Spiral Wound Research Articles

A phase-error immune approach for measuring transport AC loss by determination of minimum compensated voltage

Alternating current (AC) loss measurement is crucial for the theoretical evaluation and optimization in the fabrication of superconducting AC devices. Lock-in amplifier based on the lock-in phase is commonly adopted and inevitably involves with phase error. In this work, a novel approach for measuring transport AC loss by determining the minimum compensated voltage (MCV) was developed, in which the lock-in amplifier was removed. Since it just uses the voltage signal from an AC voltmeter, it is phase-error immune. Experimental results demonstrated that when using the lock-in amplifier, there existed a system error as the initial phase difference between the sampled (reference) and real current phases, which required careful compensation. In contrast, the phase error no longer needed to be considered by the MCV method, and the AC loss results were obtained much more conveniently with the relative error between the theoretical and the experimental of less than 5%. Finally, the AC loss of a coated conductor spiral wound on an epoxy bar was obtained using the presented approach, demonstrating its low cost, ease of operation, and high accuracy.

Industrial Scale Manufacturing Sub‐10 nm Reverse Osmotic Desalination Membrane on Metallic Single‐Walled Carbon Nanotubes Network

AbstractDifferent from extensively reported carbon nanotubes‐polyamide (PA) composite membranes, this work reports the scalable, low‐cost manufacturing of metallic single‐walled carbon nanotubes network supported PA reverse osmotic desalination membranes. Metallic single‐walled carbon nanotubes (SWCNTs) separated from high‐pressure carbon monoxide conversion (HiPCO) SWCNTs with a diameter ranging from 0.6 to 1.2 nm are deposited on polyethersulfone (PES) films by replacing surfactants around SWCNTs dispersed in aqueous solution, for supporting uniform and smooth sub‐10 nm PA nanofilm formed through aqueous‐organic bilayer interfacial polymerization. The industrial scale manufactured PA/SWCNTs/PES desalination membranes (508 mm × 915 mm) are rolled into spiral wound elements without damage through cutting, gluing, and rolling. The desalination tests on flat PA/SWCNTs/PES membranes exhibits 30 l m−2 h−1 (LMH) under 17.2 bar with 98.45% salt injection when fed with 2000 ppm NaCl at pH = 9. The normalized permeate flux of PA/SWCNTs/PES spiral wound elements is ≈17 LMH under 13.8 bar with 90% salt injection underfed with 2000 ppm MgSO4 at pH = 9–11 condition. The high‐performance sub‐10 nm smooth PA/SWCNTs/PES desalination membranes are fabricated with materials savings and can promote low operation costs compared to conventional 50–100 nm crumpled PA films on any supporting substrates.

CFD for the optimization of spiral wound film assembly

In this paper, a conventional mesh shim for a spiral wound membrane assembly is structurally optimized by adding jet holes to achieve the jet function, and the effect of curvature on fluid flow is investigated. The three different gaskets are compared with each other and the performance of the optimized gaskets is investigated by using computational fluid dynamics (CFD) techniques and analyzed parametrically. This knowledge can be supplemented by the use of CFD techniques for spacers, whereby the geometry of the spacer can be optimized and the corresponding performance of the spiral wound film assembly can be improved.

Functionalization of cellulose acetate nanofibrous membranes for removal of particulate matters and dyes

Particulates and organic toxins, such as microplastics and dye molecules, are contaminants in industrial wastewater that must be purified due to environmental and sustainability concerns. Carboxylated cellulose acetate (CTA-COOH) nanofibrous membranes were fabricated using electrospinning followed by an innovative one-step surface hydrolysis/oxidation replacing the conventional two-step reactions. This approach offers a new pathway for the modification strategy of cellulose-based membranes. The CTA-COOH membrane was utilized for the removal of particulates and cationic dyes through filtration and adsorption, respectively. The filtration performance of the CTA-COOH nanofibrous membrane was carried out; high separation efficiency and low pressure drop were achieved, in addition to the high filtration selectivity against 0.6-μm and 0.8-μm nanoparticles. A cationic Bismarck Brown Y, was employed to challenge the adsorption capability of the CTA-COOH nanofibrous membrane, where the maximum adsorption capacity of the membrane for BBY was 158.73 mg/g. The self-standing CTA-COOH membrane could be used to conduct adsorption-desorption for 17 cycles with the regeneration rate as high as 97.0 %. The CTA-COOH nanofibrous membrane has excellent mechanical properties and was employed to manufacture a spiral wound adsorption cartridge, which exhibited remarkable separation efficiency in terms of treated water volume, which was 5.96 L, and retention rate, which was 100 %.

