Vacuum Membrane Distillation Process Research Articles

Efficiency increment of CFD modeling by using ANFIS artificial intelligence for thermal-based separation modeling

This study presents a comprehensive analysis of predicting the temperature in a vacuum membrane distillation (VMD) process. The simulation was carried out via computational fluid dynamics (CFD) as well as machine learning. CFD was performed for obtaining temperature distribution in the feed solution, and the calculated temperature was used for training several machine learning models. The dataset comprises over 13,000 observations, which provide a rich source for modeling complex relationships. Three sophisticated regression models were employed: Adaptive Neuro-Fuzzy Inference System (ANFIS), Kernel Ridge Regression (KRR), and Multi-Layer Perceptron (MLP). ANFIS was chosen for its hybrid nature, combining neural networks and fuzzy logic, effectively capturing intricate non-linear relationships in data. ANFIS performance in fitting the data was compared with the other models. Hyper-parameter optimization for these models was conducted using the Tabu Search algorithm to ensure optimal performance. The ANFIS model demonstrated superior performance with an R2 score of 0.9964513 on the training set and 0.9964507 on the test set, alongside a MSE of 0.037655 and a MAE of 0.168272. The robustness of ANFIS was further confirmed by a 3-fold cross-validation mean R2 score of 0.9964579 and a standard deviation of 3.3619616e-05.

Green and Sustainable Forward Osmosis Process for the Concentration of Apple Juice Using Sodium Lactate as Draw Solution.

China is the world's largest producer and exporter of concentrated apple juice (CAJ). However, traditional concentration methods such as vacuum evaporation (VE) and freeze concentration cause the loss of essential nutrients and heat-sensitive components with high energy consumption. A green and effective technique is thus desired for juice concentration to improve product quality and sustainability. In this study, a hybrid forward osmosis-membrane distillation (FO-MD) process was explored for the concentration of apple juice using sodium lactate (L-NaLa) as a renewable draw solute. As a result, commercial apple juice could be concentrated up to 65 °Brix by the FO process with an average flux of 2.5 L·m-2·h-1. Most of the nutritional and volatile compounds were well retained in this process, while a significant deterioration in product quality was observed in products obtained by VE concentration. It was also found that membrane fouling in the FO concentration process was reversible, and a periodical UP water flush could remove most of the contaminants on the membrane surface to achieve a flux restoration of more than 95%. In addition, the L-NaLa draw solution could be regenerated by a vacuum membrane distillation (VMD) process with an average flux of around 7.87 L∙m-2∙h-1 for multiple reuse, which further enhanced the long-term sustainability of the hybrid process.

Non-targeted analysis and toxicity prediction for evaluation of photocatalytic membrane distillation removing organic contaminants from hypersaline oil and gas field-produced water

Membrane distillation (MD) has received ample recognition for treating complex wastewater, including hypersaline oil and gas (O&G) produced water (PW). Rigorous water quality assessment is critical in evaluating PW treatment because PW consists of numerous contaminants beyond the targets listed in general discharge and reuse standards. This study evaluated a novel photocatalytic membrane distillation (PMD) process, with and without a UV light source, against a standard vacuum membrane distillation (VMD) process for treating PW, utilizing targeted analyses and a non-targeted chemical identification workflow coupled with toxicity predictions. PMD with UV light resulted in better removals of dissolved organic carbon, ammoniacal nitrogen, and conductivity. Targeted organic analyses identified only trace amounts of acetone and 2-butanone in distillates. According to non-targeted analysis, the number of suspects reduced from 65 in feed to 25–30 across all distillate samples. Certain physicochemical properties of compounds influenced contaminant rejection in different MD configurations. According to preliminary toxicity predictions, VMD, PMD with and without UV distillate samples, respectively contained 21, 22, and 23 suspects associated with critical toxicity concerns. Overall, non-targeted analysis together with toxicity prediction provides a competent supportive tool to assess treatment efficiency and potential impacts on public health and the environment during PW reuse.

