Comparative Study on the Effects of Diesel Fuel, Hydrotreated Vegetable Oil, and Its Blends with Pyrolytic Oils on Pollutant Emissions and Fuel Consumption of a Diesel Engine Under WLTC Dynamic Test Conditions

The search for alternative liquid fuels for compression-ignition (CI) internal combustion engines includes waste-derived fuels such as hydrotreated vegetable oil (HVO) and pyrolytic oils from end-of-life tires (tire pyrolytic oil, TPO) and plastics—polystyrene pyrolytic oil (PSO). The application of these fuels requires meeting a number of criteria, including exhaust pollutant emissions. The scientific objective of this study was to compare pollutant emissions—carbon dioxide (CO2), carbon monoxide (CO), total hydrocarbons (THC), nitrogen oxides (NOx), particulate matter (PM)—and fuel consumption of a passenger car CI engine fueled with diesel B7, HVO, and a blend consisting of 90% HVO, 5% TPO, and 5% PSO (vol.), hereinafter referred to as HVO–TPO–PSO. The tests were carried out using a chassis dynamometer equipped for conducting standardized WLTC Class 3b driving cycles, with exhaust gases measured by laboratory-grade analyzers to ensure accuracy and repeatability. Fueling the engine with HVO resulted in the lowest CO2, CO, THC, NOx, and PM emissions across all phases of the driving cycle. The addition of pyrolytic oils to HVO increased NOx and CO2 levels while maintaining benefits in PM, THC, and CO reduction compared to the B7 reference fuel. The results demonstrated the applicability of HVO–TPO–PSO blends in engine applications while indicating the need for further durability studies. The adopted research approach addresses a significant knowledge gap by providing a unique analysis of the impact of HVO blends with tire and plastic pyrolysis oils on pollutant emissions and internal combustion engine fuel consumption under WLTC 3b operating conditions.