Improvement of methodology for determining local thermal diffusivity and heating time of green coconut pulp during its pasteurization

Abstract

The objective of this article was to determine local thermal diffusivity of green coconut pulp stored in a parallelepiped-shaped metallic container during heating in a thermal treatment. A thermocouple was placed in the center of the container with the product, initially at 25.8 °C, and then the set was dipped in a water bath at 64.85 °C. The temperature over time was recorded in a txt file, making it possible to determine the parameters of a function that represents the thermal diffusivity, using an optimization technique, which also required a three-dimensional numerical solution of the heat conduction equation. Among the functions tested to represent thermal diffusivity as a function of local temperature, the best result was obtained with the hyperbolic cosine, with chi-square and determination coefficient of 0.3188 and 0.99998, respectively. Thus, it was possible to establish the time required to safely interrupt a new heating process during another heat treatment, with a simple simulation, without the need for a new experiment.