Abstract
Experiments have been conducted for natural convection heat transfer from protruding discrete heat sources, mounted at different positions on a substrate, to determine the optimal configuration, and to study the effect of surface radiation on them, which reduces their temperature upto 12 %. The optimal configuration has been determined by a non-dimensional geometric distance parameter (λ). An empirical correlation has been proposed between the non-dimensional steady state temperature (θ) and λ, by taking into account the effect of surface radiation heat transfer.
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Abbreviations
- A :
-
Area of the heat source, m 2
- F :
-
Shape factor between the surfaces of heat sources
- g :
-
Gravitational acceleration, 9.81 m/s 2
- Gr :
-
Grashof number, \(g\beta(T_{hs}-T_{\infty})L^{3}/\nu^{2}\)
- \(Gr^{\ast}\) :
-
Modified Grashof number, \(g \beta(\Updelta T_{ref})L^{3}/\nu^{2}\)
- h :
-
Heat transfer coefficient, W/m 2 °C
- I :
-
Heat source input current, A
- k :
-
Thermal conductivity, W/m K
- L :
-
Length of the heat source, m
- Nu :
-
Nusselt number, h conv L/k f
- \(q^{\ast}\) :
-
Non-dimensional heat flux, \(Q_{supplied}L/Ak_{f}T_{\infty}\)
- Q :
-
Rate of heat transfer, W
- Ra :
-
Rayleigh number, GrPr
- t :
-
Thickness of the substrate, m
- t i :
-
Thickness of the insulation, m
- T :
-
Temperature, K
- v :
-
Volume of the heat source, m 3
- V :
-
Heat source input voltage, V
- X, Y :
-
Centroid, with the origin fixed at the left bottom corner of the heat source 51, m
- Z :
-
Geometric parameter, X/Y
- ∑ d 2 i :
-
Sum of the square of the distances, for each configuration, from the centroid of each heat source of that configuration, to the centroid of that particular configuration, m 2
- β:
-
Isobaric thermal expansion coefficient of air, 1/T mean , K −1
- \(\Updelta T_{ref}\) :
-
Reference temperature, Q supplied L/Ak f , K
- \(\varepsilon\) :
-
Hemispherical emissivity of the surfaces of heat source
- λ:
-
Non-dimensional geometric distance parameter
- σ:
-
Stefan Boltzmann constant, 5.67 × 10−8, W/m 2 K 4
- θ:
-
Non-dimensional temperature, \((T_{maximum}-T_{\infty})/\Updelta T_{ref}\)
- \(\infty\) :
-
Ambient
- i :
-
For each heat source
- c :
-
For each configuration
- cond:
-
Conduction
- conv:
-
Convection
- f:
-
Fluid (air)
- rad:
-
Radiation
- hs:
-
Heat source
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Hotta, T.K., Muvvala, P. & Venkateshan, S.P. Effect of surface radiation heat transfer on the optimal distribution of discrete heat sources under natural convection. Heat Mass Transfer 49, 207–217 (2013). https://doi.org/10.1007/s00231-012-1072-0
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DOI: https://doi.org/10.1007/s00231-012-1072-0