Print Email Facebook Twitter Heat transfer from wall to dense packing structures of spheres, cylinders and Raschig rings Title Heat transfer from wall to dense packing structures of spheres, cylinders and Raschig rings Author Moghaddam, E.M.C. (TU Delft Mechanical Engineering) Foumeny, E.A. Stankiewicz, A.I. (TU Delft Complex Fluid Processing) Padding, J.T. (TU Delft Complex Fluid Processing) Faculty Mechanical Engineering Date 2021 Abstract This paper investigates the validity of azimuthal averaging of 3D temperature fields in the analysis of lateral heat transfer in dense particle packings. This is conducted by synthetic generation of 3D packing surrogates of spheres, cylinders and Raschig rings with tube-to-pellet diameter ratio, 3 < N < 6, using an in-house Rigid Body Dynamics packing algorithm, followed by detailed discrete pellet CFD simulations of heat transfer from wall to bed for laminar, transient and turbulent flow regimes. The CFD results of hydrodynamics and temperature fields are benchmarked against empirical correlations for pressure drop and interphase heat transfer Nusselt number, Nu, offering the best fits with correlations proposed by Eisfeld and Schnitzlein (for cylinders and spheres) and Nemec and Levec (for rings) for pressure drop, and by Gunn and Sun and coworkers for the prediction of Nu. The CFD results demonstrate that fluctuations in local temperature are completely neglected by azimuthal-averaging of 3D temperature fields over the bed volume, leading to more than 150 °C deviations from the local temperature data. Furthermore, it is found that deviations between azimuthally-averaged axial velocity profile and true local velocities are in an analogous fashion transmitted to the temperature field. This is evidenced by the coincidence of the peaks in the deviation profiles of azimuthally-averaged temperature and velocity from the local data over the bed radius. This is due to thermal disequilibrium between fluid and pellet phases which is partially omitted by the azimuthal-averaging of the 3D temperature field and basically neglected in pseudo-homogenous ker-hw models. Subject Azimuthal averagingCylindersFixed bedsHeat transferParticle-resolved CFD simulationsRaschig ringsRigid body dynamics To reference this document use: http://resolver.tudelft.nl/uuid:9ace708f-f75f-4c31-a371-7265278acd21 DOI https://doi.org/10.1016/j.cej.2020.127994 ISSN 1385-8947 Source Chemical Engineering Journal, 407 Part of collection Institutional Repository Document type journal article Rights © 2021 E.M.C. Moghaddam, E.A. Foumeny, A.I. Stankiewicz, J.T. Padding Files PDF 1_s2.0_S1385894720341139_main.pdf 18.16 MB Close viewer /islandora/object/uuid:9ace708f-f75f-4c31-a371-7265278acd21/datastream/OBJ/view