Split injection strategies based RCCI combustion analysis with waste cooking oil biofuel and methanol in an open ECU assisted CRDI engine

Abstract

The objective of the present study is to investigate the combined effect of split injection techniques and RCCI-dual-fuel combustion in a single-cylinder CRDI research engine operated with waste cooking oil (WCO) biofuel and methanol. Initially, the tests were conducted at a constant speed of 1500 rpm with three fuel injection pressures (FIP) (20, 35 and 50 MPa) and three fuel injection timings (FIT) (23°, 25° and 27° CA bTDC) for the optimization of injection parameters. Then the split injection mode of combustion under optimized fuel injection conditions has been studied. Finally, with an optimized split injection case, the engine operated under RCCI-dual fuel mode to examine the influence of methanol addition in the combustion chamber was explored. The experimental result shows 32.4% thermal efficiency with the combined mode of split injection strategy and RCCI-dual-fuel combustion (at 20% of methanol energy share). In-cylinder pressure was increased from 50 MPa with static injection timing and pressure (ITP) condition to 53 MPa with optimized injection conditions. A substantial decrease in NOx emission was noticed (8.1 g/kWh at the optimized split injection condition) and further reduced to 6.5 g/kWh with RCCI dual-fuel combustion mode. Moreover, under RCCI-dual-mode, the smoke emission was reduced to 19% from 46% (at static ITP condition).