The classical photo-thermal FLASH method is a very practicable method for measurement of the conductive properties of solid materials due to its simplicity, rapidity, and to the limited size of the samples required. It has been applied successfully to a wide variety of materials. However, it is theoretically restricted to purely conductive media. Notably, it could, strictly speaking, not be used to measure the equivalent conductivity of low-density thermal insulators since a significant part of the heat transfer is due to the propagation of thermal radiation. This constitutes a major drawback of the method. Therefore, the present study investigates the possibility to extend the method to this kind of materials by estimating the errors made on the equivalent conductivity when the classical FLASH method is used. To this aim, FLASH experiments have been conducted at different temperatures on several low-density polymer foams whose radiative properties have been estimated from spectrometric measurements. By applying a least-square fit-method associated with a numerical simulation of the 1D coupled heat transfer, we managed to identify the phonic conductivities of the samples and to compute their equivalent conductivities. These values have been compared with the thermal conductivities obtained from classical FLASH method, i.e., assuming that the thermal transfer occurs only by heat conduction. It appears that the discrepancies between the conductivities stemming from the classical FLASH method and the equivalent conductivities computed are quite negligible at ambient temperature even for foams with very low densities. This demonstrates the applicability of the classical FLASH method to this type of materials for building applications. This conclusion is likely to interest foam manufacturers in view of reducing the time required for an accurate measurement of the insulating performances. On the other hand, at elevated temperatures, the errors become significant so that the method could not be considered satisfactory.

References

References
1.
Degiovanni
,
A.
, 1977, “
Diffusivité et Méthode Flash
,”
Rev. Gén. Therm.
,
185
, pp.
420
441
(English Abstract).
2.
Degiovanni
,
A.
, and
Laurent
,
M.
, 1986, “
Nouvelle Technique d’identification de la diffusivité thermique pour la méthode FLASH
,”
Revue de Physique Appliquée
,
21
(
3
), pp.
229
237
(English Abstract).
3.
André
,
S.
, and
Degiovanni
,
A.
, 1995, “
A Theoretical Study of the Transient Coupled Conduction and Radiation Heat Transfer in Glass. Phonic Conductivity Measurements by the Flash Technique
,”
Int. J. Heat Mass Transfer
,
38
(
18
), pp.
3401
3412
.
4.
André
,
S.
, and
Degiovanni
,
A.
, 1998, “
A New Way of Solving Transient Radiative–Conductive Heat Transfer Problems
,”
J. Heat Transfer
,
120
, pp.
943
955
.
5.
Tan
,
H. P.
,
Maestre
,
B.
, and
Lallemand
,
M.
, 1992, “
Transient and Steady-State Combined Heat Transfer in Semi-Transparent Materials Subjected to a Step Irradiation
,”
ASME J. Heat Transfer
,
113
, pp.
166
173
.
6.
Hahn
,
O.
,
Raether
,
F.
,
Arduini-Schuster
,
M. C.
,
Fricke
,
J.
, and
Degiovanni
,
A.
, 1997, “
Transient Coupled Conductive/Radiative Heat Transfer in Absorbing, Emitting and Scattering Media: Application to Laser-Flash Measurements on Ceramic Materials
,”
Int. J. Heat Mass Transfer
,
40
(
3
), pp.
689
698
.
7.
Lazard
,
M.
,
André
,
S.
, and
Maillet
,
D.
, 2004, “
Diffusivity Measurement of Semi-Transparent Media: Model of the Coupled Transient Heat Transfer and Experiments on Glass, Silica Glass and Zinc selenide
,”
Int. J. Heat Mass Transfer
,
47
, pp.
477
487
.
8.
Lazard
,
M.
,
Andre
,
S.
, and
Maillet
,
D.
, 2003, “
Thermal Characterization of Semi-Transparent Media: Measurement of Phononic Diffusivity of Glass and Silica
,”
Eur. Phys. J. Appl. Phys.
,
23
, pp.
207
211
.
9.
Coquard
,
R.
,
Baillis
,
D.
, and
Rochais
,
D.
, 2009, “
Experimental Investigations of the Coupled Conductive and Radiative Heat Transfer in Metallic/Ceramic Foams
,”
Int. J. Heat Mass Transfer
,
52
(
21–22
), pp.
4907
4918
.
10.
Cheheb
,
Z.
,
Albouchi
,
F.
, and
Nasrallah
,
S. B.
, 2008, “
Measurement of Thermal Radiative and Conductive Properties of Semitransparent Materials Using a Photothermal Crenel Method
,”
J. Quant. Spectrosc. Radiat. Transf.
,
109
, pp.
620
635
.
11.
Brandrup
,
J.
,
Immergut
,
E. H.
, and
Grulke
,
E. A.
, eds., 1999,
Polymer Handbook
,
4th ed.
,
Wiley-Interscience
,
New York
.
12.
Glicksmann
,
L. R.
, and
Schuetz
,
M. A.
, 1994,
Low Density Cellular Plastics
,
N. C.
Hilyard
and
A.
Cunningham
, eds.,
Chapman and Hall
,
London
, pp.
104
152
.
You do not currently have access to this content.