High accuracy, self-calibrating photopyroelectric device for the absolute determination of thermal conductivity and thermal effusivity of liquids

Abstract

An improved photopyroelectric approach to simultaneously determine the thermal conductivity and thermal effusivity of minute quantities of liquids, which is based on a combined scan of the modulation frequency and the piston-sensor distance, is presented. A thorough sensitivity analysis and statistical analysis of the fitting uncertainties show that the method is a very accurate tool for the simultaneous determination of the thermal conductivity and thermal effusivity of liquid samples.

Combined FPPE–PTR Calorimetry Involving TWRC Technique. Theory and Mathematical Simulations

“…The value of the dynamic thermal parameters (thermal diffusivity, effusivity, or conductivity) of the layers (sensor, sample, or backing) of the detection cell could be obtained by performing frequency or thickness (in the case of liquid samples) scans of the amplitude or phase of the FPPE signal. The thickness scanning procedure is associated with the so-called thermal-wave resonator cavity (TWRC) method, introduced about 10 years ago by Mandelis and co-workers and developed later by others groups [1][2][3][4][5][6][7][8]. The TWRC method, in the back detection configuration (BPPE), has been shown to be suitable and very accurate for investigating thermal properties (especially thermal diffusivity) of liquids [2,9,10].…”

Characterization of Biodiesel by Unconventional Methods: Photothermal Techniques

“…The thermal conductivity and the heat capacity per unit volume are thus indirectly determined, by inverting the expressions written above. In some special cases, depending on the sample thickness and the photothermal configuration used, it is possible to obtain directly the thermal conductivity or the specific heat (Glorieux et al, 1995;Menon et al, 2009). The thermal properties can be measured by photothermal techniques from experiments presenting good reproducibility, with uncertainties being around 1-5 %.…”

“…The thermal effusivity determination, in any way, depends on a reference material, with known thermal effusivity. In this work we chose Ethylene Glycol as the standard, assuming an averaged value (Dadarlat & Neamtu, 2006, Delencos et al, 2002, Sahraoui et al, 2002, Menon et al, 2009, 810 (Ws 1/2 m -2 K -1 ). We first present the results for the thermally thin sensor approach, in which the thermal effusivity is obtained from the signal amplitude.…”

Combined FPPE–PTR Calorimetry Involving TWRC Technique II. Experimental: Application to Thermal Effusivity Measurements of Solids

“…The value of the dynamic thermal parameters of the layers of the detection cell can be obtained by performing frequency or thickness (in the case of liquid samples) scans of the amplitude or phase of the FPPE signal. The thickness scanning procedure is associated with the so called thermal-wave resonator cavity (TWRC) method, introduced about 10 years ago by Mandelis and co-workers and developed later by others groups [1][2][3][4][5][6][7][8]. Recently, a combined FPPE-TWRC method was proposed, with the purpose of measuring the thermal effusivity of a solid material (inserted as backing in the detection cell) [9][10][11][12].…”