Development of ac Calorimetric Method for Thermal Diffusivity Measurement. II. : Sample Dimension Required for the Measurement

Abstract

In an ac light-irradiated method for thermal diffusivity measurements of rectangular plate-like samples partly shadowed by a mask, the required dimensions are considered. The contour length around the cross-section (given by the thickness times the width) should be so long that the sample has a proper amount of heat capacity; then, the external thermal relaxation time becomes sufficiently long so as not to dissipate ac thermal energy. The thickness, however, should be thin enough so as to obtain a uniform temperature across the sample during oscillations (as discussed in detail previously). For the sample length, the distance between the thermocouple and the sample boundary on which ac light is irradiated should be sufficiently long so that the thermal waves reflected at the boundary decay. However, there is no restriction on the other bourtdary shadowed by the mask, i.e., the thermocouple can be placed at the boundary.

Preparation and characterization of thermoconductive polymer nanocomposite with branched alumina nanofiber

“…The thermal diffusibility of the nanocomposite ͑␣͒ was evaluated at room temperature by the ac calorimetric method. [10][11][12] and C p of the nanocomposite were calculated by using the and C p values of the components. 13 Results of thermal conductivity measurements are shown in Table I.…”

HIGH CORROSION-RESISTANT Al ALLOY REFLECTIVE FILMS WITH LOW THERMAL CONDUCTIVITY FOR MAGNETO-OPTICAL DISKS

“…Thermal conductivity measurements were performed with a thermal constant analyzer by the AC calorimetric method at room temperature [5][6][7]. In these measurements, the thicknesses of Al alloy films and glass substrates were 10pm and 150 pm, respectively.…”

<title>Theoretical, numerical, and experimental investigation of a one-side measurement technique for thermal diffusivity</title>

“…The existing work is mostly based on one-dimensional models, in which the effects of convection are overlooked. Only a few studies exist on the conditions under which the one-dimensional models can be employed for multi-dimensional configuration, in which non-negligible convection occurs [7,12,[15][16][17]. In this paper, the proposed experimental method is analytically and numerically modeled, with the inclusion of convection heat transfer mechanisms.…”

“…C=e' L=/cxt0/it (7)(8) If the thermal diffusion length is at least two times greater than the specimen thickness, the temperature gradient across the thickness is negligible and the temperature oscillations move from the thermal input region towards the end edge like plane waves [10,15,16]. From this condition, a limit results to the oscillation period, t0: L > 2d to > 4t (9-10) The 'internal relaxation time' t is defmed as follows [15]: t=ird2/a (11) Even if cx is not known 'a priori', a rough estimate of t is usually possible and can be improved by an iterative procedure, so that the choice of t0 can be optimized.…”

“…The following non-dimensional quantities can be introduced: =x/L; t=t/t0 (16)(17)(18) Equations (12-1 5) can be rewritten in the following form:…”