Numerical analysis of flow within a packed bed using computational fluid dynamics: Effects of fluid nature and regime

This research conducts a computational fluid dynamics (CFD) analysis comparing laminar and k-epsilon turbulent models of fluid flow through a packed bed. For this, three types of fluids (water, water vapor and carbon dioxide) were examined. The CFD model was initially juxtaposed with two experimental ones reported in the literature. It was observed that the numerical model used was in reasonable agreement with the experimental data reported in literature, provided that the packed bed dimensions (column diameter and height, grain size) aligned with those used experimentally. Thus, a decrease in pressure in descending order was noticed for the three fluids studied for both regimes from the column top to the outlet. In addition, a thorough characterization of turbulence was conducted, including determination of turbulent kinetic energy (TKE) and turbulent eddy dissipation (TED). As a result, a rapid dissipation of TKE for water was observed compared to the other two fluids, where TKE decreased progressively along the column length. In contrast, the TED for water decreases gradually until the exit of the column, while for both gaseous fluids, it increases slowly along the column length. The analysis of the vapor flow included testing of two density models, namely the constant density and the Peng-Robinson model. It was observed that the PR model for vapor properties showed similar trends of TKE and TED as those predicted for carbon dioxide.