Sinusoidal shaped hollow fibers for enhanced mass transfer

TL;DR

This paper introduces sinusoidal hollow fibers with variable diameter to induce secondary vortices, enhancing mass transfer and reducing fouling in membrane processes, demonstrated by improved oxygen transport in absorption applications.

Contribution

A novel method to produce sinusoidally varying hollow fibers using a pulsation module, enabling improved mass transfer through vortex induction.

Findings

Enhanced oxygen transport in sinusoidal fibers

Reduction in fouling and polarization effects

Feasibility of integrating the flow module into existing manufacturing processes

Abstract

Inducing secondary flows and vortices is known to enhance mass transport. They can be imposed by structured flow channels for instance. In particular, these vortices reduce fouling and concentration polarization. In this work we present a new method of producing hollow fiber membranes with a sinusoidal change in diameter over the fiber length. We engineered a pulsation module that imposes a sinusoidally fluctuating bore liquid flow rate. Harmonic bore flow conditions can be varied over a wide range. The fluctuating bore liquid flow rate translates into axial membrane properties varying with respect to inner bore diameter and wall thickness. The resulting narrowing and widening of the membrane lumen channel are hypothesized to induce secondary vortices to the liquid inside the membrane lumen known as the Bellhouse effect. Improved oxygen transport from shell-to-lumen side prove superiority over straight hollow fiber membranes in G/L absorption process. We anticipate the dynamic flow module to be easily integrated into currently existing hollow fiber membrane spinning processes.