Characterization and Reduction of Nano and Ultra Fine Particulate Emissions from Diesel Engines: A look beyond 2010 Emission Regulations

近年来，柴油汽车在欧洲的销量超过了汽油汽车。虽然柴油车的行驶里程比汽油车多25-35%，二氧化碳排放量也比汽油车少，但它们排放的颗粒物却是汽油车的25- 400倍。柴油废气是细颗粒物、超细颗粒物和纳米颗粒物的最大来源之一，这些颗粒物在落到地面之前会在空气中悬浮很长一段时间。接触纳米烟尘颗粒可导致各种严重的健康问题，包括：哮喘加重、慢性支气管炎、肺功能下降、心跳不规则、心脏病发作以及患有心脏病或肺病的人过早死亡。文献表明，发动机尾气中的纳米颗粒数量密度可高达5 × 10^11颗粒/cm3，甚至可能产生低于已知最低烟尘阈值的纳米颗粒。通过使用DPF和替代燃料，可以减少废气中总烟灰质量，但仍占超细颗粒和纳米颗粒的大部分。影响健康风险的是颗粒物的数量、密度和表面积，而不是实际的烟尘质量。本项目旨在更好地了解燃油（BTL、GTL和生物柴油）对缸内最有害超细颗粒和纳米颗粒产生的影响，以及在不同喷射和EGR策略下使用和不使用催化剂辅助颗粒过滤器时废气烟尘颗粒的大小、数量分布、形态和组成。这些研究将分两个阶段进行：在第一阶段，将使用先进的激光诊断技术（如时间分辨激光诱导白炽灯）研究汽缸内烟尘颗粒的产生和氧化。这些缸内测量将在单缸光学发动机中进行。在第二阶段，取样将在多缸发动机的排气处进行：热热取样和扫描迁移率粒度测定都将被采用。通过热致取样收集的烟尘样品将进一步通过透射电子显微镜（TEM）和能量色散x射线（EDX）分析进行研究，以了解烟尘的尺寸，结构，形态和组成。

In recent years, more diesel than gasoline cars have been sold in Europe. Although diesel cars obtain 25-35% better mileage and emit less carbon dioxide than similar gasoline cars, they can emit about 25 to 400 times more particulate matter. Diesel exhaust is one of the largest sources of fine, ultra-fine and nano particulates, and they are suspended in the air for a long period of time before they settle on to the ground. Exposure to nano-soot particulates can lead to a variety of significant health problems including: aggravated asthma, chronic bronchitis, reduced lung function, irregular heartbeat, heart attack, and premature death in people with heart or lung disease. It has been shown in the literature that the nano particle number density from the engine exhaust could be as high as 5 x10^11 particles/cm3 and it is possible to produce nano-particles even below the lowest known sooting thresholds. Through the use of DPF and alternate fuels, the total soot mass can be reduced in the exhaust, but still it accounts for most of the ultra-fine and nano particulates. It is the particle number density and their surface area, which accounts for the health risk and not the actual soot mass.This project aims to understand better the fuel (BTL, GTL and bio-diesel) effects on the in-cylinder production of the most harmful ultra-fine and nano particulates and the exhaust soot particulate size, number distribution, morphology and composition with and without catalyst aided particulate filter under different injection and EGR strategies. These investigations will be carried out in two stages: In the first stage in-cylinder production and oxidation of soot particulates will be investigated using advanced laser diagnostics such as time resolved laser induced incandescence. These in-cylinder measurements will be carried out in a single cylinder optical engine. In the second stage sampling will be performed at the exhaust of a multi-cylinder engine: both thermophoric sampling and scanning mobility particle sizing will be employed. The soot samples collected through thermophoric sampling will further be investigated in a transmission electron microscope (TEM) and an energy dispersive x-ray (EDX) analysis to understand the size, structure, morphology and the composition of the soot.