Assessment of calibration procedures for accurate determination of thermal parameters of liquids and their temperature dependence using the photopyroelectric method

Abstract

Articles you may be interested inHigh accuracy, self-calibrating photopyroelectric device for the absolute determination of thermal conductivity and thermal effusivity of liquids Rev. Sci. Instrum. 80, 054904 (2009); 10.1063/1.3131625 On the accurate determination of thermal diffusivity of liquids by using the photopyroelectric thickness scanning method Rev. Sci. Instrum. 78, 024902 (2007);We present a systematic theoretical and experimental investigation on the accuracy of thermal diffusivity ␣ and thermal effusivity e of liquids measured by the photopyroelectric ͑PPE͒ method in back-detection configuration ͑BPPE͒. Special cases corresponding to different cell structures are analyzed in terms of error determination of ␣ and e for water and ethylene glycol. We propose a new normalization procedure allowing for estimation of these parameters with accuracy of 2% on ␣ and 5% on e over extended frequency range. The normalization eliminates the frequency-dependent influence of the transducer impedance and associated electronics, reduces the errors due to coupling fluid between cell components, and reduces the number of temperature-dependent parameters that must be known in order to characterize the sample. Technical solutions for improving the performances are suggested. Another goal of the study was to demonstrate the possibility of the BPPE method to yield small variations of thermal parameters as a function of temperature. We found good agreement with the literature data for the temperature coefficients (⌬␣/␣)/⌬T ϭ0.267Ϯ0.015%/K for water and (⌬e/e)/⌬Tϭ0.10Ϯ0.05%/K for ethylene glycol, between 20 and 60°C. The special case implying the normalization to a reference material and with a glass substrate for the pyroelectric sensor is shown to be the best adapted to the determination of both thermal parameters and of their temperature dependence.

Untitled

“…The eq. (7) is similar in form to the one reported by Delenclos et al but with different constant C 10 . The constant C is trivial in obtaining the value of thermal diffusivity and that is the reason why we do not consider the sample reflectivity, which is sample dependent and remains constant at single laser wavelength, in our model.…”

“…Minamide et al 8 applied the theory of thermal wave propagation suggested by Opsal and Rosencwaig 9 , in which a thermally inhomogeneous material was modeled with a system of N plane homogenous layers, to a 3-layer structure consists of graphite, air-gap and polyvinylidene diflouride (PVDF) film. In the contact method by Delenclos et al 10 , a difficult task is involved in solving 10×10 matrix by Cramer' s rule to obtain the solution for a heat transfer equation in order to reach the final expression for the average PPE voltage. In the normalization procedure, they normalized the liquid sample signal with respect to sensor signal alone, and also to other liquid sample signal.…”

High-Precision and High-Resolution Measurements of Thermal Diffusivity and Infrared Emissivity of Water–Methanol Mixtures Using a Pyroelectric Thermal Wave Resonator Cavity: Frequency-Scan Approach

“…Among other mixtures, water-alcohol solutions are of special interest, mostly in chemical, food, and environmental applications. Up to now, a variety of techniques have been employed for the measurement of the thermal diffusivity of alcohols and water-alcohol mixtures [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Photon correlation spectroscopy has been used in measurements of pure alcohols and their binary mixtures [1,2].…”

Highly accurate photopyroelectric measurement of thermal diffusivity of vegetable oils

“…The thermal diffusion length depends on the thermal diffusivity a and chopping frequency f as m = (a/pf) 1/2 . The symbols "m", "p" and "w" refer to material (sample), pyroelectric sensor and window, respectively [10,12,13].…”