The Modeling And Simulation Analysis Of Large Containership Energy Efficiency

The shipping industry faces multiple challenges recently taking into account the unprecedented rise of fuel prices and the increasing concern for the emissions.Therefore,the IMO proposed the EEOI(Energy Efficiency Operational Indicator)and set it as the new standard for assessing the energy efficiency level of operating vessels in order to save the fuel amount and limit the gaseous emissions.In this work,the energy efficiency model of a large container ship was developed in the MATLAB/Simulink environment according to the modular concept.The influence of the voyage speed,the cargo,the voyage distance,the port time as well as the wind wave on the vessel EEOI was thoroughly investigated.In addition,the reduction of EEOI was examined based on the ship speed and routine optimization for improving the energy efficiency level of operating vessels.The main contents are summarized as follows:Firstly,the mathematical model of the target ship propulsion system was built including the main engine,the propeller and the ship.The EEOI formula was manipulated to derive the relationships between the EEOI and the voyage speed,the cargo,the voyage distance,the port time and the wind wave.Subsequently,the ship energy efficiency system model was developed in the MATLAB/Simulink environment and validated using the vessel trail and operational data.Finally,the EEOI influencing factors were analyzed.The simulation results indicate that the decline of the voyage speed and the growth of the cargo capacity reduce the EEOI value considerably,whilst the increase of the voyage distance and the decrease of the port time have insignificant effect on the reduction of the EEOI.On the other side,the EEOI has the greatest impact on the voyage speed sensibility and less on the cargo capacity.Additionally,the voyage distance and port time were least affected.The dead wind and the steaming head to sea increase the EEOI at constant voyage speed,whereas the downwind reduces the EEOI with the impact becoming greater as the wind resistance and the wave resistance are added.After optimization at persistent voyage cargo capacity,the EEOI of the target vessel are declined by 14.46%,18.76% and 23.58% with the voyage speed at 21 kn,20 kn and 19 kn,respectively.The fuel consumption are consequently reduced by 411.11 t,617.75 t and 849.76 t during the voyage.The results show that the joint optimization of the voyage speed and the voyage routine can significantly reduce the vessel EEOI and improve the energy efficiency level.The ship energy efficiency model proposed herein can predict the vessel EEOI under certain conditions,which has instructive meaning for the management of the ship energy efficiency.The optimization method developed in this work provides a good reference for the shipping company regarding the energy conservation and emission reduction.