Facile preparation of superhydrophobic PVDF/MWCNTs distillation membranes: Synthesis, characteristics and separation performance

In recent years, membrane distillation (MD) has emerged as an effective solution to mitigate the high energy consumption associated with conventional fermentable sugar concentration processes. However, the inherent low mechanical strength of traditional organic membrane surfaces can result in issues related to membrane wetting during long-term MD experiments. In this work, superhydrophobic PVDF/MWCNTs (multi-walled carbon nanotubes) distillation membranes with high mechanical strength were prepared by a combination of templating and co-blending techniques. The process involved peeling the semi-gelation membrane from a sandpaper template, subsequently forming a high aspect ratio microstructure on the membrane surface via tearing and pulling. Additionally, the incorporation of MWCNTs further bolstered the mechanical strength of the membrane. At a peeling time of 90 s and a MWCNTs content of 0.08 wt%, the distillation membrane exhibited an impressive water contact angle of 153.2°, indicating it possess exceptional hydrophobicity while maintaining high mechanical strength. The separation performance of the prepared distillation membranes has been inspected by conducting both experimental analyses and computational fluid dynamics (CFD) modeling of the entire MD process. An appropriate elevation in both feed flow rate and temperature could effectively mitigate the problem of temperature and concentration polarization on the membrane surface. PVDF/MWCNTs distillation membrane demonstrated a modest reduction in permeate flux of about 11.69 % and a stable rejection rate exceeding 99.95 % throughout a 100-hour operational period, and it required only 15 h to concentration of aqueous glucose solution to 100 g/L, significantly enhancing the efficiency of the process. This study also employed a combination of experiments and simulations to optimizes the process conditions guiding the vacuum membrane distillation (VMD) process and could provide guidance for the future application of membrane distillation in the concentration of sugar solutions.

Economic assessment of a multistage surface-heated vacuum membrane distillation process for the treatment of hypersaline produced water

The treatment and disposal of hypersaline produced water remains a challenge, particularly for oil and gas producers in the Permian basin where production wells generate significant amounts of wastewater, and the traditional method of injecting wastewater into disposal wells is coming under increasing scrutiny. Here we investigate the viability of using solar energy to power a multi-stage, surface heated, vacuum membrane distillation (SHVMD) with energy recovery to treat hypersaline produced wastewater from Midland, Texas. Membrane distillation is a process that can desalinate waters with high total dissolved solids concentration, and when incorporated into a system with surface heating and energy recovery can achieve high water recovery rates. Model results show that a 6-stage SHVMD system with a 54.4 % water recovery rate and a gained output ratio (GOR) of 3.28 has the potential to be economically viable when used to treat hypersaline produced water in the Permian basin. Assuming energy costs of $0.03/kWhthermal and $0.12kWhelectric, we estimate a project net present value (NPV) of $225,525 and an internal rate of return (IRR) of 13.5 % when an air cooled condensor is used to cool the distillate and a NPV of $570,791 and IRR of 24.52 % when a liquid coooling source is available. SynopsisThis work presents a comprehensive economic assessment of utilizing a surface-heated membrane distillation system with heat recovery to treat hypersaline produced well water.

Novel bentonite modified PVDF membrane for desalination of synthetic-produced water by vacuum membrane distillation

ABSTRACT Membrane distillation (MD) has emerged as a highly promising method for the treatment of intricate and heavily contaminated water sources, such as those containing oily wastewater. The present study endeavors to advance the field by designing and evaluating a novel nanocomposite membrane comprised polyvinylidene fluoride (PVDF) and Bentonite (BNT) for application in vacuum membrane distillation (VMD) processes targeted at treating oily wastewater. A series of five nanocomposite flat sheet membranes were meticulously fabricated, incorporating varying quantities of bentonite (ranging from 0 to 0.8 g). Systematic characterizations were meticulously undertaken to comprehensively elucidate the influence of BNT incorporation on the structural and functional attributes of the developed membranes. These encompassed an array of analytical techniques, including Fourier Transform Infrared Spectroscopy (FTIR), atomic Force Microscopy (AFM), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), contact angle measurements (CA), as well as assessments of membrane thickness, porosity, pore size, and pore size distribution. The findings distinctly showcased the successful integration of BNT within the PVDF matrix, which correspondingly led to discernable augmentations in membrane surface roughness, hydrophobicity, and porosity. Employing consistent operational conditions involving a feed temperature of 50°C, a vacuum pressure of 30 kPa, and a NaCl solution with a concentration of 14.75 g/L, VMD experiments were systematically conducted. The empirical outcomes revealed that the incorporation of BNT notably conferred substantial enhancements upon the nanocomposite membrane’s performance. The pinnacle achievement was evidenced in a flux rate of 34 L/m2.h and a remarkable NaCl rejection rate of 99.92%, a result achieved by the nanocomposite membrane incorporating the highest content of BNT additives.

Performance investigation of poly(vinylidene fluoride-cohexafluoropropylene) membranes containing SiO2 nanoparticles in a newly designed single vacuum membrane distillation system.

