A Characteristics of Particle Number Distribution for the Urea Solution Injection to Urea SCR System of Commercial Diesel Engine for an Emission Regulation

While the request of diesel engine is recently increased due to its excellent fuel economy benefit, the regulation of emission becomes reinforced. The variety of method such as engine technologies and aftertreatment systems have been developed and applied to meet the criteria of regulation so far. One of recognizable technologies utilized in a heavy commercial vehicle is SCR system using urea solution as a reductant, which eliminates NOx. This paper includes the experiment of a diesel engine equipped with Urea SCR system, and its emission characteristic including particle is analyzed and evaluated against its regulation. This evaluation is performed for the diesel engine using ELPI(Electric Low Pressure Impactor) under the condition of constant engine RPM and load, and injecting urea solution to SCR system, particle number distribution of particle range from 7nm to 10μm was estimated. According to the results, the particle number was increased in the proportion of amount of urea injection, and the increase of Fine particle range(< 2.5μm) was remarkable, especially. We also verified through its experiment under the different set temperature of thermodenuder and engine exhaust temperature in the different load condition is almost negligible for the change of particle number distribution, but its distribution of particle number was changed as the injection pressure was increased from 1 to 4 bar. While the increment of particle was decreased in the proportion of injection amount in the range of Fine particle, the increment of Ultra Fine particle(< 100nm) and Nano particle(< 50nm) range were shown. The increment of particle number results in the weight increase of total PM in ESC mode. According to the leading researches, new complex matter is produced in the process of urea decomposition on SCR catalysts. In this paper, it is verified that new polymeric products were created under the urea decomposition process by analyzing the PM sample collected through FTIR, TGA/DSC, as well as TEM

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See papers presented at Asia Pacific Automotive Engineering Conference, August 2007, Hollywood, CA, USA, Session: Transportation Challenges in Emerging Markets: Environment and Energy (Part 1 of 3)

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