共查询到18条相似文献,搜索用时 140 毫秒
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柴油燃料HCCI燃烧影响因素的试验研究 总被引:4,自引:0,他引:4
本文采用在进气上止点附近进行柴油喷射,利用缸内高温残余废气促进燃油蒸发形成均质混合气,实现了柴油燃料的均质压燃(HCCI)。试验结果表明柴油燃料HCCI燃烧的放热规律呈现低温和高温放热两个阶段,并且NOx排放可以降低95%-98%。本文主要研究了影响HCCI燃烧的因素,指出负荷增大、进气温度增加和负气门重叠期的增加使HCCI着火提前,而外部EGR率的增大可以推迟着火。因此对于低温自燃性好的燃料,冷EGR是控制其HCCI着火燃烧过程的有效措施。 相似文献
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《工程热物理学报》2010,(11)
均质混合气压燃(HCCI)燃烧受爆震和NO_x排放的限制,高负荷拓展是一个难题。本文提出利用理论空燃比SICI组合燃烧作为汽油机中高负荷运行区域的高效低污染燃烧模式。在试验台架上研究了理论空燃比SICI组合燃烧的排放特性及其对三效催化剂(TWC)转换性能的影响。研究发现,通过外部EGR与点火控制相结合,理论空燃比SICI组合燃烧可以在指示平均有效压力(IMEP)0.65~0.82MPa范围内稳定实现;与传统SI燃烧相比,理论空燃比SICI组合燃烧燃油经济性提高近10%,NO_x排放降低80%以上,但HC排放有所增加;SICI组合燃烧与传统SI燃烧类似,TWC空燃比特性的高效区间在理论空燃比附近,但对HC排放的催化能力提出了更高的要求。 相似文献
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针对汽油机稀燃条件下循环变动大,燃料燃烧不充分的问题,本文在一台加装了电控氢气喷射系统的四缸汽油机上就混氢对改善汽油机稀燃条件下燃烧与排放性能的作用进行了试验研究。在发动机1400r/min,进气道绝对压力为61.5 kPa的条件下,就1%与3%两种进气混氢体积分数对稀燃汽油机燃烧与排放特性的影响进行了研究。试验结果表明,稀燃时发动机制动热效率随混氢分数增加而提高;滞燃期与速燃期随混氢分数增加而缩短;发动机稀燃极限所对应的过量空气系数由原机的1.45提高至混氢1%与3%时的1.55和1.96。混氢后发动机HC与CO排放降低,但NO_x排放有所升高。 相似文献
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废气再循环和添加剂对高辛烷值燃料HCCI燃烧的影响 总被引:1,自引:0,他引:1
本文对废气再循环(EGR)和十六烷值改进荆-过氧化二叔丁基(DTBP)对高辛烷值燃料HCCI燃烧的影响进行了研究。实验结果表明:辛烷值为90的燃料(RON90)只能在高温高负荷下才能运行HCCI燃烧模式;在其中加入少量的DTBP后,RON90实现HCCI燃烧的工况范围向低温低负荷下大幅度拓展。加入添加剂后,低负荷性能改善的同时,浓混合气的着火时刻可以通过EGR将含添加剂燃料的着火时刻推迟到上止点附近,从而大幅度提高热效率,降低了燃料消耗率。 相似文献
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多次喷射对重型柴油机影响的试验研究 总被引:2,自引:0,他引:2
本文在一台电控共轨柴油机上进行了多次喷射及多次喷射和EGR结合对重型柴油机影响的试验研究。EGR为基于VGT的高压冷却EGR系统。研究了不同喷射策略下喷射参数对柴油机性能和排放的影响。研究了EGR和多次喷射结合降低柴油机排放的效果;通过调整EGR率,将NO_x控制在2.0 g/(kW·h),研究喷射参数和EGR对柴油机的影响。研究结果表明,预喷射可以在小负荷时改善柴油机的NO_x、CO和比油耗,但在大负荷时没有明显的影响;两次预喷射可以促进油气混合;后喷射可以促进油气混合,提高碳烟的氧化速度,因而可以明显改善柴油机的烟度和CO;优化的喷射参数结合EGR可以显著降低NO_x和烟度。 相似文献
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EGR率对生物柴油颗粒纳米结构的影响 总被引:1,自引:0,他引:1
为研究同时运用废气再循环(EGR)技术和燃用生物柴油对柴油机排气颗粒纳米结构的影响,分别采集0%,15%,30% EGR率下186F柴油机燃用生物柴油时的排气颗粒,并用激光拉曼光谱仪测得颗粒光谱,使用五带法对一阶拉曼光谱进行拟合,分析拟合曲线参数,计算颗粒微晶尺寸和碳碳键长度。结果表明:EGR率为30%时,生物柴油颗粒光谱的半高宽(FWHM)最大,代表化学异相性最强并且颗粒中的物质种类最多,随着EGR率降低,半高宽逐渐减小;当EGR率从0%升高到30%,ID/IG逐渐增大,代表石墨化程度降低,颗粒中的石墨结构减少;同时,ID1/ID2从0% EGR率的8左右降低到15%和30% EGR率的4左右,代表EGR率升高,颗粒内部缺陷由空位缺陷向石墨烯边缘缺陷发展;随着EGR率升高,微晶尺寸逐渐减小,碳碳键长度基本不变。 相似文献
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Kwang Hee Yoo Alexander K. Voice André L. Boehman 《Proceedings of the Combustion Institute》2021,38(4):5529-5538
This study investigates the effects of intermediate temperature heat release (ITHR) on autoignition reactivity of full boiling range gasolines with different octane sensitivity through intake temperature and simulated exhaust gas recirculation (EGR) sweeps in a homogenous charge compression ignition (HCCI) engine. To isolate the ITHR effects, low temperature reactivity was suppressed through the use of high intake temperature and low intake oxygen mole fraction. For quantification of ITHR, a new method was applied to the engine data by examining the maximum value of the second derivative of heat release rate. Combustion phasing comparisons of fuels with octane sensitivity showed that fuel with less octane sensitivity became more reactive as intake temperature and simulated EGR ratio decreased, while fuel with higher octane sensitivity had a reverse trend. For all of the fuels that were tested, the amount of ITHR increased as the intake temperature and oxygen mole fraction increased. These ITHR trends, depending on octane sensitivity, were almost identical with the trends of combustion phasing, showing that ITHR significantly affects fuel autoignition reactivity and determines octane sensitivity. 相似文献
