共查询到20条相似文献,搜索用时 156 毫秒
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分析了稀燃天然气发动机基本控制参数(点火提前角、喷气提前角和过量空气系数)对燃料经济性和排放的影响。结果表明,增大过量空气系数有助于改善发动机燃料经济性和NOx排放,但受到发动机稀燃极限的限制;点火提前角是平衡NOx排放和燃料经济性之间矛盾非常有效的方法;而喷气正时对各污染物的排放和燃料经济性的影响则较小。针对这种多控制参数系统的天然气发动机,提出了一种标定策略:首先以提高稀燃极限为目的标定喷气正时,然后在一定失火余量的前提下标定过量空气系数,最后以排放限值为约束条件标定点火提前角。 相似文献
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《汽车安全与节能学报》2015,(4)
综述了近年来在先进点火方法和系统方面的快速进展。介绍了发动机点火的基本物理原理(它决定了点火系统的改进方向)和相关发动机以及容弹的实验结果,主要包括:高能量火花放电点火﹑高压脉冲放电点火﹑射频等离子体点火﹑激光点火。根据大量研究报道以及本文作者的实验研究结果 ,对多种点火系统的效果及应用挑战做出综合评价。结论为:未来清洁燃烧内燃机趋向于采用稀释工质低温燃烧策略,以提高汽车发动机燃油经济性并降低排放。先进缸内混合气控制手段包括:降低工质活性﹑非均匀分布以及增强气流等,然而所有这些手段也会增加发动机着火控制的难度。先进的高能量点火系统能够用来改善未来高效清洁发动机的点火控制。 相似文献
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天然气/氢气混合燃料发动机的稀燃极限和排放特性试验研究 总被引:1,自引:0,他引:1
在东风EQD210N-20天然气发动机上进行了天然气与天燃气/氢气混合燃料体积混合比例为10%、30%和50%的稀燃极限和排放特性试验研究.实验结果表明:燃烧混合燃料比燃烧天然气时的稀燃极限大,并且随着掺氢比例的增大,燃烧过程的火焰发展期和快速燃烧期缩短,发动机的指示热效率、平均指示压力和NO2的排放增加;但是当发动机在大于天然气/氢气混合气的稀燃极限工作时,其指示热效率、平均指示压力和NO2的排放迅速下降,平均指示压力变动系数、CH4和CO的浓度迅速上升. 相似文献
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本文针对发动机电子点火系统的五种常见故障,借助发动机综合分析仪测得次级点火波形,并提取特征值,构造了一种模糊神经网络模型,利用MATLAB进行仿真,通过简单测试,得出这种方法是可行的,可以准确快速的诊断出故障原因。 相似文献
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本文以某天然气重型卡车为例,介绍了T6114ZLQ3B型CNG发动机电子控制系统及相关部件的结构、工作原理和故障代码的读取。 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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《JSAE Review》1999,20(3):407-411
Ignition and combustion characteristics of a two-stage injection diesel spray were experimentally investigated. A constant volume combustion chamber was filled with air which was controlled at 3.0 MPa and 743–923 K. In order to measure the ignition delay and the ignition position, a high speed video system was used. A 306 nm interference filter and an image intensifier system were attached to the camera for detecting the OH radical emission. The results show that the ignition delay of a two-stage injection spray becomes shorter compared with that of a single injection spray. The ignition positions of two-stage injection spray are observed nearer to the nozzle than that of single injection spray. Also, the temperature limit of complete combustion on a two-stage injection spray becomes lower than that of a single injection spray. 相似文献
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介绍郑州日产尼桑牌皮卡车KA24DE发动机的电子集中控制系统(ECCS),与排放相关的部件结构、主工作原理。该系统采用超大规模集成电路的数字计算机,对发动机的空燃比、点火正时、怠速转速、排放等进行综合控制,提高了发动机的燃油经济性和排放净化性能。 相似文献
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汽油电控喷射发动机的HC和CO排放试验研究 总被引:1,自引:0,他引:1
本文研究了汽油电控喷射发动机进气涡汽、喷油方式、喷射位置、喷油正时、空燃比及点火参数和多次点火方式对汽油进气道喷射发动机的HC和CO排放的影响。试验结果表明,在试验范围内,影响混合气形成的主要因素(包括进气流动、喷射参数及点火参数)都对HC和CO有很大的影响;在优化喷射参数后采用高能点火对改进排放效果不太明显。试验中采用的连续多次点火方式对排放亦有一定的改善作用。 相似文献
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为降低HCNG发动机NOx排放,采用负阀重叠EGR策略,利用AVL-Fire软件对HCNG发动机不同进气门开启角(θIVO)下的进气过程和燃烧过程进行了三维仿真计算,对比分析了采用负阀重叠前后发动机缸内EGR分布和燃烧过程。仿真结果表明:负阀重叠EGR策略下,排气门关闭角(θEVC)固定为340°曲轴转角不变,当θIVO为380°曲轴转角时,既可避免发生回火又能保证一定的进气量及充气效率;采用负阀重叠后,在压缩冲程后期,缸内EGR率呈梯度分布(靠近火花塞位置EGR率较低),更有利于着火及火焰传播;采用负阀重叠可降低缸内最高燃烧压力及最高温度,但会减少进入气缸的新鲜工质,降低发动机功率;通过负阀重叠实现内部EGR可降低NOx排放,但会导致着火困难,燃烧速度变慢;提高点火能量可缩短着火落后期和燃烧持续期,加快燃烧速度。 相似文献
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There has been recent interest in a new engine type, Homogeneous Charge Compression Ignition (HCCI), to combine the advantages
