Simulating Flow Rate Effects on Fields in Microwave Fixed‐Bed Reactors

ABSTRACT

Microwave‐assisted fixed‐bed reactors offer high energy efficiency, but strong multiphysics coupling limits their predictability. In this study, we developed and validated a three‐dimensional (3D) finite‐element model against infrared temperature measurements. Simulations showed that localized microwave power deposition initially produces pronounced temperature gradients and hotspots within the catalyst bed. Assuming temperature‐independent dielectric properties, the same electromagnetic field and power‐deposition pattern were applied to all gas flow conditions. Increasing gas flow reduced the peak temperature and transformed localized hotspots into elongated heated regions extending downstream. The model also captured buoyancy‐driven natural convection within the microwave cavity, demonstrating how gas flow regulates heat transport and thermal stability. These results emphasize the importance of electromagnetic–thermal–fluid coupling for microwave reactor design and scale‐up.