Simultaneous Determination of Thermophysical Properties Using a Thermistor, Part 1: Numerical Model
Lahoucine, C.O., Sakashita, H. and Kumada, T.
2004 Journal of Thermophysics and Heat Transfer, vol. 18, no. 3, pp. 295-301
Lahoucine, C.O., Sakashita, H. and Kumada, T., (2004), "Simultaneous Determination of Thermophysical Properties Using a Thermistor, Part 1: Numerical Model", Journal of Thermophysics and Heat Transfer, vol. 18, no. 3, pp. 295-301.
Abstract:
A new thermistor-based technique for the measurement of thermophysical properties of liquids and porous materials is proposed. To simulate the real situation, a two-dimensional numerical thermal model of the thermistor, surrounded by a sample of cylindrical shape, is presented. The simultaneous estimation of thermal conductivity and diffusivity by the use of an inverse analysis is detailed. If the measured volume-averaged temperature rise of the thermistor is available, then thermal diffusivity of the sample is evaluated first from the plot of these measured temperatures vs the logarithm of the Fourier number. Once thermal diffusivity is evaluated, thermal conductivity is obtained through the minimization of standard deviation between calculated and experimental temperatures of the thermistor in the least-square sense. The time range used to determine the thermophysical properties is selected within the transient-state part of time-dependent temperature rise of thermistor, expressed in dimensionless form, and is situated between Fourier number Fo = 1 and Fo = 10. In addition, and to get accurate results, an analysis is performed to show the set of parameters to be adjusted before actual measurements. The parameters are the dimensions of the sample, time step, and the mesh sizes used in the numerical analysis.