This paper reviews the technical and economic feasibility of Dimethyl Ether (DME) as a future fuel for compression ignition engines. DME can produced cleanly via the conversion of various feedstock such as biomass.
Although the bulk of research has focused on the practicality of DME for use in medium or heavy-duty engines, this paper provides an overview of the feasibility of DME as a candidate fuel for environmentally-friendly compression-ignition engine regardless of size or application. DME’s shares many properties with the traditional diesel engine, such as its low ignition temperature and high cetane number. Another advantage is the particulate-matter free combustion achieved in engines due to the simple chemical structure and high oxygen content. However, in spite of these advantages, the adoption of DME hasn’t excelled due to different physical properties compared to diesel fuels, such as low values for viscosity and lubrication.
The low lubrication value becomes an issue during fuel injection as slight modification of the standard system is required to prevent corrosion. Fuel injection is performed through both conventional mechanical and low-pressure common rail systems. DME is easily applied to compression-ignition engines due to its spray characteristics, despite property differences such as easier evaporation and lower density. Ultimately, the negligible levels of particulate matter production of DME provides sufficient justification for its consideration as an alternate fuel for use in compression-ignition engines. Research has indicated that this reduction in PM production is coupled with on-par vehicle performance, hence strengthening the case for DME. Even with the advent of diesel particulate filter (DPF) technology in OECD markets, problems relating to operation, maintenance and cost issues have been regularly cited as inhibiting uniform long-term PM removal.