A mathematical model for natural convection moisture migration in stored grain
Trans. of the ASAE Vol. 38(6): 1777-1787, 1995
Kishor Khankari, S. V. Patankar and R.V. Morey
Thermal gradients that develop due to the seasonal variations in ambient temperatures cause natural convection air-flow and migration of moisture within bulk grain. In this article^ a mathematical model of moisture migration is developed by reflecting the change in air moisture on the grain moisture through the sorption isotherm. Thus the effect of temperature and moisture gradients are clearly separated in the conservation of moisture equation. The differential equations for energy are developed by using moisture dependent thermal properties. Natural convection Darcy flows are computed by solving an equation for the pressure, which represents the continuity equation. The resulting unsteady, nonlinear, coupled differential equations are numerically solved using a control-volume scheme. Natural convection moisture migration is also experimentally simulated under laboratory conditions. The validity of the numerical model is evaluated by comparing the experimental results with the predicted results.