Effect of fuel injection on emissions of diesel engine fueled with waste cooking oil biodiesel produced by ultrasonic transesterification

This study aimed to examine effect of injection timing on the use of biodiesel fuel from waste cooking oil processed with ultrasonic transesterification technology on exhaust emissions of Diesel engine. Several variations of injection timing were applied to evaluate their impact on exhaust gas characteristics and engine emissions. Engine was run at a constant speed of 2400 rpm with standard injection timing (17° CA bTDC), advanced at an angle of 3° and 6° CA (20° and 23° CA bTDC), followed by retardation at 3° and 6° CA (14° and 11° CA bTDC). The results showed that the standard injection timing of 17° CA bTDC provided optimal performance with an exaust gas temperature (EGT) of approximately 250 °C at B10. Advancing injection timing increased the EGT to 320 °C but reduced CO and UHC emissions by 11.11% and 26.30%, respectively. However, there was a significant increase in smoke opacity emissions and NOx by 14.58% and 31.1%, respectively. The retardation in injection timing decreased EGT to 220 °C as well as increased CO, UHC, and smoke opacity emissions, with NOx rising by 10.4%. These results showed that ultrasonic transesterification technology produced high quality biodiesel with better combustion characteristics. Meanwhile, increasing biodiesel content (B20-B100) tended to cause a rise in NOx emissions due to higher oxygen content.