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为了验证合成气台架上组合式催化剂((Co-Mo)/Al2O3)优异的选择催化甲醇还原NO的性能,试验在一台由增压中冷,废气再循环的电控单体泵柴油机改造的DMCC发动机上实施。结果表明:提高甲醇喷射量和EGR率,推迟柴油喷射时刻均会改善甲醇-SCR的催化效率。甲醇最优喷射量受到HC减活化作用和HC完全氧化反应的控制。各工况下甲醇-SCR对PM排放的影响较小。DMCC发动机耦合甲醇-SCR系统可以实现NOx的超低排放。A25、A75和B75工况点下的NOx体积分数的最低值分别为64×10^-6、66×10^-6和47×10^-6。 相似文献
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电控EGR阀是废气再循环技术中重要部件,主要包括步进电机式、电磁式和直流电机式,目前针对电控EGR阀测试系统研究尚不充分。为了实现对电控EGR阀各项技术指标的测试,研制了一套电控EGR阀综合性能测试系统。系统由驱动单元、控制单元、测试单元组成。驱动单元以电控EGR阀驱动器为驱动核心,控制单元以可编程控制器为控制核心,测试单元由各项指标的测试模块组成。通过对各项技术指标测试工艺流程设计,系统实现了对电控EGR阀流量特性、内漏性能、响应时间和阀内位置感应器性能的自动测试。实验结果表明,该系统稳定可靠,各项参数的机器能力指数Cmk均超过1.67,满足技术要求。系统提供了一种针对电控EGR阀综合性能的测试方案,并成功应用于某企业电控EGR阀生产测试车间。 相似文献
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Peyman Bashi Shahabi Hamid Niazmand Mohammad Reza Modarres Razavi 《Particle & Particle Systems Characterization》2012,29(4):253-262
Exhaust Gas Recirculation (EGR) method has already shown its benefits on controlling NOx emissions in internal combustion engines. An important issue associated with this method is homogeneous cylinder‐to‐cylinder distribution of the recirculating gas. Any maldistribution leads to power reduction and increase of other pollutants, which are strictly limited by recent emission laws. In addition to EGR, these limitations force the engine manufacturers to recycle blowby gases into the cylinders as homogeneous as possible. Since geometrical parameters and injection locations of EGR/blowby have substantial effects on homogenous cylinder‐to‐cylinder distribution of EGR/blowby gases, any developments in identifying the injecting locations with the least EGR/blowby maldistribution are of great practical importance. The existing experimental and numerical methods for evaluating the EGR/blowby maldistribution are based on the injection of air with different temperature or of different gas (mostly CO2) from the main air stream. However, these methods are time consuming due to the large number of possible injection locations. It has been shown that the most uniform distribution cannot be obtained by just a single injection point; therefore, the study of simultaneous injection points becomes inevitable. Clearly, such a study is practically impossible with the present methods. In this research a new method based on particle tracking is proposed, which greatly reduces the time and effort to find the injection locations with the least maldistribution, especially when multiple injections are considered. 相似文献
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This paper describes an adaptive quarter wave tube used to attenuate a tone from the exhaust noise of a large diesel engine. A sliding-Goertzel algorithm was used to calculate the phase angle of the transfer function between a microphone in the adaptive quarter wave tube and in the main exhaust duct. The control system adjusted the length of the adaptive quarter wave tube until the phase angle was −90° and caused the sound pressure level at the cylinder firing frequency in the exhaust duct to be minimized. The system was able to adapt to changes in engine speed, exhaust gas temperature, and load applied to the engine. The results demonstrate that the sliding-Goertzel algorithm can be used effectively to estimate the phase angle in an adaptive–passive acoustic control system. 相似文献