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首页> 外文学位 >Opposing effects of recirculated gases during cranking on cold start of diesel engines.
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Opposing effects of recirculated gases during cranking on cold start of diesel engines.

机译：起动过程中再循环气体对柴油机冷启动的相反影响。

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摘要

Enhancing cold start of DI diesel engines is the motivation behind this study. A new control strategy is proposed to reduce the cranking period and the white smoke emissions. In the strategy, the gases leaving the cylinder during the cranking period are recycled back into the intake manifold using two different methods. In the first method the engine-out gases during cranking are recirculated into the intake manifold and their rate is controlled by a CGR (Cranking Gases Recirculation) valve, without applying any back pressure on the engine. In the second method a butterfly valve is installed in the exhaust system after the turbocharger to increase the back pressure and the rate of recirculated gases. Since there is no combustion during cranking, these gases contain evaporated hydrocarbons (HCs) and partial oxidation products such as formaldehyde (HCHO). HCs and HCHO have two opposing effects. HCs enhance the autoignition process, while the HCHO has an opposite effect.;These opposing effects are being investigated by three different approaches. The first is experimentally in a multi-cylinder proto-type engine. The second is using high speed imaging in an optically accessible engine. The third is by using CFD and chemical kinetic simulation to gain a better understanding of the effect of the recirculated gases on the autoignition process during cold starting of a direct injection diesel engine. Cold start experiments are conducted on a 1.2L Ford DIATA 4-cylinder, 16-valve, 70 mm bore, 78 mm stroke and 19.5 compression ratio, water cooled, turbocharged and intercooled diesel engine. The engine is equipped with a common rail injection system, EGR system and a swirl control mechanism. The engine is installed in a cold room and the ambient temperature is electronically controlled. Before starting, the engine is soaked at the desired room temperature for at least eight hours. The analysis of the data demonstrated the effect of two CGR methods on reducing the cranking period and HCs emissions. The images showed the effect of aldehydes on hindering the autoignition and combustion processes. The simulation covered a wide range of the hydrocarbons and aldehydes concentrations and their effect on the ignition delay.;The simulation results agreed with the experimental findings. The results of this work will help in developing strategies to reduce the cranking period, fuel consumption and white smoke emitted during cold starting of diesel engines. In addition, a more understanding will be developed of the role of aldehydes in combustion instability and misfiring after first firing experienced in cold starting of diesel engines.
机译：加强DI柴油机的冷启动是本研究的动机。提出了一种新的控制策略，以减少启动周期和白烟排放。在该策略中，使用两种不同的方法将在起动期间离开气缸的气体再循环回进气歧管。在第一种方法中，发动过程中的发动机排出气体再循环到进气歧管中，其流量由CGR（发动气体再循环）阀控制，而无需在发动机上施加任何背压。在第二种方法中，蝶阀在涡轮增压器之后的排气系统中安装，以增加背压和再循环气体的比率。由于在启动过程中没有燃烧，这些气体包含蒸发的碳氢化合物（HCs）和部分氧化产物，例如甲醛（HCHO）。 HC和HCHO具有两个相反的作用。 HCs增强了自燃过程，而HCHO则具有相反的作用。这些相反的作用正在通过三种不同的方法进行研究。首先是在多缸原型发动机上进行实验。第二个是在光学可访问引擎中使用高速成像。第三是通过CFD和化学动力学模拟来更好地理解在直喷式柴油机冷启动过程中再循环气体对自燃过程的影响。在1.2升福特DIATA 4缸，16气门，70毫米缸径，78毫米冲程和19.5压缩比，水冷，涡轮增压和中冷柴油机上进行冷启动实验。发动机配备了共轨喷射系统，EGR系统和涡流控制机构。发动机安装在冷藏室中，环境温度由电子控制。在启动之前，将发动机在所需的室温下浸泡至少八小时。数据分析证明了两种CGR方法对减少启动周期和HCs排放的影响。图像显示醛对阻碍自燃和燃烧过程的影响。模拟涵盖了广泛的碳氢化合物和醛类浓度及其对点火延迟的影响。模拟结果与实验结果相符。这项工作的结果将有助于制定减少柴油发动机冷启动期间的起动时间，燃料消耗和白烟排放的策略。此外，在柴油机冷启动中首次点火后，醛在燃烧不稳定性和不点火中的作用将得到更多的了解。

著录项

  • 作者

    Rofail, Rafik N.;

  • 作者单位

    Wayne State University.;

  • 授予单位 Wayne State University.;
  • 学科 Engineering Automotive.;Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 217 p.
  • 总页数 217
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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