Design And Performance Analysis Of GVU System For Dual Fuel Engine

With the development of science and technology and the improvement of life quality,energy and environment issues have become the focus of people’s attention.As emissions regulations slowly became stricter,natural gas engines began to enter the field of view.The main difference between a natural gas engine and a conventional internal combustion engine is the gas supply system.The role of gas supply system is to supply gas to the natural gas engine to meet its use.In different working conditions of the engine,the pressure requirements of the gas entering the engine are different.In order to make the gas pressure meet the requirements of the engine synchronously,the gas regulating system should be set before the gas entering the natural gas engine,this system is called GVU(gas valve unit).At present,there are few researches on GVU,which mainly rely on foreign imports and is very expensive.Meanwhile,the research and development of GVU needs to match with the engine,and the imported GVU cannot meet the requirements of the engine of CSSC Power Co.,Ltd.This paper takes GVU as the research object,studies and analyzes the composition,structure and working principle of GVU system and then design and debug the GVU system according to the 9L28/32 DF engine requirements of China Shipbuilding Power Co.,Ltd.The specific contents and main conclusions are as follows:1.Study and analyze the composition and function of the GVU system,and obtain the design diagram of the GVU system.Then according to the system design diagram,the working principle of GVU is expounded to verify the feasibility of the system design.On top of,according to the requirements of the 9L28/32 DF engine,the key components of GVU are calculated and selected.Then through Solid Works software to draw the GVU three-dimensional model diagram,the GVU can be assembled and debuted by the enterprise according to the 3D diagram;Finally,the problems in the debugging process of GVU are studied.2.In view of the problem that there is still pressure fluctuation in the pipeline after the pressure regulating valve of natural gas,according to the structure and working principle of the pressure regulating valve,the model of the electric control pressure regulating valve is established by using AMESim software and the simulation calculation is carried out.The influences of spring stiffness of the main valve,mass of the main valve core,cross-sectional area of outlet damping hole and volume of outlet chamber on the outlet pressure of the electronic pressure regulating valve are analyzed.The simulation results show that the fluctuation of outlet pressure can be effectively reduced by appropriately reducing the spool mass of the main valve and increasing the spring stiffness of the main valve regulating spring.Through parameter adjustment,the outlet pressure after the pressure regulating valve is kept in a stable state.3.In view of the dual fuel engine in the sudden loading,because of the role of the filter in the GVU makes the pressure in the pipeline slowly rise,which cannot meet the requirements of the engine,the porous media model of Fluent software was used to carry out numerical simulation of two types of filters in GVU,and the flow characteristics and pressure drop of the two types of filters were obtained.The advantages and disadvantages of the two types of filters were compared and analyzed and then the filters were optimized.After optimization,the flow inside the filter is more uniform and the pressure drop is reduced.4.The simulation model of the main part of GVU was established by using AMESim software according to the method of part-first and whole-second,then connect the model of each part,and the overall model of GVU is obtained.Then,the GVU is simulated,and the outlet pressure and flow data of the GVU obtained from the simulation under different working conditions are compared with the experimental data of the enterprise,which verifies the accuracy of the model.Finally,the GVU release system after engine shutdown is simulated and calculated,and the pressure changes before and after each release valve,as well as the influence of the number of elbow and the diameter of the valve on the release situation are analyzed.The requirements of the release pipeline are obtained: D1 distribution line can have up to 3 90° bends,D2 distribution line can have up to 4 90° bends;The valve diameter of flush valve 1 shall be in the range of 15mm-20 mm,and the valve diameter of drain valve shall be in the range of 10mm-20 mm.