Numerical study of heat transfer over banks of rods in small Reynolds number cross-flow

Gabriel Gamrat,Michel Favre-Marinet,Stéphane Le Person

doi:10.1016/j.ijheatmasstransfer.2007.04.038

Abstract

This work presents numerical computations of heat transfer over banks of square rods in aligned and staggered arrangements with porosity in the range 0.44–0.98. It is focused on low Reynolds number flows (0.05–40). Two thermal boundary conditions were investigated, namely constant wall temperature and constant volumetric heat source. The effects of bank arrangements and porosity as well as the effects of Prandtl and Reynolds numbers on the Nusselt number are examined. In the case of constant volumetric heat source, the results are approximated with a power equation adapted for the case of low Re number flows. This study shows that the thermal boundary condition on the solid surface influences heat transfer when thermal equilibrium is reached in the bank of rods.

Highlights

Much work has been done in the past on convective heat transfer in banks of tubes or rods in cross-flow
The present work is devoted to numerical simulations of the flow and associated heat transfer through banks of rods with different arrangements
The work focuses on the hydrodynamic resistance and on the heat transfer coefficient for low Reynolds number flows

Summary

Introduction

Much work has been done in the past on convective heat transfer in banks of tubes or rods in cross-flow. One of the most extensive reviews in the field of cross-flow heat exchanger is that of Zukauskas [1], who proposed correlations between the Nusselt, Reynolds and Prandtl numbers for various arrangements of cylindrical tube banks. These correlations are available for moderate to high values of the Reynolds number ð1 < Re < 2 Â 106Þ. Periodic models have been considered to compute the permeability of the medium as a function of porosity and Reynolds number [2,3,4,5,6,7,8,9,10]. These models are very attractive for numerical simulations, since the computations may be restricted to a sim-

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