Optimization of Injection Pressure for Fuel Consumption and Exhaust Emissions in a Dimethyl Ether (dme) Engine with a Common Rail Type Injection System

Dimethyl Ether (DME) has been attracting attention as an alternative fuel for diesel engines because it can be produced from various feed stocks and does not create smoke. On the other hand, a DME truck require a large volume fuel tank in order to obtain the running distance equivalent to diesel trucks due to the lower energy content per unit volume of DME, and un-burned gas and fuel consumption of a DME engine tend to increase when large volume EGR are used. Therefore, DME engine research for the further improvement of fuel consumption and exhaust emissions still remains. It is important to optimize the injection pressure of the DME engine in order to improve fuel consumption and exhaust emissions. Compared to diesel fuel, DME has much lower viscosity, lower bulk modulus and higher vapour pressure, so the DME injection system commonly used a relatively low injection pressure up to 60 MPa. The effect of high injection pressure on DME engine performance has not yet been understood. In this study, the influence of injection pressure on fuel consumption and exhaust emissions were examined using a common rail type DME injection system with injection pressure up to 100 MPa, and it was demonstrated that the optimum injection pressures for fuel consumption and exhaust emissions of the DME engine in wide operating ranges.