In order to avoid the urea crystallization on urea nozzle or mixer wall of conventional SCR catalyst under low load conditions with low exhaust gas temperature, the structural optimization of SCR catalyst was conducted with CFD method and a newtyped SCR mixer was designed. The corresponding distribution pattern of urea nozzle was also proposed. The simulation results show that the optimized SCR converter can promote the mixing between urea solution and exhaust gas. The thermolysis rate and concentration distribution uniformity index of NH3 for fore end face increases by 9.76% and 6.06% respectively. A series of verifications such as steadystate test, ETC test and 30hour urea crystallization test are conducted on the test bench. The test results show that the new structure can increase NOx conversion rate by 0.89%, 1.76% and 0.61% respectively when the ratio of ammonia and nitrogen is 0.7, 0.9 and 1.2. Compared with the original structure, the new structure can significantly reduce NOx emission and avoid urea crystallization on the wall of new mixer.
SHI Dailong
,
Fu Song
,
BAI Shuzhan
,
YANG Ting
,
ZHANG Xiaoli
,
WANG Yibao
. Optimization Design and Experimental Study of SCR Converter for Heavy-Duty Diesel Engine[J]. Vehicle Engine, 2018
, 0(5)
: 65
-70
.
DOI: 10.3969/j.issn.1001-2222.2018.05.012