A review of spiral wound membrane modules and processes for groundwater treatment

The demand for freshwater keeps increasing on a global scale, and on the other hand, the availability of freshwater keeps diminishing. Groundwater has been identified as the largest source of freshwater that is readily accessible. Although the water is available for abstraction, it must be treated to meet application standards. Membrane processes are the options that industry and researchers are turning to for the purification of groundwater. This review provides an insight into the use of pressure-driven membrane processes for groundwater treatment, with focus on the spiral wound membrane module. A brief description of what a spiral wound module is and the plant set-up in which it is used is given. The various applications of the spiral wound module with regards to groundwater treatment have been reviewed. The shortcomings and challenges limiting the application of spiral wound modules and by extension, the treatment plant itself have been highlighted. To cap it all, the opportunities that can be exploited to overcome these challenges and position pressure-driven membrane processes for groundwater treatment as the go-to purification method have been discussed.

Optimizing Reverse Osmosis Feed Spacer Design for Enhanced Dimethylphenol Removal from Wastewater: A Study of Hydrodynamics and Performance Indicators

Due to its high pollutant rejection and low energy usage, the spiral wound module of reverse osmosis (RO) process is the most commonly used technology utilised in wastewater treatment. For a spiral wound module, the presence of a feed spacer is important as a key solution to mitigate the concentration polarisation phenomenon, due to disorderly fluid flow, and to improve the mass transfer coefficient. Undoubtedly, improvements in the spiral wound module design, mainly in the symmetrical shape of the feed spacer, can have a significant impact on the cost and probable use of these modules. Despite the wide interest in appraising the impact of feed spacer geometry and orientation on the performance of a spiral wound module for RO process-based water desalination, the hydrodynamics of feed spacers (pressure drop and mass transfer coefficient) and the associated influences of feed spacer design (the height of the feed spacer, the angle of the filaments, and the porosity) on the removal of pollutants from wastewater have not yet been addressed. The current investigation aims to fill this gap by studying the hydrodynamics and design parameters of the selected parallelogram feed spacer type ultrafiltration (UF−3) for the removal of dimethylphenol from wastewater. Using model-based simulation, the impacts of UF−3 feed spacer design parameters, including the height, angle between the filaments (orientation), and porosity on the pressure drop, friction factor, axial flow fluid velocity, mass transfer coefficient, water flux, dimethylphenol rejection, recovery rate, and specific energy consumption are detailed in this study. The study intends to demonstrate the optimum design features of UF−3 feed spacer that should be considered to assure the highest elimination of dimethylphenol from wastewater in addition to the lowest specific energy consumption.

Scalable nanofiltration membranes with sharpened pore distribution and enhanced negativity for mono/divalent anion separation

The petrochemical industry is an important producer of high salinity wastewater, necessitating the efficient separation of salts in zero discharge processes. This study reports the development of an industrially scalable thin film composite nanofiltration membranes that facilitate the effective separation of NaCl/Na2SO4. Employing a one-step functionalization process, the membrane pore distribution is sharpened, and the surface negativity is intensified. Branched polyethyleneimine with abundant reactive amine groups is employed as an aqueous co-monomer, leading to the generation of high density grafting active sites. Nucleophilic substitution reaction is employed to functionalize the membrane surface with negatively charged sulfonic acid groups. Simultaneously, large voids within the free volume are filled and the pore size distribution is effectively narrowed. The resultant membranes demonstrate an impressive rejection of 99.5 % for Na2SO4, a selectivity of 163.4 for NaCl/Na2SO4 and a selectivity of 488 for Cl−/SO42−, with a water flux of 45 LMH under 0.5 MPa. The corresponding 8″ × 40″ sized spiral wound membrane modules exhibit a NaCl/Na2SO4 selectivity of 100.4 and a Cl−/SO42− selectivity of 258.3, demonstrating high practical applicability. A pilot trial is planned to integrate these novel membrane products into zero discharge processes within the internal chemical enterprises of Sinopec.

