Performance and emission characteristics of a diesel engine running on optimized ethyl levulinate–biodiesel–diesel blends

• Physical and chemical properties of EL–biodiesel–diesel blends were analyzed.
• Fuel blends were optimized by methods of GRA and AHP.
• Engine power and torque for fuel blends were similar to diesel.
• Energy conversion efficiency improved with fuel blends compared with diesel.
• HC, CO and smoke opacity of fuel blends significantly lower than diesel.

In this study, biomass-based EL (ethyl levulinate) was evaluated as an additional fuel to biodiesel and diesel. Physical and chemical properties, including intersolubility, cold flow properties, spray evaporation, oxidation stability, anti-corrosive property, cleanliness, fire reliability and heating value of twelve different EL–biodiesel–diesel blends were analyzed. The results show that the fuel blends that were in line with China's national standard for biodiesel blend fuel (B5) have similar physical and chemical properties to pure diesel with improved cold flow properties. Optimized fuel blends based on grey relational analysis and analytic hierarchy process were selected to evaluate engine performance and emissions using an unmodified diesel engine test bench. The results show that engine power and torque with the fuel blends were in general similar to those with diesel (less than 3% differences). Both brake specific fuel and energy consumption were lower with the fuel blends than with diesel, suggesting higher fuel conversion efficiencies for the fuel blends. HC (Hydrocarbon) and CO (carbon monoxide) emissions and smoke opacity reduced significantly with the fuel blends compared with diesel while NOx (nitrogen oxides) and CO2 (carbon dioxide) emissions increased. Our study suggests that EL produced from lignocellulosic biomass could be used as a blending component with biodiesel and diesel for use in unmodified diesel engines and could potentially be a promising environment-friendly fuel.