HEAT-TRANSFER COEFFICIENTS FOR DRYING IN PULSATING FLOWS

Pulsating flows generated by a Rijke type combustor are studied for dr ying of grains and food particles. It is assumed that the velocity flu ctuations are the main factor in the enhancement of the drying process . The heat transfer coefficients for drying in vibrating beds are util ized to estimate the heat transfer coefficients of fixed beds in pulsa ting and permeating flows and are compared to the steady flow heat tra nsfer coefficients obtained for solid porous bodies, after perturbing the main flow. The cases considered are compared to the convective hea t transfer coefficients employed in non-pulsating drying. (C) 1998 Els evier Science Ltd.