Analysis and Simulation of Fuel Consumption and Emissions in a Heavy-Duty Diesel Truck under Real-World Driving Conditions for Hybridization and Waste Heat Recovery

Heavy-duty vehicles contribute significantly to global greenhouse gas emissions and are now facing challenges in meeting emission regulatory standards, particularly cold-start operations. These challenges are particularly significant during transient operations, where fuel efficiency drops and emissions peak due to suboptimal thermal conditions. Advanced powertrains that use hybridization and waste heat recovery with phase-changing materials offer potential pathways to mitigate fuel consumption and emissions under real-world driving conditions. Still, they need to be accurately sized, and the energy flows handled to overcome the disadvantages of increased mass and complexity. This investigation lays the groundwork for the development of advanced power systems by implementing a scalable, map-based model for heavy-duty diesel engines. The model is validated using an open-access dataset related to a heavy-duty vehicle equipped with a 6-cylinder diesel engine, which performed 28 different trips on the same route with the same driver. The trips are executed with three different payload values and contain both cold-start and hot-start operating conditions. The validation is based on quasi-static modeling of the vehicle powertrain. The proposed model can accurately predict fuel consumption and CO2 emissions for all trips, with an average relative error of 2.4%. The results of the investigation also include preliminary sizing and analysis of a hybrid electric configuration that exploits the synergy between hybridization and waste heat recovery. In comparison to the original powertrain, the proposed powertrain resulted in a roughly 15% reduction in fuel consumption and a 37.5% increase in exhaust temperature. These findings demonstrate the potential for integrated hybrid and waste heat recovery systems to enhance fuel economy in heavy-duty transportation while supporting compliance with emission regulations.