Chang M-C Oliver, Shields J Erin
a Chemical Analysis and Emissions Research Branch , California Air Resources Board , El Monte , CA , USA.
J Air Waste Manag Assoc. 2017 Jun;67(6):677-693. doi: 10.1080/10962247.2016.1268548. Epub 2017 Jan 3.
To reliably measure at the low particulate matter (PM) levels needed to meet California's Low Emission Vehicle (LEV III) 3- and 1-mg/mile particulate matter (PM) standards, various approaches other than gravimetric measurement have been suggested for testing purposes. In this work, a feasibility study of solid particle number (SPN, d50 = 23 nm) and black carbon (BC) as alternatives to gravimetric PM mass was conducted, based on the relationship of these two metrics to gravimetric PM mass, as well as the variability of each of these metrics. More than 150 Federal Test Procedure (FTP-75) or Supplemental Federal Test Procedure (US06) tests were conducted on 46 light-duty vehicles, including port-fuel-injected and direct-injected gasoline vehicles, as well as several light-duty diesel vehicles equipped with diesel particle filters (LDD/DPF). For FTP tests, emission variability of gravimetric PM mass was found to be slightly less than that of either SPN or BC, whereas the opposite was observed for US06 tests. Emission variability of PM mass for LDD/DPF was higher than that of both SPN and BC, primarily because of higher PM mass measurement uncertainties (background and precision) near or below 0.1 mg/mile. While strong correlations were observed from both SPN and BC to PM mass, the slopes are dependent on engine technologies and driving cycles, and the proportionality between the metrics can vary over the course of the test. Replacement of the LEV III PM mass emission standard with one other measurement metric may imperil the effectiveness of emission reduction, as a correlation-based relationship may evolve over future technologies for meeting stringent greenhouse standards.
Solid particle number and black carbon were suggested in place of PM mass for the California LEV III 1-mg/mile FTP standard. Their equivalence, proportionality, and emission variability in comparison to PM mass, based on a large light-duty vehicle fleet examined, are dependent on engine technologies and driving cycles. Such empirical derived correlations exhibit the limitation of using these metrics for enforcement and certification standards as vehicle combustion and after-treatment technologies advance.
为了可靠地测量达到加利福尼亚低排放车辆（LEV III）3毫克/英里和1毫克/英里颗粒物（PM）标准所需的低颗粒物（PM）水平，已提出了除重量法测量之外的各种方法用于测试目的。在这项工作中，基于固体颗粒数（SPN，d50 = 23纳米）和黑碳（BC）与重量法PM质量的关系以及这些指标各自的变异性，对其作为重量法PM质量替代指标进行了可行性研究。对46辆轻型车辆进行了150多次联邦测试程序（FTP - 75）或补充联邦测试程序（US06）测试，包括端口燃油喷射和直喷汽油车辆，以及几辆配备柴油颗粒过滤器的轻型柴油车辆（LDD/DPF）。对于FTP测试，发现重量法PM质量的排放变异性略低于SPN或BC的排放变异性，而在US06测试中观察到相反情况。LDD/DPF的PM质量排放变异性高于SPN和BC两者，主要是因为在0.1毫克/英里或以下时PM质量测量不确定性（背景和精度）较高。虽然从SPN和BC到PM质量都观察到很强的相关性，但斜率取决于发动机技术和驾驶循环，并且这些指标之间的比例关系在测试过程中可能会变化。用另一种测量指标取代LEV III PM质量排放标准可能会危及减排效果，因为基于相关性的关系可能会随着未来满足严格温室标准的技术而演变。
对于加利福尼亚LEV III 1毫克/英里FTP标准，建议用固体颗粒数和黑碳代替PM质量。基于对大量轻型车辆车队的研究，它们与PM质量相比的等效性、比例关系和排放变异性取决于发动机技术和驾驶循环。随着车辆燃烧和后处理技术的进步，这种基于经验得出的相关性显示了将这些指标用于执法和认证标准的局限性。
