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The Quasi-Steady-State Approximation for Computational Acceleration of Single Particle Modeling in Polyolefin Processes
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- Author / Creator
- Al-Khayyat, Mohammed
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In the field of polymer reactor engineering, accurately modeling the complex kinetics and mass transfer mechanics of a supported-catalyst reaction is essential for designing efficient and scalable polymerization processes. However, mesoscale modeling, which involves detailed single-particle models, is often overlooked due to its mathematical complexity, where the dynamic numerical solution of the partial differential equations that describe the intraparticle reaction-diffusion phe- nomena are computationally demanding. The quasi-steady-state approximation (QSSA) presented in this thesis provides an alternative computationally efficient approach to solving the polymer flow model, which is an established numerical model for understanding the dynamics of polymer particle growth. In both homopolymerization and copolymerization setups, the developed QSSA model is compared with the corresponding dynamic solutions assuming both uniform and nonuniform radial distribution of active sites in the growing particle. The simulations demonstrate that, after a very short initial period, the QSSA provides a perfect match with the dynamic solution when active sites are uniformly distributed within the particle. However, if the dynamic solution accounts for the local dilution of catalyst fragments in the produced polymer, resulting in a non-uniform dis- tribution of active sites decreasing with radial position, the QSSA shows promising performance only at low to medium Thiele moduli. As the Thiele modulus increases, the QSSA solution starts to deviate more from the dynamic solution due to the pronounced concentration gradient of active sites. These high Thiele modulus values correspond to high levels of mass transfer limitations, which are undesirable and often avoided in real processes.
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- Graduation date
- Fall 2024
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.