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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 NOx 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).

Recently, the shortage of fossil resources contributes to strict regulations of environmental protection. The research on the high efficiency and low emission of engines becomes an important direction all over the world. Technologies like high injection pressure, high levels of supercharging and higher levels of back pressure have come into application. Increasing the injection pressure and average cylinder pressure results in that parts of the spray can experience transcritical and supercritical regimes. In this paper, we established a surrogate fuel composed of n-Hexadecane, HMN and 1-Metylnaphthalene, to analyze the injection and atomization of diesel surrogate fuel with large eddy simulation (LES) in a cubic calculation region with high temperature and high pressure environment. The injection pressure was fixed to 150MPa, and the 900-K temperature and the 6-MPa pressure represented the ambient condition in constant volume vessel which is supercritical with respect to No.2 diesel.

Exhaust gas recirculation (EGR) has been proven an effective strategy for the ignition and combustion control in homogeneous charge compression ignition (HCCI) engines. Carbon dioxide (CO2), a major constituent in EGR, was found to pose a coupled effect on engine combustion: reduced intake oxygen concentration (dilution effect), increased gas heat capacity (thermal effect) and participation of CO2 in chemical reactions (chemical effect). In this paper, a numerical study using a detailed chemical kinetic model was conducted, aiming to isolate the dilution, thermal and chemical effects of CO2 on the two-stage auto-ignition process of n-heptane at engine-like pressure conditions. Four different initial temperatures were selected in this study, representing the low-temperature dominant region, the boundary between the low-temperature region and the negative temperature coefficient (NTC) region, the NTC region and the high temperature region, respectively.