Impact of Hydrogen Enrichment on Performance and Emissions Characteristics of a Compression Ignition Engine Operated in Dual Fuel Mode with Karanja Oil Methyl Ester-Tire Pyrolysis Oil Blend

The growing demand for fossil fuels and the search for alternatives have the potential to reduce emissions and enhance energy security. Karanja oil and tire pyrolysis oil (TPO) are identified as promising substitutes. This study examines the performance and emission characteristics of a 5.2 kW, 1500 rpm, four-stroke single-cylinder compression ignition engine. The engine was tested using diesel, the optimal combination of karanja oil biodiesel (KOME) and TPO (50:50% volume ratio), and this KOME-TPO blend with hydrogen supplied in dual fuel mode at flow rates of 10 lpm, 20 lpm, and 30 lpm, designated as H10, H20, and H30, respectively. The results indicated that BTE for H30 was the highest, reaching 32.21% compared to 30.52% for diesel at 5.2 kW BP. BSEC for H30 was the lowest at 11.18 MJ/kWh, compared to 11.80 MJ/kWh for diesel at the same BP. Emission analysis showed that smoke and HC emissions were significantly lower for hydrogen-enriched blends. At 5.2 kW BP, HC emissions for H30 were 15 ppm compared to 32 ppm for diesel, and smoke emissions were 38% for H30 compared to 67% for diesel. However, NOx emissions were higher for hydrogen-enriched blends, with 1535 ppm for H30 compared to 1245 ppm for diesel at 5.2 kW BP. CO emissions were also lower for H30, recorded at 0.07% vol compared to 0.08% vol for diesel. This study demonstrates that blending hydrogen with KOME-TPO can effectively reduce HC and smoke emissions while enhancing BTE and BSEC, although further optimization is needed to manage NOx emissions. These findings suggest that hydrogen-enriched biodiesel blends offer a promising alternative to conventional diesel fuel, supporting sustainable energy use and reduced environmental impact.