Effects of advanced injection timing and inducted gaseous fuel on performance, combustion and emission characteristics of a diesel engine operated in dual-fuel mode

Abstract

The current study aims to investigate the effects of advanced injection timing combined with dual-fuel mode on the diesel engine's overall performance, emission, and combustion characteristics under various loading conditions. In this study, blends of waste oil methyl ester (WOME) at 10%, 20%, and 30% v/v concentration and diesel fuel were used as injected fuel, while biogas was the inducted gaseous fuel through the inlet manifold with a flow rate of 0.8 kg/h. Experimentations were carried out on a 4-stroke single-cylinder water-cooled diesel engine, in which engine speed, injection pressure, and compression ratio were fixed at 1500 rpm, 220 bar, and 17.5:1, respectively. Based on experimental data, dual-fuel mode of WOME20-biogas combined with advanced injection timing to 24°bTDC depicted the most positive results. Indeed, the higher brake thermal efficiency (2.40%), lower exhaust gas temperature (15.77%), but increased brake-specific fuel consumption (3.12%) and brake-specific energy consumption (1.85%) compared to diesel fuel were found at the highest load. Furthermore, increasing trends of in-cylinder pressure (7.48%) and heat release rate (4.71%), but diminished ignition delay (6.96%) as opposed to diesel fuel at higher loads were also reported. For emission analysis, a significant reduction of unburnt hydrocarbon (44.5%), carbon monoxide (61.72%), oxide of nitrogen (64.13%), and smoke intensity (47.42%) was obtained in comparison to conventional diesel fuel. Generally, the test diesel engine working on dual-fuel mode of WOME20-biogas combined with advanced injection timing of 24°bTDC would be helpful to enhance the overall efficiency and emission characteristics.