SIMULATED TEMPERATURES OF STORED GRAIN BULKS

Temperatures of grain bulks stored near Winnipeg, Canada were stimulat ed using a three-dimensional heat transfer model to study the influenc e on the grain temperatures of bin diameter, grain-bulk height, bin wa ll material, bin shape, and turning of the grain with auger. A time la g was observed between the seasonal ambient temperature and the grain- bulk centre temperatures. Large diameter bins maintained warmer centre temperatures than small diameter bins. The influence of heat transfer from or to the top and bottom of the grain surface on the grain centr e temperatures was negligible for tall grain bulks. A small-diameter, tall-grain bulk maintained lower grain temperatures than a large-diame ter short-grain bulk. A white-painted steel bin maintained the lowest temperatures and a galvanized steel bin gave the highest temperatures among the bin wall materials studied. The shape of the bins (circular, rectangular, square) had little influence on the grain temperatures. If it is necessary to construct a rectangular bin in the northern hemi sphere, the bin should be placed with its longer dimension in the nort h-south direction. The simulation results showed that the north-south orientation would maintain a lower temperature difference between nort h and south sides of the grain bulk than an east-west orientation. Tur ning grain was effective because it reduced centre grain temperatures by about 10-degrees-C immediately after turning during winter. Turning had negligible influence on the grain temperatures over long periods of storage.