Simulation And Research Of Heavy Duty Diesel Engine DOC System Based On BOOST

With the strengthening of people's environment awareness of protection and the rapid increase in the number of motor vehicles,in recent years,countries around the world have gradually introduced increasingly strict emission regulations.The diesel engine post-processing system has gradually become an important measure to control harmful exhaust emissions.The DOC as a simple and effective,low-cost post-processing device is widely used.The diesel engine DOC system is the main post-treatment device for reducing CO,HC,and NO emission regulations above the national VI,as well as the efficiently reduce CO,HC and NOx emissions in the exhaust.Based on AVL-BOOST software,this paper establishes a one-dimensional calculation model of DOC catalytic oxidation converter,and compares the corrected one-dimensional calculation model with experimental data through the genetic algorithm model in MATLAB environment to verify the accuracy of the model..Using the established DOC model,the effects of geometric parameters and gas composition of the DOC catalyst on the conversion efficiencies of CO,HC,and NO were investigated.Its main work is as follows:Establish one-dimensional DOC calculation model and pressure drop model;Use the test data to identify the DOC model parameters,and compare the test values with the calculated values;1)Study the effect of different DOC?length,diameter,number of holes,wall thickness?on CO,HC,NO conversion efficiency;2)Study the effect of different NO₂/NO_X ratio and O₂ concentration on the conversion efficiency of CO,HC,and NO;The main conclusions are as follows:1)According to the assumptions,set up a single-hole mathematical model for the catalytic reactor,study the oxidation mechanism of HC,CO and NO in the DOC catalyst,and prepare for BOOST modeling.2)In this chapter,the diesel engine DOC system performance test is conducted,and the AMA4000 gas analysis system and AVL test bench are used in the test.The following tests are mainly completed.The oxidation efficiencies of CO,HC and NO at different temperatures for DOC catalysts with different geometries and different precious metal coating schemes were studied under the conditions of airspeed of80,000h^-1.The test adopts the working condition point method,and the purpose of keeping the airspeed unchanged by adjusting the engine speed and torque.3)In this chapter,the one-dimensional pressure drop model and conversion efficiency model of DOC were established using AVL-boost software and the calculation model was verified by experiments.The DOC pressure drop was analyzed by changing the length,diameter,number of holes,wall thickness of DOC,and the impact of DOC conversion efficiency.