Simulation Model of a Dual-Fuel Four Stroke Engine for Low Emission Ship Propulsion Applications

The present study deals with the computational simulation of a marine four-stroke dual-fuel engine, working both in diesel and natural gas modes, with a particular focus on the turbocharger system behaviour. The engine model, developed by the authors, was implemented as a computer code and used to compare the performance of the engine when using the two different fuels. The variable geometry turbine operation has been studied and simulated in detail as well as the compressor matching. The paper points out the different implications of the turbocharger functioning due to the different features of the mix air-fuel introduced in the engine. The developed computer model has been validated with good results by comparisons with reference steady state engine data, provided by the manufacturer, referred to both design and off design situations. The good results obtained from these comparisons confirm the possibility of using the calculation procedure to optimize the control logic of both the engine and the variable geometry turbine, thus extending the application possibilities of the simulation model.