DOC+CDPF对生物柴油公交车排放特性的影响

Effects of DOC+CDPF on emission characteristics of a city bus fueled with biodiesel

采用便携式排放测试系统PEMS,研究某加装催化型连续再生颗粒捕集器(DOC+CDPF)的柴油公交车长期燃用生物柴油混合燃料B5时,整车常规气态物和颗粒物排放性能随行驶里程的变化规律.结果表明:随行驶里程的增加,一氧化碳(CO),总碳氢化合物(THC),颗粒物质量(PM)减排率均呈先增后减的趋势,THC减排率在行驶里程达到2.5×104km之前呈上升趋势,之后呈降低趋势,至8×104km时THC减排率较DOC+CDPF初装时减少41.05%,CO和PM减排率在行驶里程到达3.5×104km之前均呈上升趋势,之后呈降低趋势,至8×104km时CO和PM减排率较DOC+CDPF初装时分别减少20.24%和11.74%;氮氧化物(NOx)和颗粒物数量(PN)减排率整体上均呈降低趋势,在行驶里程8×104km处,NOx和PN减排率较DOC+CDPF初装时分别降低33.83%和10.35%.B5生物柴油公交车在行驶里程到达8×104km左右时,污染物的减排率明显降低,需对DOC+CDPF后处理装置进行保养,以延长其工作寿命.

To assess the gaseous and particle emission characteristics of a city bus equipped with DOC+CDPF after-treatment fueled with diesel and biodiesel with 5% blend ratio while the driving distance increases, a study has been performed using portable emission measurement.The results show that the decreasing amplitudes of CO, THC, and PM increased first and then decreased with the increase of mileage. The degraded amplitude of THC continuously enhanced before 25000 km, and then decreased. It became lowest at 80000 km, which was 41.05% lower than the first test. The decreasing amplitudes of both CO and PM continuously increased before 35000 km, and then decreased. The degraded amplitudes of CO and PM were respectively 20.24% and 11.74% at 80000 km. The reduction of NOx and PN both showed the downward trend with the increase of mileage. The reduction amplitudes of NOx and PN both became lowest at 80000 km, which were respectively 33.83% and 10.35% lower than the first test. The gaseous and particle emissions emitted from the city bus fueled with B5 equipped with DOC and CDPF increased obviously at around 80000 km, and the decreasing amplitudes were sharply down, so the DOC+CDPF after-treatment should be maintained to extend life cycle and reduce emissions.