| EGR(Exhaust Gas Recirculation) is an important technical measure to reduce NO_x emissions of diesel engine. This article is based on Cooled-EGR(Cooled Exhaust Gas Recirculation) technical route to SC4H170Q4 B diesel engine as the research object, the valve timing, fuel injector, EGR cooling parameters and EGR rate on the subjects in-depth study of performance and emissions. First, AVL-Boost software is used to simulate to calculate the distribution of timing, fuel delivery advance angle, EGR cooling temperature and EGR rate performance of the subjects and the impact of emissions, and the optimal parameter values can be got. Then we carry on testing with the optimal distribution of simulation to calculate the timing and fuel delivery advance angle parameter values, and get the original machine external characteristic curve and discharge value, then set out the related target value of experimental subject, through optimizing the parameters of the injector and the supercharger, combined with the simulation calculation of EGR cooling temperature and the whole working condition of EGR rate of optimal parameter values, we test the diesel after the parameter optimization, and developing the diesel which meet discharge standards, at same time, in the premise of guaranteeing the power performance and fuel economy of the original machine. Specific work is described as follows:(1) The AVL-Boost software is applied to simulate diesel engine of low load and high load distribution timing(intake advance Angle, inlet la g closed Angle, exhaust advance Angle and exhaust lag closed Angle) and fuel delivery advance Angle, get a set of optimal parameter values;(2) The EGR cooling temperature simulation: backflow of exhaust gas temperature in cylinder direct impacts on performance and emissions of diesel engine, the higher temperature is good for the performance of diesel engine, but would lead to NO_x emissions increased. the lower temperature can not guarantee the performance of diesel engine. Through simulation, The influence of EGR cooling temperature on the performance and NO_x emissions of SC4H170Q4 B diesel engine are obtained.;(3) Whole working condition simulation of optimum EGR rate: according to the comprehensive performance of diesel engine SC4H170Q4 B EGR rate under various working conditions are optimized, it is concluded that the best EGR control MAP, and then simulated the working condition of 13 emissions and fuel economy, according to the weighted proportion of each operating mode, the ultimate of NO x and PM and specific fuel consumption values, all within the setting goals;(4) Experimental bench optimization testing: according to the simulation calculation of the optimal distribution timing and fuel delivery advance angle parameter values, we carry on the experiment on the original machine, obtain the external characteristic of the original machine and emission value, then the parameters of the injector and the supercharger is optimized, at the same time the EGR system and DOC devices are loaded, the ESC(European steady-state cycle) and ETC(European transient loop) emission test are carried out, while maintaining the power performance and fuel economy of engine basically remain unchanged, NO_x is reduced by 68.6%, the PM is reduced by 50%, achieving the goal of development. |
