Studies of Fundamental Combustion Properties of Dimethyl Ether Flames

Abstract

Recently there have been many problems related with automotive engineering, such as environmental issues and energy problems. These social circumstances motivate the adoption of urgent measures such as alternative fuel and new combustion techniques for the internal combustion engine. In this context, dimethyl ether (DME) is thought to be a potential alternative to diesel fuel due to lower overall pollutant emissions and more excellent fuel economy. DME has no carbon-carbon bonds and lowest possible carbon to hydrogen ratio after methane. The main features that make DME so attractive are : 1) the high oxygen content of 35% by weight, which provides smokeless combustion and high exhaust gas recycle tolerance ; and 2) the combination of a cetane number of 55 to 60 and a boiling point of-25°C, which provides fast mixture formation, reduced ignition delay, and excellent cold starting. Several recent publications have already presented results from diesel engines operated on pure DME. These experiments showed that DME is an excellent diesel fuel with a high cetane number. This fuel produces very low particulate emissions, while the NOx emissions are similar to those from current diesel fuel under the same engine operating conditions. This allows the engine operating conditions to be adjusted to reduce NOx without an accompanying increase in particular emissions. The purpose of this study is to clarify the combustion properties of DME/Air flames, which should be useful data for combustion modeling and simulation, using the spherical bomb that can embody the real engine conditions.