哈尔滨工程大学硕士学位论文
II
Abstract
In recent years, environmental pollution and energy shortage have become two major obstacles
to human development, so the dual fuel engine has been paid more and more attention because of its
advantages of cleanness, high efficiency and good economy. Compared with pure diesel engine, the
combustion process of Diesel / dual fuel engine is more complicated, The traditional marine diesel
engine adopts the diffusion based combustion mode, while the marine diesel / natural gas dual fuel
engine uses natural gas to replace most of the diesel, which changes the energy ratio and chemical
reaction rate released in the premixing and diffusion combustion stage of the original diesel engine.
Therefore, the research on modeling technology and combustion characteristics of Diesel / natural
gas engine has become a hot and difficult point.
Based on the MATLAB / Simulink software platform, taking the Yuchai 6K marine diesel /
natural gas engine as the research object, this paper adopts the modular modeling concept, the
comprehensive use of charging and discharging method, the average value method, the combination
of map and empirical formula to establish the dual fuel engine model. Through the comparison and
repeated correction of simulation results and test results, the control model error is about 0.5%. The
effects of three different operation modes of the dual fuel engine on the combustion process in the
cylinder under different working conditions are studied. The results show that the dual fuel engine is
suitable to operate in the pure diesel operation mode or the dual fuel mode with low natural gas
substitution rate, while the maximum gas mode and the dual fuel mode with high substitution rate
are more suitable to operate in the medium and high conditions Load condition: the influence of the
intake parameters of the dual fuel engine cylinder on the working process in the cylinder is studied.
The results show that the intake pressure of the cylinder is increased by 1 bar, the maximum
explosion pressure of the engine is increased by 22 bar, and the maximum average temperature is
decreased by 21%, while the intake temperature of the cylinder is increased by 60 K, The maximum
average temperature in the cylinder is increased by 14%. Therefore, increasing the intake pressure of
the cylinder and reducing the intake temperature of the cylinder are conducive to improving the
overall performance of the engine and reducing the emissions of pollutants. The characteristics of
the two injection strategies of single injection and two injection of the fuel system of dual fuel
engine are studied. The results show that increasing the injection timing properly in a single
injection can improve the performance of the engine Pressure and temperature to optimize the
combustion process. When two times of injection, proper increase of pre injection timing and pre
