Research Team: Kanok Boriboonsomsin (lead), Kent Johnson, George Scora, Daniel Sandez, Alexander Vu, Tom Durbin, and Yu (Jade) Jiang
UC Campus(es): UC Riverside
Problem Statement: Due to the great variety of their operation, there is no one-size-fits-all alternative fuel/vehicle technology for heavy-duty vehicles. Heavy-duty vehicles comprise a variety of vocations, each of which may have distinct operational requirements resulting in different activity patterns. It is important to understand the extent of these differences so that appropriate energy and emission reduction strategies can be developed.
Project Description: This project supported additional analysis for an existing research study commissioned by the California Air Resources Board. For the full project, the project team recruited and collected instantaneous location and engine activity data for a minimum of 4 weeks for each of 90 heavy-duty vehicles with gross vehicle weight ratings (GVWR) of 26,000lbs or higher. Eight of the 90 vehicles were not equipped SCR aftertreatment systems: five express buses powered by natural gas and three diesel trucks older than 2010 model year. A total of 19 vocation types were identified covering a range of vocational uses, GVWR, and geographic regions. Activity profiles of idling, diurnal distribution of activity, trips per day, soak time distribution, SCR temperature profiles, and characteristic of driving cycles were characterized for each vocation type. These activity profiles are extremely important for improving the heavy-duty NOx emission inventory and estimating the frequency of good SCR function.