Prediction and application of urea deposition in close-coupled dual SCR system
ZHOU Hailei
LÜ Zhihua
GENG Lei
WANG Mingda
Abstract：To meet the design requirements of the front-end selective catalytic reduction(SCR)mixer in a two-stage SCR device,a SCR urea crystallization prediction model is built in Fluent based on a chemical kinetics model to predict the quality,location,and composition distribution of urea crystals.The accuracy of the model is verified through engine bench crystallization tests.A new front-end SCR mixer is designed based on the crystallization prediction model to evaluate its performance.The results show that the simulation accuracy of crystal quality under low,medium,and high temperature conditions is 76%,79%,and 78%,respectively.The simulated crystallization position matches well with the experimental crystallization position,and the crystallization position is affected by exhaust temperature and exhaust flow rate.The crystal composition at different temperatures is basically consistent with existing related studies.The performance indicators of the new mixer are superior to existing products,with an increase of about 68%in anticrystallization ability.Ammonia uniformity and velocity uniformity are positively correlated with back pressure,while ammonia uniformity is negatively correlated with anticrystallization ability.
Keywords：diesel engine after treatment systemclose coupled mixerSCR crystallization prediction modelFluent
Publication Date：2025-07-30
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：11( 34-44 )