Acoplamento massa-energia na descrição de secagem de produtos cilíndricos.

Abstract

This work aims to study the phenomenon of the transient diffusion of heat and mass in solids with geometric form of an infinite cylinder. The study presents solutions for the diffusion equation with boundary condition of the third kind. Numerical tools for describing the diffusion of heat and mass in the ways mentioned were developed. For the numerical solutions proposed, the one-dimensional diffusion equation was discretized using the finite volume method with a fully implicit formulation, using cylindrical coordinates. For the numerical solution in cylindrical coordinates, two software have been developed on the Windows platform, one for mass migration and one for the heat transfer, using the Fortran programming language, Quick Win Application option. The software was validated using solutions known for cylinders with both constant and variable thermophysical parameters. It can be concluded that the developed tools were appropriate for the study of diffusion problems in general. The above tools were used to describe the process of drying whole banana. In the description, we considered the volume and diffusivities with variables values. It can be concluded that the proposed model to describe the process showed excellent statistical indicators to describe the kinetics of heat and mass transfer. One can also conclude that the exclusion of the vapor heating in the calculations performed does not significantly alter the results. In addition that using the latent heat of free water instead of this property in the product does not produce significant effects. On the other hand, discard the latent heat of vaporization and the consideration of density and specific heat of the product as constant properties should be avoided.