Exploitation of injection fusion strategies in diesel engines equipped with solenoid injectors
01 Aug 2018-International Journal of Engine Research (SAGE PublicationsSage UK: London, England)-Vol. 19, Iss: 6, pp 653-667
TL;DR: In this paper, pilot-main injection strategies were investigated in the short dwell-time range at medium load and speed conditions for a low-temperature combustion diesel engine endowed with indirect-acting soleno...
Abstract: Pilot–main injection strategies are investigated in the short dwell-time range at medium load and speed conditions for a low-temperature combustion diesel engine endowed with indirect-acting soleno...
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TL;DR: In this paper, a visualisation set called shadowgraph optical technique is implemented to capture the injected fluid spray inside the combustion chamber by common rail direct injection, and the effective estimation of spray intensity between 1st spray injection and 2nd spray injection supports in a way to choose the appropriate dwell time between successive injections which avoid the formation of the pocketed fuelrich region.
12 citations
TL;DR: In this paper, the state-of-the-art Common rail solenoid and direct acting piezoelectric injectors have been tested at a dynamometer cell.
12 citations
TL;DR: In this paper, an experimental investigation has been carried out to highlight the effects of different injection strategies on the performance and emissions of a low compression ratio Euro 5 diesel engine operated with high EGR rates.
Abstract: An experimental investigation has been carried out to highlight the effects of different injection strategies on the performance and emissions of a low compression ratio Euro 5 diesel engine operated with high EGR rates. Rate-shaped main injections, achieved with piezoelectric and solenoid injectors by means of boot and injection fusion, respectively, as well as optimized multiple injection patterns have been compared. The results of the comparisons, performed with reference to a state-of-the-art double pilot-Main (pM) strategy, are presented in terms of engine-out exhaust emissions, combustion noise (CN) and fuel consumption. Rate-shaped main injections, when included in delayed multiple injection patterns, have shown a minor influence on reducing NOx, while a slight deterioration in soot has been found. Both a double pilot and a boot injection schedule have been able to reduce CN at low loads. A higher reduction in CN has been obtained with an injection fusion event. Finally, DoE optimized triple and quadruple injection strategies have led to improved soot-NOx trade-offs, with respect to the pM calibration. In fact, splitting the injection helps to entrain air inside the fuel plumes, thus creating locally leaner mixture (less prone to forming soot) and allowing increasing the EGR rates (reducing NOx formation).
8 citations
TL;DR: In this paper , a new model to predict the instantaneous mass flow rate from a diesel injector is proposed based on the analytical solution of a first-order linear dynamic system exposed to an impulsion.
Abstract: Models used to predict the instantaneous injected fuel mass are of varied interest in automotive applications, including for providing inputs to CFD calculations or for engine control. While multiple injection strategies are now commonly used in diesel engines, the overall approach may be susceptible to injection fusion, which is defined as two successive injections that are partly or totally coupled due to the short time interval between each event. In this work, a new model to predict the instantaneous mass flow rate from a diesel injector is proposed based on the analytical solution of a first-order linear dynamic system exposed to an impulsion. Experiments are also conducted to quantify the main injection characteristics of a solenoid indirect-action injector under different injection pressures, backpressures and injection durations, representing a total of 33 different conditions. From these results, a model is proposed and validated against experimental data using a single injection strategy. Then, the model is enhanced to predict split injection with and without injection fusion. Successful comparisons are realized between the model and the experiment. The model is then used to successfully simulate a piezoelectric injector experiencing different levels of fusion available in the literature so as to illustrate the universality of the proposed approach.
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TL;DR: In this paper, the effects of exhaust gas recirculation (EGR) on diesel engine combustion and exhaust emissions were identified and investigated experimentally: the reduction in oxygen supply to the engine, participation in the combustion process of carbon dioxide and water vapour present in the EGR, increase in the specific heat capacity of the engine inlet charge, increased INLET charge temperature and reduction in the inLET charge mass flowrate arising from the use of hot EGR.
Abstract: An investigation was conducted with the aim of identifying and quantifying the effects of exhaust gas recirculation (EGR) on diesel engine combustion and exhaust emissions. Five effects of EGR were identified and investigated experimentally: the reduction in oxygen supply to the engine, participation in the combustion process of carbon dioxide and water vapour present in the EGR, increase in the specific heat capacity of the engine inlet charge, increased inlet charge temperature and reduction in the inlet charge mass flowrate arising from the use of hot EGR. The experimental methodology developed allowed each one of these effects to be investigated and quantified separately. The investigation was carried out on a high-speed, direct injection diesel engine, running at an intermediate speed and load. A limited number of tests were also conducted in an optically accessible diesel engine, which established the effects of EGR on local flame temperature. Finally, tests were conducted with simulated EGR...
213 citations
TL;DR: In this article, the authors have been partially supported by the Ministerio de Educacin y Ciencia through Grant No. TRA2006-13782 through the Santiago Grisolia Program of Generalitat Valenciana.
143 citations
TL;DR: In this paper, the authors present a new methodology for the analysis of in-cylinder pressure in direct injection (DI) diesel engines, based on three phenomena taking place during diesel engine operation: pseudo-motored, combustion and resonance excitation.
Abstract: The objective of this paper is to present a new methodology for the analysis of in-cylinder pressure in direct injection (DI) diesel engines. Indeed, for some applications, the traditional study of total pressure is shown to be insufficient and the proposed technique is intended to be an alternative and more efficient tool, since it may provide a better understanding of the physical mechanisms. The main idea is to decompose the in-cylinder pressure evolution according to three phenomena taking place during diesel engine operation: pseudo-motored, combustion and resonance excitation. In order to validate this new method, it is applied to combustion noise analysis. Actually, the combustion process in DI diesel engines may be considered as an important source of noise, and the traditional approach is mainly based on the interpretation of objective overall spectral levels of both in-cylinder pressure and radiated noise, obtained from Fourier analysis. However, this approach has been shown unable to describe all the relevant aspects of the problem, whereas the results obtained from the proposed decomposition technique exhibit a fair qualitative correlation between in-cylinder pressure and combustion noise issues. Further development of this approach could provide a useful tool for the development of optimal injection strategies fulfilling not only performance considerations but also sound quality requirements for combustion noise in DI diesel engines.
118 citations
"Exploitation of injection fusion st..." refers background in this paper
...On the other hand, diesel propulsion systems suffer from major problems concerning the significant production of nitrogen oxides (NOx) and particulate matter (PM) emissions as well as high levels of combustion noise (CN), which is caused by the sudden in-cylinder pressure rise during the combustion process.(2) The efforts that have been made to reduce NOx usually lead to an increase in the PM and vice versa (this behavior is referred to as the NOx–PM trade-off)....
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TL;DR: In this paper, the effects of pilot injection quantity and EGR rate on HCCI-DI combustion and emissions were investigated in a heavy-duty diesel engine using the early pilot injection in the intake stroke and the main injection around compression top dead center (TDC).
98 citations
"Exploitation of injection fusion st..." refers background in this paper
...There is still room for further studies on pilot–main (pM) injection strategies in the short DT range that includes injection fusion, due to the very high degree of freedom of fuel injection schedules offered by the most recent common rail (CR) systems.(17,18) It has been observed that a significant reduction in CN can be achieved in a closely coupled injection regime when the pilot combustion is significant and the steepness of the pilot heat release profile is similar to the initial main heat release rise....
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