Hollow Fiber Membrane Bundle Research Articles

Effect of artificial lung fiber bundle geometric design on micro- and macro-scale clot formation.

The hollow fiber membrane bundle is the functional component of artificial lungs, transferring oxygen to and carbon dioxide from the blood. It is also the primary location of blood clot formation and propagation in these devices. The geometric design of fiber bundles is defined by a narrow set of parameters that determine gas exchange efficiency and blood flow resistance, principally: fiber packing density, path length, and frontal area. These same parameters also affect thrombosis. This study investigated the effect of these parameters on clot formation using 3D printed flow chambers that mimic the geometry and blood flow patterns of fiber bundles. Hollow fibers were represented by an array of vertical micro-rods (380 μm diameter) arranged with three packing densities (40%, 50%, and 60%) and two path lengths (2 and 4 cm). Blood was pumped through these devices corresponding to three mean blood flow velocities (16, 20, and 25 cm/min). Results showed that (1) clot formation decreases dramatically with decreasing packing density and increasing blood flow velocity, (2) clot formation at the outlet of the fiber bundle enhances deposition upstream, and consequently (3) greater path length provides greater clot-free fiber surface area for gas exchange than a shorter path length. These results can help guide the design of less thrombogenic, more efficient artificial lung designs.

BIO13: Effect of Artificial Lung Fiber Bundle Geometric Design on Micro- and Macro-scale Clot Formation

Purpose of Study: The hollow fiber membrane bundle is the functional component of artificial lungs, transferring oxygen and carbon dioxide to and from the blood. It is also the primary location of blood clot formation and propagation in these devices. The geometric design of fiber bundles is defined by a narrow range of parameters that determine gas exchange efficiency and blood flow resistance, such as fiber packing density, path length, and frontal area. However, these parameters also affect thrombosis. Methodology: This study investigated the effect of these parameters on clot formation using 3-D printed flow chambers that mimic the geometry and blood flow patterns of fiber bundles. Hollow fibers were represented by an array of vertical micro-rods (380 micron diameter) arranged with varying packing densities (40, 50, and 60%) and path lengths (2 and 4 cm), all of which are fiber bundle parameters in commercially available artificial lung devices. Blood was pumped through the device corresponding to three mean blood flow velocities (16, 20, and 25 cm/min), which were scaled from 4 L/min flowrates in an Adult Quadrox oxygenator. Results: Results showed that (1) clot formation decreases dramatically with decreasing packing density and increasing blood flow velocity, (2) clot formation at the outlet of fiber bundle enhances deposition upstream, and consequently (3) greater path length provides more clot-free fiber surface area for gas exchange than a shorter path length. Summary: These results can be used to create less thrombogenic, more efficient artificial lung designs.Figure 1. a) The experimental flow chamber was designed to be 2 or 4 cm and with a packing density of 60%, 50% or 40% rods to simulate the flow path of blood through an artificial lung hollow fiber bundle. (b) The flow circuit involved one-way flow from a syringe pump, connected to the flow chamber and then to a waste container. A manometer measured the pressure drop across each experimental device. (c) The averaged clot volumes from the microCT scans show more clot (red) at the outlets of all devices. There was also less clot in the chambers with a longer path length device, faster flow rate, and less density.

Evaluation of a Novel Cuboid Hollow Fiber Hemodialyzer Design Using Computational Fluid Dynamics.

Conventional hollow fiber hemodialyzers have a cylindrical shell-and-tube design. Due to their circular cross-section and radial flow distribution and collection in the headers, the flow of blood in the header as well as in the hollow fiber membranes is non-uniform. The creation of high shear stress and high shear rate zones or stagnation zones could result in problems, such as cell lysis and blood clotting. In this paper, a novel cuboid hemodialyzer design is proposed as an alternative to the conventional cylindrical hemodialyzer. The primary motivation behind the proposed design is to create uniform flow conditions and thereby minimize some of the above-mentioned adverse effects. The most salient feature of the proposed design is a cuboid shell within which the hollow fiber membrane bundle is potted. The lumen of the fibers is fed from one side using a flow distributor consisting of embedded primary and secondary channels, while the fibers are drained from the other side using a flow collector, which also has embedded primary and secondary channels. The flow characteristics of the lumen side of the cuboid hemodialyzer were compared with those of a conventional hemodialyzer based on computational fluid dynamics (CFD) simulations. The results of CFD simulations clearly indicated that the flow of liquid within the cuboid dialyzer was significantly more uniform. Consequently, the shear rate and shear stress were also more uniform. By adopting this new design, some of the problems associated with the conventional hemodialyzer design could potentially be addressed.

