首页|Thermal radiation effects on heat transfer in slender packed-bed reactors: Particle-resolved CFD simulations and 2D modeling
Thermal radiation effects on heat transfer in slender packed-bed reactors: Particle-resolved CFD simulations and 2D modeling
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Radial heat management is crucial for a safe and stable operation of fixed-bed reactors with small tube-to-particle diameter ratios (N). Under high temperature conditions, thermal radiation can contribute substantially to the overall heat transfer. In the present work, the influence of radiation is studied with particle resolved computational fluid dynamics (PRGFD) in a fixed-bed reactor consisting of 1000 spheres and rings with N = 5.1 over 300 < Re_p< 2000 and for three different temperature levels (300-800 ℃). Two heat transfer parameters, i.e., the wall Nusselt number Nuw and the effective radial thermal conductivity of the bed k_(eff, r), are derived directly from PRGFD. While the radiation effect is minor in k_(eff, r), it is substantial for Nu_w, which is not captured adequately in the current correlations presented in literature. Depending on the temperature level and flow conditions, thermal radiation between the hot wall and the packed bed intensifies the radial heat transfer represented by an increase of up to 170 % in Nuw and 65% in k_(eff, r). A 2D axisymmetric pseudo-homogeneous model including the derived heat transfer parameters can predict the radial temperature profile of the PRCFD with reasonable accuracy also with radiation except for the near-wall region.
Heat transferCFDPacked bed reactorThermal radiation
Gregor D. Wehinger、Florian Scharf
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Institute of Chemical and Electrochemical Process Engineering, Clausthal Uniuersity of Technology, Leibnizstr. 17, Clausthal-Zellerfeld 38678, Germany
BASF SE, Carl-Bosch-Str. 38, Ludwigshafen am Rhein 67056, Germany
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