Multi-Cylinder Diesel Engine Tests with Unstabilized Water-in-Fuel Emulsions

Two diesel engines representative of the four-stroke cycle and two-stroke cycle main propulsion units installed in U.S. Coast Guard WPB class vessels were operated in a test environment in an attempt to demonstrate significant fuel savings associated with water-in-fuel emulsions. A prototype fuel system was assembled that would supply unstabilized emulsions for which the water concentration could range from zero to 25% of the total volume of liquid supplied to the engine as fuel.

The test results for the four-stroke cycle engine indicated that an average diesel fuel savings of about 2.5% could be obtained at the most frequently encountered operating conditions using water concentrations of 15-25%. For the two-stroke cycle engine, no significant reduction in fuel consumption could be identified.

Based upon the results obtained, it was concluded that water-in-fuel emulsions of the type utilized did not offer an advantage to USCG cutter operations.