# Analysis of CO2 Absorption in Gas/Liquid Membrane Contactors with Inserted Descending Hydraulic Diameters of 3D-Printed Turbulence Promoters

## TL;DR

This study explores how 3D-printed turbulence promoters in membrane contactors improve CO2 absorption efficiency while managing energy costs.

## Contribution

The novelty lies in optimizing descending hydraulic diameters of 3D-printed turbulence promoters to enhance CO2 absorption flux while considering energy consumption.

## Key findings

- Descending hydraulic-diameter operations improve absorption flux more efficiently than uniform diameters.
- A simplified Sherwood number expression predicts mass transfer coefficients for modules with turbulence promoters.
- Economic analysis shows improved absorption flux-to-power consumption ratios with descending diameters.

## Abstract

The decline in absorption flux across membrane modules is attributed to the increase in concentration polarization resistance in flat-plate membrane contactors for CO2 absorption using monoethanolamine (MEA) as the absorbent. Researchers have discovered that this effect can be mitigated by inserting turbulence promoters, which enhance turbulence intensity at the cost of increased power consumption, thereby improving CO2 absorption flux. The performance of flat-plate membrane contactors for CO2 absorption was further enhanced by reducing the hydraulic diameters of embedded 3D-printed turbulence promoters, considering the increased power consumption. The mass-balance modeling, incorporating chemical reactions, was developed theoretically and conducted experimentally on a flat-plate gas/liquid polytetrafluoroethylene/polypropylene (PTFE/PP) membrane module in the present study. A one-dimensional theoretical analysis, based on the resistance-in-series model and the plug-flow model, was conducted to predict absorption flux and concentration distributions. An economic analysis was also performed on modules with promoter-filled channels, considering different array configurations and geometric shapes of turbulence promoters, weighing both absorption flux improvement and power consumption increment. Device performances were evaluated and compared with those of modules using uniform promoter widths. Additionally, the Sherwood number for the CO2 membrane absorption module was generalized into a simplified expression to predict the mass transfer coefficient for modules with inserted 3D-printed turbulence promoters. Results showed that the ratio of absorption flux improvement to power consumption increment in descending hydraulic-diameter operations is higher than in uniform hydraulic-diameter operations.