Dimethyl ether (DME) is a synthetic diesel substitute used in specially designed compression ignition diesel engines. Under normal atmospheric conditions, dimethyl ether is a colorless gas. It is widely used in the chemical industry and as an aerosol propellant. Dimethyl ether requires approximately 75 pounds per square inch (psi) of pressure to be in a liquid state. Because of this, the treatment requirements for dimethyl ether are similar to those for propane - both must be stored in pressurized storage tanks at ambient temperature. 

The use of dimethyl ether in vehicles requires a compression ignition engine, and its fuel system is specifically developed for dimethyl ether. Many DME vehicle demonstrations have been held in Europe and North America, including a customer driving 10 cars for 750000 miles. 

production 

Although dimethyl ether can be produced from biomass, methanol, and fossil fuels, in the United States, the possible raw material for large-scale production of dimethyl ether is natural gas. Dimethyl ether can be directly produced from synthetic gas produced from natural gas, coal, or biomass. It can also be indirectly produced from methanol through dehydration reaction. Dimethyl ether is not commercially sold in the United States. 

benefit 

Dimethyl ether has several fuel characteristics, which make it attractive in diesel engines. Its cetane number is very high, which is a measure of fuel flammability in compression ignition engines. The energy efficiency and rated power of dimethyl ether and diesel engines are actually the same. 

Due to the lack of carbon to carbon bonds, using dimethyl ether as a substitute for diesel can almost eliminate particulate emissions and may not require expensive diesel particulate filters. However, the energy density of dimethyl ether is only half that of diesel, requiring a fuel tank twice as large as diesel. 

research and development 

In 2013, Pennsylvania State University, Volvo, and Oak Ridge National Laboratories completed on-site testing of DME truck prototypes. This heavy-duty truck performs well under actual driving conditions, and its efficiency is comparable to traditional diesel trucks. The test results indicate that the emission standards can be met without the use of diesel particulate filters. Like traditional diesel vehicles, the reduction of nitrogen oxides (NOx) can be addressed through standard nitrogen oxide post-treatment systems. Additionally, the engine can be calibrated to eliminate the need for such a system, but this will reduce efficiency.