Mitigating particulate matter from a multi-cylinder high-sulfur diesel engine using waste-cooking-oil biodiesel blends: Emissions and efficiency assessment

Multi-cylinder engines powered with significant-sulfur diesel oil release diesel particulate matter (PM) that has severe health and environmental hazards because of its minute size and lethal chemical structure. This paper will set out to measure the effect of biodiesel mixes made out of waste restaurant cooking oil on PM emissions and other key performance indicators of a four-cylinder direct-injection diesel engine operating on high-sulfur diesel and at various loads, speeds, and injection timing conditions. Tests were performed with pure diesel, B20, B50, and B100 blends of biodiesel, measuring the concentration of PM, brake-specific fuel consumption (BSFC), and brake thermal efficiency (BTE) at a wide operating map, and finding an optimum injection timing (OIT) of each fuel. The findings demonstrate that the addition of the biodiesel proportion in the mixture lowers the PM emissions significantly: during idle operation, PM declined by approximately 8.6% in the B20 mix and 18% in the B50 mix. These benefits of PM are accompanied by the moderate rise in BSFC with a slight decrease in BTE with increased biodiesel content due to the lower heating value of biodiesel and alterations in in-cylinder combustion. Further optimization of the injection timing of each blend increases the combustion further, resulting in further PM reductions than the normal timing at the same load and speed. This is a novel study since it experimentally couples biodiesel blends of real waste cooking oil with a high-sulfur multi-cylinder diesel engine and systematically maps the interaction between blend ratio, engine operating conditions, and injection timing on PM, BSFC, and BTE; much of the literature on this topic has used single-cylinder or low-sulfur diesel engines, making the present study a realistic guide to the reductions of particulate emissions in areas with still high levels of high-sulfur diesel and multi-cylinder engines.