Libro de Resúmenes / Book of Abstracts (Español/English)

Resumenes 28
Computational simulation to determine thermal
properties of soybean as a function of the drying
process
Knowing the drying kinetics, as well as the parameters and thermal
properties that characterize the drying process of the agricultural products
has become important in supporting the implantation of technologies to
improve the conservation of these products. This experimental research
area has shown improvements all over the world, as can be found in the
specific post-harvest technology literature. Particularly at College of
Agricultural Engineering at University of Campinas, located in Brazil and
known as FEAGRI/UNICAMP, pioneer-research work has been carried out
using also applied mathematical as an important tool by Ito, Amendola and
Park (2002). The main purpose of using this methodology is to compare its
theoretical results with experimental data, in the least square method
sense, in order to be able to identify the thermal conductivity of the
product. The experimental data considered in this investigation were
selected from those recorded previously to the soybean [1]. In this case, to
perform the experiment, it was constructed a cylindrical equipment to place
the product to be dried in such way that the process occurs in the spatial
domain defined between two cylinders with radii R1 = 0.013 [m] and R2 =
0.0.049[m], subject to a heat source, qf = 393.7 [W/m 2 ], placed at its
central axis. For a certain height of the equipment and at four positions
along this radial domain the values of soybean temperature, T [°C], were
recorded along the time, t [s], approximately at each 100s during 6000s.
The following fixed parameters of the process or product must be
established: initial temperature T0 [°C], density ρ [kg/m 3 ] and heat capacity
Cp [J/kg°C]. The mathematical model considered is the one-dimensional
mathematical model based on Fourier’s law second equation in cylindrical
coordinates, under initial and boundary conditions according to the specific
experiment described previously but the algorithm is elaborated according
to the scheme implicit of the finite differences method as recommended [2],
once this investigation involves several simulations till reach the best value
of the conductivity thermal, k [W/m°C], and is carried out for all the
referred 4 positions. To determine the referred best value it is necessary to
know some value of k in order to initialize the search for the minimal
residual value, which is taken from the literature. The whole algorithm was
implemented with MATLAB6.5. We notice that this kind of problem, as it is a
problem inverse, is ill posed and, for that, it requires a regularization
technique, which is still being in development
References
[1] ITO, A. P., AMENDOLA, M e PARK, K. J. Construção e avaliação de um
sistema de determinação de condutividade e difusividade térmica em regime
transiente. In: Congreso Agronômico De Chile y Congreso Ibero Americano
de Tecnología Postcosecha y Agronegócios, 3. Resumen. Simiente, v. 72 (3-
4). ISSN 0037 - 5403. Santiago – Chile. 2002. p.141-142.
[2] MENDOLA, M. Considerations to continue researches in drying process
numerical simulation of agriculture products at FEAGRI/UNICAMP. Abstract