(20e) A CFD Pressure Drop Model for Microfibrous Entrapped Catalyst Filters Using Micro Scale Imaging

A new structure of matter called microfibrous entrapped catalyst (MFEC) was developed to replace monolith reactors in many high mass flow applications. This structure is manufactured by wet-lay process of metal fibers. Catalyst support particles (γ-Al₂O₃ 150-250 μm) were entrapped by the sinter-lock structure of the metal fibers. Pressure drop across the reactor at high mass flow conditions is a crucial factor when designing the reactor. This work presents experimental and simulation method used to evaluate pressure drop across this novel material.

Because of the amount of calculation involved, pressure drop modeling for the whole filter structures is usually difficult, if the details like fiber dimension and entrapped particle shapes are considered. This issue is solved by studying the fiber media in both micro and macro scale scope, which separates the problem and simplifies the calculation. Micro scale Computational Fluid Dynamics (CFD) pressure drop model for microfibrous material entrapped catalyst (MFEC) is used to calculate the pressure drop across a flat sheet of MFEC. The micro scale CFD model is based on theoretical calculation of velocity profile within the fiber material, which shows the plug flow pattern. SEM imaging for top and side view of the fiber media is obtained to sketch the geometric structure of the simulation area. Fiber and particle contribution to the pressure drop are studied separately. Shape factor and fiber compressibility are also considered for model accuracy. The simulations are compared with experimental findings to verify accuracy before being transferred into macro scale pleated filter structures for pressure drop modeling. Two kinds of filter fairing added to the filer pleat tips are also studied for pressure drop reduction performance. All simulation results are compared with experiment data.