Ducted fuel injection (DFI) is a novel combustion strategy that has been shown to significantly attenuate soot formation in diesel engines. While previous studies have used optical diagnostics and optical filter smoke number methods to show that DFI reduces in-cylinder soot formation and engine-out soot emissions, respectively, this is the first study to measure solid particle number (PN) emissions in addition to particle mass (PM). Furthermore, this study quantitatively evaluates the use of transient particle instruments for measuring particles from skip-fired operation in an optical single cylinder research engine (SCRE). Engine-out PN was measured using an engine exhaust particle sizer following a catalytic stripper, and PM was measured using a photoacoustic analyzer. The study improves on earlier preliminary emissions studies by clearly showing that DFI reduces overall PM by 76%–79% and PN for particles larger than 23 nm by 77% relative to conventional diesel combustion at a 1200-rpm, 13.3-bar gross indicated mean effective pressure operating condition. The degree of engine-out PM reduction with DFI was similar across both particulate measurement instruments used in the work. Through the use of bimodal distribution fitting, DFI was also shown to reduce the geometric mean diameter of accumulation mode particles by 26%, similar to the effects of increased injection pressure in conventional diesel combustion systems. This work clearly shows the significant solid particulate matter reductions enabled by DFI while also demonstrating that engine-out PN can be accurately measured from an optical SCRE operating in a skip-fired mode. Based on these results, it is believed that DFI has the potential to enable fuel savings when implemented in multi-cylinder engines, both by lowering the required frequency of active diesel particulate filter regeneration, and by reducing the backpressure imposed by exhaust filtration systems.

管道式燃料喷射（DFI）是一种新颖的燃烧策略，已被证明可以显着降低柴油发动机中的烟灰形成。尽管先前的研究已经使用光学诊断和光学过滤器烟尘数量方法显示DFI分别减少了缸内烟灰的形成和发动机排出的烟尘排放，但这是除颗粒之外还测量固体粒子数（PN）排放的第一项研究质量（PM）。此外，本研究定量评估了瞬态粒子仪器在光学单缸研究引擎（SCRE）中测量跳跃燃烧操作产生的粒子的用途。在催化汽提器之后，使用发动机排气粒度仪测量发动机排气PN，并使用光声分析仪测量PM。该研究明显地表明，相对于传统柴油以1200 rpm，13.3巴的总指示燃烧量而言，DFI可使总PM降低76％–79％，而PN大于23 nm的PN降低77％，从而改进了早期的排放研究。有效压力工作条件。在工作中使用的两种颗粒物测量仪器中，使用DFI减少发动机排出的PM的程度相似。通过使用双峰分布拟合，还显示出DFI可将积聚模式颗粒的几何平均直径减小26％，这与常规柴油燃烧系统中增加喷射压力的效果类似。这项工作清楚地表明了DFI可以显着减少固体颗粒物的排放，同时还证明了可以通过以跳火模式运行的光学SCRE准确测量发动机排出的PN。基于这些结果，相信通过在降低多级柴油机主动过滤器再生所需的频率以及降低排气过滤系统施加的背压方面，DFI在多缸发动机中实施时都具有节省燃油的潜力。