Department of Mechanical Engineering, and ‡Center for Environmental Research and Technology (CE-CERT), College of Engineering, University of California Riverside , Riverside, California 92521, United States.
Environ Sci Technol. 2014;48(3):1779-86. doi: 10.1021/es403578b. Epub 2014 Jan 15.
It is important to understand the differences between emissions from standard laboratory testing cycles and those from actual on-road driving conditions, especially for solid particle number (SPN) emissions now being regulated in Europe. This study compared particle mass and SPN emissions from a heavy-duty diesel vehicle operating over the urban dynamometer driving schedule (UDDS) and actual on-road driving conditions. Particle mass emissions were calculated using the integrated particle size distribution (IPSD) method and called MIPSD. The MIPSD emissions for the UDDS and on-road tests were more than 6 times lower than the U.S. 2007 heavy-duty particulate matter (PM) mass standard. The MIPSD emissions for the UDDS fell between those for the on-road uphill and downhill driving. SPN and MIPSD measurements were dominated by nucleation particles for the UDDS and uphill driving and by accumulation mode particles for cruise and downhill driving. The SPN emissions were ∼ 3 times lower than the Euro 6 heavy-duty SPN limit for the UDDS and downhill driving and ∼ 4-5 times higher than the Euro 6 SPN limit for the more aggressive uphill driving; however, it is likely that most of the "solid" particles measured under these conditions were associated with a combination release of stored sulfates and enhanced sulfate formation associated with high exhaust temperatures, leading to growth of volatile particles into the solid particle counting range above 23 nm. Except for these conditions, a linear relationship was found between SPN and accumulation mode MIPSD. The coefficient of variation (COV) of SPN emissions of particles >23 nm ranged from 8 to 26% for the UDDS and on-road tests.
了解标准实验室测试循环和实际道路行驶条件下的排放差异很重要，特别是对于现在在欧洲受到监管的固体颗粒数量 (SPN) 排放。本研究比较了一辆重型柴油车在城市动态行驶循环 (UDDS) 和实际道路行驶条件下的颗粒质量和 SPN 排放。使用积分粒径分布 (IPSD) 方法计算颗粒质量排放，并称为 MIPSD。UDDS 和道路测试的 MIPSD 排放比美国 2007 年重型颗粒物 (PM) 质量标准低 6 倍以上。UDDS 的 MIPSD 排放介于道路上坡和下坡行驶之间。对于 UDDS 和上坡行驶，SPN 和 MIPSD 测量主要由核化粒子主导，而对于巡航和下坡行驶，主要由积聚模式粒子主导。SPN 排放比 UDDS 和下坡行驶的 Euro 6 重型 SPN 限值低约 3 倍，比更具侵略性的上坡行驶的 Euro 6 SPN 限值高约 4-5 倍；然而，在这些条件下测量的“固体”颗粒很可能与存储硫酸盐的组合释放以及与高温废气相关的增强硫酸盐形成有关，导致挥发性颗粒在 23nm 以上的固体颗粒计数范围内生长。除了这些条件外，还发现 SPN 和积聚模式 MIPSD 之间存在线性关系。对于 UDDS 和道路测试，>23nm 颗粒的 SPN 排放的变异系数 (COV) 范围为 8%至 26%。
