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空气污染和全球变暖问题逐步恶化,全球能源紧缺和环境污染带来严峻形式逐渐进入人们的视野,探索NSGA-Ⅱ在发动机尾气排放多目标优化问题中的应用以应对各国日渐严格的燃油消耗政策和汽车排放法规。文章对双燃料(柴油和富氢压缩甲烷)反应性控制的压缩着火(RCCI)系统进行优化,建立数学模型,将发动机排放和性能特性对发动机负荷、发动机转速、当量比和燃料百分比等因素的响应进行关联。最后,利用所建立的模型和NSGA-Ⅱ(非支配排序遗传算法Ⅱ)方法,对各因素进行了优化。用NSGA-Ⅱ法优化发动机参数的结果令人满意,并提出了不同试验条件下的帕累托前沿。研究结果表明,在使用双燃料发动机,可用数值模拟和分析来优化发动机的运行参数,从而减少污染物排放,达到双燃料(柴油和富氢压缩甲烷)反应性控制的压缩着火(RCCI)点火在不同负荷下一氧化碳和氮氧化物的排放是双燃料发动机优化问题的改进。 相似文献
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汽油发动机从开始点火(即火花塞跳火)到该缸活塞运行到上止点位置这段时间所对应的发动机曲轴转角称为点火提前角。因为混合气在气缸内从开始点燃到完全燃烧需要一定的时间,设置适当点火提前角的目的就是在压缩行程接近终了时为火焰中心的形成预留时间,以便活塞在到达上止点时, 相似文献
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1发动机失火概述
发动机失火是指“点燃式发动机由于没有点火、燃油计量不准、压缩压力太低或其他原因导致气缸内混合气不能燃烧,就车载诊断(OBD)系统检测而言,是指失火次数占总点火次数的百分比”。 相似文献
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在国际著名投资公司IDG的资金支持下,稀薄燃烧摩托车技术(北京)有限公司依靠自身的技术力量,自主研发出又一摩托车高科技产品——稀薄燃烧高能数字点火系统。稀薄燃烧高能数字点火系统有2方面的含义:一是高能点火,二是数字点火。高能点火,顾名思义就是发动机点火的能量更高,其主要优点:1)点火能量提高,有利于改善摩托车的起动性和怠速稳定性,特别是改善了摩托车的低温冷起动性能,可在-20℃环境下“一触即发”。这对于寒冷地区使用的摩托车来说,具有非常重要的意义。2)点火能量提高,有利于可燃混合气体充分燃烧,从而提高了发动机的动力,节省了燃油,降低了排放。3)点火能量提高,发动机能适应较为稀薄的油气混合状态,这对于高 相似文献
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U. Egüz N. C. J. Maes C. A. J. Leermakers L. M. T. Somers L. P. H. De Goey 《International Journal of Automotive Technology》2013,14(5):693-699
The objective of new combustion concepts is to meet emission standards by improving fuel air mixing prior to ignition. Since there is no overlap between injection and ignition, combustion is governed mainly by chemical kinetics and it is challenging to control the phasing of ignition. Reactivity Controlled Compression Ignition (RCCI) combustion aims to control combustion phasing by altering the fuel ratios of the high- and low octane fuel and injection timings. In this study the dual fuel blend is prepared with gasoline and diesel fuels. The applied injection timings of the diesel are very early (90 to 60° CA bTDC). In the detailed reaction mechanism, n-heptane and iso-octane represent diesel and gasoline fuel, respectively. A multi-zone model approach is implemented to perform RCCI combustion simulation. Ignition characteristics are analyzed by using CA50 as the main parameter. In the experiments for the early direct injection (DI) timing advancing the injection time results in a later ignition. Qualitatively, the trend effect of the diesel injection timing and the effect of the ratio gasoline/diesel are captured accurately by the multi-zone model. 相似文献
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J. Lee S. Choi H. Kim D. Kim H. Choi K. Min 《International Journal of Automotive Technology》2013,14(4):551-558
Recent studies on dual-fuel combustion in compression-ignition (CI) engines, also known as diesel engines, fall into two categories. In the first category are studies focused on the addition of small amounts of gaseous fuel to CI engines. In these studies, gaseous fuel is regarded as a secondary fuel and diesel fuel is regarded as the main fuel for combustion. The objectives of these studies typically involve reducing particulate matter (PM) emissions by using gaseous fuel as a partial substitution for diesel fuel. However, the addition of gaseous fuel raises the combustion temperature, which increases emissions of nitrogen oxides (NOx). In the second category are studies focused on reactivity-controlled compression-ignition (RCCI) combustion. RCCI combustion can be implemented by early diesel injection with a large amount of low-reactivity fuel such as gasoline or gaseous fuel. Although RCCI combustion promises lower NOx and PM emissions and higher thermal efficiency than conventional diesel combustion, it requires a higher intake pressure (usually more than 1.7 bars) to maintain a lean fuel mixture. Therefore, in