Abstract:

The effects of the Fischer-Tropsch synthetic (F-T) diesel proportion and the engine compression
ratio on the combustion characteristics in combustion mode were investigated by using bench tests to improve
the rough combustion running at heavy load for a dual-fuel engine. In the tests, an F-T diesel with high cetane
number was adopted to ignite the premixed methanol-air gas in a whole coal based dual-fuel engine with F-T
diesel and methanol. The results show that the combustion of dual-fuel engine is more gentle compared that of
original engine, the combustion duration declines obviously, and the economy becomes worse with increasing
F-T diesel portion and decreasing compression ratio. The decrease of compression ratio is conducive to reduce
the combustion rough degree under low F-T diesel portion. Therefore, by using a low F-T portion and a suitable
small compression ratio can improve the combustion performance and economy for methanol/F-T diesel dualfuel
engine.

Key words: dual-fuel engine, Fischer-Tropsch synthetic (F-T) diesel, methanol, combustion, thermal efficiency