柴油机SCR尿素沉积物模拟分析

Simulation Analysis of Diesel Engine SCR Urea Deposition

构建了14步反应和11种组分的柴油机SCR尿素喷射系统详细化学反应模型。考虑了氨气和异氰酸的生成,还涉及到缩二脲、三聚氰酸和三聚氰酸一酰胺等重要固体副产物的形成。就柴油机中尿素在喷射点到催化器入口前端间的排气管路中的分解过程构建三维模型,分别调入详细机理模型与总包反应机理模型进行比较,结果表明两种机理模型预测的NH3浓度生成趋势相符,详细机理模型能够预测主要沉积物缩二脲和三聚氰酸的生成规律。

A detailed chemical reaction model of the 14-step reaction and 11 components of the diesel SCR urea injection system was constructed. Not only the formation of ammonia and isocyanic acid but also the formation of important solid by-products such as biuret, cyanuric acid and cyanuric acid monoamide are considered. A three-dimensional model was constructed for the decomposition process of urea in the diesel engine from the injection point to the exhaust pipe between the front end of the catalyst inlet, and the detailed mechanism model and the total package reaction mechanism model were respectively transferred. The results show that the trend of NH3 concentration prediction predicted by the two mechanism models is consistent. At the same time, under different exhaust temperatures, the formation of biuret and cyanuric acid in the main sediments.