Performance, Combustion, and Emission Comparisons of a High-Speed Diesel Engine Fueled with Biodiesel with Different Ethanol Addition Ratios Based on a Combined Kinetic Mechanism

Abstract

In this work, different ethanol ratios (5%, 10%, 15%, and 20%) blended with biodiesel were used to investigate the effects of ethanol addition on engine performance, combustion, and emission characteristics of a high-speed diesel engine in terms of brake power, brake specific fuel consumption, brake thermal efficiency, cylinder pressure, cylinder temperature, heat release rate, NOx, CO, and soot emissions. First, a three-dimensional CFD model was established by AVL-Fire combined with the CHEMKIN code. Then, an improved kinetic mechanism with 430 reactions and 122 species was developed by combining a three-component biodiesel combustion mechanism and ethanol mechanism to accurately simulate the blended fuel combustion processes. The results indicated that compared with biodiesel, the maximum brake specific fuel consumption increased by 6.08%, and the maximum brake thermal efficiency increased by 2.09% for the blended fuel. In addition, NOx and CO emissions for EE20 were reduced by 29.32% and 39.57% at full engine load. Overall, the ethanol addition can significantly decrease pollution emissions.