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The effective thermal conductivity of insulation materials reinforced with aluminium foil at low temperatures

Abstract

The effective thermal conductivity (ETC) of multilayer thermal insulation materials was experimentally investigated as a function of temperature (0–25 °C). The materials consisted of binary/ternary glass wools or ternary expanded polystyrene foams reinforced with aluminium foil. The experimental measurements were performed using a guarded hot plate with temperature differences of 5, 10 and 15 °C. The results indicated that significant correlations exist between ETC and the characteristics of the materials with decreasing temperature. The ETC decreases with reinforcement with aluminium foil at the same temperature or with temperature differences of 5 and 15 °C. In addition, it was clearly observed that the ETC decreases sharply with decreased temperature. Consequently, reflective materials may reduce the ETC at low temperatures.

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Abbreviations

d:

Mean diameter or particle size (m)

F:

Effective scattering factor

k:

Thermal conductivity (Wm−1 K−1)

\( {\bar{\text{n}}} \) :

Index of refraction of porous medium

R:

Sphere radius (m)

rc :

Radius of contact area (m)

TR :

Local radiation temperature (K)

β:

Effective extinction coefficient (m−1)

ε:

Porosity (%)

∈:

Emissivity coefficient

σ:

Stefan-Boltzmann constant (5.67 × 10−8 Wm−2 K−4)

XR :

Effective radiation length (m)

e:

Effective

ex:

Exponent

f:

Filled/discontinuous/dispersed phase

g:

Gas

c:

Gas and solid

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Acknowledgments

This study was supported by Uludağ University Scientific Research Projects Fund under Project No. M-2008/48.

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Correspondence to N. Yüksel.

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Yüksel, N., Avcı, A. & Kılıç, M. The effective thermal conductivity of insulation materials reinforced with aluminium foil at low temperatures. Heat Mass Transfer 48, 1569–1574 (2012). https://doi.org/10.1007/s00231-012-1001-2

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  • DOI: https://doi.org/10.1007/s00231-012-1001-2

Keywords

  • Insulation Material
  • Effective Thermal Conductivity
  • Radiation Heat Transfer
  • Aluminium Foil
  • Glass Wool