Numerical and experimental investigation of fibrous coalescing media for gas–Liquid separation: Effects of material, porosity, thickness and gas velocity

This study combined computational fluid dynamics (CFD) simulations with experiments to investigate the flow characteristics of coalescing modules made of polytetrafluoroethylene, polypropylene, and glass fiber under various operating conditions. CFD simulations employed a simplified two-dimensional model to predict the pressure and velocity distributions within the coalescing bed. In the experiment, the gas velocity, porosity, bed thickness, atomization rate, and liquid-phase properties were systematically varied to measure the relevant parameters. CFD simulations indicated that, at a constant porosity, the pressure drop across the coalescing separator decreases as the fiber diameter increases. As porosity decreases, the pressure drop across the coalescing separator gradually increases. Experimental data indicate that increasing porosity leads to a decrease in separation efficiency and pressure drop for both polytetrafluoroethylene and polypropylene. At low porosity levels, the quality index of polytetrafluoroethylene is 16.7% higher than that of polypropylene. Meanwhile, the pressure drop was positively correlated with thickness, and the overall quality index first increased and then decreased. Additionally, high gas velocity significantly improved separation efficiency, but the efficiency declined over time, stabilizing after approximately 40 minutes. When the inlet gas velocity was 1.0 m/s, the initial separation efficiency reached 96.87%, and the steady-state efficiency was 93.35%. Overall, for gas-liquid coalescence separation, when the modules thickness is 50 mm and the porosity is 0.928, the optimal gas velocity range is 0.9 to 1.0 m/s. When the modules thickness is 40 mm and the gas velocity is 0.9 m/s, the optimal porosity is 0.7 to 0.8.