Design and In Vitro Evaluation of an Artificial Placenta Made From Hollow Fiber Membranes.

For infants born at the border of viability, care practices and morbimortality rates vary widely between centers. Trends show significant improvement, however, with increasing gestational age and weight. For periviable infants, the goal of critical care is to bridge patients to improved outcomes. Current practice involves ventilator therapy, resulting in chronic lung injuries. Research has turned to artificial uterine environments, where infants are submerged in an artificial amniotic fluid bath and provided respiratory assistance via an artificial placenta. We have developed the Preemie-Ox, a hollow fiber membrane bundle that provides pumpless respiratory support via umbilical cord cannulation. Computational fluid dynamics was used to design an oxygenator that could achieve a carbon dioxide removal rate of 12.2 ml/min, an outlet hemoglobin saturation of 100%, and a resistance of less than 71 mmHg/L/min at a blood flow rate of 165 ml/min. A prototype was utilized to evaluate in-vitro gas exchange, resistance, and plasma-free hemoglobin generation. In-vitro gas exchange was 4% higher than predicted results and no quantifiable plasma-free hemoglobin was produced.

Improvement of a Mathematical Model to Predict CO2 Removal in Hollow Fiber Membrane Oxygenators.

The use of extracorporeal oxygenation and CO2 removal has gained clinical validity and popularity in recent years. These systems are composed of a pump to drive blood flow through the circuit and a hollow fiber membrane bundle through which gas exchange is achieved. Mathematical modeling of device design is utilized by researchers to improve device hemocompatibility and efficiency. A previously published mathematical model to predict CO2 removal in hollow fiber membrane bundles was modified to include an empirical representation of the Haldane effect. The predictive capabilities of both models were compared to experimental data gathered from a fiber bundle of 7.9 cm in length and 4.4 cm in diameter. The CO2 removal rate predictions of the model including the Haldane effect reduced the percent error between experimental data and mathematical predictions by up to 16%. Improving the predictive capabilities of computational fluid dynamics for the design of hollow fiber membrane bundles reduces the monetary and manpower expenses involved in designing and testing such devices.

Comparative analysis of energy discharge characteristics between hollow fiber membrane and flat membrane energy accumulators

The hollow fiber membrane energy accumulator (HFMEA) and the flat membrane energy accumulator (FMEA) were designed. Dynamic mathematic models of the heat and mass transfer in the full-scale membrane energy accumulators (MEAs) were built in order to consider the membrane-to-membrane interactions and boundary effect in MEAs. The reliability of mathematic models has been verified by the experimental results. The maximum relative deviations of the mass transfer flux and solution temperature were 14.9 % and 14.6 %, respectively. The change rate of LiBr mass fraction in the FMEA was 1.38 times of that in the HFMEA. The hollow fiber membrane bundle in HFMEA is more conducive to the mass transfer process when the arrangement of the fibers is triangular. When the length of the membrane channel increased from 50 mm to 160 mm in HFMEA, the mass transfer per membrane surface area decreased by about 5 %. With increasing the vapor inlet pressure from 700 Pa to 1500 Pa, the mass transfer flux was tripled. And the average temperature of the solution increased by more than 3.75°C in 10 minutes. If the membrane filled density increased from 1.4 % to 2.1 %, the mass transfer flux increased to 2.04 times in FMEA.

Numerical modeling of pulsatile blood flow through a mini-oxygenator in artificial lungs

While previous in vitro studies showed divergent results concerning the influence of pulsatile blood flow on oxygen advection in oxygenators, no study was done to investigate the uncertainty affected by blood flow dynamics. The aim of this study is to utilize a computational fluid dynamics model to clarify the debate concerning the influence of pulsatile blood flow on the oxygen transport. The computer model is based on a validated 2D finite volume approach that predicts oxygen transfer in pulsatile blood flow passing through a 300-micron hollow-fiber membrane bundle with a length of 254 mm, a building block for an artificial lung device. In this study, the flow parameters include the steady Reynolds number (Re = 2, 5, 10 and 20), Womersley parameter (Wo = 0.29, 0.38 and 0.53) and sinusoidal amplitude (A = 0.25, 0.5 and 0.75). Specifically, the computer model is extended to verify, for the first time, the previously measured O2 transport that was observed to be hindered by pulsating flow in the Biolung, developed by Michigan Critical Care Consultants. A comprehensive analysis is carried out on computed profiles and fields of oxygen partial pressure (PO2) and oxygen saturation (SO2) as a function of Re, Wo and A. Based on the present results, we observe the positive and negative effects of pulsatile flow on PO2 at different blood flow rates. Besides, the SO2 variation is not much influenced by the pulsatile flow conditions investigated. While being consistent with a recent experimental study, the computed O2 volume flow rate is found to be increased at high blood flow rates operated with low frequency and high amplitude. Furthermore, the present study qualitatively explains that divergent outcomes reported in previous in vitro experimental studies could be owing to the different blood flow rates adopted. Finally, the contour analysis reveals how the spatial distributions of PO2 and SO2 vary over time.

