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ISBN 978-3-8439-4313-0

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Sebastian Meinicke
Understanding transport phenomena in consolidated, highly porous media – a pore-scale CFD approach

278 Seiten, Dissertation Karlsruher Institut für Technologie (2019), Softcover, A5

Zusammenfassung / Abstract

This work shall contribute to an improved understanding of momentum and heat transfer processes in porous media for process engineering applications (e.g. in heat exchangers, chemical reactors or separators), using a numerical approach. Pore-scale CFD (computational fluid dynamics) simulations have been set up and evaluated for a selected subgroup - consolidated, highly porous media.

First, so-called sponge structures have been used as benchmark geometry to develop the specific CFD setup needed. It embeds a representative elementary volume of the sponge structure into a larger simulation environment, which is modeled as a homogeneous porous medium with equivalent effective pressure drop and heat transfer properties. The CFD analysis has been restricted to laminar air flow conditions and included an extensive comparison of the pressure drop and heat transfer results with available experimental data and established literature correlations. This proof of concept confirmed the reliability of the CFD approach, which is why it has been exploited for further predictive analyses.

Then, the CFD results and accessible information on the flow tortuosity, frictional and form drag contributions of pressure drop have been used to derive physically plausible laws behind the prevailing transport processes. Thus, the applicability of the Generalized Lévêque equation (GLE) for the analogy of momentum and heat transfer has been shown and new correlations for pressure drop and heat transfer derived. They comply with the analytical laws of the boundary layer theory.

In a last step, it was dared to transfer these laws to other, regular types of consolidated, highly porous media. The pressure drop results and qualitative heat transfer result trends have been found to match well for all representatives with a permanent reformation of boundary layers. Furthermore, first steps towards a heat transfer efficiency analysis based on the GLE have been conducted.