EMISIA SA , Antoni Tritsi 21 , GR 57001 , Pylaia , Greece.
School of Civil Engineering , University of Queensland , Brisbane , Queensland 4001 , Australia.
Environ Sci Technol. 2019 Apr 16;53(8):4440-4449. doi: 10.1021/acs.est.8b07223. Epub 2019 Mar 26.
This study reports on the results of gaseous pollutants emission measurements of double-decker buses in an urban road network, using portable emission measurement systems (PEMS). Measured vehicles were tested by following in-service buses on regular routes. Six Euro II and Euro III buses were retrofitted with diesel particulate filters (DPF) and selective catalytic reduction (SCR) or a combined SCR+DPF (SCRT) device. Substantial and statistically significant technology impacts were observed for several pollutants. Optimized SCR and SCRT retrofit technology reduced real-world NO emissions by approximately 70%, on average. Retrofit DPF slightly reduced NO emissions but increased direct NO emissions by more than a factor of 8, on average. SCRT led to about 70% lower NO levels than DPF alone, but for some vehicles higher NO levels were observed as compared with the "no retrofit" situation, warranting further investigation. None of the SCR systems were found to lead to a substantial increase in NH emissions after operation optimization. High NH and NO emissions were occasionally observed while experience with the system calibration was being accumulated. Observed average NO emission levels for "DPF+SCR" technology were relatively high at 182 mg/kg fuel, corresponding to 1.5% of total greenhouse gas emissions. The study shows that SCR retrofit programs can be effective for NO reduction of transit buses but that proper calibration and regular emission monitoring are required.
本研究报告了使用便携式排放测量系统（PEMS）对城市道路网络中双层巴士气态污染物排放测量的结果。测量车辆通过跟随常规路线上的现役巴士进行测试。六辆欧 II 和欧 III 巴士配备了柴油颗粒过滤器（DPF）和选择性催化还原（SCR）或 SCR+DPF 组合（SCRT）装置。对于几种污染物，观察到了实质性的、具有统计学意义的技术影响。经过优化的 SCR 和 SCRT 改装技术平均可将实际道路 NOx 排放量减少约 70%。DPF 改装略微降低了 NOx 排放量，但平均直接 NOx 排放量增加了 8 倍以上。SCRT 导致的 NO 水平比单独的 DPF 低约 70%，但对于一些车辆，与“无改装”情况相比，NO 水平更高，需要进一步调查。在进行操作优化后，没有发现任何 SCR 系统会导致 NH 排放量显著增加。在系统校准经验积累的过程中，偶尔会观察到 NH 和 NO 排放较高的情况。对于“DPF+SCR”技术，观察到的平均 NO 排放水平相对较高，为 182 毫克/千克燃料，相当于总温室气体排放量的 1.5%。研究表明，SCR 改装计划可有效减少过境巴士的 NOx 排放，但需要进行适当的校准和定期排放监测。
