Genetic-algorithm based method for thermophysical properties identification in a wide temperature range


A. Smotritskiy1, A. Kazakov2, A. Starostin1, A. Yampol'skiy1 and P. Skripov1

1Institute of Thermal Physics, Russian Academy of Sciences, Russia
2Thermophysical Properties Division, National Institute of Standards and Technology, U.S.A.

Keywords: wide temperature range, genetic algorithm, transient hot wire
property: thermal conductivity, volumetric heat capacity
material: saturated hydrocarbons, nanofluids

Generally, measurements of thermal transport properties for fluids are carried out under small temperature perturbation with respect to thermostat temperature [1]. Due to the complexity of experimental conditions, the region of elevated temperatures and especially the region beyond the line of absolute stability of a substance remains poorly known. We are developing a method of controlled pulse heating of a thin wire probe [2] combined with the numerical modeling, suitable for investigation of thermophysical properties of substances over wide temperature ranges. The probe combines functions of both heater and resistance thermometer. The method is characterized by short (from 0.1 ms to 10 ms) heating time. The entire histories of the probe temperature and the heat-flux density in a continuous fluid are recorded in the course of experiment.

Temperature dependencies of thermophysical properties are obtained from the collection of the recorded temperature histories by solving numerical optimization problem using genetic algorithm. Property temperature dependencies are approximated with polynomial functions, and their coefficients are optimized to achieve the best agreement between the experimental and predicted temperature histories. The predicted temperature histories are obtained from the direct numerical solution of transient heat transfer problem for the system using the finite difference method.

The performance of the method over temperature ranges up to 700 K was demonstrated using a set of saturated hydrocarbons (as the reference fluids) and nanofluids based on suspensions of oxide particles in isopropanol. The present results for the reference fluids agree within 1% with accepted literature evaluations.

For A.A.S., S.B.R., A.D.Y. and P.V.S. the study was supported by the Russian Foundation for Basic Research (project No. 10-08-00538-а).

References
  1. M.J. Assael, K.D. Antoniadis, W.A. Wakeham. Int. J. Thermophys. 31, 1051-1072 (2010)

  2. Skripov P.V., Smotritskiy A.A., Starostin A.A., Shishkin A.V. A J. Eng. Thermophys. 16 (3), 155-163 (2007)

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