Membrane Module Design Research Articles

Three-dimensional CFD modeling for hollow fiber gas separation membrane modules based on a dual porous media model

Mathematical modeling is crucial to optimizing the design of the hollow fiber membrane (HFM) module. A Computational Fluid Dynamics (CFD) model enables efficient three-dimensional (3D) simulations of HFM modules, which integrates a dual porous media approach, significantly reducing computational costs. Validation against alternative simulations and experimental data confirms its prediction capability (<7% deviation). Comparative analyses demonstrate the superior reliability of the 3D approach over one-dimensional simulations. Detailed velocity, pressure, and concentration profiles for the shell and tube sides reveal optimization opportunities such as dead zones within the module. Aerometric studies show significant pressure drops (>30%) for smaller fiber diameters (<100μm) on the permeate side. The model's adaptability suggests broader applications in membrane gas separation processes with modifications. This research highlights the efficacy of CFD modeling in enhancing the design and optimization of HFM modules, highlighting the cost savings of the dual porous media approximation.

MODELLING OF HYDROGEN FLOW FROM GAS MIXTURES THROUGH NICKEL CAPILLARIES CONSIDERING THE NONUNIFORMITY OF TEMPERATURE DISTRIBUTION

A mathematical model of the flow of hydrogen from gas mixtures through the walls of capillary tubes made of metallic nickel has been developed, taking into account the inhomogeneity of the partial pressure of hydrogen along a long tube, as well as temperature nonuniformity in different regions of the tube. Using the model and relying on experimental data, the kinetic parameters of hydrogen transport were calculated within the temperature range of 600-850 °С and the hydrogen partial pressure range of 0.3-0.8 atm. The model can be used in the design of membrane modules for hydrogen separation from gas mixtures to calculate the length of individual membranes, their number, and the optimal flow rate of the hydrogen-containing gas mixture through the membrane.

Numerical study of energy consumption in spacer-filled feed channels through 3D inverse modeling and computational fluid dynamics

This project employs advanced Computational Fluid Dynamics (CFD) simulations to investigate the complex flow field dynamics within the channel of membrane module featuring a commercially available feed spacer. Utilizing Micro-CT scanning, the intricate three-dimensional (3D) structure of the spacer is accurately captured, enhancing the precision of the simulation models. The project focuses on the effects of varying Reynolds number (Re) and Aspect Ratio (AR) on the energy consumption within the feed channel of membrane module, analyzing streamline patterns, vorticity, and flow separation angles in detail. Findings indicate that the total enstrophy identification method effectively pinpoints areas of high energy consumption, especially at lower Re levels where flow separation significantly contributes to hydraulic losses. As Re increases, the separation vortex shifts rearward, resulting in a marked decrease in the energy consumption coefficient. Furthermore, the flow separation angle consistently declines with increasing Re, stabilizing at higher levels. Significantly, a reduction in AR from 1.015 to 0.725 more than doubles the decrease in flow separation angle, highlighting substantial potential energy savings through spacer design optimization. These insights are crucial for improving the design and efficiency of spiral wound membrane modules and for refining feed spacer configurations to enhance performance.

Progress in module design for membrane distillation

There have been tremendous advances in membrane distillation (MD) since the concept was introduced in 1961: new membrane designs and process configurations have emerged, and its commercial viability has been evaluated in several pilot-scale studies. However, its high energy consumption has hindered its commercialization. One of the most promising ways to overcome this obstacle is to develop more energy-efficient membrane modules. The MD research community has therefore developed diverse new module configurations for hollow fiber and flat sheet membranes that increase the thermal energy efficiency of MD by minimizing thermal polarization, increasing mass transfer across the membrane, and improving heat recovery from the condensed vapor. This review summarizes the progress made in the design of hollow fiber and flat sheet membrane modules for MD applications. It begins with a brief introduction to MD and its configurations before describing developments in module fabrication and highlighting key areas where further research is needed.

What will it take to get to 250,000 ppm brine concentration via ultra-high pressure reverse osmosis? And is it worth it?

