Effects of corrugation parameters on fluid mixing characteristics in corrugated passages

Abstract

Static mixers are well established in process engineering. Their particular advantages are in-line mixing, no moving parts, low power consumption, and simultaneous homogenization of residence time behavior. Several species of static mixers are well known. An example of their arrangement is based on corrugated passages formed by layers of single plates with opposing orientation. Until now, the corrugation parameters of this species have mainly been designed according to few experimental studies. However, flow phenomena, implied by the geometry of the corrugated structure, are of significant influence on the mixing behavior, the pressure drop, and the residence time characteristics in corrugated passages. In new investigations, the effects of a variety of corrugation parameters on flow phenomena, mixing characteristics/and pressure drop have been systematically determined. The results prove that there are quite different kinds of flow phenomena depending on the geometrical parameters of the structure. Some parameter combinations lead to no mixing at all, others lead to a homogeneous mixing within a small length. Examples are shown of flow behavior in corrugated passages; here the flow has been traced locally making the flow direction evident. The effects of corrugation parameters on the fundamental flow phenomena will be discussed. In order to describe and predict the flow behavior in these corrugated passages, a model has been set up based on the fundamental flow phenomena. This model allows the simulation of flow behavior in corrugated passages, thereby allowing, also, the simulation of the mixing characteristics and the residence time behavior of the fluid in these structures. Examples of the simulation, where the local addition of a tracer and its mixing across the structure has been simulated, are shown. Further results of flow simulation on mixing characteristics and dynamic aspects will be compared to experiments. Combined with the pressure drop in corrugated passages, the model allows the optimization of motionless mixer design. Several aspects of structure optimization will be discussed.