Numerical analysis of natural convection heat transfer in stored high moisture corn

Abstract

A numerical study was performed on the simulated natural convection heat transfer occurring inside a grain bin which contains stored corn. The simulations were intended to reveal the effects of flow inertia, container aspect ratio, and temperature dependent thermophysical properties on grain temperatures. These simulations utilized a uniformly heat-generating porous medium in a short, vertical circular cylinder with an adiabatic lower end and an isothermal cylinder top and side. The thermophysical properties of air and corn were used for the porous medium. Modified Darcy momentum equations, which include inertia terms, were used. Streamline and isotherm patterns were developed for different cylinder height to radius ratios, boundary temperatures, and heat-generation rates. Results show that unicellular flows exist for large height to diameter bin aspect ratios and multicellular flows develop for small aspect ratios. Maximum temperatures are greater for simulations using equations which included temperature dependent property terms. The location of the maximum temperature moves up from the bottom of the cylinder as storage time increases. In general, maximum temperatures at steady-state decrease as the cylinder height increases, at constant radius. Isotherms developed are very similar to previously published experimental data.