Study of the removal of nitrate and dissolved iron pollutants from industrial wastewater to become raw water using nanofiltration

Nowadays, industrial nanofiltration membrane technology is widely used, particularly when it comes to recovering and recycling water for preservation. This research is related to the processing of wastewater from one of the industrial areas in Indonesia into raw water using nanofiltration on a pilot scale. This research aims to identify the removal of nitrate and dissolved iron from industrial area wastewater through flow recirculation in nanofiltration and identify the effect of variations in wastewater concentration and variations in product recovery. The wastewater being treated is wastewater from an industrial area owned by PT. Jababeka Infrastruktur is composed of a ratio of 100% WWTP effluent, 9:1, 8:2, 7:3, and 6:4 between WWTP influent and effluent ratio. This study’s membrane module employs a two-stage membrane system and a spiral wound with model specifications NF2-4040. Recirculation is used in the reactor to process the material and provide cross flow. The results of the study stated that variations in concentration made a significant difference to the removal of nitrate and dissolved iron (p value < 0.05), but variations in product recovery the opposite response. The processed water meets the raw water quality standards for nitrate parameters, but not for dissolved iron parameters at processed water concentrations of 7:3 and 6:4.

To The Extreme

Spiral wound gaskets can operate in the harsh environments where standard gaskets would fail. Dobson Gaskets explores the qualities that make them so resistant.

A clear view of biofouling in spacer filled membrane filtration channels: Integrating OCT and CT for improved visualization and localization

Spiral wound membrane elements for reverse osmosis (RO) seawater desalination are increasingly important to produce clean water to cope with the rising global freshwater scarcity. Spiral wound elements are prone to biofouling development which can be monitored in-situ using optical coherence tomography (OCT). Although OCT has emerged as a dominant technology for nondestructive monitoring of membrane fouling, the application of OCT to study fouling on feed spacers has been limited because image processing of spacers is complex. In this study, an automated image processing algorithm was developed for visualization and quantification of fouling in spacer filled channels. The spacer shadow was used to estimate the location of the spacer in the OCT image. Subsequently, a computed tomography (CT) scan of the same spacer type was overlaid, providing a clear indicator of the spacer position. The spacer position was used to i) correct the distortion below the spacer, ii) visualize fouling in 3D with reference to the membrane and spacer, and iii) reproducibly and precisely locate images to make time series and compare parallel experiments. The results showed that the addition of a spacer geometry as a solid object in a 3D representation of an OCT-scan greatly improves visualization, because fouling and the spacer can be distinguished and the position of fouling relative to the spacer and membrane can be clearly seen. Moreover, the ability to select a dataset relative to the orientation of the spacer will enable objective and automated quantitative analysis in future work.

Experimental and numerical study on the offshore adaptability of new FLH2 floating hydrogen liquefaction production storage and offloading unit

With the development of hydrogen production technology from offshore wind power and natural gas, the deep-sea energy interconnection system using hydrogen energy as the medium is constantly improving. The floating hydrogen liquefaction production storage and offloading unit (LH2-FPSO, FLH2) is an effective method for large-scale utilization of offshore hydrogen energy. By filling the heat exchanger with ortho-parahydrogen conversion catalyst, a new porous medium heat exchange channel is formed. Integrating the spiral wound heat exchanger with the ortho-parahydrogen catalytic conversion reactor can reduce the deck area of FLH2 process system and lower the investment cost of floating hydrogen liquefaction device. The performance of FLH2 can be influenced by the offshore wave and typhoon. In this paper, the methods of floating cryogenic visualization experiment, theoretical analysis and numerical simulation are conducted to study the coupled flow and heat transfer mechanism of working fluid applied in FLH2 under offshore conditions. The results show that the sea state has little influence on the ortho-parahydrogen conversion and cooling process of hydrogen in the porous heat exchange tube. The complex flow and heat transfer challenges brought by the integrated process of new floating hydrogen liquefaction and ortho-parahydrogen conversion have been overcome. With the effect of co-current shear of gas-phase mixed refrigerant, a large dry area will not appear on the outer wall surface of porous tube under offshore conditions. The FLH2 process system shows good adaptability at sea.

