MODEL FOR CONTACT HEAT-TRANSFER IN MECHANICALLY STIRRED ANTIGRANULOCYTES BEDS

Although widely used in industry, design of mechanically stirred heated vessels is still an art. This research attempts, possibly for the first time, to evaluate surface-to-bed contact heat transfer rates for particulate beds stirred by paddle-type blades on the basis of a fundamental knowledge of the particle flow characteristics. A physical model for the wall-to-bed contact heat transfer coefficient based on particle renewal rates at the heated surface is presented. The particle renewal rates are estimated exclusively from measured information on particle movement in the vicinity of the heated vessel wall in a two-dimensional configuration. The heat transfer model includes the effects of agitator rotational speed, wall-to-blade clearance size, solids flowability and aeration.