A sustainable fueling strategy for CI engines: Synergistic role of waste plastic oil, hydrogen, and cerium doped nickel oxide nanoparticles

This study examines the performance, combustion, and emission characteristics of a single‐cylinder, four‐stroke diesel engine fueled with waste plastic oil (WPO), hydrogen enrichment, and cerium‐doped nickel oxide (Ce–NiO) nanoparticles. WPO was produced through pyrolysis of non‐recyclable plastics, while Ce–NiO nanoparticles were synthesized via co‐precipitation. Engine tests revealed that WPO exhibited higher specific fuel consumption (SFC) and lower brake thermal efficiency (BTE) than diesel, owing to its lower calorific value and poor volatility. The addition of hydrogen (10 and 12 LPM) improved combustion, reflected in higher cylinder pressure, heat release rate (HRR), and BTE, alongside reductions in SFC, carbon monoxide, unburned hydrocarbons, and smoke opacity. Further enhancement was achieved with Ce–NiO nanoparticles, with the 5% Ce–NiO blend showing optimal performance. At this condition, cylinder pressure increased by 4.29 bar and HRR by 3.15 J/°CA relative to diesel, while SFC decreased by 30.32% and BTE improved by 6.60%. Emission reductions included CO (44.69%), UBHC (31 ppm), smoke opacity (30.56%), and NOx (34.8 ppm). The synergistic effect of hydrogen and Ce–NiO demonstrates a viable pathway to enhance WPO utilization in diesel engines with improved efficiency and reduced emissions.