Determining Thermal Conductivity For Biological Materials In A Drying Process

Abstract

It is key issue for the Agricultural Engineering to identify thermo physical properties of
biological materials. There is a special interest in the thermal conductivity and diffusivity coefficient
estimation, which can be performed by comparing data obtained from a specific experimental
procedure and theoretical data obtained from some mathematical model – capable for simulating the
referred procedure. The experimental data of temperature were previously obtained from one thermal
measuring system consisting of concentric cylinders to hold the biological material (a soybean sample
in this study), with a heat source placed at the central axis and keeping the cylindrical, as well the
circular cross sectional outer surfaces insulated . In such a procedure, only radial heat transfer is
effective, minimizing the heat flux in the axial direction. Simulated data of temperature are obtained
by using the mathematical model based on the Fourier’s law with initial and boundary conditions
according to the experimental procedure, which requires estimative of one the thermal conductivity
value. The direct problem is solved by using an implicit forward time and centered space finite
difference scheme, with Neumann boundary at the center and the outer surface. Results show a
dependency of the thermal conductivity with radial component. The thermal property is estimated by
computing the value having the best agreement.