Development of a reduced mechanism of a three components surrogate fuel for the coal-to-liquid and diesel combustion simulation

Abstract In order to explore the difference between coal-to-liquid (CTL) and diesel in the combustion and the pollutant formation process, in this study, a reduced mechanism of the CTL and diesel surrogate fuel for the 3D computational fluid dynamics (CFD) simulation is developed. According to the physicochemical properties, the CTL surrogate fuel is determined to be composed of 88.99% n-dodecane and 11.01% iso-octane by mass. Using a series of reduction methods including Directed Relation Graph with Error Propagation, Directed Relation Graph, Directed Relation Graph with Path Flux Analysis and isomer lumping, the CTL surrogate reduced mechanism with 132 species and 873 reactions is obtained. For the diesel surrogate fuel, 74.31% n-dodecane and 25.69% iso-octane by mass are selected. By coupling the m-xylene sub-mechanism derived from a jet fuel surrogate to the CTL reduced mechanism, the CTL and diesel surrogate reduced mechanism with 146 species and 924 reactions is developed. The sensitivity analysis is conducted to optimize the rate parameters and improve the accuracy of predicting the ignition delay (ID). The CTL and diesel reduced mechanism is then validated against experimental data on fundamental reactors and is confirmed to well reproduce the IDs, the laminar flame speeds and the species profiles for a wide range of conditions. Finally, the 3D CFD validations on the compression ignition (CI) engine are conducted. All the errors of key combustion parameters are lower than 25%, demonstrating the strong capability of the reduced mechanism to predict the conventional CI combustion of CTL and diesel at medium loads.