title: Comparison of boundary conditions to describe drying of turmeric (Curcuma longa) rhizomes using diffusion models.
abstract: Turmeric is harvested with high moisture content and should be dried before the storage. It is observed that drying is quickest when the rhizomes are peeled and cut in small cylindrical pieces. In order to describe the process, normally a diffusive model is used, considering boundary condition of the first kind for the diffusion equation. This article uses analytical solutions considering boundaries conditions of the first (model 1) and third (model 2) kinds coupled to an optimizer to describe the drying process. It is shown that, for model 1, the fit of the analytical solution to the experimental data is biased, despite the good statistical indicators (chi-square χ(2) equal to 1.7095 × 10(-3) and coefficient of correlation R(2) of 0.9988). For model 2, the errors of the experimental points about the simulated curve can be considered randomly distributed, and the statistical indicators are much better than those obtained for model 1: χ(2) = 3.5596 × 10(-4) and R(2) = 0.9996.
authors.affiliation: Departamento de Física, Universidade Federal de Campina Grande, Campina Grande, PB Brazil.
authors.forename: Wilton Pereira
authors.initials: WP
authors.lastname: da Silva
authors.affiliation: Departamento de Física, Universidade Federal de Campina Grande, Campina Grande, PB Brazil.
authors.forename: Cleide M D P S
authors.initials: CM
authors.lastname: E Silva
authors.affiliation: Engenharia Agrícola, Universidade Federal de Campina Grande, Campina Grande, PB Brazil.
authors.forename: Josivanda Palmeira
authors.initials: JP
authors.lastname: Gomes
keywords: Analytical solution; Cauchy boundary condition; Convective mass transfer coefficient; Effective mass diffusivity; Finite cylinder