| Navier-Stokes equations together with energy balance in steady state were solved using commercially available finite volume code software Fluent® 6.0. The fluid was taken to be supercritical CO2 in a laminar flow regime. C-written programmed modules were incorporated to the CFD code as user defined functions for calculating the transport properties of the fluid. SRK equation of state was used to estimate density and heat capacity of the fluid, Lucas method was used to estimate the viscosity, and thermal excess method was used to estimate the thermal conductivity.
First order upwind discretization schemes were selected to compute field variables, excepting for the pressure-velocity coupling algorithm, in which a second order discretization scheme was applied. The generated mesh had 120.000 tetrahedral elements, and several processes of mesh adaption and refinement were made in order to avoid large variables gradients that could cause numerical divergence of the solution. Numerical convergence of the model was checked based on the numerical residuals of all computed variables. For a more complete convergence checking, the drag force over the particles surface and the average static temperature, density and viscosity at the bed outlet were also chosen as monitors.
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