Simulation Study On Matching Performance Of Marine High Pressure SCR Diesel Engine

With the rapid development of the shipping industry,marine diesel engine emission is the main factor of the pollution of coastal areas and the marine environment.To protect the environment,the International Maritime Organization decided to put into effect the Tier III emission regulations on in the emission control area on January 1,2016,to further limit NOx emission from exhaust gas.Therefore,the new type of NOx emission control technology has become a popular research field.Selective catalytic reduction technology(SCR)is considered to be the most effective and the most promising NOx emission control technology,which can fully meet the standards of Tier III emission.MAN has made unremitting efforts for this reason,together with Wartsila and other ship manufacturers.In this paper,establishing the mean value engine model of the 6S46MC-C diesel engine with high pressure SCR,to study the influence of high pressure SCR system on the matching of diesel engine.further more,the measures to improve the inlet temperature of the reactor are proposed to optimize the performance of the reactor during low load operation,and the simulation of diesel engine acceleration and deceleration process are conducted with bypass.In addition,the energy saving program of the diesel engine is put forward.Get the following conclusions in this paper:(1)The mean value engine model of marine high pressure SCR diesel engine was established on Matlab/Simulink simulation platform to study the effects of high-pressure SCR system on diesel engine operation from steady state and dynamic simulation respectively.The steady-state results show that the high pressure SCR system has little effect on the operating parameters of the host and does not affect the power and economy of the diesel engine.The dynamic results show that the high pressure SCR system has a large thermal inertia,which has a certain influence on the dynamic process of the diesel engine,and prolongs the stability time of the dynamic process of the system.(2)The effects of two modes of scavenging bypass and exhaust gas bypass on the diesel engine of high pressure SCR system were studied.The results show that,when the Clinder bypass valve(CBV)opening is 0.55 or the exhaust gas bypass valve(EGB)opening is about 0.7,the reactor inlet temperature can meet the requirements and the effect is good..At the same time,the dynamic simulation of the rapid loading,normal loading,rapid unloading and preheating of the diesel engine with bypass modulation is studied well compared with the experimental data.(3)Proposing two energy-saving programs such as power turbine power generation technology and the use of Variable Geometry Turbocharger technology can use more heat from the exhaust gas,Variable Geometry Turbocharger can reduce the fuel consumption rate,both of which can achieve the purpose of energy conservation.