Technical Papers and Presentations

Packed bed microreactors (PBMR) and ferrofluids are independently enormously used in a broad range of applications in the healthcare sector. In a PBMR, one of the primary factors for controlling the reaction rate is the bed porosity which immediately affects the catalyst distribution and the reactant flow [1]. When exploiting ferrofluid as the reactant, an alternative approach is offered to regulate the flow in microreactors by employing external magnetic fields alongside the impact of pressure-driven flow. Intensifying mass transport inside a PBMR is rendered attainable by the application of ferrofluid reactants. As an example, for the extraction of succinic acid from n-butanol to water inside a laminar flow microreactor (e.g., PBMR), the addition of ferrofluids regulated by an external fixed magnetic field was shown to significantly increase the overall mass transfer coefficient considerably up to 70% [2]. On the contrary, periodic variations in ferrofluid velocity triggered by the applied magnetic field have a negative impact on the liquid-solid mass transfer [3]. To enhance the mass transfer rate within a PBMR, further magnetic field manipulation and catalyst distribution optimization are recommended. The topology optimization method, one of the most prevalent approaches, spatially optimizes the ordering of the material within a specific domain by minimizing a predetermined cost function and attaining specified constraints. In the present work, we provide a topology optimization method for improving the reaction conversion by achieving an ideal catalyst bed porosity for ferrofluid reactants and including the external non-uniform magnetic field that additionally modifies the optimized reaction conversion. To provide a fundamental understanding, we considered a first-order reaction in a tubular microreactor and expanded the influence of the magnetic field intensity on the average bed porosity and reaction conversion. To accomplish the objectives, we employed the finite element method-based solver COMSOL Multiphysics. We utilized the ‘Fluid Flow’ module of the COMSOL Multiphysics software to solve the flow field, the ‘Chemical Species Transport’ module for the reaction kinetics, and the ‘AC/DC’ module for the magnetic field analysis. The outcomes from the simulation demonstrated that the addition of a non-uniform magnetic field may regulate the optimization process, and as a consequence, depending on the field orientation, we may attain either a higher or lower conversion in comparison to the optimum conversion in the absence of a magnetic field.

References: [1] Bhattacharjee, D., & Atta, A. (2022). Topology optimization of a packed bed microreactor involving pressure driven non-Newtonian fluids. Reaction Chemistry & Engineering, 7(3), 609-618. [2] Azimi, N., Rahimi, M., & Abdollahi, N. (2015). Using magnetically excited nanoparticles for liquid–liquid two-phase mass transfer enhancement in a Y-type micromixer. Chemical Engineering and Processing: Process Intensification, 97, 12-22. [3] Lisk, P., Bonnot, E., Rahman, M. T., Pollard, R., Bowman, R., Degirmenci, V., & Rebrov, E. V. (2016). Magnetic actuation of catalytic microparticles for the enhancement of mass transfer rate in a flow reactor. Chemical Engineering Journal, 306, 352-361.