The aim of this work is to analyse experimental results on radial heat transfer in a packed bed column with cocurrent downflow of liquid and gas, focused on the influence of radial liquid distribution and column to particle diameter ratio. For this purpose, two kinds of measurements were carried out: radial liquid distribution and radial temperature profiles. Heat transfer data as analysed with a model consisting of two regions: a lumped wall region up to a distance of a particle radius from the tube wall, and a distributed core region covering the rest of the bed. Three parameters arose: the radial effective thermal conductivity of the core region (k_er,c), the heat transfer coefficient between both zones (h_I), and the heat transfer coefficient from the wall region to the tube wall (h_w,w). Suitable correlations for the mentioned parameters as a function of gas and liquid Reynolds number and particle diameter were developed.

This work studies the performance of two open-source CFD codes, OpenFOAM and MFiX, to address bubbling fluidized bed system at different temperature and heat transfer conditions. Both codes are used to predict two parameters that are relevant for the design of fluidized units: the minimum fluidization velocity as a function of the temperature of the bed and wall-to-bed heat transfer coefficient from a lateral wall and from internal tubes. Although the CFD solvers are structuraly similar, there are some key differences (available models, meshing techniques, and balance formulations) that are often translated into differences in the fields prediction. The computational results are compared between both codes and against the experimental data. The minimum fluidization velocity can be correctly predicted with both codes at different temperatures while, in general, for the heat transfer and the fluidization patterns, MFiX shows slightly more accurate results compared to OpenFOAM but with low versatility for meshing curved geometries which might translate into higher computational costs for the same level of accuracy.

This contribution is focused on the analysis of the structure of packed beds of spherical particles at relatively low aspect ratios (i.e., particle to tube diameter ratio) as those arising in multitubular fixed bed reactors. On one hand, the computed tomography (CT) technique is employed to evaluate the position of each particle in the packing and from this information local properties such as particle center distribution and radial porosity profile were obtained. On the other hand, results from a previously developed algorithm to simulate packings were compared with those from our CT data and from literature sources. The agreement was very satisfactory.

Classical density functional theories usually separate the formulation of the excess Helmholtz free energy in hard-body and energetic contributions. Fundamental measure theories (FMTs) have emerged as the preferred choice to account for the former contribution. The evaluation of geometrically weighted densities (convolutions) arisen in FMT for hard spheres in long cylindrical cavities is addressed in this paper. Previously, Malijevský [J. Chem. Phys. 126, 134710 (2007)] reported expressions containing elliptic integrals for the kernels of the convolutions involving scalar and vectorial weights. Here, the set of kernels is extended to second and third order tensorial weights that introduce desirable dimensional crossover properties to the evaluation of the excess free energy. An alternative formulation for the convolutions, which greatly facilitates their computation, is also proposed. Integrals of the original kernels arise in this way and a set of expressions for them, again expressed in terms of elliptic integrals, is presented here. With the aim of providing a computationally simple framework to evaluate equilibrium density profile with cylindrical symmetry, a procedure based on direct minimization of the discretized grand potential energy, rather than employing the Euler–Lagrange equilibrium conditions, is discussed and used to identify differences between two FMT formulations, including or not second order tensorial kernels in very narrow cylindrical pores.