Natural convection heat transfer enhancement using adiabatic block: Optimal block size and Prandtl number effect
Numerical methods are used to solve the finite volume formulation of the two-dimensional mass, momentum and energy equations for steady-state natural convection inside a square enclosure. The enclosure consists of adiabatic horizontal walls and differentially heated vertical walls, but it also conta...
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Published in | International journal of heat and mass transfer Vol. 49; no. 21; pp. 3807 - 3818 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Oxford
Elsevier Ltd
01.10.2006
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Numerical methods are used to solve the finite volume formulation of the two-dimensional mass, momentum and energy equations for steady-state natural convection inside a square enclosure. The enclosure consists of adiabatic horizontal walls and differentially heated vertical walls, but it also contains an adiabatic centrally-placed solid block. The aim of the study is to delineate the effect of such a block on the flow and temperature fields. The parametric study covers the range 10
3
⩽
Ra
⩽
10
6 and is done at three
Pr namely, 0.071, 0.71 and 7.1. In addition the effect of increasing the size (characterized by the solidity
Φ) of the adiabatic block is ascertained. It is found that the wall heat transfer increases, with increase in the
Φ, until it reaches a critical value
Φ
=
Φ
OPT, where the wall heat transfer attains its maximum. Further increases in the block size beyond
Φ
OPT, reduces the wall heat transfer, for as the block size becomes larger than the conduction dominant core size it reduces the thermal mass of the convecting fluid. A steady-state heat transfer enhancement of 10% is observed for certain
Ra and
Pr values. Useful correlations predicting this optimum block size and the corresponding maximum heat transfer as a function of
Ra and
Pr are proposed; these predict within ±3%, the numerical results. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0017-9310 1879-2189 |
DOI: | 10.1016/j.ijheatmasstransfer.2006.04.017 |