this study, practical applications of dual-fuel combustion with a low air-fuel ratio (AFR), which implies a low intake pressure, were systemically evaluated using propane in a diesel engine. The characteristics of dualfuel combustion for high and low AFRs were first evaluated. The proportion of propane used for four different operating conditions was then increased to decrease emissions and to identify the optimal condition for dual-fuel combustion. Although the four operating conditions differ, the AFR was maintained at 20 (? approximately equal to 0.72) and the 50% mass fraction burned (MFB 50) was also fixed. The results show that dual-fuel combustion can reduce NOx and PM emissions in comparison to conventional diesel combustion. 相似文献
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内燃机微波点火研究进展综述 总被引:1,自引:0,他引:1
综述了国内外运用于内燃机的微波点火的研究现状和技术特点,将微波点火主要分为3类,即微波谐振炬点火(Microwave resonator Torch Ignition,MTI)、微波辐射空间点火(Microwave radiation Space Ignition,MSI)、微波等离子体助燃(Microwave plasma Assisted Ignition,MAI),并介绍了微波点火可能的着火燃烧机制。指出微波点火有可能大幅拓展发动机稀燃极限,相对传统火花点火有显著的节能和减排潜力。 相似文献
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射流点火是实现稳定的稀薄燃烧,大幅度提升发动机热效率的有效技术途径。该文利用设计的一种射流点火器,对气相射流点火(GJI)的燃烧开展研究,揭示了主动式射流点火(射流室内有补充燃料)和被动式射流点火(射流室内无补充燃料)的燃烧和排放特性。结果表明:相比于被动式射流点火,主动式射流点火将过量空气系数拓展至2.0,热效率提升1.5%;进一步引入废气再循环(EGR)后,热效率提升至44.5%。主动式射流点火时,最高热效率点NOx排放较被动式射流点火下降低66%,THC及CO排放的增加使燃烧效率降低3%;引入EGR后,NOx进一步降低79%,燃烧效率保持稳定在96%。 相似文献
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Y. Tsutsumi A. Iijima K. Yoshida H. Shoji J. T. Lee 《International Journal of Automotive Technology》2009,10(6):645-652
The Homogeneous Charge Compression Ignition (HCCI) engine has attracted much interest because it can simultaneously achieve
high efficiency and low emissions. However, the ignition timing is difficult to control because this engine has no physical
ignition mechanism. In addition, combustion proceeds very rapidly because the premixed mixture ignites simultaneously at multiple
locations in the cylinder, making it difficult to increase the operating load. In this study, an HCCI engine was operated
using blended test fuels comprised of dimethyl ether (DME) and methane, each of which have different ignition characteristics.
The effects of mixing ratios and absolute quantities of the two types of fuel on the ignition timing and rapidity of combustion
were investigated. Cool flame reaction behavior, which significantly influences the ignition, was also analyzed in detail
on the basis of in-cylinder spectroscopic measurements. The experimental results revealed that within the range of the experimental
conditions used in this study, the quantity of DME supplied substantially influenced the ignition timing, whereas there was
little observed effect from the quantity of methane supplied. Spectroscopic measurements of the behavior of a substance corresponding
to HCHO also indicated that the quantity of DME supplied significantly influenced the cool flame behavior. However, the rapidity
of combustion could not be controlled even by varying the mixing ratios of DME and methane. It was made clear that changes
in the ignition timing substantially influence the rapidity of combustion. 相似文献
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对Curran的异辛烷详细化学动力学机理和Li的甲醇化学动力学机理进行了甲醇着火滞燃期特性对比研究,发现Curran异辛烷机理基本能反映甲醇的自燃着火过程。基于此,利用Curran异辛烷机理对甲醇—异辛烷混合燃料在初始温度为600 K~1 600 K、压力为1.0 MPa~4.0 MPa、当量比为0.3~1.5范围内的着火滞燃期特性进行了计算研究,分析燃料特性和初始条件对混合燃料滞燃期的影响。结果表明,初始温度对甲醇—异辛烷混合燃料的滞燃期影响较大,当初始温度增加时,滞燃期大幅缩短;部分掺醇混合燃料(掺醇率低于25%)中甲醇含量对燃料滞燃期的影响因温度范围的不同而不同,在850 K以下甲醇比率增加使混合燃料滞燃期延长,在850 K以上甲醇比率增加使其滞燃期缩短。 相似文献
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摩托车用数字式CDI点火器 总被引:1,自引:0,他引:1
根据点火储能元件的不同,点火器主要有电容充放电点火(CDI)和晶体管点火(TCI)两种类型。介绍了摩托车用数字式CDI的工作原理及软、硬件结构。其突出的优点在于能够根据预先给定的进角曲线对发动机点火提前角进行精确控制,从而使发动机在各种工作转速范围内均能够达到最佳性能。 相似文献