downstream outflow, the centerline, and the wall of the reaction
tube. Details of the boundary conditions are described in Fig. 1a.
2.3. Reaction mechanism and kinetics
In the energy and species equations, the indirect mechanisms of
CPOM, consisting of methane combustion, steam reforming, and
dry reforming, are regarded and they are expressed as
CH4 þ 2O2! CO2 þ 2H2O; DH ¼ 803 kJ mol1 (2)