Abstract
This study is carried out to investigate the combustion characteristics during 500 hour durability test of an actual diesel engine using emulsified fuel. In order to understand the effect of emulsified fuel in wide range of engine running condition, D-13 mode is selected and 13% to 15% water-emulsified fuel is used. Combustion pressure in cylinder, exhaust emissions, specific fuel consumption, sound level and maximum torque are measured. The results of water-emulsified fuel show that the cylinder pressure risen during compression goes deeply down without ignition. The pressure rises steeply soon after self-ignition start. The behaviors of pressure variation are similar to one another with load and engine speed variation. But the pressure goes down more deeply in the low load and low engine speed case. Those say that the self-ignition of water-emulsified fuel is sensuously affected by the engine running condition. If the cylinder has enough energy to absorb a water-cooling effect, the cylinder pressure smoothly rises like the case of high load and speed. Specific fuel consumption varies with engine load variation. The only diesel fuel case is best in the low load region, but the emulsion case becomes better with engine load higher. NOx and PM are reduced about 12%, 33% respectively for the D-13 mode test. Those results are not varied during 500-hour-durability-test and also there is no trouble and any damage on the engine parts.