Kanagawa University Develops New Diesel Emulsion Fuel

4 October 2006

Test vehicle for Super Emulsion Fuel.

Researchers at Kanagawa University in Japan have developed a new emulsified diesel fuel—Super Emulsion Fuel—that reduces emissions and improves fuel economy compared to standard diesel and also maintains stability much longer than conventional emulsified fuels.

Emulsified diesel fuel is a mixture of diesel fuel with water and emulsifying and stabilizing additives. The practice of adding water to diesel dates back to the early 1900s, and there are hundreds of different patented implementations. Depending on the application, the water content may vary from 8%-35%, with a typical 13% water formulation for diesel engine use.

There are numerous benefits to adding water to diesel. Water vaporization increases fuel dispersion in the form of smaller droplets and the contact surface between fuel and air is increased. As a result, combustion is more efficient; combustion temperature peaks are lowered, thereby reducing NO_x; and PM formation is reduced.

The newly developed emulsion fuel is also a mixture of water and oil, but the team developed a novel method of emulsification. Rather than relying on surfactants, the new three-phase emulsification process uses the weak molecular attraction (van der Waals force) between hydrophilic nano-particles. A single type of emulsifying particle can be used to emulsify many different oil types. Conventional surfactant-based emulsification uses different surfactants for different oils.

The new process relies on the size and shape of the particles alone and not on the unique properties of a surfactant substance.

Click to enlarge.

Tests with a heavy-duty (30-ton) dump truck used two emulsified blends: 65 to 35 wt% diesel to water and 70 to 30 wt% diesel to water. Test results showed significant drops in emissions and an increase in fuel efficiency of 10-15%.

New emissions regulations phasing into effect in Japan require a 25 to 43% reduction in NO_x, a 15 to 50% reduction in PM and a 33 to 60% reduction in HC over existing regulations for different weight classes of vehicles. The dump truck using the Super Emulsion Fuel met the requirements.

Resources:

• Emulsified Fuels in Western Europe—an Overview