Dimethyl Ether (DME) has been recognised as a clean alternative for diesel oil for some years now. Fuelling diesel engines with DME solves their two most significant problems: The emission of particulate matter is virtually eliminated and the level of NOx can be reduced considerably by exhaust gas recycling. A significant problem arises when conventional injection equipment is used for pumping DME: It breaks down prematurely due to the poor lubrication qualities of DME compared to those of diesel oil. These qualities consist of the lubricity, which is important in the boundary lubrication regime, and the viscosity, which plays a major role in the hydrodynamic lubrication regime. The lubricity of DME has been established by the medium frequency pressurised reciprocating rig (MFPRR) to be very low compared to the one of diesel oil. But the DME film limits the wear extent significantly compared to the case of dry sliding. By mixing DME with additives, the lubricity level is easily raised even above the one of diesel oil. The viscosity of DME has been established by the volatile fuel viscometer (VFVM) to be as low as 0.185 cSt @ 25 oC. It is also shown that this viscosity cannot be raised significantly by mixing the DME with reasonable amounts of additives. The main conclusion drawn from these measurements is that a combination of lubricity and viscosity comparable to one of diesel oil cannot be reached in the case of DME unless a huge amount of additive is used. This is not an attractive solution, as the clean emission advantage obtained when using DME will be lost.
|Title of host publication||Proceedings of the 13th Colloquium Tribology|
|Publication status||Published - 2002|
|Event||the 13th Colloquium Tribology - Esslingen, Germany|
Duration: 1 Jan 2002 → …
|Conference||the 13th Colloquium Tribology|
|Period||01/01/2002 → …|