Optimization of Aeration Systems for Value-Added Crop Preservation

Temperature management during grain storage is one of the most critical variables that affect the rate of deterioration. By maintaining proper temperatures during storage the development of insects can be minimized without the use of residual pesticides or fumigation. The overall goal of this research is to develop alternative aeration systems and strategies that would control grain temperatures during spring and summer storage more effectively. Grain is a good insulator and if it was properly aerated during the winter the only portion of the bin that will rewarm is the region near the wall. By designing a second aeration system into a bin the airflow could be targeted towards the wall. This partial aeration system would allow the outer periphery of the bin to be cooled without rewarming the interior portions. This would reduce the cost and improve the effectiveness of ambient and chilled aeration as non-chemical pest control techniques in food grain. An existing finite element model of the heat, mass, and momentum transfer during periods of nonaerated and aerated storage would be modified to take into account the effect of non-uniform airflow. Other researchers have developed and solved the equations that govern non-uniform airflow through grain masses of arbitrary shapes. However, the effects of non-uniform airflow have not been integrated into a heat and mass transfer model. The feasibility and application of partial ambient or chilled aeration could then be investigated. Verification of the airflow model would be done in laboratory flat bottom bins. Further verification of the non-uniform airflow heat and mass transfer model will be done using temperature data collected at commercial facilities. Heat and mass transfer due to natural convection during periods of nonaerated storage can be very significant. Natural convection currents are primarily a function of the permeability of the grain mass. Before aeration systems or strategies are modified the effect of permeability on the natural convection currents and moisture migration needs to be further documented. The permeability of grain has not been well documented as a function of fine material, moisture content, or bulk density. The permeability of corn, soybeans, and wheat will be determined experimentally. After the laboratory work is completed the results will be implemented and demonstrated at a commercial facility. The results from this study will be important in evaluating and promoting aeration as the alternative non-chemical pest control strategy.