Influence of split injection strategies and Trade-off study on the CRDI engine characteristics powered with waste cooking Oil/Diesel blend

Abstract

An investigation has been conducted on a CRDI (common-rail diesel injection) engine utilizing a blended fuel with waste cooking oil (WCO20) to explore the influence of fuel injection strategies (i.e., split injection strategy with different fuel injection pressure) on the engine characteristics. It is observed that specific fuel consumption (BSFC) and nitrogen oxide emission (NOx) increased with a decrease in brake thermal efficiency (BTE) in the case of WCO20 at a base FIP of 40 MPa. The volatility and viscosity (physical properties) of the WCO20 fuel blend influenced the combustion phenomena resulting in a reduction in engine performance. The higher viscosity of the methyl ester blend restricts the fuel atomization process during the injection. Fuel injection pressure (Pinj) was raised from 40 to 100 MPa in increments of 25 MPa in the first phase to maximize the use of the WCO20 blend. High injection pressures (100 MPa) have higher BTE (12.33%) and better combustion characteristics (2.86 %) than lower fuel injection pressures (40 MPa). The concentrations of smoke (3.62 %), CO (15.6 %), and HC (2.8 %) were reduced as injection pressure was raised, owing to the better formation of the mixture and improved spray atomization. When used as a pilot injection before the main injection (BMI), 5% WCO20 reduces HC and CO emissions and NOx (7.82%) and smoke emissions while compromising only a marginal amount of thermal efficiency in the second phase.