Simulation and modelling of the pressure drop in industrial polymer melt filters depending on different process conditions and their contamination

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Extrusion is one of the most common methods in polymer processing. One of the main requests of polymer processing is a steady quality of the final product. This quality directly depends on the melt quality in the extrusion process. During processing there are multiple possibilities of bringing in a contamination into the extrusion line. These contaminations can negatively affect the melt quality. Because of todays high requirements to extrusion products, melt filtration is widely used especially in the field of fiber- and filmextrusion.The technical design of polymer melt filters, the knowledge of the resulting pressure drop and the soiling behavior of filter elements are basics for optimal processing and high quality extrusion products. In practice, filter systems are often designed based on long time experience. The calculations of pressure loss are usually based on general calculations of porous media.The primary objective of this research project is to map the flow situation of a polymer melt filters during the extrusion process with the help of CFD simulations an a small scale. This small scale should then be extrapolated to relevant sizes. The central target value in this case is the resulting pressure loss of the filter medium. The shear thinning behavior of polymers should also be taken into account.For this investigation geometric data of different filter mediums shall be created in CAD format. This data should then be handed over to CFD simulations for calculating the pressure drop of through the filter medium. These simulations will be validated and optimized based on experimental studies in order to obtain a realistic calculation of the pressure drop through a filter medium.In the second step, the contamination of a filter should be analyzed by using solid particles. For this purpose, the deposition behavior of the particles in the filter medium should be calculated by using a DEM simulation. The resulting new flow cross section of the filter area should be passed back to the CFD pressure drop simulation. By this, the soiling behavior and the resulting increase in pressure on the filter can be represented by the simulation.At the end of the research project it should be analyzed if it is possible to simulate a filter contamination with soft dirt particles, so called gels. For this it should be investigated whether the behavior of gel particles can be simulated with a DEM simulation. The simulation and experimental study of soiling a filter with gel particles can then be investigated during a possible extension of the requested research project.