Numerical simulation on gas behavior inside pellet based on X-ray micro-computed tomography

The objective of this work is to investigate gas behavior inside a realistic pellet model while varying inlet velocities and comparing it against published studies. A CT three-dimensional (3D) reconstruction technique was performed to construct a realistic pellet model from the two-dimensional (2D) tomographic images. The distribution of gas velocity, pressure, and species inside the pellet was investigated with computational fluid dynamics (CFD) and microfluidic boundary layer theory. The results indicated that pellet morphology, pore size, and position were responsible for the variability in velocity anisotropy inside the pellet. The pressure gradient between the windward and leeward sides of the pellet tended to rise as the inlet velocity increased, up to a maximum value of 4.2 Pa. Moreover, the pressure gradient resulted in a higher species concentration on the windward side, particularly at lower flow velocities. Finally, the potential effect of the pellet structure on the reduction process is proposed.