Study On Performance Matching And Optimization Of Two-stroke Low-speed Marine Diesel Engine

Study on performance matching and optimization of marine two-stroke low-speed diesel engine has important implications for reducing diesel power rebuilt. In this paper, based on the energy efficiency, reducing power rebuilt project undertaken by Shanghai Hudong Heavy Machinery CO., LTD and the detailed analysis of main engine structure, an engine performance simulation model was developed for the MAN B&W 6S60 MC MK5 two-stroke low-speed diesel engine.Through detailed analysis of the mathematical model of diesel engine working process, its accurate performance simulation model was developed. This paper studied cylinder scavenging process of low-speed two-stroke diesel engine by 3D CFD simulations, a cylinder scavenging model was set up for 6S60 MC MK5. According to the analysis of measured cylinder pressure for different loads of 6S50 MEC diesel engine, the characteristics of the heat release rate were analyzed; the combustion models for different loads were set up. Based on these models, the performance of 6S60 MC MK5 diesel engine at part and rated load were simulated. The results showed that the simulation is consistent with the experiment and the simulation model is accurate.After detailed analysis of the actual reduced power demand of marine engine, the new diesel engine rated power point was determined. The engine performance matching and optimization was carried out according to this rated power point. The turbocharger matching and optimization was calculated, as well as the compression ratio adjustment caused by reducing power. The layout of engine rebuilt was set up according to the turbocharger matching and compression ratio adjustment. The engine was rebuilt according to the newly designed parameters. It was tested during the sea trial. The fuel consumption was reduced after the engine was rebuilt. The energy efficiency was also improved.In order to explore if further optimization is possible, injection timing and exhaust valve timing optimization were carried out after engine rebuilt. By optimizing these parameters, the performance parameters, rebuilt program have been further optimized.