Performance Study And Optimization Based On VGT/EGR Technology For Yacht Engine

With the increasing number of yachts in C hina,the issue of energy saving and emission reduction has attracted widespread attention.As the key technology of yacht engine,there are important research value in variable geometry turbocharger technology(VGT)and exhaust gas recirculation technology(EGR).In this paper,a yacht engine O ED483 Q is used as a prototype,then study is launched based on GT-Power software,aimed to improve the performance of the yacht engine,as well as to provide the theoretical guidance for making control strategy of the VGT system and the EGR system.First,the working process of the yacht engine is described by mathematical model,the purpose is to explore theoretical basis of GT-Power simulation.Then the whole model of the yacht engine is established.The results of the simulation are calibrated against experimental data,after that the accurate simulation model is obtained,which lays the foundation for the subsequent calculation.The matching theory and evaluation system of the engine for the turbocharger are analyzed.The matching calculation of the GTB15(a variable geometry turbocharger)shows that both the turbine and the compressor are in good match with the yacht engine.Secondly,the advantages of variable geometry turbocharging to waste-gated turbocharging for yacht diesel engine is analyzed at full load.Under the condition of propulsion characteristic,the influence of different VGT rack positions on the performance of the yacht diesel engine is studied when EGR is not used.The PID control model based on VGT rack positions is also established by using the simulation software.After calculation,the best VGT rack positions is found under the propulsion characteristic.Then,the performance of typical fixed rack position and best rack positions is compared,and the superiority of VGT is further revealed.At the same time,on the basis of the optimum VGT rack positions,the EGR system is introduced to the yacht diesel engine,then the influence of different EGR rate on its performance under the propulsion characteristic condition is analyzed.Finally,a DO E simulation of the VGT rack positions and EGR rate is selected to research the influence for the performance of the yacht diesel engine by the two factors.Using DOE post-processing optimization tools,a appropriate optimization scheme was selected,then the best VGT rack position and EGR rate were obtained.Under the woking co ndition,the yacht diesel engine can meet the emission standard,and the effectual fuel consumption rate also reaches a low level.