Analysis on a vibration character of hollow fiber membrane bundle in MBR

We have focused on membrane vibration in MBR to find an effective design for the reduction of membrane fouling. In the previous study, we developed a direct measurement method for membrane vibration of a hollow fiber membrane (HFM) using an accelerometer (ACM). In this study, we studied on vibration characters on an HFM bundle in a practical membrane module in MBR using the ACMs in a large transparent water tank. Three ACMs were attached at the middle (P1), top (P2) and bottom (P3) position along a center line in the HFM bundle in which air was supplied from a diffuser below the membrane module with different aeration rates from 0 to 250 L/min. The acceleration of membrane vibration time series for the X-axis direction (left-right displacement) and Z-axis direction (back-front displacement) was recorded at three positions. The average vibration amplitudes of the acceleration along both directions at each position were increased as the aeration rate was increased. The HFM bundle showed a collective vibration with a frequency peak between 0 and 50 Hz. The Z-axis motion character of HFM bundle is regarded as a sheet vibration. The obtained vibration character was useful for the new design of a membrane module in MBR against the membrane fouling.

CFD simulations of fiber-fiber interaction in a hollow fiber membrane bundle: Fiber distance and position matters

This CFD study aims to simulate the impact of fiber distance and position on fiber-fiber interaction within a bundle. In order to display the filtration performance of fibers at different positions, a hollow fiber membrane filtration setup based on nine fibers arranged in a 3 × 3 square array was constructed. A CFD porous media model approach was employed using the liquid phase as the main phase. The numerical simulation of multiphase flow on the average velocity of each fiber is validated by the experimental results. The presence of “bundle resistance” and “permeate competition” among fibers was confirmed by the axial liquid velocity simulation. When fiber distance was less than the fiber diameter, the interaction between fibers became notable due to “permeate competition”. When fiber distance was equal to fiber diameter, the “permeate competition” effect disappeared, while the “bundle resistance” became dominant within the bundle. When the fiber distance was larger than the fiber diameter, both “permeate competition” and “bundle resistance” could be neglected. The variations of fiber flux at different positions along the fiber height also proved the distribution of axial liquid velocity and sludge density in the bundle. These results highlight the difference between fiber distance and position in the bundle that ensured the fouling deposition.

Three-dimensional turbulent flow and conjugate heat and mass transfer in a cross-flow hollow fiber membrane bundle for seawater desalination

A cross-flow hollow fiber membrane bundle for humidification (MBH) is used for seawater desalination. Fluid flow and conjugate heat and mass transfer in the bundle are studied by numerically solving the continuity, momentum, energy and concentration equations for air side, water side and membrane side, simultaneously in a conjugated way. Contrary to previous studies which considered only 2D laminar or turbulent flow, in this research the full three-dimensional turbulent flow in air side is modelled with a three-dimensional low-Reynolds-number k-ε turbulence model (3D Low Re k-ε). For comparison, besides the proposed 3D turbulence model, other three previously used models, namely, a 2D Low Re k-ε turbulence model, a 2D laminar model, and a 3D laminar model, are also used to investigate the effects of air side turbulence on fluid flow and heat and mass transfer properties in the bundle under a wide range of Reynolds numbers from 100 to 900. It is found that the 3D turbulence model best predicts the friction factors and Nusselt and Sherwood numbers for various module packing fractions under higher Reynolds numbers above 650. The results are validated by velocity measurement and performance test with a seawater desalination system.

