Department of Chemistry and Biochemistry MSC 9020 , University of Denver , Denver , Colorado 80208 , United States.
Environ Sci Technol. 2018 May 15;52(10):6070-6076. doi: 10.1021/acs.est.8b00621. Epub 2018 Apr 25.
Two California heavy-duty fleets have been measured in 2013, 2015, and 2017 using the On-Road Heavy-Duty Measurement System. The Port of Los Angeles drayage fleet has increased in age by 3.3 model years (4.2-7.5 years old) since 2013, with little fleet turnover. Large increases in fuel-specific particle emissions (PM) observed in 2015 were reversed in 2017, returning to near 2013 levels, suggesting repairs and or removal of high emitting vehicles. Fuel-specific oxides of nitrogen (NO ) emissions of this fleet have increased, and NO after-treatment systems do not appear to perform ideally in this setting. At the Cottonwood weigh station in northern California, the fleet age has declined (7.8 to 6 years old) since 2013 due to fleet turnover, significantly lowering the average fuel-specific emissions for PM (-87%), black carbon (-76%), and particle number (-64%). Installations of retrofit-diesel particulate filters in model year 2007 and older vehicles have further decreased particle emissions. Cottonwood fleet fuel-specific NO emissions have decreased slightly (-8%) during this period; however, newer technology vehicles with selective catalytic reduction systems (SCR) promise an additional factor of 4-5 further reductions in the long-haul fleet emissions as California transitions to an all SCR-equipped fleet.
2013 年、2015 年和 2017 年，加利福尼亚州的两个重型车队使用了道路重型测量系统进行了测量。自 2013 年以来，洛杉矶港的拖运车队的车龄增加了 3.3 个车型年（4.2-7.5 年），车队的周转率很低。2015 年观察到的燃料特定颗粒物排放（PM）大幅增加在 2017 年得到了扭转，恢复到接近 2013 年的水平，这表明对高排放车辆进行了维修或淘汰。该车队的燃料特定氮氧化物（NOx）排放量有所增加，而在这种情况下，NOx 后处理系统似乎表现并不理想。在加利福尼亚州北部的考顿伍德称重站，自 2013 年以来，由于车队的周转率，车队的车龄有所下降（从 7.8 岁降至 6 岁），这大大降低了 PM（-87%）、黑碳（-76%）和颗粒物数量（-64%）的燃料特定平均排放量。对 2007 年及更早车型的车辆进行了改装后的柴油颗粒过滤器的安装，进一步降低了颗粒物的排放。在这段时间内，考顿伍德车队的燃料特定 NOx 排放量略有下降（-8%）；然而，随着加利福尼亚州向配备选择性催化还原系统（SCR）的全车队过渡，具有 SCR 系统的新技术车辆有望使长途车队的排放进一步减少 4-5 倍。
