Investigation of the pressure-throughput behaviour of different faceted mixer geometries on an analytical and simulative basis

Polymers are rarely processed in their natural state. Single-screw extruders, in particular, have to perform increasingly challenging mixing tasks, often in order to save the additional compounding step in the course of economic efficiency. In this course, special mixing geometries are often used to increase mixing performance. Since the mixing part geometry usually acts as a pressure consumer and thus has a significant influence on the output, knowledge of the pressure-throughput behavior is of enormous importance. One of the most frequently used mixer geometries is the so-called faceted mixer or pineapple mixer. However, this has a high number of degrees of freedom, which is advantageous for the design because it allows the conveying or mixing effect to be adjusted. On the other hand, an unfavorable design can quickly lead to enormous pressure losses and, as a consequence, high throughput losses. Since an extensive investigation would be associated with high manufacturing costs, CFD simulations offer enormous potential for analyzing a large number of geometry variants. Due to this fact a large set of variants based on a simulate CCD test plan with 151 trial points is used. Based on these simulations, a pressure throughput model is then presented and compared with existing analytical models.