A heuristic method for modeling the initial pressure drop in melt filtration using woven screens in polymer recycling

Abstract

This paper addresses the use of heuristic optimization algorithms to generate generally valid analytic equations for estimating the initial pressure drop of square and Dutch woven screens in polymer recycling. We present a mathematical description of the isothermal initial pressure drop of non-Newtonian polymer melt flows through woven screens without the need for numerical methods. We first performed numerical CFD simulations to create a set of 9,000 physically independent modeling set-ups as a basis for heuristic modeling. Then, we applied symbolic regression based on genetic programming to develop pecScreen models, achieving coefficients of determination R 2 > 0.9995. For verification of our models, we performed experiments using both virgin and slightly contaminated in-house and postindustrial recycling materials. The experimentally determined data are in good agreement with the approximation results, which yielded a coefficient of determination R 2 of 0.926. Our modeling approach, the accuracy of which we have proven, allows fast and stable computational modeling of the initial pressure drop of polymer melt flows through woven screens.

Characterization of Composition and Structure–Property Relationships of Commercial Post-Consumer Polyethylene and Polypropylene Recyclates

“…The literature provides some coverage of processing related aspects of melt filtration systems in polymer processing [ 76 ] and recycling [ 38 , 39 , 76 ]. Methods for calculating the pressure drop at the filter, the average residence time of the melt within the filter, or the self-cleaning efficiency [ 77 , 78 ], can be found there. Furthermore, it has been shown that melt filtration of recycled post-consumer PP is key to achieve higher performance levels, e.g., in solid-state drawing [ 71 ].…”

Expanding Plastics Recycling Technologies: Chemical Aspects, Technology Status and Challenges

“…The addition of a filter helps remove unwanted non-volatile contaminants from the plastic and increases the mechanical properties of the recycled plastic. 176 When selecting recycling technologies in manufacturing processes, it is important to select the appropriate mechanism to minimize the degradation of the plastic for highquality new parts. 159…”

Mechanical Recycling of Packaging Plastics: A Review

“…[ 33,36,37 ] Melt filters are chosen according to specific extrusion contamination and can include screen‐changers such as slide plates, woven screens, or filter cartridges. [ 38,39 ] Lengthening extruders must be balanced against the increase in system dwell times that can exacerbate chain scission. Recycling systems must be designed with consideration to specific degradation mechanisms.…”