废气循环 (EGR) 对柴油发动机碳质 PM 排放的影响
Xinling Li1,2, Pengcheng Zhao3
1College of Smart Energy, Shanghai Jiao Tong University, Shanghai, 200240, China. lxl@sjtu.edu.cn.
概括
柴油发动机的废气再循环 (EGR) 增加了颗粒物 (PM),特别是元素碳 (EC) 和多环芳 (PAH),而更高的EGR率导致更大的排放. 将EGR与其他策略相结合,可以帮助减少碳质PM.
科学领域:
- 环境科学 环境科学
- 机械工程 机械工程
- 燃烧科学 燃烧科学
背景情况:
- 废气循环 (EGR) 对于减少柴油发动机中的氧化 (NOx) 非常重要.
- 然而,EGR的应用往往会加剧颗粒物 (PM) 排放.
- 在高EGR率下,PM的详细化学成分仍未得到充分研究.
研究的目的:
- 综合分析柴油发动机中有机碳 (OC),元素碳 (EC) 和半挥发性有机化合物 (SVOC) 的排放特性.
- 在各种稳定状态条件下,研究轻度和高EGR率对这些排放的影响.
- 确定受EGR影响最严重的PM的特定组件.
主要方法:
- 在PM中分析OC (OC1-OC4),EC (EC1-EC2),18个n-和20个多环芳 (PAH) 的含量.
- 在四个稳定状态条件下测试常轨柴油发动机,其EGR速率各不相同 (高达最大稳定燃烧).
- 排放变化与发动机操作参数的相关性,如热释放率和空气-燃料比率.
主要成果:
- EGR率对EC排放产生重大影响,从0-30%略有增加,从30-45%的EGR急剧上升.
- 总碳 (TC) 组成随着EGR率的增加而向EC1和EC2转移.
- 所有分析的PAH和n- (C16-C33) 排放量随着更高的EGR率而增加,PAH的敏感性低于EC.
结论:
- 柴油发动机中EGR率是EC和PAH排放的主要驱动因素,比负载或转速更重要.
- 高的EGR率导致燃料衍生和石油衍生n-基的形成增加.
- 建议将EGR与其他控制策略相结合,以减轻碳质PM的形成.
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