Experimental study on combustion and particle size distribution of a common rail diesel engine fueled with GTL/diesel blends

• The effect of GTL on PSD and combustion were investigated particularly.
• A particular classification based on particle size was provided.
• A relativity was found between size range and blend ratio.
• Increasing blend ratio was found to reduce the nucleation mode particle number.
• It is of benefit to decrease the total particle number with GTL under transient condition.

The effect of GTL/diesel blends on combustion and particle size distribution were experimentally investigated in a turbocharged intercooled common-rail direct injection (CRDI) engine under steady-state and transient-state operating conditions. The experiments include six fuels: fossil diesel (G0), G10, G20, G30, G60 and G100 (GXX means a blend of XX vol% GTL in diesel). Particle size distribution was measured by TSI EEPS 3090 through a two-stage dilution tunnel. The engine was tested without exhaust gas recirculation (EGR) in all modes. The results indicate that the majority of particles are in the diameter region of 10–200 nm with GTL under middle speed. Compared with fossil diesel, the GTL/diesel blends shorten the ignition delay and reduce the proportion of premixed burning. With the proportion of GTL increasing in blends, the heat-release rate and pressure-rise rate of premixed burning drop. Increasing blend ratio is also found to reduce the nucleation mode particle number and favor the accumulation mode particles formation, while total particle number concentration increases. A relativity is also found between size range and blend ratio. For transient-state condition, a higher nucleation mode particle number and accumulation mode particle number are found; the effect on PSD with GTL is less sensitive than that with fossil diesel. Besides, it is of benefit to decrease the total particle number and nucleation mode particle number with the ratio of GTL become larger in the blends fuel under transient cycle.