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ISSN Online: 2377-424X

ISBN Print: 0-89116-559-2

International Heat Transfer Conference 8
August, 17-22, 1986, San Francisco, USA

IDENTIFICATION OF NONLINEAR THERMAL PROPERTIES BY AN OUTPUT LEAST SQUARE METHOD

Get access (open in a dialog) DOI: 10.1615/IHTC8.1020
pages 1811-1816

Аннотация

For liquids or phase change materials, the classical methods for the determination of thermophysical properties are usually difficult to use. But on the other hand, it is easy to implement thermal sensors inside the material, thereby allowing efficient identification methods developped in otpimal control theory.
The method presented here is termed the Output Least Square Method (OLSM). It consists in minimizing, with respect to the unknown parameters, a criterion, in order to match the computed outputs of the model to the available measurements. The criterion is computed all over the time of experiments. The nonlinear variations of the parameters are represented by continuous piecewise linear functions. Because of poor conditioning of the problem, the approximation of the gradient by differences is avoided and the so-called Lagrangian method is used.
The identification results are obviously dependent on the boundary conditions. A previous simulation allowed to choose the best of the realistic easily applicable conditions.
In order to evaluate the feasibility of the method in a realistic situation, experimental results using a parafine wax with a melting range are reported.