Abstract
Heat transfer between air and particles in rotary dryers and coolers is analyzed with some assumptions. As a result, the relation is derived between the effective number of falling particles per unit length, which is obtained by using experimental data of volumetric heat transfer coefficient, and the average number of falling particles per unit length. This equation has two parameters to be determined experimentally.
These are determined by using all the data obtained by the authors and other investigators. Two equations are consequently obtained in two regions divided by the average number of falling particles per unit length. One equation shows that the effective number of falling particles per unit length is in proportion to the three-fourths power of the average number of falling particles per unit length. The other shows that the effective number is in proportion to the one-half power of the average number. These equations make clear the relation between the volumetric heat transfer coefficient and the operating variables.
A method of design for a rotary dryer is also illustrated.
