封装结构对催化剂起燃性能的影响

The Influence of Packaging Structure on the Ignition Performance of DOC Catal

对现有柴油机氧化型催化转化器(Diesel Oxidation Catalyst,DOC)进气导流结构进行优化,通过测试两种结构DOC老化前后的HC起燃性能,对起燃、老化过程及影响因素进行研究。结果表明:增加前整流板可以有效提高载体的内部温度以及流场的均匀性,最高流速从11.3m/s降低到10.6m/s,速度均匀性系数从0.947提升到0.961。柴油机颗粒捕捉器(Diesel Particulate Filter,DPF)再生时,DOC内部存在完全起燃、不完全起燃、无法起燃三种状态,随着HC喷射量的变化,三种状态互相转变,通过优化HC最大油量限制,能够防止HC泄露过大或者区域温度过高。封装结构导致的局部空速过大、催化剂老化后性能不足是催化剂老化后不起燃的主要原因,设计开发时结合流场仿真结果优化流场分布或选择合适的DPF传感器位置,可以改善再生效率,提高DOC的耐久性。

The existing DOC inlet diversion structure was optimized,and the ignition performance of HC before and after aging of two DOC structures was tested.The ignition,aging process and influencing factors were studied.The results show that the addition of the front rectifier plate can effectively improve the internal temperature and flow field uniformity of the carrier,the maximum flow rate is re-duced from 11.3m/s to 10.6m/s,and the velocity uniformity coefficient is increased from 0.947 to 0.961.During DPF regeneration,there are three states inside DOC:complete ignition,incomplete ignition and non-ignition.With the change of HC injection volume,the three states change with each other.By optimizing HC maximum oil volume limit,large HC leakage or excessive regional high tem-perature can be prevented.The main reasons of non-ignition of catalyst after aging are the excessive local space velocity caused by package structure and the insufficient performance of catalyst after aging.Optimization of flow field distribution or selection of appropri-ate DPF sensor location combined with flow field simulation results during design and development can improve regeneration efficiency and enhance DOC durability.