Experimental method to determine anisotropic permeability of hollow fiber membrane bundles

The hydrodynamic flow resistance at low Reynolds numbers through hollow fiber membrane bundles is modeled, e.g. for computational fluid dynamics (CFD), as Darcy permeability K following the porous media approach. Experimental determination of the permeability of a particular hollow fiber bundle arrangement (fiber angle, diameter, and distance) is limited to one-directional flow measurements due to problems preparing representative elementary volume (REV) and following permeability is usually assumed to be isotropic. This ignores the fact that hollow fibers are usually arranged in an organized manner, or fiber bundle, and that resistance to flow is assumedly anisotropic. In this study, we developed a method of creating scaled-up REVs of almost any kind of geometry (by rapid prototyping) that can be measured in multi-dimensional directions within a permeameter. By means of a dimensional analysis the measured anisotropic flow resistances can be expressed in dimensionless friction factors, which can then be transformed into directional permeabilities on an arbitrary scale. The method was developed on two different fiber angle configurations (24° and 90°) in staggered and in-line fiber arrangements that are usually applied as blood oxygenator fibers. As a result, maximum anisotropy of the permeabilities were proven for flow along the fibers compared to cross-flow to the fibers with Kmax/Kmin = 4.77 for the 24° fiber layout. A comparison between the implementation of anisotropic vs. the commonly assumed isotropic permeabilities promises an improvement, especially in a more accurate estimation of stagnation zones in such modules.

An extracorporeal carbon dioxide removal (ECCO2R) device operating at hemodialysis blood flow rates

BackgroundExtracorporeal carbon dioxide removal (ECCO2R) systems have gained clinical appeal as supplemental therapy in the treatment of acute and chronic respiratory injuries with low tidal volume or non-invasive ventilation. We have developed an ultra-low-flow ECCO2R device (ULFED) capable of operating at blood flows comparable to renal hemodialysis (250 mL/min). Comparable operating conditions allow use of minimally invasive dialysis cannulation strategies with potential for direct integration to existing dialysis circuitry.MethodsA carbon dioxide (CO2) removal device was fabricated with rotating impellers inside an annular hollow fiber membrane bundle to disrupt blood flow patterns and enhance gas exchange. In vitro gas exchange and hemolysis testing was conducted at hemodialysis blood flows (250 mL/min).ResultsIn vitro carbon dioxide removal rates up to 75 mL/min were achieved in blood at normocapnia (pCO2 = 45 mmHg). In vitro hemolysis (including cannula and blood pump) was comparable to a Medtronic Minimax oxygenator control loop using a time-of-therapy normalized index of hemolysis (0.19 ± 0.04 g/100 min versus 0.12 ± 0.01 g/100 min, p = 0.169).ConclusionsIn vitro performance suggests a new ultra-low-flow extracorporeal CO2 removal device could be utilized for safe and effective CO2 removal at hemodialysis flow rates using simplified and minimally invasive connection strategies.

Fiber Bundle Design for an Integrated Wearable Artificial Lung.

Mechanical ventilation (MV) and extracorporeal membrane oxygenation (ECMO) are the only viable treatment options for lung failure patients at the end-stage, including acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). These treatments, however, are associated with high morbidity and mortality because of long wait times for lung transplant. Contemporary clinical literature has shown ambulation improves post-transplant outcomes in lung failure patients. Given this, we are developing the Pittsburgh Ambulatory Assist Lung (PAAL), a truly wearable artificial lung that allows for ambulation. In this study, we targeted 180 ml/min oxygenation and determined the form factor for a hollow fiber membrane (HFM) bundle for the PAAL. Based on a previously published mass transfer correlation, we modeled oxygenation efficiency as a function of fiber bundle diameter. Three benchmark fiber bundles were fabricated to validate the model through in vitro blood gas exchange at blood flow rates from 1 to 4 L/min according to ASTM standards. We used the model to determine a final design, which was characterized in vitro through a gas exchange as well as a hemolysis study at 3.5 L/min. The percent difference between model predictions and experiment for the benchmark bundles ranged from 3% to 17.5% at the flow rates tested. Using the model, we predicted a 1.75 in diameter bundle with 0.65 m surface area would produce 180 ml/min at 3.5 L/min blood flow rate. The oxygenation efficiency was 278 ml/min/m and the Normalized Index of Hemolysis (NIH) was less than 0.05 g/100 L. Future work involves integrating this bundle into the PAAL for which an experimental prototype is under development in our laboratory.

