Thermal diffusivity measurement by a radial heat flow method

Abstract

A method is presented whereby the thermal diffusivity of a solid is measured by observing the temperature excursion which results from a radial flow of heat. The radial heat flow is produced by the instantaneous deposition of energy on a disk region of one surface of a planar specimen. Experimental results which utilized this technique are presented for Armco iron and they are compared to results based on an axial heat flow method with a radial heat flow correction.

A Simplified Low Cost Converging Thermal Wave Technique for Measuring Thermal Diffusivity of Thin Foils

“…Curve fitting is performed in order to evaluate the value of thermal diffusivity (α) for each sample and the estimated value of thermal diffusivity is calculated using equation (6). The t p is found from the polynomial curve fit as shown in Fig.…”

“…This method reversed the radial heat flow method by exchanging the central annular short pulse energy to the specimen with the circular ring departs from the central part of the specimen, with the detector located at the centre of the rear surface. Converging thermal wave technique provides a much stronger detected signal compared to the diverging heat flow [6], as it was a collection of energy that converged to the centre of the rear surface of the specimen.…”

“…Cielo et al [5] have developed a new method called converging thermal wave (CTW) technique which originated from the concept of radial heat flow method [6]. This method reversed the radial heat flow method by exchanging the central annular short pulse energy to the specimen with the circular ring departs from the central part of the specimen, with the detector located at the centre of the rear surface.…”

Measurement of in-plane diffusivity in non-homogeneous slabs by applying flash thermography

“…For this purpose, different experimental configurations and data processing procedures have been proposed in the past . Heat can be applied over a point [7][8][9][10][11][12], a Gaussian distribution (spot or strip) [13,14], a disk area [15,16], an annular area [16,17], a line or a strip [18][19][20][21], a half plane [22], or a square corner [23]. Recently it was also suggested to use a moving line heat source [24] or a heat pulse with random distribution [25].…”

Measurement and Prediction of Thermal Properties of Foods

“…The temperature increase at the back face of the sample or at any other two points in the sample is recorded, usually for less than one second. This was used by Oshita (1985) on bulk rice, , Henninge (1961) and Donaldson and Tyler (1975). Moyne et aI., (1988) accounted for the latent heat due to evaporation and condensation in the pores as samples are heated.…”