灰分沉积对不同结构CDPF再生特性的影响

对某高压共轨柴油机的催化型颗粒物捕集器(CDPF)进行台架试验,研究了两种不同结构的CDPF对发动机性能的影响和不同碳载量下CDPF的压降特性。通过建立三维CDPF热力学模型,分析了灰分量和灰分分布系数对不同结构CDPF再生特性的影响。结果表明:CDPF会使柴油机动力性、经济性略有下降,但非对称结构CDPF可有效降低载体对柴油机性能的影响;CDPF压降会随载体孔道内碳烟累积量的增大而升高,非对称结构CDPF可有效减小CDPF压降,且随着碳载量增加,非对称结构的优势更加明显。灰分沉积有利于降低载体向环境传热的导热率,提高载体热容量,有利于碳烟的氧化再生;CDPF再生过程中载体的温度呈边缘低中心高、前端低后端高的分布规律。灰分分布系数对碳烟氧化速率影响较小,载体结构、灰分量和灰分分布系数对CDPF最大再生温度梯度影响也不大。

Effects of Ash Deposition on Regeneration Characteristics of CDPF with Different Structures

A bench test is conducted on the catalytic diesel particulate filter(CDPF)of a high-pressure common rail diesel engine to study the effects of different structures of CDPF on the performance of engine and the pressure drop characteristics of CDPF under different soot loadings.A 3D thermodynamic model of CDPF is established,and the influences of ash loadings and ash distribution coefficients on the regeneration characteristics of CDPF with different structures are analyzed.The results show that CDPF would lower the performance and economy of diesel engine,but the CDPF with asymmetric cell technology(ACT),i.e.asymmetric CDPF,can effectively weaken the effects of the filter on the performance of diesel engine.The pressure drop of CDPF will rise with the accumulation of soot loading in filter channels and the CDPF with ACT can effectively reduce the pressure drop of filter,and the advantage of the asymmetric CDPF becomes more obvious as the amount of soot loading increases.Ash deposition is beneficial to the reduction of the thermal conductivity of the filter to the environment and increase the heat capacity of the filter,conducive to soot oxidation regeneration.The temperature of the filter during CDPF regeneration is higher in the center and rear end and lower in the periphery and front end.The ash distribution coefficient has little effect on soot oxidation rate.The filter structure,ash loading and ash distribution coefficient also have less effects on the maximum regeneration temperature gradient of CDPF.