Conjugate heat and mass transfer in a cross-flow hollow fiber membrane bundle used for seawater desalination considering air side turbulence

Fluid flow and heat and mass transfer in a hollow fiber membrane bundle for air humidification (MBH), which is the key process of a membrane desalination system, are investigated. The MBH is like a cross-flow shell-and-tube heat exchanger where heated seawater flows inside the fibers and the process air stream flows across the fiber bundle. Fluid flow and heat and mass transfer in the bundle are studied by considering the air side turbulence which exists even when the Reynolds numbers are as low as 50. Air side, water side and membrane side transfer equations are solved together in a conjugated way. Two turbulence models namely the standard k-ε model (STD k-ε) and the low-Reynolds-number k-ε model (Low Re k-ε) are adopted for the prediction of turbulent kinetic energy and its dissipation rate. In order to validate the numerical results and to compare the performance of the different turbulence models, a membrane-based air humidification-dehumidification desalination (MHDD) system is designed and constructed to aid the investigation. Effects of module packing fractions and Reynolds numbers as well as the transverse and longitudinal pitches of the fibers on the mean Nusselt, Sherwood numbers and friction factors for air flow and water flow are analyzed. Correlations for performance analysis are regressed.

Laminar flow and conjugate heat and mass transfer in a hollow fiber membrane bundle used for seawater desalination

A hollow fiber membrane-based bundle or humidifier (HFMH) is used for air humidification in the process of membrane type seawater desalination, where seawater flows inside the fibers and the process air stream flows across the fiber bundle. The HFMH has a staggered arrangement of cylindrical fiber tubes with equal transverse and longitudinal pitches. The forced convection heat and mass transfer in the cross-flow tube bundle under naturally formed boundary conditions are investigated numerically on a periodic computational cell. A membrane-based air humidification-dehumidification type sea-water desalination (MHDD) system is constructed and used to validate the model. The mathematical model proposed here takes into account of the fiber-to-fiber interactions. The typical velocity vector profiles, temperature contours as well as the concentration contours for both the air stream and saline water stream are plotted to disclose the heat and mass transfer mechanisms. The effects of air Reynolds numbers (ranging from 50 to 300) as well as the module packing fractions (ranging from 0.126 to 0.503) on the fluid flow and heat mass transfer properties of the module are investigated. A set of correlations are also proposed for the prediction of the friction factor, mean Nusselt numbers and Sherwood numbers in air side. These fundamental data is of interest for the design and optimization of the HFMH, a promising membrane type seawater desalination system.

Development of an Improved Intravascular Membrane Oxygenator: Induction of Blood Flow into Hollow Fiber Membrane Bundles for Emergency Medicine

Development of an Improved Intravascular Membrane Oxygenator: Induction of Blood Flow into Hollow Fiber Membrane Bundles for Emergency Medicine

Darcy Permeability of Hollow Fiber Membrane Bundles Made from Membrana Polymethylpentene Fibers Used in Respiratory Assist Devices.

Hollow fiber membranes (HFMs) are used in blood oxygenators for cardiopulmonary bypass or in next generation artificial lungs. Flow analyses of these devices is typically done using computational fluid dynamics (CFD) modeling HFM bundles as porous media, using a Darcy permeability coefficient estimated from the Blake-Kozeny (BK) equation to account for viscous drag from fibers. We recently published how well this approach can predict Darcy permeability for fiber bundles made from polypropylene HFMs, showing the prediction can be significantly improved using an experimentally derived correlation between the BK constant (A) and bundle porosity (ε). In this study, we assessed how well our correlation for A worked for predicting the Darcy permeability of fiber bundles made from Membrana polymethylpentene (PMP) HFMs, which are increasingly being used clinically. Swatches in the porosity range of 0.4 to 0.8 were assessed in which sheets of fiber were stacked in parallel, perpendicular, and angled configurations. Our previously published correlation predicted Darcy within ±8%. A new correlation based on current and past measured permeability was determined: A = 497ε - 103; using this correlation measured Darcy permeability was within ±6%. This correlation varied from 8% to -3.5% of our prior correlation over the tested porosity range.

Bioinspired hollow fiber membrane bioreactor using human liver microtissue spheroids

