The Nozzle Flows and Atomization Characteristics of the Two-Component Surrogate Fuel of Diesel from Indirect Coal Liquefaction at Engine Conditions

摘要

Recently, all world countries facing the stringent emission regulations have been encouraged to explore the clean fuel. The diesel from indirect coal liquefaction (DICL) has been verified that can reduce the soot and NO_x emissions of compression-ignition engine. However, the atomization characteristics of DICL are rarely studied. The aim of this work is to numerically analyze the inner nozzle flow and the atomization characteristics of the DICL and compare the global and local flow characteristics of the DICL with the NO.2 diesel (D2) at engine conditions. A surrogate fuel of the DICL (a mixture of 72.4% n-dodecane and 27.6% methylcyclohexane by mass) was built according to its components to simulate the atomization characteristics of the DICL under the high-temperature and high-pressure environment (non-reacting) by the Large Eddy Simulation (LES). The simulation results show that the DICL is more likely to form cavitation compared with D2, and the turbulence level at the orifice exit is larger for DICL. The liquid penetration of DICL is shorter than that of D2, while the vapor penetrations between DICL and D2 have no obvious difference. The spray cone angle of DICL is larger than that of D2. In addition, the gas-phase axial velocity of the DICL along the spray center line is slightly larger than that of D2 in the upstream of the spray. Moreover, the SMD of the DICL is larger than that of D2. Generally, this study is helpful to understand the differences in the inner nozzle flow features and the atomization characteristics between DICL and D2.