HEAT AND MASS TRANSFER IN STORED MILO (TEMPERATURE, MOISTURE, STORAGE)

Experiments were conducted to study heat and mass transfer in stored milo by observing the changes in temperature, moisture, and quality of milo stored in cylindrical steel bins as affected by changes in outside ambient air temperature, the initial moisture content of the grains, and the size of the storage bins.;Grain temperature distribution in all bins indicated temperature gradients in both the radial and axial directions. Natural convection enhanced heat transfer in grain near the wall and at the top of the bin.;Grain moisture distribution showed moisture gradients in both the radial and axial directions. Moisture reduction was more rapid near the wall and at the top of the bin where the effects of natural convection was more pronounced. Moisture loss in all stored grain was partly due to the higher vapor pressure of moisture in the grain compared to that in the ambient air at the average storage conditions.;Moisture migration caused by convective air currents was more severe in high moisture grain than in drier grain and slower in small bins than in larger bins. Quality deterioration was confined to the bottom grain layers that was high in moisture content.;Experimental results indicated that the average grain temperature inside the storage bins followed the average outside air temperature profile. The time lag between a change in ambient air temperature and a change in grain temperature was approximately seven to ten days.;Two mathematical models were also developed to simulate temperature and moisture contents of stored grain based on partial differential equations of heat and mass transfer. The models were validated by comparing predicted temperatures and moistures with data obtained from experimental bins containing milo. The two models successfully predicted temperatures and moisture contents during a one year of static storage period.