UC Riverside

This dissertation provides investigation and evaluation of new engine technologies and aftertreatment systems on reducing emissions of critical pollutants on in-use heavy-duty vehicles or off-road equipment under real-world operation conditions. Real-world driving emissions have become a key factor to understand or identify high-emitting events under real-world driving conditions.This dissertation evaluated emissions from in-use heavy-duty on-road vehicles, off-road equipment under a variety of different conditions. This dissertation characterized NOx and PM emissions for 10 pieces of Tier 4 final construction equipment including 3 excavators, 3 wheel loaders, 2 crawler tractors and 2 backhoe/loaders. The duty cycles included a pre-defined combined sequence of a cold-start phase, trenching, backfilling, travelling, and idling. The information obtained in this study provides a more accurate dataset for emissions inventory development, and for designing or optimizing emissions models such as NONROAD or OFFROAD, which are currently utilized for estimating off-road emissions. The dissertation also discussed gaseous and particulate emissions from a fleet of 14 heavy-duty vehicles. The test matrix includes vehicles from vocations including transit buses, school buses, refuse trucks, delivery trucks, and goods movement trucks fueled with a combination of alternative fuels, conventional and alternative diesel fuels. This thesis evaluated the impact, issues, improvement, and benefits of the current technologies for heavy-duty vehicles. This thesis also measured and characterized NOx emissions from five heavy-duty diesel and natural gas goods movement vehicles with different engine technologies under real-world conditions. All five vehicles were tested on-road under four pre-defined goods movement routes in SCAB, representing grocery distribution, port-drayage operation, and highway driving with and without elevation change. NOx emissions were measured using a mobile emissions laboratory. Understanding emissions from ultra-low NOx CNG vehicles is important as CNG vehicles/engines are capable of meeting more stringent emission standards. This dissertation in detail evaluated and characterized two near-zero NOx stoichiometric ultra-low natural gas engines in different vocations. This demonstration of this engine technology was done in a goods movement vehicle and a yard tractor. Both vocations represent a major source of NOx emissions and other pollutants within the heavy-duty vehicle population.