Experimental Research On Diesel Particulate Filters

Safety, energy conservation and environmental protection are three important topics in the development of today's automobile industry. Nowadays, a majority of automobiles use internal combustion engine as their power plants. Though the internal combustion engine has small volume and high thermal efficiency, the big air pollution it caused shouldn't be ignored.The particulate matter (PM) emitted from diesel engines is much more than those from gasoline engine. PM can cause DNA mutagenicity and damnification for human beings. Moreover they can reduce visibility, erode buildings and other outside materials. Because the huge number of in-using automobiles, it's unpractical to rebuild each engine. Therefore, aftertreatment technology is used to control PM emissions. Bag filters are relatively inexpensive and have high filtration efficiency as one kind of particulate filters, and they also demonstrated good reliability.In order to make this technology easier for practical application, work has been done as follows:1.Test bench for diesel particulate emission measurements on a SD1100 diesel engine was set up. A sampler was made to collect the PM with type 59 filter paper.2. While the engine speed and load were kept stable, the exhaust gas was cooled. The exhaust smoke was measured and it would decrease when the temperature fell.3. The influence of exhaust temperature on five particulate collection mechanisms including, interception, inertial impaction, sieving, diffusion, and electrostatic attraction was investigated. 4. The effects of the back pressure on filtration efficiency were investigated when the engine speed and load were constant. Within the back pressure limit, any change of the back pressure caused little change in the filtration efficiency.5. When the engine speed and temperature of the exhaust were kept stable, the mass concentration from the measured exhaust smoke was calculated and it is found that change of the load had no influence on the filtration efficiency at the medium speed.6. Ultrasonic washing and GC-MS methods have been used to analyze the components of the exhaust PM before and after the bag filter. The result showed that, after the filtration, each of the polycyclic aromatic hydrocarbons was reduced, and the total mass of the polycyclic aromatic hydrocarbons decreased more than 89 percent.