Numerical research on the heat transfer and pressure drop of supercritical CO2 in spiral wound tubes

The microtube heat exchanger (MSTE) is suitable for the pre-cooler and gas cooler in the supercritical CO2 brayton cycle and the CO2 heat pump cycle. This article presents a numerical study on the heat transfer characteristics of supercritical CO2 (sCO2) during the cooling process in capillaries with different shapes and sizes. The effects of tube types, spiral pitch, spiral diameter, and mass flow rate were investigated on the heat transfer and pressure drop of sCO2. The centrifugal force in the rotating flow also has an effect on the fluid flow, which in turn leads to a unique secondary flow. The heat transfer and pressure drop increase as the mass flow rate increases in all of the tubes. The straight tube showed the worst heat transfer performance and the best pressure drop performance. The spiral tube showed a better performance on the heat transfer and a worse performance on the pressure drop than the straight tube. The total heat transfer amount and pressure drop increase as the spiral pitch and spiral diameter decrease. The field synergy angles in different locations were further analyzed. It was found that the field synergy angle could further reveals the mechanism of heat transfer enhancement in spiral tubes.

Removal of total phosphate and sulfate from industrial wastewater by recirculating flow in nanofiltration

This study is related to industrial wastewater treatment in Indonesia using nanofiltration membrane technology and was carried out on a pilot scale. This research aims to study the total removal of phosphate and sulfate from industrial wastewater through flow recirculation in nanofiltration and the membrane pressure factors that influence the removal of these pollutants. The treated wastewater is industrial wastewater belonging to Jababeka Infrastruktur Corp. and is arranged in various concentrations. The membrane module in this study uses a spiral wound with model specifications NF2-4040 and a two-stage membrane system. The reactor used provides crossflow velocity and is processed by recirculation. The research results stated that variations in concentration and recovery rate provided total removal of phosphate and sulfate in the range of 70-90% and pressure reached 11 bar as both increased. This research has proven that nanofiltration membrane technology can remove total phosphate and sulfate, with the consequence that the more concentrated the wastewater being treated, the greater the pressure required.

Entropy generation analysis on condensation upward flow for hydrocarbon mixture in two types of helical wavy pipes

This paper proposed the application of two types of wavy structures for spiral wound heat exchanger, and conducted numerical simulations on the condensation flow of a hydrocarbon mixture with methane, ethane, and propane in them. The effects of saturation pressure and mass velocity are also studied. It was found that both types of helical wavy pipes produce higher condensation heat transfer coefficients and frictional pressure drop than those in helical smooth one, and both of them increase with the rise in mass velocity and the decrease of saturation pressure. The influence of saturation pressure on heat transfer and pressure drop is greater than that of mass velocity. Meanwhile, the comprehensive performance of the two types of helical wavy pipes is analyzed using entropy generation. It can be found that the horizontal wavy pipe has a better overall performance than vertical wavy one with a lower irreversible loss. Finally, prediction models for the condensation heat transfer coefficients and frictional pressure drops are established using RBF neural networks, with 95 % of the predicted results having a relative deviation within 10 %.

