Abstract: Ethanol is being promoted as a renewable fuel and as a means of improving energy security. The
blends of gasoline and ethanol from 0 – 100 % ethanol were studied to evaluate their spray characteristics,
combustion performances, and particulate emissions with blends of ethanol and water with up to 40 % water
by volume being tested to research the combustion performances of different water ethanol blends and the
miscibility of water with ethanol/gasoline blends using ternary phase diagrams for gasoline, ethanol, and water.
The results show that presence of water in ethanol/gasoline mixtures is not an impediment to their use as a fuel
in gasoline direct injection (GDI) engines. Adding ethanol to gasoline increases the injected fuel volume and the
persistence of the fuel sprays, especially for a cold engine, leads to reduced mixture homogeneity, a decrease
in the combustion stability, and an increase in particulate matter emissions for a stoichiometric mixture. Adding
water to ethanol further increases injected fuel volume, but the increase in combustion duration and reduction in
combustion stability are not significant with up to 30 % water by volume.

Key words: gasoline direct injection (GDI) engine, particulate emissions, blends, ethanol, aqueous ethanol, sprays combustion