engleski

Computer Subprogram with a Graphical User Interface in Matlab for Accurate Thermal Diffusivity Estimation Using Levenberg-Marquardt Method for Numerical Inverse Solution of Transient 1D Heat Conduction

A numerical approach is developed to obtain accurate estimate of thermal diffusivity of granular materials based on improved transient measurements. An improved experimental technique and a numerical approach for thermal diffusivity estimation are employed for better accuracy and precision on materials which require a sample holder. An iterative procedure, based on minimizing a sum of squares function with the Levenberg-Marquardt method, is used to solve the inverse problem. Fourier’ s one dimensional radial heat conduction model and the sensitivity problem obtained by differentiating the model with respect to the unknown parameter were solved using Matlab’ s built-in solver “ pdepe” . The sub-program comprising a specially built graphical user interface (GUI) was written for the setting of Matlab 6.5 (The MathWorks, Inc., Natick, MA). Based on the built GUI and a guided instructions written by the author even the first time users of Matlab with no programming skills are encourage to use the developed numerical method for accurate inverse thermal diffusivity estimation of granular materials. The required inputs for the developed GUI are: the temperature-time input, radial grid, (introduced as the axial starting point (always zero), increment and inner radius of used tube R), the initial temperature condition, radial position of ‘ axial’ thermocouple, initial guess, prescribed tolerance for the stopping criteria, and maximal number of iterations. The output of the numerical model gives a result of thermal diffusivity estimate. Ten iterations for such data run on Intel Pentium 4 CPU 3.00 GHz, 1 GB RAM, take about 40s.

Computer program; Graphical user interface; Thermal diffusivity; Inverse problem; Levenberg-Marquart method; Granular materials

Računalni potprogramski paket s grafičkim sučeljem u Matlabu za procjenu toplinske difuzivnosti materijala primjenom Levenberg-Marquardt-ove metode i numeričkog rješenja 1D modela vođenja topline