Highly permeable nanofibrous polyamide membranes for multi-component wastewater treatment: Exploration of multiple separation mechanism

Multi-component wastewater containing a variety of organic toxins, e.g., dyes and inorganic particulates induces serious environmental concerns, which must be addressed by innovative approaches instead of conventional chemical and physical processes, which are limited by purification efficiency, secondary pollution, and cost-effectiveness. Therefore, it is important to find new avenues of purification methods that are both sustainable and effective. Ultra-fine nanofibrous microfiltration membranes were fabricated by multi-nozzle electrospinning of polyamide-66 (PA-66) and were employed to remove 0.2-μm-nanoparticles and dyes simultaneously from wastewater through filtration and dynamic adsorption performance, in an attempt to discover a one-step filtration system for both dyes and nanoparticles. The fiber diameter and surface morphology of the nanofibrous membranes varied with the concentrations of polyamide solutions, where the ultra-fine nanofibrous membrane exhibited optimum mechanical properties at a specific concentration of PA-66 (11 wt%). The nanofibrous membranes had adsorption capabilities of 133.3 and 204.5 mg/g, respectively, against both anionic dyes (e.g., metanil yellow) and cationic dyes (e.g., chrysoidine), respectively. The membrane also selectively filtrated fine nanoparticles with a nearly 100% rejection ratio. A multiple separation mechanism, including adsorption based on electrostatic interaction, hydrogen bonding interaction, and hydrophobic interaction, as well as depth filtration, was proposed. As an applicable demonstration, the spiral wound cartridge fabricated by PA-66 nanofibrous membrane was used for a simulated multi-component wastewater treatment that contained dyes and nanoparticles of different concentrations. During the multicomponent test at flow rate 1 mL/min, a rejection rate of 97% and greater than 99% were achieved against dyes and nanoparticles, respectively.

Numerical simulation of heat transfer performance of spiral wound heat exchanger under sloshing condition

LNG floating production storage and offloading (FPSO) unit is a new type of floating production unit developed for offshore natural gas fields. It performs the functions of natural gas extraction, pretreatment, liquefaction, and storage. In this study, the heat transfer characteristics of a spiral-wound heat exchanger were studied using numerical simulations, which provides a basis for equipment selection and structural optimization of spiral-wound heat exchangers. The main research contents and conclusions are as follows. Under land-based simulation conditions, the heat transfer coefficient of the shell side of the spiral-wound heat exchanger decreases with an increase in the winding angle of the heat exchange tube, decreases with an increase in the spacing of the heat exchange tube, and increases with an increase in the outer diameter of the heat exchange tube. When the winding angle increased from 5° to 8°, the heat transfer coefficient decreased by 6.70%. The heat transfer coefficient of the shell side decreased by 13.21% when the heat exchange tube spacing increased from 14 to 17 mm. The heat transfer coefficient of the shell side increased by 22.89% when the outer diameter of the heat exchange tube increased from 9 to 12 mm. When the sloshing angle is constant, the heat transfer coefficient of the spiral-wound heat exchanger decreases with an increase in the winding angle and spacing of the heat exchange tubes, and increases with an increase in the outer diameter of the heat exchange tubes. When the structural parameters of the heat exchanger are constant, the heat transfer coefficient decreases as the sloshing angle increases. When the sloshing angle was less than 3°, the sloshing promoted heat transfer on the shell side. When the sloshing angle was higher than 7°, the heat transfer effect of the shell side deteriorated considerably, which weakened the heat transfer performance of the heat exchanger. When the sloshing period is constant, the heat transfer coefficient of the wound heat exchanger decreases with an increase in the winding angle and spacing of the heat exchange tubes, and increases with an increase in the outer diameter of the heat exchange tubes. When the structural parameters of the heat exchanger are constant, the heat transfer coefficient increases with sloshing period. When the sloshing period was greater than 15 s, the influence of sloshing on the heat transfer on the shell side of the heat exchanger was relatively weak.