The possibility of ultra-high pressure reverse osmosis (UHPRO) to replace thermal brine concentration promises to reduce up to 50 % of both energy consumption and capital cost. However, commercially available reverse osmosis (RO) membranes lose up to 50 % of their water permeability when operated up to 200 bar. Higher temperature operations such as in Middle East seawater desalination and brine mining further exacerbate compaction due to softening of the polysulfone support membrane. Assuming that pressure and temperature-related compaction issues can be resolved through innovations in membrane materials and/or module designs, this study asks the questions, “What will it take to get to 250,000 ppm via ultra-high pressure reverse osmosis? And is it worth it?” Herein we comprehensively examine a three stage RO process beginning with seawater RO (SWRO) to high-pressure RO (HPRO) and ultra-high-pressure RO (UHPRO). We elucidate the influence of thermophysical properties, hydraulic pressure, permeate flux, water permeability, feed spacer design, concentration polarization (CP), salt rejection and stage design on recovery and specific energy consumption (SEC). Our analysis of high rejection (HR) and high flux (HF) RO membranes reveals that while HF RO membranes boast superior water permeability and lower trans-membrane (hydraulic) pressure (TMP), they require higher operating flux, which leads to severe CP and operating pressures of 300 to 400 bar to meet the targeted brine concentration of ~250 g/L TDS. In addition, membrane compaction drives up the TMP, SEC, and capital cost of UHPRO systems. To bring the applied pressure below 300 bar, compaction-resistant UHPRO membranes and mass-transfer enhancing feed spacers will be required. The findings herein show that it will take time, money and technological innovation to enable UHPRO at commercial scale, and it may or may not be worth it. Further, this work makes clear the technological refinements needed to enable UHPRO membrane brine concentration.

Coral‐tentacle‐inspired antifouling membrane spacer: A natural solution for biofouling prevention

AbstractFouling of membrane spacers leads to increased pressure drop and reduced lifespan of membrane modules. Cleaning these fouled spacers is challenging due to strong foulant‐membrane spacer interactions. To address this issue, we introduce a novel spacer, PP‐N‐F, inspired by coral's antifouling properties. This spacer features on‐demand antifouling capabilities through a sequential growth process of functional polymer brushes on its surface. It not only possesses lower surface free energy characteristics than polypropylene spacers, but also exhibits controllable morphological changes similar to swaying coral tentacles. Temperature control strengthens the interfacial hydration layer, mitigating the trade‐off between anti‐adsorption and hydrophobicity of fluorinated surface. The temperature‐responsive surface changes enhance foulant desorption efficiency. Compared to a commercial spacer, PP‐N‐F shows an 89.3% reduction in foulant adsorption and a 61.7% decrease in pressure drop increment after 48 h cross‐flow filtration experiments. This work provides valuable insights for advanced anti‐fouling membrane module design.

Pervaporative Desulfurization: A Comprehensive Review of Principles, Advances, and Applications

Pervaporative desulfurization is a potential method for removing sulfur compounds from liquid hydrocarbon streams, having many advantages over existing methods. This overview covers the fundamentals, recent breakthroughs, and different applications of pervaporative desulfurization. The paper begins by explaining pervaporative desulfurization's core concepts, focusing on how polymeric membranes selectively separate sulfur molecules from liquid hydrocarbons. It explores membrane properties, operating conditions, and feed composition in pervaporative separation. It highlights how pervaporative desulfurization may reduce sulfur content to ultra-low levels and meet strict environmental and fuel quality standards. Finally, this comprehensive review paper concludes with a discussion on the future prospects and research directions in the field of pervaporative desulfurization. It highlights the need for continued innovation in membrane materials, module design, and process optimization, as well as the importance of addressing challenges related to scale-up and industrial implementation. Overall, this review paper provides valuable insights into the advancements, challenges, and potential applications of pervaporative desulfurization, offering a comprehensive understanding of this technology for researchers, engineers, and all parties involved in the development and implementation of sustainable sulfur removal processes.

