Research Projects

Project at a Glance

Project Status: active

Title: Investigate the durability of diesel engine emissions controls

Principal Investigator / Author(s): Stedman, Donald

Contractor: University of Denver

Contract Number: 11-309

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels

Research Summary:

Introduction of new engine emissions standards for particulate matter (PM) and oxides of nitrogen (NOX) will result in a substantial decrease of these pollutants over the course of the next several years. This reduction is generally achieved by using aftertreatment devices such as diesel particulate filters (DPF) and selective catalytic reduction (SCR) to reduce PM and NOX respectively. The Air Resources Boardís (ARB) recently revised fleet rules will lead to gradual introduction of these technologies on California highways and ports, thereby reducing emissions from diesel engines.

While various studies have been performed to assess the efficiency of these devices, so far minimal data exists on durability and deterioration. The primary reason for limited data includes fairly recent introduction of these devices along with the challenges related to sampling thousands of trucks over a course of multiple years. The available data is especially sparse in terms of PM measurement and has often utilized technologies that donít measure PM directly. In essence, while the available data can demonstrate fleet emission changes due to improvement in engine technology, it does not provide a good understanding of emission changes related to the introduction of aftertreatment devices over an extended period of time. It is important to measure pollutant concentrations in the real world because trucks with malfunctioning aftertreatment devices could emit tens to hundreds of times higher emissions than a truck meeting certification standards. Potential aftertreatment failures and related emissions increases would reduce the air quality and health benefits of the new engine standards and also generate inaccurate emission inventories. Additionally, the data generated from this study may provide clues about tampering/mal-maintenance of these devices that could cause increases in pollutant concentrations.

The project will build upon existing databases of on-road measurements (remote sensing, vehicle chase studies, etc.), to provide a comprehensive analysis of pollutant profiles over the course of several years. At a minimum, data will include measurements of criteria pollutants, such as carbon monoxide (CO), total hydrocarbons (THC), black carbon (BC), NOX, and PM. Particle number and size distribution will also be collected based on instrumentation availability from ARB.


For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893

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