Verification of a porous media model for the partial oxidation of a chemically reacting fixed-bed

In this work, two numerical approaches, namely particle-resolved simulations (3D PRS) and porous media model (PMM), are assessed using a 2D axisymmetric CFD pseudo-state approach (PSS) for validation of the gasification of carbon char particles in a chemically reacting fixed-bed. Simulations are performed using the commercial software Ansys® Fluent, implementing a six-reaction semi-global scheme, including three heterogeneous, and three homogeneous chemical reactions. The effects of the inflow gas temperature (Tin= 900–1500 K), mass fraction of oxygen (YO2,in= 0.05, 0.11), and laminar flow regime (Rein = 50, 75 and 100) reveals a significant role of Tin, observing important deviations at Tin = 1300 K. Minimum deviations when comparing 3D PRS and 2D PMM models are observed for YO2,in = 0.05, being 3.6% for CO, 5.5% for CO2 and 0.76% for temperature inside the porous zone at different operating conditions. Thermal conductivity of the solid material, axial dispersion coefficient, and radial variation of porosity are analyzed and discussed, showing good agreement between numerical models, remarking the role of geometrical features of the unit in the gasification process.