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

Abstract

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.