Integrated Optimization of Hot-Melt Cell Geometry and Pleat Angle for Pressure Drop Reduction and Flow Uniformity Enhancement in H14 HEPA Minipleat Filters

This work presents a unified aerodynamic framework for the optimization of H14 HEPA minipleat filters by integrating two critical design scales: the hot-melt cell, which governs local airflow distribution, and the pleat angle, which determines the balance between channel friction and porous media resistance. A multiscale model combining Darcy flow, Darcy–Weisbach friction losses, and Falkner–Skan wedge-flow theory was developed to predict airflow behavior, pressure gradients, and velocity distributions within the filter structure.

Experimental testing under representative H14 operating conditions (600 m3/h, frontal velocity 0.45 m/s) demonstrated that airflow near the outlet surface exhibits strong local velocity variations driven by pleat geometry nozzle dynamics, with hot-melt spacers inducing localized flow accelerations near cell boundaries that generate additional friction losses. Measurements confirmed that this heterogeneity is concentrated near the filter face (≤5 mm ) and progressively decays downstream, providing a clear basis for cell level geometric optimization.

The results demonstrate that filter pressure drop depends not only on media permeability but also on the interaction among hydraulic diameter, hot-melt spacing, pleat depth, and pleat angle. Increasing hot-melt spacing enlarges the hydraulic diameter, reducing local friction losses and improving airflow uniformity. Meanwhile, pleat angle controls the trade-off between channel resistance and effective filtration area: small angles increase viscous losses through channel constriction, whereas large angles reduce channel resistance but decrease available filtration area. 

An optimized configuration featuring wider cells, fewer hot-melt lines, increased pleat depth, and a moderate pleat angle might achieve a pressure drop reduction of up to 30.00% relative to the current industrial design while preserving filtration efficiency, structural integrity, and airflow uniformity. The proposed methodology provides a quantitative design tool for the development of next-generation HEPA, EPA, and ULPA filtration systems, enabling enhanced aerodynamic performance and reduced energy consumption.