Abstract ▼ AI-Helper

The selective catalytic reduction(SCR) system is a highly-effective device for reducing NOx in diesel engines. Generally, ammonia(NH₃) generated from a liquid urea-water solution is used as the reductant. The ideal ratio of NH₃ molecules to NOx molecules is 1:1 based on NH₃ consumption and having NH...

The selective catalytic reduction(SCR) system is a highly-effective device for reducing NOx in diesel engines. Generally, ammonia(NH₃) generated from a liquid urea-water solution is used as the reductant. The ideal ratio of NH₃ molecules to NOx molecules is 1:1 based on NH₃ consumption and having NH₃ available for reaction of all of the exhaust NOx . SCR system has good NOx conversion performance in the temperature window about 250 to 400℃, low space velocity also leads to increase of NOx conversion efficiency, due to long residence time in the catalyst. This paper basically reviews a laboratory study to evaluate the effects of NOx and NH₃ concentrations, gas temperature and pace velocity on the NOx conversion efficiency of the SCR system. The maximum conversion efficiency is indicated when the NH₃ to NOx ratio is 1.2 and the space velocity is 30,000 h-1 without NH₃ slip. But, NH₃ slip increases when NH₃ to NOx ratio becomes high, specially in the low NOx conversion cases. Based on results of the rig-test, this study suggests the control strategy of NH₃ injection for optimizing NOx conversion efficiency and NH₃ slip.

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