共查询到20条相似文献,搜索用时 187 毫秒
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分别在数种化油器式发动机轿车,对装用圆柱形铂-铑贵金属催化器进行了台架试验和使用试验,以考核无调节混合气浓度功能的催化器降低汽车有害排放物的效果。介绍了试验方案,给出了试验结果对其进行了分析。 相似文献
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Urea-SCR system optimization with various combinations of mixer types and decomposition pipe lengths
Y. S. Cho S. W. Lee W. C. Choi Y. B. Yoon 《International Journal of Automotive Technology》2014,15(5):723-731
The demand for NOx after-treatment system has increased dramatically due to the stricter NOx emission regulations for diesel vehicles. The urea-SCR system is one of the NOx after-treatment methods found to be quite effective to meet the regulation requirement enforced by various authorities including the Euro-6. In order to develop an effective urea-SCR system, it is critical to establish an even distribution of reductant over the catalyst surface since this favorable distribution can increase reduction reaction and in turn, improve NOx conversion efficiencies. In the current study, a number of design variations of the urea-SCR system which included two mixer types and three decomposition pipe lengths, were evaluated systematically using CFD analysis and experimental measurements. The purpose of the CFD analysis was to estimate the distribution of reductant within the urea-SCR system with a specific configuration and the purpose of the engine emission test was to measure the amount of NOx reduction, respectively. The results from the systematic analysis revealed the relation between the reductant distribution over the SCR and the performance of the NOx reduction. 相似文献
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This paper presents an observer design for SCR mid-catalyst ammonia concentration estimation using tailpipe NOx and ammonia sensors. Urea-SCR has been popularly used by Diesel engine powered vehicles to reduce NOx emissions in recent years. It utilizes ammonia, converted from urea injected at upstream of the catalyst, as the reductant
to catalytically convert NOx emissions to nitrogen. To simultaneously achieve high SCR NOx conversion efficiency and low tailpipe ammonia slip, it is desirable to control the ammonia storage distribution along the
SCR catalyst. Such a control method, however, requires a mid-catalyst ammonia sensor. The observer developed in this paper
can replace such a mid-catalyst ammonia sensor and be used for SCR catalyst ammonia distribution control as well as serves
for fault diagnosis purpose of the mid-catalyst ammonia sensor. The stability of the observer was shown based on the sliding
mode approach and analyzed by simulations. Experimental validation of the observer was also conducted based on a medium-duty
Diesel engine two-catalyst SCR system setup with emission sensors. 相似文献
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配电线路的电缆选型除考虑载流量、电压损失和热稳定外,还应对长距离配电线路的断路器进行灵敏度校验。结合工程实例,对隧道内远距离配电线路的断路器灵敏度进行探讨,阐述远距离配电线路安全性校验中断路器灵敏度校验的必要性和重要性,并提出当校验结果不满足要求时,可采用加大电缆截面、装设具有剩余电流保护功能的断路器、在满足配电和保护功能的前提下降低断路器动作电流的整定值等方法,从而提高断路器的灵敏度。 相似文献
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FSC赛车空气套件CFD优化设计 总被引:1,自引:0,他引:1
在满足FSC赛车设计规则要求前提下,对空气套件进行了结构优化设计,重点完成了赛车尾翼的优化设计和分析。利用CFD技术对赛车车身模型进行了外流场分析,并通过在赛车尾部加装不同间隙和攻角的尾翼,进行车身外流场模拟对比分析,研究尾翼在改善赛车气动特性方面的影响规律,研究确定了空气动力学装置在不同比赛项目时的调教策略。通过对比分析赛车车辆周围气流的压力分布和速度分布规律,研究高速赛车的负升力效果,对于提高赛车的操纵稳定性和安全性具有非常重要的意义,对于指导赛车尾翼的正确安装、确定尾翼在不同比赛项目时的调教策略有一定的指导意义。 相似文献
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沥青路面车辙产生的主要原因是沥青混合料抗剪强度不足所致,仅依赖改性沥青的粗型密级配沥青面层将无法满足路面抗车辙要求.在沥青混合料中掺加各种外加剂后,对其动稳定度进行比较、分析,表明该方法是提高沥青混合料路用性能的有效途径. 相似文献
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为减少甚至解决倒虹吸隧道中污物沉积和堵塞问题,提出一种新型倒虹吸隧道工作井智能排污结构。利用SolidWorks软件对隧道及工作井进行建模和数值模拟优化,并进行物理模型试验验证。研究结果表明: 1)外加辅助块体有助于降低湍流位置,而在一定范围内改变入口处水流流速对引水结构的影响不大; 2)在工作井内加入矩形三角块和在入口区加阶梯双三角块、出口区加矩形三角块是倒虹吸隧道较优的智能排污结构方案; 3)雨水方沟断面尺寸大小会对水流湍流位置和流速分布有所影响,但添加适当的辅助块仍具有较好的智能排污效果。 相似文献
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实时动态路段行程时间预测的一种实用方法 总被引:8,自引:2,他引:8
针对智能运输系统(ITS)亟待解决的理论热点问题,利用随机服务系统理论给出进入路段(含信号交叉口)车辆数服从Poisson分布的实时动态行程时间预测的基本公式,为提高预测的精度,又结合多元统计回归方法添加修正项,进而提出一般性公式,并给出预测结果。 相似文献