The current study focuses on the development of a superhydrophobic poly(vinylidene fluoride-cohexafluoropropylene) nanocomposite membrane suitable for vacuum membrane distillation by incorporating SiO2 nanoparticles. At loading hydrophobic nano-SiO2 particle concentration (0.50-1.50 wt.%), the developed nanocomposite membranes are optimized in terms of vacuum membrane distillation performance. The influence of temperature, vacuum pressure, and feed water flow is studied for desalinating high-salinity brine. The results show that the developed vacuum distillation membrane is capable of 95% salt rejection during the treatment of a highly saline feed (65,000 ppm) at fixed flow rates of 120L/h saline feed and different operating conditions consisting of feed inlet temperatures ranging from 40°C to 70°C and distillate inlet temperatures of 7-15°C. The vacuum membrane distillation process achieves 0.38-1.66% water recovery with increasing concentration factor, meaning that recovery is increased, and shows a specific electrical energy consumption of 5.16-23.90 kWh/m3 for product water. Overall, the newly designed membrane demonstrates suitability for a vacuum membrane distillation system. PRACTITIONER POINTS: Desalinate high-salinity brine (TDS > 35,000 ppm) using a vacuum membrane distillation system. A hydrophobic PVDF-HFP/SiO2 nanocomposite membrane development for vacuum membrane distillation. A newly designed single vacuum membrane distillation system for RO brine treatment.

Tailored PVDF membrane with coordinated interfacial nano/micro-structure for enhanced membrane distillation

Membrane distillation (MD) has attracted growing attention as a sustainable green membrane process technology for seawater and high saline water desalination, yet seriously challenged by the potential membrane wetting and fouling. Herein, a controllable approach to fabricate tailor-made MD membranes was proposed via combining in-situ growth of SiO2 nanoparticles with membrane surface activation and low surface energy substances. SiO2 nanoparticles distributed uniformly on the membrane surface and combined with the intrinsic microstructure of the membrane, a hybrid macro/micro-structure was constructed, further endowing the membrane with superhydrophobicity. The modified membranes exhibited excellent wetting-resistance properties and over 99.9 % salt rejection during vacuum membrane distillation (VMD) process. The surface wetting and anti-nucleation theory special for MD membranes was uncovered. This theory and VMD experiments synchronously indicated that the hybrid macro/micro structure with optimized nanoparticle size rendered the resulting fabricated membranes enhanced permeate flux and anti-fouling properties. The optimal L-F-3 membrane achieved high flux (16.08 kg/(m2·h)) under feed temperature of 60 °C with a water contact angle of 150° and LEP (liquid entry pressure) of 2.9 bar. Finally, the modified membranes possessed the enlarged effective evaporative surface and intensified the nucleation barrier as well as the interfacial nanoscale turbulent flow without potential scaling.

Efficient purification of high-salt rural groundwater in the areas along the Yellow River in Henan Province, China, by hollow fiber membrane distillation process

The vast rural drinking water sources along the Yellow River basin in Henan Province mainly come from the local high-salinity groundwater, which cannot be directly drunk. Zeolitic imidazolate framework-71/polyvinylidene fluoride hollow fiber composite membrane was applied to treat rural groundwater through membrane distillation technology. The variations of water quality parameters from 12 different rural regions after membrane distillation treatment were well analyzed and compared. Membrane separation performance for water samples from different regions during the membrane distillation process was investigated, including water flux and salt rejection. During a continuous 24-h membrane distillation process for the treatment of these water samples, hollow fiber membrane exhibits high solute retention rates (>99%) for salt ions, suspended solids and total dissolved solids, which are within the limits of national standards (GB 5749-2006), meanwhile membrane permeation water flux can remain stable. After the acid-cleaning for 180 min, all hollow fiber membranes can recover water flux well with a flux recovery rate above 98%. Even if the concentration ratio continued to increase, the water production rate of membrane distillation was basically maintained between 50% and 60%, which was obviously higher than the 30% of the reverse osmosis process. The economic analysis confirmed that the water production cost varied between US$0.45 and US$0.29/m3. With the extension of membrane service life, the specific membrane cost decreased rapidly in the first 6 years and then leveled off. The proposed vacuum membrane distillation process proved to be a promising water purification method for treating rural high-salinity groundwater.

