Thermal Effusivity Testing with the Hot Disk Thermal Constants Analyser
When testing uniaxial homogeneous materials (isotropic or anisotropic) with the Hot Disk method, a computation of the thermal effusivity is possible. It can be analytically shown that utilizing the original model, the thermal effusivity in the through-plane direction is estimated. Experimental testing with this approach indicates that for rather short test times, where the individual thermal conductivity and thermal diffusivity estimations may individually fluctuate (due to sensitivity coefficients of both these properties are low for total to characteristic times smaller than 0.1), the computed value of thermal effusivity remains stable and reasonably accurate. In the following, tests are performed, addressing differences in single-sided vs. double-sided testing. One experimental parameter of interest to consider is the experimental test time: In situations in which the volumetric specific heat of the sample is known – or roughly known – the thermal depth of probing in the normal direction can be controlled. Situations in which the thermal effusivity is of typical interest to test in industry, involves textiles, fabrics, as well as situations in which the human touch of an objects surface are concerned. For situations where the thermal depth of probing can be controlled, the application of a thin film or coating between the sensor and the bulk sample, will produce apparent thermal effusivity values which varies with the experimental test time. Hence, a special method for analyzing and comparing the apparent behavior of different types of surface treatments, in terms of apparent thermal effusivity vs. duration of heating, is made possible.
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Dale Hume (POC,Primary Presenter,Co-Author), Thermtest Inc, email@example.com;
Chris Vail (Co-Author), Thermtest Inc, firstname.lastname@example.org;
Andrey Sizov (Co-Author), Hot Disk AB, email@example.com;
Daniel Cederkrantz (Co-Author), Hot Disk AB, firstname.lastname@example.org;
Yi Ma (Co-Author), Hot Disk AB, email@example.com;
Besira Mihiretie (Co-Author), Hot Disk AB, firstname.lastname@example.org;
Mattias Gustavsson (Co-Author), Hot Disk AB, email@example.com;
Silas Gustafsson (Co-Author), Hot Disk AB, firstname.lastname@example.org;