School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing, 100084, China.
School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing, 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing, 100084, China.
Environ Pollut. 2020 Jul;262:114280. doi: 10.1016/j.envpol.2020.114280. Epub 2020 Feb 29.
Emissions of major reactive nitrogen compounds, including nitric oxide (NO), nitrogen dioxide (NO) and ammonia (NH), from heavy-duty diesel vehicles (HDDVs) place substantial pressure on air quality for many large cities in China. To control nitrogen oxide (NO) emissions from HDDVs, selective catalytic reduction (SCR) systems have been widely used since the China IV standards. To investigate the impacts of aftertreatment technologies and driving conditions on real-world emissions of reactive nitrogen compounds, a portable emissions measurement system was employed to test eighteen heavy-duty diesel trucks in China. The results showed that the China IV and China V HDDVs with appropriate SCR functionality could reduce NO emissions by 36% and 53%, respectively, compared to the China III results, although their real-world emissions were still higher than the corresponding emission limits for regulatory engine tests. For these HDDVs, five samples were tested with NH emissions, ranging from 1.67 ppm to 51.49 ppm. The NH emission rates tended to significantly increase under high-speed driving conditions. The results indicate that the current SCR technology may have certain risks in exceeding the future China VI NH limit. However, five China IV/V HDDVs were found to have SCR temperature sensors that were intentionally tampered with, resulting in comparable or even higher NO emissions and zero NH emissions. Increased NO emissions due to the adoption of diesel oxidation catalysts and diesel particulate filters were also found from our experiments. This study highlights the importance of enhancing in-use compliance requirements and eliminating aftertreatment tampering for China IV and China V HDDVs.
中国许多大城市的空气质量受到重型柴油车（HDDV）排放的主要活性氮化合物（包括一氧化氮（NO）、二氧化氮（NO ）和氨（NH ））的巨大压力。为了控制 HDDV 排放的氮氧化物（NO ），自中国 IV 标准以来，选择性催化还原（SCR）系统已被广泛应用。为了研究后处理技术和驾驶条件对活性氮化合物实际排放的影响，采用便携式排放测量系统对中国的 18 辆重型柴油卡车进行了测试。结果表明，具有适当 SCR 功能的中国 IV 和 V 型 HDDV 可分别将 NO 排放降低 36%和 53%，与中国 III 型相比，但它们的实际排放量仍高于监管发动机测试的相应排放限值。对于这些 HDDV，有五个样本进行了 NH 排放测试，范围从 1.67 ppm 到 51.49 ppm。NH 排放率在高速行驶条件下往往会显著增加。结果表明，目前的 SCR 技术在未来达到中国 VI NH 限值方面可能存在一定风险。然而，发现五辆中国 IV/V HDDV 的 SCR 温度传感器被故意篡改，导致可比甚至更高的 NO 排放和零 NH 排放。我们的实验还发现，由于采用了柴油氧化催化剂和柴油颗粒过滤器，NO 排放也有所增加。本研究强调了加强中国 IV 和 V 型 HDDV 实际合规要求和消除后处理篡改的重要性。