Dissolved gas recovery from water using a sidestream hollow-fiber membrane module: First principles model synthesis and steady-state validation

This paper presents a first-principles model for the recovery of dissolved gases from liquids using a sidestream hollow-fiber membrane module. The model avoids the use of new empirical coefficients, thus providing a parametric understanding of the process behavior for future design and optimization of membrane modules. This type of first-principles model could be particularly useful when gas recovery is beneficial to biological or chemical reactions of interest, such as the acetogenesis reactions in two-stage anaerobic digesters. The steady-state behavior of the model was validated against both new experimental data for the recovery of H2, CH4 and H2–CH4 mixtures from pure water, as well as existing published data. The modeled gas recovery predictions agreed with experimental data to an absolute average error of 13%, and an average R2 value of 0.98. Parametric analysis of mixed-gas recovery suggests possible key transition points in the composition of the recovered gases. For example, at 40 °C, increasing trans-membrane pressure while keeping hydraulic residence time (HRT) under 0.5 s will result in an increase in the ratio of H2 to CH4 recovered. Otherwise, increasing trans-membrane pressure will instead decrease the ratio of H2 to CH4 recovered. The model has potential to be extended to transient analysis, but has yet to be validated with transient experimental data. This model was successfully implemented in both Python and MATLAB, and provides valuable insights for future net-energy optimization for anaerobic digestion systems with in-situ gas recovery.

Lithium solvent extraction by a novel multiframe flat membrane contactor module

Comparing to conventional liquid–liquid extraction, membrane extraction is an efficient and environmentally friendly separation technique to recover lithium from the salt-lake brine. Development of suitable hydrophilic solvent resistant nanoporous membranes for membrane extraction has been based on bench-scale small module. Because module design has significant impact on the performance, this work reported a novel multiframe flat membrane contactor module (MFMC) for lithium extraction from synthetic brine. The hydrophilic poly (ethylene-co-vinyl alcohol)/sulfonated poly(etheretherketone) membrane supported with polypropylene nonwoven (EVAL/SPEEK-NW) was prepared for module evaluation. The membrane mass transfer coefficients km of 1.1 × 10-6 m/s was obtained by Wilson plot. The global mass transfer coefficient Ke increased from 4.5 × 10-7 m/s to 9.9 × 10-7 m/s following the flow velocity from 0.4 to 1.8 cm/s in membrane extraction. We further evaluated the characteristics of MFMC via height of transfer units (HTU) and module efficiency (ME). High module efficiency of 90% was obtained, demonstrating MFMC’s efficient flow distribution. HTU of 28 m was estimated and was expected to decrease to 3 m by optimizing thickness of gasket and spacer as well as membrane performance. The MFMC module effectively reduced the loss of tributyl phosphate (TBP) by 91% comparing to liquid–liquid extraction. The research presented herein provides a flat membrane module design for potential future application of membrane extraction in wide applications.

Evaporative cooling performance prediction and multi-objective optimization for hollow fiber membrane module using response surface methodology

• A counter-flow hollow fiber membrane-based evaporative cooler is proposed. • A numerical model is established and validated by experimental data. • The regression models for performance prediction are derived by response surface methodology. • The desirability function is adopted to perform multi-objective optimization. • The accurate regression models can facilitate the regional applicability analysis. The proposed hollow fiber membrane-based evaporative cooler (HFMEC) is expected to be an alternative to the conventional direct evaporative cooler because of its advantages such as the isolation of air from liquid water and the large specific surface area. For the common counter-flow HFMEC with many influencing parameters, it is a bit laborious or even incompetent to rely on experiment or numerical simulation for the parametric study and optimization. Therefore, this study aims to develop accurate and rapid performance prediction models for the proposed HFMEC with the statistical method. An experimental test system for a counter-flow HFMEC was set up. 120 sets of simulations were carried out based on the experimentally validated numerical model and the response surface methodology. Five accurate and practical empirical equations were derived using simulated data: the considered eight input factors consisted of four operating parameters and four membrane module design parameters; the five output responses included the outlet air temperature, outlet air relative humidity, saturation effectiveness, cooling capacity per unit volume, and COP. These simplified equations were adopted to facilitate parameter sensitivity analysis and multi-objective optimization. A case study on the regional applicability of the counter-flow HFMEC demonstrated the ability of the derived equations to conveniently make performance predictions. The results indicated that the regression models could contribute to the rapid performance prediction of the counter-flow HFMEC, aiding in optimization and design.

