VELOCITY-FIELD AND HEAT-TRANSFER IN A VORTEX FLOW EXCHANGER

This study deals with the flow of newtonian and non-newtonian fluids, inside a cylindrical flat cavity, provided with a tangential injection device, model of heat exchangers with spiral flow. The dynamic analysis which requires essentially a laser Doppler velocimeter focusses on the determination of the velocity field and brings out the existence of secondary flows which are important for heat transfer. In turbulent regime, the law of exchange agrees with the Chilton-Colburn analogy. On the other hand, for laminar flow, it becomes necessary to include the variations with temperature of the consistency (K); the Nusselt number (Nu) not only depends on the flow rate, but also on the density of transferred heat flux. © 1990 Springer-Verlag.