Combustion System Development of Direct-Injection Diesel Engine Based on Spatial and Temporal Distribution of Mixture an
This study developed a Distributed Combustion Design (DCD) method, based on spatial and temporal distribution of mixture and temperature in cylinder, to optimize the combustion of high-pressure common-rail direct-injection diesel engine. Due to the signif
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Abstract This study developed a Distributed Combustion Design (DCD) method, based on spatial and temporal distribution of mixture and temperature in cylinder, to optimize the combustion of high-pressure common-rail direct-injection diesel engine. Due to the significant improvements of fuel atomization and evaporation by high-pressure common-rail system, mixing control of fuel and air becomes a critical factor to improve efficiency and emissions. Bowl shape, spray angle, multiple-injection and swirl ratio are effective approaches to control the fuel distribution and movement in cylinder both spatially and temporally, therefore can be used to improve the mixing. The whole space in cylinder was divided into three zones, Chamber, UPcham and Outerclearance. And the start of combustion, the timing of injection impacting on bowl lip, the end of injection and the end of combustion were selected as critical timings for temporal zoning controls. Studies proved that the history of fuel quantity distributed to Chamber was an important parameter affecting mixture and temperature distribution, then thermal efficiency and emissions. Combustion and emissions histories and their relationship with mixture distribution were studied under different approaches and schemes and were validated by single cylinder optical engine tests. Furthermore, the DCD method was put forward. As a result of its application, 2 % reduction of fuel consumption was achieved on a 9 L diesel engine.
Keywords Distributed combustion design Spatial and temporal zoning control Fuel distribution Air–fuel mixing CFD
F2012-A06-048 J. Li (&) K. Li (&) H. Chen (&) H. Jin (&) F. Hu FAW Co., Ltd. R&D Center, Changchun, China e-mail: [email protected]
SAE-China and FISITA (eds.), Proceedings of the FISITA 2012 World Automotive Congress, Lecture Notes in Electrical Engineering 190, DOI: 10.1007/978-3-642-33750-5_25, Ó Springer-Verlag Berlin Heidelberg 2013
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Fig. 1 Volume percentage of bowl to cylinder Volume percentage / -
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1 Introduction The main goal of engine combustion design is high efficiency and low emissions. Conventional diesel engine combustion is mainly the diffusive combustion. If the mixing is not sufficient, some local mixture will be over-rich and the other overlean, which will not only affect combustion efficiency, but also produce a large amount of NOx and soot emissions. Studies have shown that the main harmful emissions from engine combustion are generated in the specific mixture concentration and the combustion temperature [1, 2]. Therefore, for high-pressure common-rail direct-injection diesel engine, a reasonable mixture distribution, which can be achieved by optimizing air flow and fuel distribution, is the critical factor to improve combustion and emissions. The DCD concept is using spatial and temporal zoning controls of fuel distribution in cylinder to control the history of mixtu
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