A Review on Hollow Fiber Membrane Contactors for Carbon Capture: Recent Advances and Future Challenges

Energy need is predicted to increase by 48% in the next 30 years. Global warming resulting from the continuously increasing atmospheric CO2 concentration is becoming a serious and pressing issue that needs to be controlled. CO2 capture and storage/use (CCS/CCU) provide a promising route to mitigate the environmental consequences of CO2 emission from fossil fuel combustion. In recent years, hollow fiber membrane contactors are regarded as an advanced technique with several competitive advantages over conventional technologies such as easy scale-up, independent control of flow rates, more operational flexibility, absence of flooding and foaming as well as high interfacial area per unit volume. However, many factors such as the membrane material selection, proper choice of solvent, and membrane module design are critical to success. In this regard, this paper aims at covering all areas related to hollow fiber membranes, including membrane material, membrane modification, membrane surface modification, shape, solvent characterization, operating parameters and costs, hybrid process, membrane lifetime, and energy consumption as well as commercially available systems. Current progress, future potential, and development of pilot-scale applications of this strategy are also assessed carefully. Furthermore, pore wetting as the main technical challenge in membrane contactor industrial implementation for post- and pre-combustion CO2 capture processes is investigated in detail.

Coupling of forward osmosis with desalination technologies: System-scale analysis at the water-energy nexus

Couplings of forward osmosis (FO) with reverse osmosis (RO) or membrane distillation (MD) are investigated at the water-energy nexus. The treatment of low and hypersaline feed solutions was assessed, followed by discussion of the most effective hybrid scheme for different conditions. Two FO configurations are presented, suggesting the potential applicability of a versatile multi-stage approach for treating low-saline wastewater sources under co-current membrane module design. Subsequently, energy and exergy consumption of the post-treatment RO / MD were evaluated. Finally, the coupling of FO and RO or MD units is investigated, highlighting the dependence of the two hybrid systems upon the operating parameters in FO. While FO-RO coupling is the most efficient solution in terms of power and exergy consumption, it is narrowed by the choice of the salinity gradient in the draw solution. A 2 order of magnitude higher power consumption is required by the MD to drive back the draw solution in FO while treating low saline wastewater. When dealing with hypersaline solutions instead, the FO-MD becomes more competitive, mostly from the exergy standpoint, highlighting the ability to use low-grade heat. Overall, FO-MD is more versatile, showing a broader application range while potentially approaching zero liquid discharge.

Textured ceramic membranes for desilting and deoiling of produced water in the Permian Basin

SummaryOil production in the Permian Basin gives rise to large volumes of produced water contaminated by silt, emulsified oil, and additives used for enhanced oil recovery. There is intense interest in the design of membrane modules as sustainable alternatives for produced water treatment to enable the reuse of produced water for agricultural applications, injection into aquifers, and redeployment in oil recovery. Here, we report a hierarchically textured cement-based membrane exhibiting orthogonal wettability, specifically, superhydrophilic and underwater superoleophobic characteristics. The in situ formation of ettringite needles accompanied by embedding of glass spheres imbues multiscale texturation to stainless-steel mesh membranes, enabling the separation of silt and oil from produced water at high flux rates (1600 L h−1۰m−2, at ca. 2.7 bar). Oil concentration is reduced as low as 1 ppb with an overall separation efficiency of 99.7% in single-pass filtration. The membranes show outstanding mechanical resilience and retention of performance across multiple cycles.

Photocatalytic nanohybrid membranes for highly efficient wastewater treatment: A comprehensive review.

