Research Projects

Project at a Glance

Project Status: active

Title: Collection of Activity Data From On-Road Heavy-Duty Diesel Vehicles

Principal Investigator / Author(s): Boriboonsomsin, Kanok

Contractor: UC Riverside

Contract Number: 13-301

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels

Research Summary:

This project addresses the importance of collecting activity data from heavy-duty diesel trucks equipped with SCR aftertreatment systems. SCR reduces NOX in the exhaust stream, but requires adequate temperatures, typically at least 200°C, for the reduction to take place. However, there will be times when this temperature requirement is not met, such as initial engine start and during low loads experienced when the engine is idling, or when the vehicle is moving slowly on flat terrain. It is thus critical to characterize heavy-duty diesel truck activity profiles including operation duty cycles, number of engine starts, and engine soak time distributions, by their vocation type. Because there are 68 different SCR-equipped engines sold in California, and 27 different medium heavy-duty and heavy heavy-duty truck categories in EMFAC2011, a strategic data collection plan is important for the limited funding resources. This project first identifies major truck vocation types that are most likely to contribute the most to the state’s NOX emission inventories, then instruments 80 trucks with GPS data loggers and 20 trucks with Electronic Control Units (ECU) + Global Positioning System (GPS) data loggers, and collects instantaneous truck activity data for at least one month and up to six months on each vehicle. The collected data will be used to develop truck activity profiles by their vocation type. The activity profiles will provide critical information for updating emission inventories, quantifying the frequency of good SCR function from trucks meeting the 2010 NOX certification standard, and comparing the vocational duty cycles to the certification duty cycles.


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

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