掺混PODE对DOC+CDPF氧化及再生特性的影响

在高压共轨柴油机上研究了使用掺混20%聚甲氧基二甲醚的柴油(D80P20)对搭载柴油氧化型催化器(DOC)和催化型颗粒捕集器(CDPF)的后处理装置(DOC+CDPF)的影响,包括小负荷时的低温氧化特性和大负荷时的颗粒物加载和再生特性.研究表明:小负荷工况下在1400~2000 r/min内,DOC和DOC+CDPF对柴油排放的CO转化效率平均分别高达70%和90%,而对D80P20排放的CO转化效率则仅近19%和36%,燃用柴油时DOC和CDPF后端的排气升温现象较为明显,低温氧化特性优于D80P20;在大负荷低速工况下,燃用D80P20时,DOC前/后两端排气氧质量分数以及NO2排放均明显高于柴油,但CO原始排放和不透光烟度显著低于柴油.因而DOC+CDPF对D80P20的CO、PM氧化放热量较低,DOC后端温升明显低于柴油.此外,大负荷下DOC+CDPF对D80P20排放的CO净化效率和PM氧化再生效率高达近100%,DOC+CDPF前/后端压差峰值仅是柴油的1/3,其可显著降低CDPF的堵塞风险,减少主动再生频率.

Effect of Blending PODE on DOC+CDPF Performance of a Diesel Engine

Effects of D80P20 fuel(diesel blended 20%polyoxymethylene dimethyl ethers)on low temperature oxidation performance of the DOC+CDPF at low load conditions,and on particle loading and regeneration of the CDPF at high load conditions were experimented on a high pressure common rail diesel engine with DOC and CDPF aftertreatment devices.Experiment results show that,in speed range of 1400—2000 r/min under low load conditions,the CO conversion efficiency of DOC and DOC+CDPF for diesel is as high as 70%and 90%respectively,while D80P20 reaches only 19%and 36%respectively.Diesel gives better low temperature oxidation characteristics than D80P20 and hence the exhaust temperature increases more obviously after the DOC and CDPF.Under high-load and low-speed conditions,D80P20 gives significantly higher oxygen and NO2 concentrations in the front and rear of the DOC than diesel,but much lower engine-out CO and opacity smoke than diesel.Therefore,D80P20 presents lower CO and PM oxidation heat release of DOC+CDPF,and much lower DOC rear temperature rise than diesel.In addition,D80P20 gives nearly 100%of the CO conversion efficiency and particle matter(PM)oxidation regeneration efficiency and 1/3 lower peak pressure difference of the DOC+CDPF than diesel under high load conditions,leading to significant reduction of CDPF clogging risk and active regeneration frequency.