Abstract: The preparation of water containing diesel oil emulsion and microemulsion by using nonionic surfactants as emulsifiers was studied. The combustion heat of water-doped diesel oil was measured under different combustion conditions. The results showed that the incorporation of water in diesel oil did not improve the combustion efficiency under rich oxygen condition(in the oxygen bomb), but the calorific efficiency was improved when the diesel oil containing water was atomized directly into the combustion chamber under atmospheric condition. To get a higher combustion efficiency, the amount of water incorporated in diesel oil generally should be about 10%～20%, but it can be up to 30% in the presence of some metallic ions in water. The diesel oil microemulsion is much more stable than the emulsion containing equal content of water, but the combustion heat in both of them is all the same.

Key words: nonionic surfactant, emulsification of diesel oil, combustion efficiency