Optimization Of A Diesel Engine Coupling Injection Law And EGR Based On DOE

With the development of diesel engine technology, the required calibration parameters are continuously increasing. This makes the diesel engine calibration workload into exponential growth, the traditional calibration method has been difficult to meet the requirements. One of the technical means to solve this problem is design of experiments (DOE) based on the model. DOE is a scientific method to optimize the experimental design, to reduce the experimental error, production cost, workload and carry out scientific analysis of the experimental results.Use the engine performance simulation software GT POWER to build a model of a diesel engine, and verify the accuracy of the model. Selection the fuel injection parameters (including the injection timing, nozzle diameter, injection pressure and EGR rate)which have a larger influence of the diesel engine performance as the experimental factor, apply multi-objective optimization DOE to reduce NOx and Soot emissions based on the power and economy performance. Through the simulation results established the Response Surface Methodology model, evaluated the accuracy of the response surface and established the coefficients of the experimental factors, analyzed the influence of the experimental factors on the experimental target.Optimization of injection timing, nozzle diameter, injection pressure and EGR rate are obtained by using the multi-objective Pareto method.Outcome show that the fitting results are basically consistent with the simulation results. When the maximum torque operation mode EGR rate increased to 19.63%, nozzle diameter decreased to 0.13mm, injection timing advance to -18.74°CA and injection pressure increased to 168.71 MPa,There is no obvious change in the power and economy performance, but the emission performance is greatly improved, especially the Soot emissions reduced by 86.6% compared to the original machine.Further, apply DOE method to the research of multi-section injection of diesel engine. And apply pre-injection law researched on the original machine. Finally obtained the best injection quantity, injection timing, injection pressure and EGR rate of the maximum power optimization. Simulation results show that the NOx emission, torque and fuel consumption rate is slightly improved, while the Soot emission was reduced by 57.4%. Illustrate that based on DOE method can effectively solve the complex multi-objective optimization problem of fuel injection law and EGR coupling. It has positive significance to improve the design and calibration of diesel engine.