Event Abstract Back to Event Bioinspired hollow fiber membrane bioreactor using human liver microtissue spheroids Loredana De Bartolo1, Haysam M. Ahmed1, 2, Simona Salerno1, Shervin Khakpour1, 2, Sabrina Morelli1 and Lidietta Giorno1 1 National Research Council of Italy - CNR, Institute on Membrane Technology, Italy 2 University of Calabria, Department of Environmental and Chemical Engineering, Italy Introduction: The development of bioartificial devices that are able to favour the liver reconstruction and to modulate cell behaviour is an important challenge in liver tissue engineering. As strategy we realized liver microtissue spheroids in a crossed hollow fiber membrane bioreactor, which was developed for the in vitro long-term perfusion. The bioreactor consists of two bundles of hollow fiber (HF) polyethersulfone (PES) membranes cross-assembled in alternating manner. One bundle of HF membranes provides cells nutrients and metabolites whereas the other HF bundle removes catabolites from cell compartment mimicking in this way the in vivo arterious and venous blood vessels. The combination of these two fiber set creates three compartments: two intraluminal compartments of PES HF in which the medium flows and one extraluminal compartment represented by extracapillary network formed by the fibers in which spheroids are cultured. Materials and Methods: The bioreactor consists of two bundles of PES HF membranes cross-assembled in alternating manner and potted with polyurethane adhesive within glass housing. The membranes were previously characterised in order to establish the physico-chemical, structural and transport properties[1]. The oxygenated medium enters to the membrane bioreactor with a flow rate Qf of 1.5 mL/min that was set on the basis of average retention time. Its fluid dynamics were characterized in terms of cumulative residence time distribution (RTD). Spheroids of primary human hepatocytes were realized in agarose mold and then cultured in the extralumen compartment of the bioreactor. The oxygen uptake, urea synthesis and albumin production rates as well as biotransformation functions were evaluated with time by using specific assays[2]. Numerical analysis of the mass transfer model for oxygen, urea and albumin concentration was performed using COMSOL Multiphysics. Results and Discussion: The geometry of the bioreactor ensured optimal perfusion conditions, which plaid a crucial role together with the surface and transport properties of the HF membranes in guiding the self-assembling of liver microtissue spheroids. Indeed, adjacent spheroids fused in the extracapillary space forming liver microtissues (Fig. 1). The liver microtissue spheroids expressed liver specific functions in terms of urea synthesis, albumin production and diazepam biotransformation at high levels up to 2 weeks. The liver specific functions of the bioreactor were significantly higher with respect to those of the batch system. Furthermore, the bioreactor provided an adequate oxygenation of the liver microtissue spheroids maintaining oxygen concentration levels well above the in vivo liver periportal zone concentration. Conclusion: The bioreactor thanks to its fluid dynamics and mass transfer properties of the fibers allowed to promote the formation liver microtissue spheroids with high specific functionality.

Oblique fluid flow and convective heat transfer across a tube bank under uniform wall heat flux boundary conditions

Fluid flow and convective heat transfer in an oblique-flow tube bank under uniform wall heat flux boundary conditions are investigated. Most previous studies on heat transfer across tube banks have concerned only on two extreme cases, i.e., pure parallel flow or pure cross flow. For more general and practical conditions in engineering, fluid flow is in an intermediate state and it often impinges the tubes with an oblique angle as a result from duct or heat mass exchanger structures. In this research, fluid flow and convective heat transfer is investigated for an oblique-flow tube bank. Uniform wall heat flux boundary conditions are considered. Numerical solution has been performed to obtain the shell-side fluid field and convective heat transfer rates with various impinging angles. Experimental work is conducted to validate the solution. The analysis reveals that the convective heat transfer rates and friction factors rise with an increase in the oblique angles from 0° to 90° to the tube axes. Correlations are proposed for the prediction of convective heat transfer coefficients and friction factors at different oblique angles with various geometrical parameters. The results can be extended to mass transfer in hollow fiber membrane bundles with Chilton–Colburn analogy.

Hollow fiber modules with ceramic-supported PDMS composite membranes for pervaporation recovery of bio-butanol

The practical application of hollow fiber membranes for pervaporation technology has been received growing attention in recent years. This work reports the development of hollow fiber modules of ceramic-supported polydimethylsiloxane (PDMS) composite membranes applied for pervaporation process. Computational fluid dynamics (CFD) technique was used to simulate and optimize the flow field distribution in the modules with different packing density and cross-section layout. The hollow fiber modules with proposed configurations were fabricated in our lab and evaluated by pervaporation measurement in model butanol aqueous solution and real fermentation broth. The results suggested that the design of packing density and cross-section layout could realize the optimization of module configuration. The optimized module filled with 7 bundles of hollow fiber membranes at a high packing density of 560m2/m3 exhibits a high and stable performance in the real ABE fermentation broth during 120h continuous operation at 40°C. The average total flux was 1000g/m2h and separation factor were 6.4 for ethanol, 22.2 for butanol and 28.6 for acetone, respectively. Our results demonstrated that the hollow fiber modules developed in this work could be competitive candidates for the practical application in pervaporation recovery of bio-butanol.