The Effects Of DOC And DPF On Emission Performance Of Diesel Engine

With the environmental pollution increasing rapidly, in order to control thepoisonous emission from vehicles validly, many countries have formulated a series ofemission regulations which meet the international requirement. Diesel technology hasbeen confronted with the challenge of more severe emission limits while developingquickly. Under the circumstances, apart from taking advanced technological measuresto realize high-efficiency internal purification, how to make reasonable use of theafter-treatment devices to meet the emission limit, and then, to drastically solve theproblem of diesel engine poisonous emission, has become the key to diesel enginetechnology developing recently.This project exactly meet the requirement of market and company. In order toresearch the after-treatment devices performance, bench tests were conducted on acommon-rail electronic-controlled heavy-duty diesel engine named CY4102-CE4B,according to the European steady state cycle (ESC) from emission regulationGB17691-2005. The main research and conclusions are as follows:1. Under the circumstance of using the GB-Ⅳ fuel, when different kind of dieseloxidation catalyst (DOC) and diesel particulate filter (DPF) provide by Sunny MetalInc. were equipped on the diesel engine, the emission performance were measured byexhaust gas analyzer, partial flow dilution channel system and micro balance,meanwhile, the purification efficiencies of different after-treatment devices onemission pollutants were also figured out. In addition, by comparing brake specificemission to emission limit GB-Ⅳ, technical parameters and theoretical direction wereprovided to the company to improve the after-treatment devices. This part of the testresults show that:(1) diesel engine with DOC, C-DPF, DOC+(P-DPF), DOC+(C-DPF) after the purification effect of CO and HC is very obvious, especially in theDOC+(C-DPF), the conversion efficiency of CO and HC can be as high as99.8%and 91.8%respectively, and P-DPF CO and HC emissions impact is extremely weak;(2)compared with the original machine, equipped with DOC, P-DPF, C-DPF, DOC+(P-DPF), DOC+(C-DPF) after these five kinds of post-processing system, it has no effecton NOX emissions are almost, NOXemissions to a constant;(3) P-DPF, C-DPF,DOC+(P-DPF), DOC+(C-DPF) for diesel engine particles PM purification effect aremore apparent, conversion efficiency between58%-66%, of which DOC+(C-DPF) asthe highest, value of65.7%, and the purification of DOC to PM to have certain effect,but not obvious.2. In view that China’s national conditions, regional differences, respectively,using the Beijing market countries Ⅳ diesel (0#), the Beijing market countries Ⅴdiesel (0#) and Luoyang sell diesel (0#), on the original machine and add the same typeof DOC+(P-DPF) combination of ESC test cycle, contrast different quality affect theperformance of fuel on diesel engine exhaust emissions, in addition, the use of highperformance liquid chromatography and the fluorescence of sulfur and nitrogenanalyzer, respectively determine the above three kind of main chemical compositionsof the fuel oil quality, and considering the change of engine emission characteristics,emphatically analyzed the fuel chemical composition change on the effects of after-treatment device working effect. The results show that:(1) with the total aromatics infuel oil (including the ring, double ring and polycyclic aromatic hydrocarbons) content,to reduce the original CO and HC emissions significantly reduced, and the originalmachine NOXemissions only modestly;(2) the original machine PM emissionsdecreased with the content of polycyclic aromatic hydrocarbons in the fuel is reduced,when polycyclic aromatic hydrocarbon content lower than3.5%, the PM emissionschanged little;(3) the high sulfur content in fuel oil, can make the DOC poisoning intail gas PM emission greatly increased at the same time; And when the sulfur contentis low, as the sulfur content, DOC+(P-DPF) combination for PM conversion efficiencycan be increased, at the same time on the conversion efficiency of CO and HC hasedged higher.