of SI and CI engines. In this paper, a locally deterministic approach is employed to consider spatial inhomogeneities using
the KIVA-CHEMKIN package. Validation is performed for two experimental HCCI engines fueled, respectively, by hydrogen and
n-heptane. The full mechanism for hydrogen and a skeletal mechanism for n-heptane are used for combustion chemistry. Differences
in the reaction flow paths are shown at ignition and the heat release reaction stages of the two fuels. Results show good
agreement between measured and calculated pressures for different initial mixture temperatures with estimated residual fractions.
A parametric study is performed in both engines to consider the influences of the physical parameters wall temperature, swirl
ratio and global equivalence ratio. The ignition time of n-heptane is shown to be relatively insensitive to variations in
these parametric due to its two-stage ignition behavior. 相似文献
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Jeongwoo Lee Sanghyun Chu Jaegu Kang Kyoungdoug Min Hyunsung Jung Hyounghyoun Kim Yohan Chi 《International Journal of Automotive Technology》2017,18(6):943-950
Environmental problems have become a major issue for diesel engine development. Although emission aftertreatment systems such as DPFs (diesel particulate filters), LNTs (lean NOx traps) and SCR (selective catalytic reduction) have been used in diesel vehicles, the manufacturing cost increase caused by this equipment can be hard to be control. Thus, it is better for engine emissions to be reduced by improving the combustion system. A dual-fuel combustion concept is a recommended method to improve a combustion system and effectively reduce emissions. Low reactivity fuel including gasoline and natural gas, which was supplied to the intake port by the FPI (port fuel injector), improved the premixed air-fuel mixture conditions before ignition. Additionally, a small amount of high reactivity fuel, in this case diesel, was injected into the cylinder directly as an ignition source. This dual-fuel combustion promises lower levels of NOx (nitrogen oxide) and PM (particulate matter) emissions due to the elimination of local rich regions in the cylinder. However, it is challenging to control the dual-fuel combustion because the combustion stability and efficiency deteriorate due to the lack of ignition source and reactivity. Thus, it is important to establish an appropriate dual-fuel operating strategy to achieve stable, high efficiency and low emission operation. As a result of this research, a detailed operating method of dual-fuel PCI (premixed compression ignition) was introduced in detail at a low speed and low load condition by using a single cylinder diesel engine. Engine operating parameters including the gasoline ratio, a diesel injection strategy consisting of multiple injectors and timing, the EGR (exhaust gas recirculation) rate and the intake pressure were controlled to satisfy the low ISNOx (indicated specific NOx) and PM emissions levels (0.21 g/kWh and 0.1 FSN, 0.040 g/kWh, respectively) as per the EURO-6 regulation without any after-treatment systems. The results emphasized that a well-constructed dual-fuel PCI operating strategy showed low NOx and PM emissions and high GIE (gross indicated fuel conversion efficiency) with excellent combustion stability. 相似文献