Cold Start Emission Characteristics of Heavy-Duty Diesel Engine under WHTC Cycle
Based on a diesel engine that meets the China Ⅵb emission standard,WHTC cycle emission testing was conducted on an engine bench equipped with a low-temperature climatic chamber.Different simulated temperatures were set and the spe-cific emission results of CO,HC,NOx ,PN,and PM were compared.Then the relationships of ambient temperature,inter-cooled temperature and exhaust temperature with exhaust pollutants were analyzed,and the differences in CO,HC,NOx ,and PN emission characteristics at different ambient temperatures during the three stages of WHTC cycle were also analyzed.The results showed that the specific emissions of NOx ,CO,and HC gradually increased,while the overall specific emissions of PN decreased,and the specific emissions of PM first decreased and then increased with the decrease of ambient temperature.The NOx emissions under -10 ℃ and -15 ℃ in frozen urea state were 1.2 times and 3.3 times of those in unfrozen urea state. NOx emission control mainly relied on DOC and EGR at stage 1 and stage 2 and was more dependent on SCR under the high torque and load conditions of stage 3.The differences caused by ambient temperatures in the CO and HC specific emission re-sults mainly occurred in stage 1.At -15 ℃ and -20 ℃ conditions,the average concentration of PN in stage 1 to stage 3 was below 100 unit/cm3 .
万方数据
维普
