Mathematical model for determining thermal properties of whole bananas with peel during the cooling process

摘要

Usually, the thermophysical parameters of bananas available in the literature refer to the flesh of the product. However, to prolong the shelf life avoiding injuries, product cooling should be performed for bananas with peel (from room temperature to 13 degrees C). Thus, the main objective of this article was to determine thermal properties of banana with peel during its cooling. A solver was developed for the direct problem, using a two-dimensional solution of the diffusion equation to describe heat transfer. For the inverse problem, we used an experimental dataset of the temperature over time at the center of a banana, and a ready-to-use optimizer software. Convective heat transfer coefficient and thermal diffusivity were h = (2.186 +/- 0.021) x 10(-6) m s(-1) and alpha = (1.45 +/- 0.06) x 10(-7) m(2) s(-1), respectively. Heat transfer coefficient and thermal conductivity were h(H) = (4.93 +/- 0.05) W m(-2) K-1 and k = (0.328 +/- 0.014) W m(-1) K-1, respectively. The chi-square and determination coefficient of the optimization process were 3.5484 x 10(-2) and 0.999955, respectively. (C) 2018 Elsevier Ltd. All rights reserved.