Abstract
Two-stage injection with different biodiesel percentage is investigated where first and second injections were implemented with different SOI timings at various mass ratio under constant speed of 2000 rpm and 60 Nm of torque. The results reveal that maximum BTE of 32.4% and minimum BSFC of 245.5 g/kWh can be achieved simultaneously with injection mass ratio of 50:50 at advanced SOI timing using baseline diesel. A considerably lower level of NOx below 90 ppm is achievable via late SOI timing by using B20 or B50 biodiesel blends with injection mass ratio of 25:75. Specifically, the lowest NOx of 82 ppm can be achieved with smoke emission level still remains below 5% when B50 biodiesel blend and 25:75 injection mass ratio is tested. The highest reduction of 5.3% of smoke compared to diesel was achieved when B50 was used with 50:50 mass ratio at retarded SOI of 2°ATDC. It was found that simultaneous NOx and smoke reduction compared to that of fossil diesel is feasible with the application of B50 biodiesel blend and execution of retarded SOI timing and injection mass ratio of 25:75. Lastly, two-stage fuel injection is a practical strategy to simultaneously decrease NOx and smoke emissions.
•Effect of biodiesel blend, SOI and mass ratio of two-stage injection was investigated.•Optimum BTE and BSFC were obtained with early SOI and 75:25 injection mass ratio.•Lowest NOx of 82 ppm was achieved with smoke emission level still remains below 5%.•Simultaneous NOx and smoke reduction with B50, late SOI and 25:75 injection ratio.