抄録
In CIMAC in May 2001, the largest congress for marine and stationary engines in the world, many engine builders have announced that they apply the water injection into the cylinder to reduce the NOx emission. There are three methods of water injection into the cylinder, FWE (Fuel Water Emulsion), SFWI (Stratified Fuel Water Injection) and DWI (Direct Water Injection) [1]. At the last COMODIA in 1998, the authors presented about the effect of stratified fuel water injection to reduce NOx and smoke at the same time [2]. In the present study, to confirm the effect of fuel-water emulsion on combustion, experiments have been carried out using a visual engine and a visual combustion chamber. Figure 1 shows the burning flames in the two cases, (a) pure BFO (Bunker Fuel Oil) and (b) BFO-water emulsion. The combustion system of the visual engine simulates the one for low-speed marine engines. According to it, the flame of (b) shows the better combustion state, less soot-cloud and less after-burning than the flame of (a). In the presentation, reduction of the flame temperature measured by the two-color method and reduction of the soot formation inside the flame observed by the back diffused laser photo technique applying the fuel-water emulsion are introduced.
