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United States Department of Agriculture

Agricultural Research Service

Title: 3-D and quasi-2-D discrete element modeling of grain commingling in a bucket elevator boot system

Authors
item Boac, Josephine -
item Casada, Mark
item Maghirang, Ronaldo -
item Harner, Iii, Joseph -

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2012
Publication Date: March 1, 2012
Repository URL: http://naldc.nal.usda.gov/download/54153/PDF
Citation: Boac, J.M., Casada, M., Maghirang, R.G., Harner, III, J.P. 2012. 3-D and quasi-2-D discrete element modeling of grain commingling in a bucket elevator boot system. Transactions of the ASABE. 55(2):659-672.

Interpretive Summary: Unwanted grain commingling reduces grain purity, which impair the effectiveness of new quality-based grain handling systems. Experimental studies of commingling are expensive and time consuming so this study developed experimentally validated models that can reduce the time and expense of studying grain commingling. Grain commingling in a pilot-scale bucket elevator boot was modeled in (1) three-dimensional (3-D) discrete element method (DEM) simulations and (2) in two-dimensional (2-D) DEM simulations, which provides faster simulations. Grain commingling in the pilot-scale boot was measured in experiments using red and clear soybeans. Predicted results from both 3-D and 2-D models followed the trends of the experimental data, with a tendency to under predict commingling early in the process. Since the models predicted the cumulative commingling well over the whole run, they were considered effective for evaluating commingling in the boot. The 2-D model reduced simulation run time by approximately 70% compared to the 3-D model of the pilot-scale boot. Results of this study will be used to accurately predict impurity levels and improve grain handling, which can help farmers and grain handlers reduce costs and maintain grain purity during transport and export of grains.

Technical Abstract: Unwanted grain commingling impedes new quality-based grain handling systems and has proven to be an expensive and time consuming issue to study experimentally. Experimentally validated models may reduce the time and expense of studying grain commingling while providing additional insight into details of the particle flow. In this study, grain commingling in a pilot-scale bucket elevator boot was first modeled in three-dimensional (3-D) discrete element method (DEM) simulations. Experiments on the pilot-scale boot were performed using red and clear soybeans to validate the 3-D DEM model. Predicted results from the 3-D boot model generally followed the experimental data but tended to under predict commingling early in the process. To reduce computational time, quasi-two-dimensional (quasi-2-D) DEM simulations were also evaluated. Comparison of predicted average commingling of four quasi-2-D boot models with reduced control volumes (i.e., with boot widths from four to seven times the mean particle diameter) led to the selection of the quasi-2-D model with boot width of 5.6 times the mean particle diameter (i.e., 5.6d) to reduce computation time. In addition, the 3-D and quasi-2-D (5.6d) models were refined by accounting for the initial surge of particles at the beginning of each test and correcting for the effective dynamic gap between the bucket cups and the boot wall. The quasi-2-D (5.6d) models reduced simulation run time by approximately 70% compared to the 3-D model of the pilot-scale boot. Results of this study will be used to accurately predict impurity levels and improve grain handling, which can help farmers and grain handlers reduce costs and maintain grain purity during transport and export of grains.

Last Modified: 9/2/2014
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