29E-16 |
Numerical study related with 2-d natural convection of heat and mass in stored grains in cylindrical silos |
H. JIMÉNEZ-ISLAS1, J. L. Navarrete-Bolaños1, and E. Botello-Alvarez. (1) Ingeniería Química-Bioquímica, Instituto Tecnológico de Celaya, Av. Tecnológico esq. A.G. Cubas, Celaya, Gto., 38010, Mexico Phenomena transport knowledge in bulk storage grains in silos is necessary for proposal optimum conditions storage that allow increase the shelf life of cereal grain. In this work, we studied the natural convection heat and mass related with storage of cereal grains that is originated by temperature gradients produced via environment conditions and heat respiration grain. The study beginning from the momentum, heat and mass equations with multiphasic-media approach, including the effects of respiration-produced heat and the equilibrium between the grain and the interstitial air. The governing equations were solved through spatial-coordinates discretization using orthogonal collocation with Legendre polynomials with a mesh of 21x21 nodes, following of generation of an implicit scheme for the time coordinate. The nonlinear set of algebraic equations obtained was solved employing Newton-Raphson method with LU factorization for each integration step. In this work, we used sorghum (Sorghum vulgare) as example, which was stored in a cylindrical silo of 44 m3 volumetric capacity. The bulk grain has at 30 °C as initial temperature and the environmental temperature is of 25 °C at 50% relative humidity. The computer simulation was carried out for 42 days, analyzing the flow patterns, isotherms and humidity isolines as much in the grain as in the intergranular air. It was observed the formation of hot nucleus that reaches a temperature of 30.5 °C. By other hand, the grain moisture is the controlling variable, which, at steady state, reaches his thermodynamic equilibrium with the relative humidity of the air, starting this fact at 35th day of storage. The above facts lead to establishment of optimal parameters for storing bulk grain in silos that allow increase the shelf life of cereal grain. In addition, this prediction allows know the conditions that could be favor growth fungi or infestation by insects.
Session 29E, Food Engineering: Transport processes and kinetics
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