Effect of high reactive fuel injection advancement and hydrogen-biodiesel premix ratio on combustion, performance and emission of a CI engine under RCCI mode

The combustion mode known as Reactivity Controlled Compression Ignition (RCCI) has the capability to enhance engine performance and reduce emissions through the utilization of both high-reactivity fuel (HRF) and low-reactivity fuel (LRF). However, the potential of controlling combustion phasing through HRF injection advancement and utilization of a Hydrogen-biodiesel premix remains relatively unexplored. This study investigates the influence of high reactive fuel injection advancement and Hydrogen-biodiesel premix ratio on the combustion, performance, and emissions of an RCCI engine. The HRF injection angles varied from 30°bTDC to 90°bTDC, whereas the premix ratio of Hydrogen and biodiesel varied from 10 % to 70 %. Results showed that the combustion stability improved with increasing HRF injection angle up to 70°bTDC. The hydrogen premix ratio could be raised to 60% in the same condition without hampering engine performance. The brake thermal efficiency was improved by 15 % with a 50 % premix ratio and 70°bTDC HRF injection advancement. At the same operating point, a 73 % reduction in NO_X emission, 85 % reduction in soot emission, 61 % reduction in CO emission, and 42 % reduction in UHC emission was also observed concerning base diesel CDC operation. Thus, HRF injection advancement was beneficial in extending the LRF range of the engine.