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

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.