Analysis of temporal and spatial temperature gradients at pronouncedly fluctuating cooling conditions

Abstract
Realised cooling velocities of a probe (cylinder) at discrete radius points during cooling at pronouncedly fluctuating cooling conditions are presented. Submerging the probe into an air-corundum (Al₂O₃) particles fluidised system of insufficient cooling capacity imposes the fluctuating cooling conditions. The particles have an average granulation of 95 m; the cylindrical probe diameter is 50 mm and its height 175 mm. The probe surface temperature and the temperature 1.5 mm beneath its surface are measured with built-in thermocouples. The thermocouples have a very high sensitivity, which enables temperature variation recording according to the cooling dynamics. The relevant cooling time is 125 seconds. The temperature changes in discrete points of the cylinder radius are determined by the control volume method. The calculation results indicate a shift of the maximum cooling velocity towards the interior of the cylinder.