Study On Electronic Control System And Spray Characteristics For Low-Pressure Common Rail Fuel Injection System Of Dimethyl Ether Engine

Recently, dimethyl ether (DME) has received attention as a clean alternative diesel fuel due to its low NOX emissions; near-zero smoke and less engine noise compared with the values of traditional diesel fuels. As an oxygen-clean alternative fuel, DME is adapted to the compression-ignition internal combustion engine; compared with the majority of diesel and other alternative fuels, it has the advantages such as high efficiency, low emission, low noise, smoke-free combustion, etc. At the same time, it can be efficiently produced from natural gas or coal. It is available to solve our country's issues of worsening environmental pollution and deficiency of oil sources supplies. It is good to our country's strongpoint of plenty of gas and coal but lacking in oil. In recent years, DME as an alternative diesel fuel of diesel engines has aroused widespread concern around the world, thus the development of DME engine is one of China's major research projects.However, the traditional diesel fuel supply and injection system can not meet the DME engine'requirements of supply and injection, as a result of the differences of physical and chemical properties between DME and diesel. In this paper ,based on the low-pressure common-rail fuel supply and injection system of DME engine (rail pressure 5MPa ~ 20MPa), a set of electronic control systems was designed to apply to the low-pressure common-rail fuel injection system, including the hardware circuit, fuel injection control strategies, system the processes and procedures of control software , and software testing.In order to optimize the DME engine Parameters of injection system and combustion system and an in-depth understanding of the combustion mechanism of DME, the subject chose general-purpose CFD software FLUENT for simulating DME spray atomization process. According to the characteristics of fuel injector, the subject chose rational model of DME spray atomization, simulated the mixing process of DME and air, obtained the spray atomization patterns at different stages of oil and gas to be mixed, and extracted the characteristic parameters of the spray atomization patterns the distance and the spray cone angle. On basis of the model, changing the parameters of spray factors, including environmental pressure, the initial injection pressure and nozzle diameter, the subject analyzed the DME spray characteristics of changes in the law.In this paper, combining the domestic and foreign study of DME, with the front of the electronic control system and diesel instead of DME,the subject built the oil pump test bench, simulated the DME injection on the low-pressure common rail fuel injection system, collected test data under different working conditions and analyzed the test data, drew the fuel injection characteristics about low-pressure common-rail DME fuel injection system.Finally, this article drew the concludes that under the conditions of the appropriate changes in the structure of high-pressure common rail diesel engine and design and development of reasonable Fueled with DME of the electronic control system including the development of fuel injection control strategies, the DME low-pressure common-rail system can be put into practical use; that through the FLUENT simulation study of DME spray, the spray jet laws are initially known, but the DME spray characteristics and combustion mechanism has yet to be further researched.