Modelling Supercritical CO2 Bubble Breakup Dynamics in Twin Screw Extruders

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Abstract

Twin screw extruders are commonly used in polymer processing. Key design features of these devices are the kneading blocks, which are designed and arranged such that e.g., additives and fillers are efficiently distributed in the polymer melt. This work presents CFD analysis of bubble breakup in these kneading zones, comparing counterrotating to corotating systems using both 2D and 3D analyses. The Level Set method is used to model a multiphase system of dispersed supercritical CO2 bubbles in a polypropylene phase. Droplets with radii of 0.5 mm are initialized close to the zone in between the kneading blocks. The results show that the bubble breakup phenomena differ in counter and corotating systems due to different flow profiles. In both cases the breakup shapes are predominantly driven by flow characteristics with counterrotating configurations showing stronger elongation of the bubbles due to elongational flow sections close to the initialization of the original bubble, leading to pinch-off of smaller bubbles compared to the corotating cases.

Original languageEnglish
Title of host publicationComputational Fluid Dynamics (CFDTC); Micro and Nano Fluid Dynamics (MNFDTC); Flow Visualization
PublisherAmerican Society of Mechanical Engineers (ASME)
Number of pages7
ISBN (Electronic)9780791888131
DOIs
Publication statusPublished - 10-Sept-2024
EventASME 2024 Fluids Engineering Division Summer Meeting, FEDSM 2024 collocated with the ASME 2024 Heat Transfer Summer Conference and the ASME 2024 18th International Conference on Energy Sustainability - Anaheim, United States
Duration: 15-Jul-202417-Jul-2024

Publication series

NameAmerican Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM
Volume2
ISSN (Print)0888-8116

Conference

ConferenceASME 2024 Fluids Engineering Division Summer Meeting, FEDSM 2024 collocated with the ASME 2024 Heat Transfer Summer Conference and the ASME 2024 18th International Conference on Energy Sustainability
Country/TerritoryUnited States
CityAnaheim
Period15/07/202417/07/2024

Keywords

  • Bubble breakup
  • CFD
  • Kneading Blocks
  • Level Set method
  • Supercritical CO2
  • Twin Screw Extruders

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