Working-process Simulation And Heat Release Research Of Marine Natural Gas Engine

With the increasing requirement of the emission regulation and concern about energy shortage,it becomes an inevitable trend for shipping industry to apply natural gas to marine engines,which is both cleaner in emission and richer in resource.Generally the marine natural gas engine share the similar structure profile with diesel or petrol engine but the combustion characteristic of natural gas is varied from the fuels,so it is meaningful to research on the working-process simulation and heat release calculation of marine natural gas engines.Firstly,a heat-release calculation model of marine gas engines is built in MATLAB/SIMULINK environment,basing on the difference in fuel and working-process of marine gas engine and conventional diesel engine.Then the model is used to calculate the heat release of 2135 G natural gas engine under different working conditions.A working-process model is built to simulate the gas pressure during in-cylinder process and gas-exchange process.The simulation result shows good agreement with experimental data from 2135 natural gas engine.Furthermore,the influence of natural gas compositions on engine performance is investigated.Secondly,the combustion characteristic of marine dual-fuel engine is analyzed on basis of marine gas engine and conventional internal combustion engine.An in-cylinder process model of marine dual-fuel engine is built on the assumption that three Vibe functions can well characterize the combustion process in dual-fuel engine.Then the main performance parameters of 6170 dual-fuel engine are calculated under the rated working conditions.A new method of heat-release calculation in dual-fuel engine is proposed on basis of in-cylinder process model.The method uses Vibe parameters which meets the in-cylinder process model with experimental data to fit the heat release in dual-fuel engine.Finally,a research is carried out to investigate the influence of natural gas substitution rate on dual-fuel engine performance.In this paper,the working process of both marine gas engine and dual-fuel engine are considered.The corresponding working-process simulation and heat-release calculation model are built with the reference of simulation model for diesel engine.It provides theoretical basis for the application of natural gas engines to marine ships.