The evolution of pore fractal dimensions for three Chinese chars was i
nvestigated. The pores of porous chars can be classified into macro-,
micro- and transition-pores based on their fractal dimensions. The rad
ius ranges of the macro-, micro- and transition-pores may be different
for various chars. For different conversions in the char combustion p
rocess, the fractal dimensions of the micro-pores for different chars
are almost the same and the fractal dimensions of macro-pores for the
same kind of chars are roughly unchanged. The effects of fractal struc
ture on combustion rate are also discussed. (C) 1998 Elsevier Science
Ltd. All rights reserved.