In-plane conductive heat tansfer in solid and porous planar structures
Methods for determining the in-plane thermal diffusivity in a planar sample geometry
were developed. These methods were tested and verified by measuring planar
metal samples with known thermal properties. The techniques used were based on
heating the sample at one edge and recording the evolution of the temperature field
in the sample by a thermographic camera. The temperature fields at different times
were processed and then fitted by a solution to a heat equation describing the experimental
setup, thermal diffusivity as one of the fitting parameters.
In the first experimental setup the sample was placed in a weak constant flow
of air, and the situation was improved in the second setup by placing the sample
in a vacuum chamber, where convective heat transfer was totally removed. After
verification measurements, the latter setup was applied to porous sintered bronze
samples, and their effective thermal conductivities were determined. The sintered
samples were also imaged by X-ray microtomography so as to obtain a 3D model for
their structure. It was shown that the effective thermal conductivity of the samples
could be predicted by an analytical expression which involved certain parameters
determined from the 3D images.
Finally, as another application of the heat equation, propagation of temperature
profiles in the form of slow-combustion fronts were studied in sheets of paper.
The dynamical properties of these fronts belong to the KPZ universality class,
for which theoretical results are available for the height-fluctuation distributions.
Height fluctuations for such fronts were determined experimentally, and their distributions
were found to be well fitted by corresponding theoretical distributions.
...
Publisher
University of JyväskyläISBN
978-951-39-4580-0ISSN Search the Publication Forum
0075-465XContains publications
- Artikkeli I: Miettinen, L., Myllys, M., Merikoski, J., & Timonen, J. (2005). Experimental determination of KPZ height-fluctuation distributions. The European Physical Journal B - Condensed Matter and Complex Systems, 46, 55–60. DOI: 10.1140/epjb/e2005-00235-y
- Artikkeli II: Miettinen, L., Kekäläinen, P., Merikoski, J., Myllys, M., & Timonen, J. (2008). In-plane Thermal Diffusivity Measurement of Thin Samples Using a Transient Fin Model and Infrared Thermography. International Journal of Thermophysics, (29), 1422. DOI: 10.1007/s10765-008-0498-6
- Artikkeli III: Miettinen, L., Kekäläinen, P., Merikoski, J., & Timonen, J. (2009). Measurement of the In-plane Thermal Diffusivity and Temperature-Dependent Convection Coefficient Using a Transient Fin Model and Infrared Thermography. International Journal of Thermophysics, (30), 1902. DOI: 10.1007/s10765-009-0690-3
- Artikkeli IV: Miettinen, L., Kekäläinen, P., Turpeinen, T., Hyväluoma, J., Merikoski, J., & Timonen, J. (2012). Dependence of thermal conductivity on structural parameters in porous samples. AIP Advances, 2(1), 12101. DOI: 10.1063/1.3676435
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