ID 34

The droplet evaporation characteristics of the blends of diesel from direct coal liquefaction (DDCL) and diesel from indirect coal liquefaction (DICL)

 

Abstract:

Diesel from direct coal liquefaction (DDCL) is an alternative fuel for compression-ignition engine. Compared with petro-diesel, DDCL contains no sulfur element, and several other properties are similar to those of petro-diesel. However, the cetane number (CN) of DDCL is only 40.5. In this work, the high CN (78.4) fuel, diesel from indirect coal liquefaction (DICL) is applied to blend with DDCL to improve the CN of DDCL. A multi-component evaporation model based on Universal Functional Activity Coefficient (UNIFAC) method and the non-equilibrium evaporation law is implemented to predict the evaporation characteristics of the DDCL/DICL droplets with different mass fractions at compression-ignition engine condions. Generally, increasing ambient temperature can raise the peak evaporation rate and shorten the lifetime of droplet. However, the variation of the ambient pressure does not affect much on the lifetime of droplet. The evaporation characteristics of the DDCL and DICL droplets are similar at relative low ambient temperature (723K), while the DICL droplet has larger peak evaporation rate than that of DDCL droplet at relative high ambient temperature condition (923K). In addition, the evaporation characteristics of DDCL/DICL blend droplet are close to that of DICL droplet regardless of the mass fraction of DICL, and increasing the mass fraction of DICL has no obvious effect on the evaporation characteristics of the blended droplet.