Study Of Conjugate Heat Transfer Accompanying
Mixed Convection In A Vertical Tube Submitted
To A Step Of Entry Temperature
Author(s)
O. Kholai, M. Kadja & T. H. Mai
Abstract
The paper presents the results of a numerical study on transient mixed laminar
convection for the case of an ascending flow inside a vertical tube in which the
wall conduction is significant. The outer surface of the tube is submitted to a
convective heat exchange. The transient regime is provoked by a step type
perturbation in temperature at entry of the tube. The governing equations are
solved using a finite volume method. Results are presented for water (Pr=5) and
for two values of Grashof numbers of 104 and 105. This method shows that no
matter what the value of the imposed step is, it provokes the birth of a big
recirculation cell next to the wall, and gives rise to an instability situated
between the cool and the hot regions of the flow.
Keywords: transient convection, temperature step, convective heat exchange,
finite volume method, instabilities.
1 Introduction
Conjugate heat transfer (mixed convection + conduction) in transient regime in
internal flows is present in many industrial installations: such as compact heat
exchangers, solar collectors, cooling of electronic components etc. As a matter of
fact, the importance and complexity of this phenomenon and the consequences
have stimulated the interest of many researchers: so that a very important
number of studies have been done in this field.
Nguyen et al. [1] performed a numerical study on transient mixed convection
in vertical tubes having a wall, which is submitted to variable heat flux. Their
Keywords
transient convection, temperature step, convective heat exchange,finite volume method, instabilities.
Related Book
Other papers in this volume
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