Optimizing nozzle opening pressure for performance, combustion, and emissions in hybrid biodiesel engines

To meet the growing global energy demands while addressing sustainability and environmental concerns, it is imperative to develop alternative energy sources in lieu of relying on fossil fuels. This study investigates the potential of a hybrid biodiesel blend to reduce the reliance on fossil fuels in compression ignition engines. This research examines the potential of variable compression ratio (VCR) engines when fuelled with hybrid biodiesel. The experiments centred on a novel hybrid biodiesel blend formulated with 20 percentage rubber seed oil and 80 percentage waste plastic oil. The experiments employed four distinct injection pressures, specifically 200 bar, 210 bar, 220 bar, and 230 bar. The engine performed significantly better at 100% load with 230 bar injection pressure. Brake thermal efficiency increased by 33.8%, indicating more effective use of fuel. This was reflected in a reduction of brake specific fuel consumption by 0.23 kg/kWh. Exhaust emissions also improved, with significant decreases in hydrocarbons (63 ppm), carbon monoxide (0.27% volume), and smoke (20%). Though a drawback emerged with increased NOx exhaust emissions (1002 ppm) compared to standard diesel (820 ppm), likely due to the higher injection pressure. Other key engine parameters included a peak cylinder pressure of 61 bar, an ignition delay of 9 °CA, a heat release rate of 83.79 J/°CA, and an exhaust gas temperature of 274 °C. The promising performance of this hybrid biodiesel suggests its potential to reduce emissions in automobiles, power generation, and marine transportation.