A STUDY OF PARAMETERS INFLUENCING WALL-TO-BED HEAT-TRANSFER IN LOW-TEMPERATURE ROTARY DESORBERS

Heat transfer between a rotating wall and a bed of granular material is investigated. Three specific areas of this problem are studied. First, a Stefan-type model is used to evaluate the importance of evaporation near the wall on the wall-to-bed heat transfer coefficient. Next, a heat-balance integral method is used to model wall-to-bed heat transfer, including both evaporation within the bed and a thermal contact resistance between the wall and the first layer of particles. The method is evaluated and then compared to an approximate means with which to include the thermal contact resistance. Thirdly, the wall-to-bed heat transfer problem is solved under the condition of a linearly changing wall temperature. This solution is used to evaluate the consequences of the common isothermal wall assumption.