Effect of injection parameters on performance and emission characteristics of a CRDi diesel engine fuelled with acid oil biodiesel–ethanol blended fuels

ABSTRACT

The objective of this paper is to study the effect of injection timing and injection pressure on the engine performance and emission characteristics in a single-cylinder common rail direct injection (CRDi) diesel engine fuelled with acid oil biodiesel, diesel and ethanol blends. The biodiesel used for the study was obtained by a suitable esterification of acid oil named as acid oil methyl ester (AOME) and was subsequently blended with diesel and ethanol in varied percentage. Characterization of these fuels and their blends has been done to ascertain the applicability of these fuels for the existing engine. The feasibility of using a high percentage of biodiesel in diesel–ethanol blends has been investigated. Initially the experiments were carried out on a CRDi engine with diesel, biodiesel and their blends to optimize the injection timing (IT), where IT was varied from 25° before top dead centre (bTDC) to 5° after top dead centre (aTDC) keeping injector pressure (IP) of 600 bar, compression ratio (CR) of 17.5 and speed of 1500 rpm. Results showed that improved brake thermal efficiency (BTE) is achieved between IT of 15 to 10° bTDC. Increased ethanol content in the blend resulted in increased BTE and the blends showed higher HC and CO and reduced NOx emissions compared to diesel fuel. Finally, experiments were conducted to optimize IP where IP was varied from 600 to 1000 bar keeping optimized IT of 10° bTDC, CR of 17.5 and speed of 1500 rpm. Results revealed that maximum BTE was obtained at 900 bar. As the alcohol concentration in the blends increases, CO and HC emissions increased while NOX emissions reduced. From the experimental study, IT of 10° bTDC and IP of 900 bar were optimized for better performance with significant reduction in emissions. AOME (60%) and their blends with ethanol and diesel can be successfully used as an alternative fuel with high injection pressures in diesel engines.

KEYWORDS:

• Diesel
• ethanol
• acid oil methyl ester (AOME)
• common rail direct injection (CRDi)
• engine performance and emissions

Disclosure statement

No potential conflict of interest was reported by the authors.