vaporization model in KIVA-II was replaced by a multicomponent fuel vaporization model (based on the model suggested by Jin and Borman). The model has been extended to model diesel sprays under typical diesel conditions, including the effect of fuel cetane number variation. Necessary modifications were carried out in the atomization and collision sub-models. The ignition model was also modified to account for fuel composition effects by modifying the Shell ignition model. The improved model was applied to simulate diesel engine cold-starting. The effect of fuel residual from previous cycles was studied and was found to be important. Other injection parameters, such as injection timing and duration were also studied. Another factor that was investigated was engine geometry and how it can be modified to improve on cold-starting in diesel engines. Cold-starting was found to be enhanced by the presence of a small fuel vapor residual and by a shorter injection duration, while engine geometry modifications were found to be helpful in selecting an optimum location on the cylinder head for an ignition aid.
Author: P. A. Lakshminarayanan Publisher: Springer Science & Business Media ISBN: 904813885X Category : Technology & Engineering Languages : en Pages : 313
Book Description
Phenomenology of Diesel Combustion and Modeling Diesel is the most efficient combustion engine today and it plays an important role in transport of goods and passengers on land and on high seas. The emissions must be controlled as stipulated by the society without sacrificing the legendary fuel economy of the diesel engines. These important drivers caused innovations in diesel engineering like re-entrant combustion chambers in the piston, lower swirl support and high pressure injection, in turn reducing the ignition delay and hence the nitric oxides. The limits on emissions are being continually reduced. The- fore, the required accuracy of the models to predict the emissions and efficiency of the engines is high. The phenomenological combustion models based on physical and chemical description of the processes in the engine are practical to describe diesel engine combustion and to carry out parametric studies. This is because the injection process, which can be relatively well predicted, has the dominant effect on mixture formation and subsequent course of combustion. The need for improving these models by incorporating new developments in engine designs is explained in Chapter 2. With “model based control programs” used in the Electronic Control Units of the engines, phenomenological models are assuming more importance now because the detailed CFD based models are too slow to be handled by the Electronic Control Units. Experimental work is necessary to develop the basic understanding of the pr- esses.
Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
An experimental and numerical study was carried out to simulate the diesel spray breakup, vaporization, ignition, and combustion during cold starting conditions. This report summarizes the optical diagnostics and multi-dimensional computation results for two single-cylinder optically accessible engines. The results showed that optically accessible engines provide very useful information for studying the diesel cold starting conditions, which also provide a critical test for diesel combustion models. The pre-ignition chemistry showed great sensitivity to the compressed air temperature. KIVA with a modified shell model responds accordingly to the change of inlet air temperatures and fuel injection parameters. However, other submodels do not have enough sensitivity to simulate the starting of diesel engine without careful validation and further improvements. A method to compute the ignition delay in engines from data obtained in constant volume vessels was also developed. The method accounts for the effect of variations in charge pressure and temperature on the formation of the chain carriers from the combustible mixture during the ID period. A comparison is made between the computed ID and data obtained in a LABECO research engine under different ambient temperatures ranging from +200 to - 100 C.
Author: American Society of Mechanical Engineers. Internal Combustion Engine Division. Spring Technical Conference Publisher: ISBN: Category : Internal combustion engines Languages : en Pages : 746
Author: Publisher: ISBN: Category : Languages : en Pages : 8
Book Description
A multidimensional simulation of Auxiliary Gas Injection (AGI) for late cycle oxygen enrichment was exercised to assess the merits of AGI for reducing the emissions of soot from heavy duty diesel engines while not adversely affecting the NO(subscript x) emissions of the engine. Here, AGI is the controlled enhancement of mixing within the diesel engine combustion chamber by high speed jets of air or another gas. The engine simulated was a Caterpillar 3401 engine. For a particular operating condition of this engine, the simulated soot emissions of the engine were reduced by 80% while not significantly affecting the engine-out NO(subscript x) emissions compared to the engine operating without AGI. The effects of AGI duration, timing, and orientation are studied to confirm the window of opportunity for realizing lower engine-out soot while not increasing engine out NO(subscript x) through controlled enhancement of in-cylinder mixing. These studies have shown that this window occurs during the late combustion cycle, from 20 to 60 crank angle degrees after top-dead-center. During this time, the combustion chamber temperatures are sufficiently high that soot oxidation increases in response in increased mixing, but the temperature is low enough that NO(subscript x) reactions are quenched. The effect of the oxygen composition of the injected air is studied for the range of compositions between 21% and 30% oxygen by volume. This is the range of oxygen enrichment that is practical to produce from an air separation membrane. Simulations showed that this level of oxygen enrichment is insufficient to provide an additional benefit by either increasing the level of soot oxidation or prolonging the window of opportunity for increasing soot oxidation through enhanced mixing.
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Author: P. A. Lakshminarayanan
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Author: Philip William Stephenson
Author: Donald W. Stanton
Author: Cathy Youngmi Choi
Author: American Society of Mechanical Engineers. Internal Combustion Engine Division. Spring Technical Conference
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Author: Andreas M. Lippert
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