Analysis and prediction of SWM feed spacer performance based on CFD results with an emphasis on the effect of micro-scale lateral and longitudinal washing flows

In reverse osmosis applications, feed spacers are used in spiral wound membranes to separate the membrane surfaces and enhance mass transfer while incurring an acceptable pressure drop. In this study, an attempt has been made to understand the effect of spacer characteristics, such as arrangement and size, on mass transfer and pressure drop. Power-law equations were successfully developed to describe different spacer performance measures as a function of Reynolds number (Re), where both the multiplier of the Re term and the Re exponent vary for each spacer arrangement. Although at the macro level, it was not possible to adequately correlate the equation parameters with the spacers’ geometrical parameters (such as porosity), examining the post-processed CFD results at the micro level led to explanations for the observed concentration profiles, trends in spacer performance and changes in the equation parameters. A key observation was the importance of lateral flow recirculation, which was termed side-washing. Overall, based on the Spacer Configuration Efficacy performance measure and by assessing the trade-off between Sherwood number and pressure drop, the Woven configuration shows the best performance among the spacer arrangements and range of flowrates studied.

Influence of internal design on the performance of pilot vacuum-assisted air-gap membrane distillation modules for brine concentration with solar energy

Membrane distillation (MD) in batch operation is proposed for brine concentration with solar energy in zero liquid discharge (ZLD) desalination processes, but there are some research gaps yet. Energy efficiency is key for implementing the technology with solar energy and there is not enough experience and experimental results of operation of MD pilot modules at high salinity feeds. This research focuses on the experimental evaluation and comparison of two multi-envelope spiral wound commercial membrane distillation modules operating in vacuum-assisted air gap MD at the solar MD pilot facilities of Plataforma Solar de Almería in Spain. These modules have similar membrane area (24 and 25.9 m2) and residence time (large, to maximize thermal efficiency), but different internal design: 6 envelopes 5 m long and 12 envelopes 2.7 m long, respectively. This difference affects mostly the feed circulation velocity for equal feed flow rate. Performance parameters such as permeate production and specific thermal energy consumption (STEC) are compared and experimental models performed and validated for different feed salinities. Permeate quality and specific electrical energy (SEEC) consumption are also evaluated. The results show that the best module for batch operation is the one with a larger number of channels but of shorter length.

Angular vibrations for fouling control during ultrafiltration of microalgae in a spiral wound module

Previous studies have shown that vibration- or rotation-based techniques can effectively mitigate the fouling and concentration polarization during membrane filtration. However, it is difficult to incorporate these active enhancement techniques with spiral wound modules (SWMs), which are widely employed in drinking water and wastewater treatment. In this work a prototype membrane system was developed to accommodate angular vibrations with a modified SWM. With this prototype system, a series of filtration experiments were designed and implemented to investigate the effect of angular vibrations on the ultrafiltration algal fouling process in an SWM. The experimental results indicate that the algal fouling in an SWM can be effectively controlled (up to ∼28.5 % at 15 Hz) by applying angular vibrations in conjunction with appropriate operating conditions; the underlying mechanisms are discussed using a mathematical model that accounts for the relative motion between the fluid and membrane when they are subject to external accelerations, related to the vibration frequency, filtration period and position along coiled membrane leaves. A quantitative analysis is also presented to demonstrate the potential of using angular oscillations to control the algal fouling in an SWM with a lower energy consumption compared to the conventional method of increasing the cross-flow rate.

Modeling of spiral wound ultrafiltration membrane forward flushing during secondary wastewater upgrading for unrestricted irrigation

A two-stage membrane system comprising of an ultrafiltration (UF) stage followed by a reverse osmosis (RO) leg was employed for unrestricted irrigation. The UF stage served as a vital pretreatment step for the RO stage. To address the fouling phenomenon of the UF membrane, field experiments were meticulously conducted to thoroughly characterize the flow decline employing forward flushing. Forward flushing of the UF membrane was the preferred selected method although no other cleaning method was evaluated (besides once a week chemical cleaning). Optimal frequency of forward flushing and the associated costs per flush in the UF stage were carefully investigated.The spiral wound UF membranes was economically modeled to achieve most efficient filtration. Modeling considers a range of factors, including energy costs and clean water consumption per forward flush. General curves were obtained to describe the system's performance under diverse filtration conditions.Frequency of forward flushing, almost every 30 min, emerged as the recommended option. This approach proved to be effective in minimizing membrane fouling and sustaining filtration. Modeling of this strategy considered the costs associated with the frequent flushes, and it was found to be a justifiable investment given the considerable benefits in membrane performance and overall system efficiency.