The Potential of Dme-diesel Blends as an Alternative Fuel for Ci Engines

This paper provides a comprehensive review of the technical feasibility of DME-Diesel blend as an alternative fuel for compression-ignition engines for automotive applications. DME is a synthetic fuel produced by the conversion of various feedstocks such as natural gas, coal, oil residues and bio-mass. The compatible properties such as high cetane number and low auto-ignition temperature with spray characteristics of DME enable its application to CI engines despite of its easier evaporation and lower density. In addition, simple chemical structure of DME (CH3-O-CH3) with only C–H and C–O bonds and no C–C bond with high oxygen content result in soot-free combustion justifies its consideration for diesel engines. Recent research and development shows that the operation of DME combustion system needs the adoption of rigorous procedures for safe operation due to the wide flammability limits. Practically, the blending of some oxygenated DME to diesels to reduce engine emissions with few engine modifications seems to be a more attractive proposition. Hence, the relative ―benefit‖ of each fuel might be utilized by blending DME with diesel fuel. The blending of DME to diesel fuel changes its physicochemical properties. The review compares key properties of diesel, neat DME and DME-Diesel blended fuels which are relevant to this application. The increase of DME mass fraction decreases the density, calorific value, kinematic viscosity and aromatic fractions of the blends, while the C/H ratio, cetane number and oxygen content of the blends are enhanced, which affects the performance and emission characteristics of the engine. Recent research and development shows that the blending of DME with diesel as an alternative fuel for CI engine and its application for automotive vehicles is promising solution for the future. Keywords— Alternative fuels, Blend, CI engine, Diesel, DME