莫瑞,刘学渊,吴瑞婷,等.基于非道路用柴油机选择性催化还原混合器优化及验证研究[J].内燃机工程,2024,45(6):31-38. |
基于非道路用柴油机选择性催化还原混合器优化及验证研究 |
Research on Optimization and Verification of Selective Catalytic Reduction Mixer for Off-Road Diesel Engines |
DOI:10.13949/j.cnki.nrjgc.2024.06.004 |
关键词:选择性催化还原 混合器 均匀性 结晶 |
Key Words:selective catalytic reduction(SCR) mixer homogeneity crystallization |
基金项目:云南省教育厅科研基金项目(2022J0500);云南省农业联合面上基金项目(202101BD070001-110) |
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摘要:为了解决装载机空间小、筒式后处理无法布置的问题,提出一种U型非道路用的柴油机选择性催化还原器(selective catalytic reduction, SCR)系统混合器优化及结晶性能验证方案。首先,通过计算流体动力学(computational fluid dynamics, CFD)软件,对建立的3种柴油机U型SCR系统典型混合器结构模型进行了3种典型工况条件下湍流运动、速度场和氨(NH3)分布均匀性等性能的数值仿真分析,研究了不同混合器结构对NH3分布及NOx转化效率的影响。基于仿真结果分析,部分结构设计方案可以加速液滴破碎、水解和雾化过程,提高NH3的分布均匀度,并提高SCR系统在新鲜状态下的NOx转化效率,但这些方案更容易产生并累积结晶,从而导致SCR系统的NOx转化性能下降。因此提出了一种组合导流装置、扰流板、出气孔板等设计的柴油机U型SCR系统混合器方案优化新方法,获得一款同心、内外筒式静态混合器结构,搭载装载机发动机结晶试验失效时长大于28.0 h。 |
Abstract:In order to solve the problem that the loader space is small and the cylindrical post-processing cannot be arranged, a hybrid optimization and crystallization performance verification scheme of non-road diesel selective catalytic reduction (SCR) system with U-type structure was proposed. Through computational fluid dynamics (CFD), the turbulent motion, velocity field and ammonia (NH3) distribution uniformity of the typical mixer structure model of 3 U-type SCR systems for diesel engines under 3 typical working conditions were simulated and analyzed. The influences of different mixing structures on NH3 distribution and NOx conversion efficiency were studied. Based on the analysis of simulation results, some structural design schemes can accelerate the process of droplet breaking, hydrolysis and atomization, improve the distribution uniformity of NH3 and the NOx conversion efficiency of SCR system in the fresh state. But these schemes are more likely to generate and accumulate crystals, resulting in a decline in the NOx conversion performance of SCR system. Therefore, a new method was proposed to optimize the mixer scheme of U-type SCR system of diesel engine, which was designed with a combination of guide device, spoiler and vent plate, etc. A concentric internal and external cylinder static mixer structure was obtained. The duration of crystallization test failure of engine carrying loader was more than 28.0 h. |
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