Experimental investigation of fuel injection timing effects on a CRDI diesel engine running on hydrogen-enriched waste plastic oil

Abstract

In response to fossil fuel concerns and the imperative of effective plastic waste management, this study investigates the impact of hydrogen-plastic oil (WPO) blends on a CRDI diesel engine. Six combinations (WPO10, WPO20, WPO30, WPO10 + H2, WPO20 + H2, WPO30 + H2) are examined across varying loads and fuel injection timings. Notably, WPO10 + H₂ (H2 energy share i.e., 8 lpm) exhibits a 15.1 % increase in brake thermal efficiency, an 11.2 % fuel consumption reduction, improved peak cylinder pressure (66 bar), and maximum heat release rate (40.16 J/°CA) compared to diesel. It also shows reduced emissions of CO, HC, CO2, and smoke opacity—34.8 %, 15.1 %, 10.7 %, and 28.5 %, respectively, relative to diesel. Elevated nitrogen oxide (NOx) emissions are observed across all blends. This study underscores the environmental benefits of blending waste plastic oil with diesel, promoting recycling, reducing reliance on traditional diesel, lowering greenhouse gas emissions, and supporting sustainability. Advanced fuel injection timing at higher loads slightly mitigates NOx emissions, while increasing the blend proportion leads to prolonged ignition delays, reduced thermal efficiency, and heightened emissions.