Analysis and optimization of blown film cooling systems based on an integrative and calibrated process model

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The blown film extrusion as well as any other extrusion process is limited by its cooling capacity. Only an optimization of the cooling system can improve the production throughput. Motivation of this research project is the numerical analysis and optimization of blown film cooling systems using a process model. This model is able to simulate a realistic blown film behavior depending on the cooling situation for several different materials and process conditions. For example a counter flow cooling system was analyzed and benchmarked using this simulation model.The aim of the second project phase is the development of basic methods for the numerical optimization and benchmark of existing and novel cooling systems for the blown film process. A prediction model to identify a suitable cooling configuration and the developed process model are used for this simulation task. The challenge of such a new method to optimize cooling systems is a realistic computation of the tube formation zone at variable cooling condition induced by different cooling geometries. Furthermore, this approach has to be validated for conventional and novel cooling systems.To verify the optimization method and prediction capability of the process model an alternative cooling system has to be dimensioned using the developed simulation tools and tested on the laboratory blown film extrusion line. The important issue of the new cooling device is an improvement in performance of the heat transfer for different polymers and process conditions. Such an improvement can be achieved in guiding the blown film near to the cooling system and in reducing or locally destroying the laminar sublayer. By reducing the temperature of the cooling system itself, the heat transfer mechanism thermal radiation can be improve. Furthermore, the tubular film has to be calibrated and guided during the cooling process.