The Influence Of Diesel Injection Strategy On The Combustion And Emission Characteristics Of Marine Duel Fuel Engine

The depletion of global fossil energy,the increasingly stringent regulations ofemission and the enhanced environmental awareness of the public promote the application and promotion of Marine diesel/natural gas dual fuel engine.While gas/diesel dual fuel engine can reduce NO_x and PM at the same time,having the same thermal efficiency under most conditions,compared with the traditional diesel engine,there are still many problems in dual fuel engine at low and middle load,such as:lower thermal efficiency,greater THC and CO emissions,poor stability of combustion.so how to improve the combustion and emission characteristics of dual fuel engine at low or middle load become the focus of scientific research in the institutions at home and abroad.Although a large number of studies both at home and abroad have shown that usingappropriate advance ignition diesel injection timing,increase the pilot diesel quantity,increasing inlet temperature,diesel fuel injection pressure,reduce the rate of substitution are the effective methods to improve thermal efficiency of the engine at low load,reduce the THC and CO emissions,but the application of these methods have some limitations,therefore,the researchers form domestic and foreign scholars began to put forward and study the influence of different diesel injection strategies on the dual fuel engine combustion and emissions,especially with a pre-injection of diesel fuel injection ignition strategy.Although a large number of studies have shown that diesel fuel injection strategy with pre-injection is a kind of richer potential fuel injection strategy for improving the combustion and emission characteristics of dual fuel engine at low load,but under the pre-injection,the study of the influence of parameters on the combustion and emissions,and the study of how to optimize the parameters are less.So the purpose of this article is to explore the influence of different diesel injection parameters on the combustion and emission characteristics of the gas/diesel dual fuel engine in low and middle load and how to optimize these parameters.Which can to provide theoretical and experimental guidance for optimize the diesel injection strategy and improve the combustion and emission characteristics of dual fuel engine in low load.In this paper,the main work includes:(1).At first,analyze the structure of the system witch is a diesel/gas engine modified form high pressure common rail diesel engine,then puts forward the control requirements for dual fuel engine;Then in order to meet the demand of dual fuel engine control,puts forward the methods of distribution coordination control for diesel ECU and gas ECU,and designed the hardware of the control system.(2).Designed the software of control system.In order to implement of the the switch of dual fuel and diesel,speed closed-loop,accuracy and flexibility control of micro pilot diesel,the researcher designed fuel design model managementfuel,distribution control,diesel injection coordination control,which can provide technical support for exploring the influence of diesel spray strategy on the combustion and emission characteristics of dual fuel engine at low and middle load.(3).The optimization for the combustion and emission characteristics of Diesel/natural gas dual fuel engine low and medium load.By using experimental method to explore the influence of different diesel injection strategy(single,two diesel injection)on the combustion and emission characteristics of dual fuel engine under low load,especially fo high replacement rate,and the influence of different diesel injection parameter on the combustion and emission characteristics of dual fuel engine with pre-injection strategy.,thus put forward the method of how to improve the performance of dual fuel engine in low load From the perspective of optimizing diesel injection strategy.