Wastewater is inevitably generated from human activities as part of the life cycle chain that potentially damages the environment. The integration of photocatalytic reaction and membrane separation for wastewater treatment has gained great attention in recent studies. However, there are still many technical limitations for its application such as toxic metal release, catalyst deactivation, fouling/biofouling, polymer disintegration, and separation performance decline. Different types, combinations, and modifications of photocatalysts material combined with membranes such as semiconductor metal oxides, binary/ternary hybrid metal oxides, elemental doped semiconductors, and metal-organic frameworks (MOFs) for improving the performance and compatibility are presented and discussed. The strategies of incorporating photocatalysts into membrane matrix for pursuing the most stable membrane integrity, high photocatalytic efficiency, and excellent perm-selectivity performance in the very recent studies were discussed. This review also outlines the performance enhancement of photocatalytic membranes (PMs) in wastewater treatment and its potential for water reclamation. Photocatalysts enhanced membrane separation by inducing anti-fouling and self-cleaning properties as well as antibacterial activity. Based on the reviewed study, PMs are possible to achieve complete removal of emerging contaminants and ∼99% reduction of bacterial colony that leading on the zero liquid discharge (ZLD). However, the intensive exposure of photo-induced radicals potentially damages the polymeric membrane. Therefore, future studies should be focused on fabricating chemically stable host-membrane material. Moreover, the light source and the membrane module design for the practical application by considering the hydrodynamic and cost-efficiency should be a concern for technology diffusion to the industrial-scale application.

Simple scalable approach to advanced membrane module design and hydrogen separation performance using twelve replaceable palladium-coated Al2O3 hollow fibre membranes

A phase-inversion approach was used to manufacture Al2O3 hollow fibre supports, which were then sintered at 1723 K. The electroless plating technique is developed to prepare palladium-coated Al2O3 hollow fibre membranes for hydrogen separation. Three different scaling-up configurations were produced and tested: single membrane, membrane unit obtained by assembling three membranes, and advanced membrane module obtained by assembling twelve replaceable membranes. The hydrogen flux was investigated under vacuum and without vacuum using a feed gas of pure H2 (100%) and a binary feed gas mixture of H2 (80%) and CO2 (20%) at different feed gas pressures (100–800 kPa), feed gas rate (0.2–6.0 L min−1), and temperature (673–723 K). The hydrogen flux increases from 0.2162 mol m−2 s−1 (feed gas pressure = 600 kPa, feed gas rate = 0.2 L min−1) to 0.4487 mol m−2 s−1 (feed gas pressure = 800 kPa, feed gas rate = 6.0 L min−1) under the binary gas mixture at 723 K by switching from a single to the advanced membrane module, while the hydrogen purity remains above 97.5% throughout the experiment. Some aspects about the scalability of palladium-coated Al2O3 hollow fibre membranes for hydrogen separation are discussed.

Decolorization and control of bromate formation in membrane ozonation of humic-rich groundwater

Membrane ozonation of bromide-containing, high-color natural organic matter (NOM) containing groundwater was performed using single-tube polydimethylsiloxane (PDMS) and multi-tube polytetrafluoroethylene (PTFE) membrane contactors, and compared to batch ozonation. For membrane ozonation, dissolved ozone concentration, water color (VIS436), ultraviolet light absorption (UV254) and bromate formation were correlated with ozone dose, ozone gas concentration, hydraulic retention time and Hatta number (Ha). NOM color removal of up to 45 % for the single-tube contactor and 17 % for the multi-tube contactor were achieved while containing bromate formation below 10 µg L−1. Higher color removal using higher ozone doses was associated with high bromate formation i.e. >>10 µg L−1. In membrane ozonation, low ozone gas concentrations, long hydraulic retention times and high Ha resulted in low dissolved ozone concentrations due to quenching of ozone by NOM. At specific ozone doses of < 0.5 mg O3/mg DOC and Ha > 1, single-tube ozonation resulted in comparable results to batch ozonation while bromate formation was higher in the single-tube contactor at specific ozone doses > 0.5 mg O3/mg DOC and Ha < 1. At comparable ozone doses and Ha, bromate formation in the multi-tube contactor was always higher compared to single-tube and batch ozonation. This could be associated with the uneven ozone distribution within the multi-tube contactor. Results show that ozone dose is the major driver for selectivity between bromate formation and NOM color removal in both membrane and batch ozonation. Bromate formation in membrane ozonation may be controlled by adjusting gas concentration, Ha and hydraulic retention time. Membrane module design and process parameters of membrane ozonation reactors significantly affect treatment performance and should be optimized for selective target compound removal over by-product formation.

Advances in Membrane Distillation Module Configurations.

