ESTUDIO NUMÉRICO DE LA CONVECCIÓN NATURAL DE CALOR Y MASA 2-D EN GRANOS ALMACENADOS EN SILOS CILÍNDRICOS NUMERICAL STUDY OF THE NATURAL CONVECTION OF HEAT AND 2-D MASS OF GRAIN STORED IN CYLINDRICAL SILOS

In this work a numerical study was carried out on the natural convection of heat and mass in cereal grains stored in silos, originated by the temperature gradients produced by environmental conditions and respiration heat of the grain, utilizing transport equations of the momentum, heat, and mass for multiphasic-media. The governing equations were solved through discretization of spatial coordinates using orthogonal collocation with Legendre polynomials with a mesh of 19×19 nodes, and the formation of an implicit scheme for the time. The nonlinear system was solved with the Newton-Raphson method with LU factorization for each integration step. Sorghum (Sorghum bicolor) was used as model, stored inside a cylindrical silo of 44 m3 capacity. The numerical study was done for 42 d, analyzing the flow patterns, isotherms, and humidity isolines in the grain as well as in the intergranular air. Grain moisture is the controlling variable and begins to become stable at 32 d of storage. With the abovementioned, bases for predicting the effect of environmental conditions on shelf life of grain are established.