About DME

 DME (Di-Methyl Ether) is a substance of which the chemical formula is shown by CH3OCH3. DME is a colorless gas at ambient temperature as its boiling point is -25.1℃. As its saturated vapor pressure is as low as 0.6Mpa, it is easily liquefied. As the physical properties of DME are similar to those of propane and butane, main components of Liquid Petroleum Gas (LPG), the storage and handling technology of LPG is applied to DME.

 When DME was introduced as spray propellant, it had already been confirmed that its toxicity is low and its negative environmental impact is small. As for the safety evaluation for voluminous distribution of DME, detailed examinations were later conducted and it was concluded that DME is as safe as LPG.

 As DME has no carbon-carbon bond, no soot is generated on burning. It doesn't contain sulfur not to emit SOX. It is rich in hydrogen and CO2 emission per calorie is little, and NOX emission is little. It is "Next generation's clean energy carrier" of which the negative environmental impact is extremely small.

 DME can be produced from wide range of raw materials; not only from the fossil resources such as natural gas and coal, but also from the renewable resources such as biomass and hydrogen generated by photovoltaic electricity.

 Like LPG and natural gas, DME is expected to be a new energy that can be used for wide usage such as home fuel, power generation fuel, diesel engine fuel, and furthermore fuel for the fuel cell.

Physical properties of DME

 Fundamental physical properties of DME as fuel are shown in comparison to other relating fuels.

Property DME Methane Propane Methanol Gas oil
Chemical Formula CH3OCH3 CH4 C3H8 CH3OH -
Boiling point (℃) -25.1 -161.5 -42.0 64.6 180〜360
Liquid density (g/cm3,20℃) 0.67 - 0.49 0.79 0.84
Gas density (vs. AIR) 1.59 0.55 1.52 - -
Saturated vapor pressure (MPa,25℃) 0.6 - 0.9 - -
Auto-ignition point (℃) 235 650 470 450 250
Explosion limit (%) 3.4〜17 5〜15 2.1〜9.4 5.5〜36 0.6〜7.5
Cetane number 55〜60 0 5 5 40〜55
Lower Heating value (MJ/kg) 28.8 50.2 46.4 20.1 42.7
Lower Heating value (MJ/m3) 59.2 35.8 90.9 - -

Quality standard of DME

 The examination of DME quality standardization has been progressing in consideration of DME production method, DME distribution method, and conditions on DME utilization equipment, and JIS standard K2180 of fuel DME was issued in March, 2013. JIS of DME fuel for the vehicle is at present under examination.
 International Standard ISO of fuel DME is now under examination and expected to be issued in 2014.
 JIS standard K2180 of fuel DME is shown.

Item Unit Standard value
DME purity mass % 99.5 or more
Methanol mass % 0.050 or less
Water mass % 0.030 or less
Hydrocarbon (C4 or less) mass % 0.050 or less
Carbon dioxide mass % 0.10 or less
Carbon monoxide mass % 0.010 or less
Methyl formate mass % 0.050 or less
Ethyl methyl ether mass % 0.20 or less
Residue after evaporation mass % 0.0070 or less
Total sulfur mg/kg 3.0 or less