The effect of solid bed dispersity on the contact heat transfer in rotary drums

Abstract

Experimental work was conducted to study the influence of bulk bed dispersity on contact heat transfer. The contact heat transfer between the inner drum wall to the covered surface of the solid bed was experimentally investigated in an indirectly heated rotary drum with a diameter of D = 0.6 m and a length of L = 0.45 m. The temperature of the inner drum wall and the solid bed were measured by K-type thermocouples assembled on a rod, upon which these thermocouples were specifically arranged at different radial distances from the inner wall. Experiments have been carried out with glass beads as the test material, with systems defined as monodisperse, bidisperse and polydisperse and with different particle size ratios. The operating parameters, rotational speed and filling degree are varied in the range of 1 to 6 rpm and 10 to 20% respectively. The measured contact heat transfer coefficients for all disperse systems were compared with four model approaches from the literature in terms of R2 values. Good agreement between the experimental measurements and the two model approaches were achieved.