Combustion performance, noise, and vibrations of an IDI engine fueled with carinata biofuel

The performance of an indirect injection engine fueled with a biodiesel blend was investigated at 2400 rpm and 6 bar IMEP. The single cylinder experimental engine was run using C50 and compared to a ULSD#2 baseline. Brassica carinata oilseed was studied as it can potentially provide improvements for existing fuel infrastructures. Cylinder pressure data for C50 showcased a lower heat release and slightly higher injection pressure due to higher SMD. Brake specific fuel consumption was 6% higher for C50 given the characteristic LHV of biodiesel. Vibrations and sound measurements were analyzed in the frequency and crank angle domain through the Brüel & Kjær PULSE software platform. Sound pressure correlations were determined according to the piston normal force on the cylinder liner, intake and exhaust valve timing, and operating speed. For both fuels, vibrations parallel to the cylinder axis reached 1.6-2.6 m/s² in the 40-120 Hz frequency range; noise reached 80-87 dB at frequencies of 1-4 kHz. C50 produced 0.4 g/kWh fewer NOx emissions which correlate to a lower maximum bulk gas temperature and richer air-fuel ratio. The average ringing intensity was 0.05 MW/m² for both fuels due to a comparable pressure rise rate. When the engine was run with C50, the reference mechanical efficiency of 53% was effectively maintained. This offers validation for further implementation of blended biodiesel fuel in IDI engines.