Research And Development Of In Cylinder Direct Injection LNG/Diesel Dual Fuel Supply System And Electric Control Strategy

For the energy and environmental issues have become increasingly prominent, theemission has been attended. In all emissions, the ship engine emissions account for a largeproportion. For the large account of natural gas has been confirmed, with the hydrocarbonslower than the others and the good emissions features, meeting the International MaritimeOrganization (IMO) Tier III emission standards ship will be implemented, has beenwidespread attention. How to make better use of the natural gas as a motor fuel has becamea hot research.Currently in the most field of natural gas engines use its gaseous form. so the fuel gassupply system is supplied to the gas system. Although in this way can effectively reduce thesoot particles and greenhouse gas emissions, but not obvious for the improvement of NOxemissions. If the natural gas in liquid form is injected into the engine cylinder, not only canreduce soot and greenhouse gas emissions, but also can take use of latent heat ofvaporization for liquefied natural gas in the cylinder, effectively reducing the maximumcylinder temperature, thereby reducing NOx generation. These all require to research anddesign a liquefied natural gas fuel supply system.The main task of this paper is to model and simulate the engine and control system for6L21/31medium-speed diesel engine converted into a fuel supply/LNG dual fuel. Byanalysis the existing diesel and natural gas fuel supply system, determine the form of themodified diesel and natural gas fuel supply system, i.e., a high pressure common rail dieselfuel supply system as a system has been confirmed, but for the liquid and gas supply systemwithout a corresponding paper creative work using high pressure common rail fuel supplysystem in the form of a liquefied natural gas supply system. For diesel and liquid natural gasfuel supply system can be have a good match, so the modified engine can perform well, inthis paper the dual-fuel engine control strategy is also studied, and the control strategy of themodified dual-fuel engine is determined, ultimately, determining the engine for the overallconversion program. Firstly, a model is created in AMESim for establishing common raildiesel injection system, and analysis the effect of the more important characteristicparameters for injector fuel injection. Secondly, in AMESim software, the LNG fuel supplyto the engine system was designed and modeled and do some research for LNG fuel injectorspray injection characteristics. Again, in simulink, the control system for a diesel/LNG dualfuel engine is established. Finally, through joint simulation simulink with AMESim,making the two fuel supply system and control system carried out a joint operation to achieve a variety of fuel injection starting time, continuous spray and spray quality control,so that it meets the post-modification dual fuel engine power does not drop, while reducingthe NOx emissions requirements needed for each fuel injection.