Modelising the grain mass aeration process using the Thorpe Model with the Finite Volume Method

Resumo

By the technological advancements in agriculture, rural production is searching for ways to improve
grain storage. Rigorous control of temperature and moisture is essential as they are the main factors contributing
to product deterioration and plague proliferation. One of the most effective ways of achieving this is by aeration, a
process widely applied to maintaining grain quality in silos and warehouses. This work aimed to develop a control
system for the aeration of stored grains based on experimental data from literature and process simulations. The
control strategy employed in the aeration aims to maintain temperatures uniform inside the silo and cool down the
grain mass whenever possible. During this process, the grain mass is split into multiple thin layers according to
the flow of air (upwards). The mathematical model used was proposed by Thorpe and associates psychometric
properties of the air with mass and energy balance equations. In this sense, the system of equations resulting
from the mass and energy balances was solved iteratively for each time increment and each layer. Additionally,
the model equations were discretized using the Finite Volume Method combined with the Upwind Differencing
Scheme for the spatial approximations as well as explicit, implicit, and Crank-Nicolson temporal formulations.
Moreover, a posteriori analysis of the discretization error orders was carried out. The proposed model in this study
has proved satisfactory, with some variations depending on the combination between the method and the spatial
and temporal approximations employed.