Membrane Distillation (MD) is a membrane-based, temperature-driven water reclamation process. While research emphasis has been largely on membrane design, upscaling of MD has prompted advancements in energy-efficient module design and configurations. Apart from the four conventional configurations, researchers have come up with novel MD membrane module designs and configurations to improve thermal efficiency. While membrane design has been the focus of many studies, development of appropriate system configurations for optimal energy efficiency for each application has received considerable attention, and is a critical aspect in advancing MD configurations. This review assesses advancements in modified and novel MD configurations design with emphasis on the effects of upscaling and pilot scale studies. Improved MD configurations discussed in this review are the material gap MD, conductive gap MD, permeate gap MD, vacuum-enhanced AGMD/DCMD, submerged MD, flashed-feed MD, dead-end MD, and vacuum-enhanced multi-effect MD. All of these modified MD configurations are designed either to reduce the heat loss by mitigating the temperature polarization or to improve the mass transfer and permeate flux. Vacuum-enhanced MD processes and MD process with non-contact feed solution show promise at the lab-scale and must be further investigated. Hollow fiber membrane-based pilot scale modules have not yet been sufficiently explored. In addition, comparison of various configurations is prevented by a lack of standardized testing conditions. We also reflect on recent pilot scale studies, ongoing hurdles in commercialization, and niche applications of the MD process.

Direct visualization of hollow fiber membrane fouling distribution

Submerged membrane bioreactor system is commonly used for water and wastewater treatment processes. This system is a more economical alternative to conventional activated sludge process due to small footprint and better effluent quality. Nevertheless, membrane fouling is a major issue that requires further studies. This paper covers the use of an optical microscope to observe membrane fouling. Bentonite was used as model particles to simulate activated sludge. In-situ observation of particle deposition along the surface of hollow fiber membranes during filtration was performed at various operating conditions. Results from this studies indicated that the flux distribution was affected by the permeate flux and cross flow velocity. Lower CFV and higher flux caused the flux to be more non-uniformly distributed due to more severe fouling. These findings provided useful information to further improve the membrane module design to achieve more evenly distributed permeate flux.

Preliminary study on air-to-air latent heat exchanger fabricated using hollow fiber composite membrane for air-conditioning applications

In this study, an air-to-air type hollow fiber composite membrane latent heat exchanger was built and its latent heat exchange characteristics were experimentally investigated under various test conditions. Based on experiments conducted on four prototypes, polyethersulfone with 9 wt% of polyvinyl-pyrrolidone was selected as the membrane material suitable for the latent heat exchanger. Using the selected material, shell-and-tube structured hollow fiber membrane modules were fabricated and tested under various operating conditions. The experimental data showed that the proposed membrane modules exhibited 35.3%–82.7% latent effectiveness and moisture removal rates of 0.027–0.124 g/s under various operating conditions; furthermore, the modules could provide latent cooling with few temperature changes. In addition, the results of the parametric analysis indicated that the inlet primary air humidity ratio was a critical factor affecting the latent cooling performance of the proposed system and the optimal ratio of the secondary to primary air flow was 1.0. The number of mass transfer units (NTUm) in the membrane module design should be higher than 1.7 to attain satisfactory latent cooling performance, that is, higher than 70% latent effectiveness.

Osmotic membrane under spacer-induced mechanical compression: Performance evaluation and 3D mechanical simulation for module optimization

Osmotically-driven membrane process (ODMP), the low energy process that has attracted significant attention recently, has a relatively short history of development and there is a large room for improvement in membrane module design. Especially, it is significant but neglected how much membrane area should be packed into the module housing without undermining structural integrity and performance of the membrane. In this regard, this study aims to experimentally investigate the variation of osmotic membrane performance under varying spacer-induced mechanical compression and determine the critical compression ratio. 3D FEM (Finite element method) mechanical stimulation was employed to analyze the variation of stress and strain of membrane under mechanical compression and critical stress and strain were determined based on the experimental results. The study found that the performance of commercial osmotic membrane did not decrease significantly up to 30–40% of compression ratio and 45.5%–69.6% of the packing density of spiral-wound membrane module can be saved. The findings and methods suggested in this study will facilitate the structural optimization of ODMP membrane modules. Also, the discrepancy of the membrane performance between the lab-scale experiment (non-compressed) and commercial-scale membrane module (compressed) validated in this study emphasizes the importance of caution in the reporting of membrane performance.