Energy Efficiency Improvement Methods For Inland Diesel/LNG Dual Fuel Ship

In recent years,with the increasing requirements of IMO and governments for ship emissions,the number of diesel/LNG dual fuel ships has gradually increased.Although the emissions of exhaust gas pollutants and CO₂ from diesel/LNG dual fuel ships are reduced compared with diesel engine ships,with the increase of the number of diesel/LNG dual fuel ships,the emission of exhaust gas pollutants and CO₂ from diesel/LNG dual fuel ships will become more and more serious.Ship emissions are closely related to ship energy efficiency.Ship emissions can be effectively reduced by improving ship energy efficiency level.Therefore,research on energy efficiency improvement methods for diesel/LNG dual fuel ship is of great significance for reducing ship emissions and promoting energy saving and emission reduction of ships.In this paper,an inland diesel/LNG dual fuel ship is taken as the research object.Based on the calculation of calm water resistance and the navigational environment resistance,the ship energy efficiency simulation model is established according to the ship-engine-propeller interaction relationship.And the ship minimum fuel consumption speed optimization model,minimum CO₂ emission speed optimization model and minimum fuel cost speed optimization model are established considering the ship energy efficiency relationship,and the optimization calculation are carried out.The main research work of this paper is as follows:（1）The energy efficiency monitoring system of the object ship is designed.Firstly,according to the characteristics of diesel/LNG dual fuel ship and ship energy efficiency system,the requirement analysis of dual fuel ship energy efficiency monitoring system is carried out.Then,combined with the design principle of ship energy efficiency monitoring system,the energy efficiency monitoring system for inland dual fuel ship is designed,and the selection of sensors for the system is analyzed.Finally,the error characteristics of the collected energy efficiency data are analyzed and the data are cleaned.（2）Based on different navigational environments and rotational speeds,the energy efficiency simulation models of dual fuel ships is established.Aiming at the object ship,Holtrop method is used to calculate the calm water resistance,and empirical formulas are selected to calculate the additional resistance of the navigational environment caused by air and shallow water.On the basis of resistance calculation,combined with ship-engine-propeller matching relationship and ship kinematics theory,the energy efficiency simulation model of the target ship is established by using MATLAB/Simulink software,and the simulation calculation is carried out.The energy efficiency simulation is verified by the data collected from the real ship,and the accuracy of the model is analyzed.The influence of navigational environment factors,such as water velocity,water depth and wind speed,on the fuel consumption and gas consumption of 100 km is analyzed.The results show that the maximum error between the simulated and measured values of the total fuel consumption of the main engine is4.62%,the average error is 3.00%,the maximum error between the simulated and measured values of the total gas consumption of the main engine is 5.53%,and the average error is 2.82%.（3）The energy efficiency improvement methods for inland diesel/LNG dual fuel ships are studied.The relationship between main engine fuel consumption,main engine gas consumption,ship speed through water and main engine speed is analyzed by using the established ship energy efficiency simulation model.The mathematical models for speed optimization of the minimum fuel consumption,minimum CO₂ emission and minimum fuel cost are established.The model is optimized by using LINGO software,and the optimum speed of each voyage section under the minimum fuel consumption,minimum CO₂ emission and minimum fuel cost are obtained.