An improved technique for determining transport parameters in cooling processes

摘要

In order to describe cooling processes, the thermal diffusivity a and the convective transfer coefficient h must be known. To this end, in general the analytical solution of the diffusion equation with only the first term is fitted to an experimental dataset of the temperature versus time, in which the temperature is measured in a known position. Despite this technique to describe well the major part of the cooling kinet-ics, this procedure contains a flaw for Fourier numbers less than 0.2 (lag factor). This article presents an algorithm based on optimal removal of experimental points to minimize errors in the determination of a and h. The algorithm was validated for several physical situations, and applied in cucumber cooling. The whole cooling kinetics was simulated with success (chi-square = 2.8756 x 10~(-3) and determination coef-ficient = 0.9991), including the region responsible by the lag factor.