Numerical Modelling and Performance Evaluation of Vacuum Membrane Distillation for Energy-Efficient Seawater Desalination: Towards Energy-Efficient Solutions

Vacuum membrane distillation (VMD) is a compelling technique for desalinating water because it exhibits superior pure water permeability at lower operating temperatures compared to other membrane distillation technologies. This leads to reduced energy consumption, lower heat loss via conduction across the membrane surface, and minimal heat transfer through conduction due to the low pressure on the permeate side. Detailed modelling of heat and mass transfer in VMD is essential for optimizing the process as it provides valuable insights that contribute to the advancement and successful implementation of seawater desalination using VMD technology. The aim of this study is to establish a comprehensive numerical model that describes the water vapor transfer across a hydrophobic micro-porous membrane in single-stage and multi-stage VMD processes for seawater desalination. The numerical predictions were compared to experimental data in addition to numerical computations based on an existing literature database, and good agreement has been found. The investigation also conducted a sensitivity analysis of process variables and membrane specifications on the VMD performance, as well as an assessment of the impact of temperature and concentration polarization. The obtained results showed that the permeation flux reached 18.42 kg/m2·h at 35 g/L feed concentration, 65 °C feed temperature, 50 L/h feed flow rate, and 3 kPa vacuum pressure. Moreover, the findings revealed that the feed temperature was the most significant factor, while the feed flow rate was the least important in determining the permeation flux. Additionally, the findings suggested that the effectiveness of the VMD process heavily relies on the composition and permeability of the support materials. Finally, the results confirmed that temperature polarization had a more significant effect on the reduction of the permeate flux than the concentration polarization.

Thermal analysis of condensation-induced vacuum and its feasibility for operating a vacuum membrane distillation system

Vacuum pumps are primarily used in vacuum membrane distillation (VMD) for vacuum generation. However, vacuum pumps are characterized by low operational durability and a high energy demand. In this study, a steam condensation process was combined with the VMD process such that the vacuum created during the steam condensation process drove the VMD operation. A thermodynamic cycle comprised of three main processes: steam purging, vacuum creation, and water recovery was described. This paper presents a detailed thermal analysis of each process of the thermodynamic cycle based on heat transfer and thermodynamic models. The modeling results are compared with experimental data. The pressure in the vacuum chamber increased during the water recovery process because of the accumulation of non-condensable gases, which permeated the chamber along with the water vapors. Consequently, the mass flux of the VMD permeate decreased, and finally, the permeation ceased when the pressure in the chamber reached ~20 kPa; after this stage, the cycle restarted. For the current experimental conditions and vacuum chamber design, the durations of the purging, vacuum creation, and recovery processes were 30, 500, and 270 s. At least three linked vacuum chambers must be synchronized and operated simultaneously to realize continuous water recovery.

Optimization of the design and operating parameters of a large-scale vacuum membrane distillation system to improve process performance

This study investigates the performance and optimal operating of a proposed large-scale vacuum membrane distillation (VMD) system with an external condenser for enhanced productivity and energy consumption. The VMD configuration reduces the resistance of vapor mass transfer across the membrane to increase its permeation rate. A comprehensive parametric analysis to evaluate the effects of various operational and design parameters of the MD module and the condenser unit has been performed. The optimized results were compared to the conventional direct-contact membrane distillation (DCMD) configuration. Results revealed that the feed temperature and flowrate have the most significant impacts on system productivity and energy consumption. Increasing the vacuum improves productivity, while increasing the membrane thickness decreases system productivity. Increasing the membrane pore diameter slightly enhances system productivity. Using smaller coil diameters for condenser and cooling the system using water at room temperature can minimize the energy consumption of the system. The proposed model outperforms the traditional DCMD unit of the same module design. The system can produce 388 L/h of freshwater, with a minimum SEC of 645 kWh/m3 at the optimum conditions. These findings demonstrate the potential of the vacuum membrane distillation process as a promising technology for water desalination treatment applications.

Simulating two Algerian cities' desalination plants coupled with solar energy systems using TRNSYS

Abstract Our study aimed to design a prototype for a desalination unit coupled with a solar collector, utilizing TRNSYS 16, to address the needs of both Bouzaréah in northern Algeria and Ghardaïa in southern Algeria. The desalination unit is composed of vacuum membrane distillation (VMD) coupled with a solar collector, and the photovoltaic has been designed according to the climatic conditions of each region. In this work, the approach adopted is to integrate a model developed in the literature into a simulation environment (TRNSYS) coupled with the CODE-BLOCKS compiler and FORTRAN programming language to create a new component (i.e., VMD process). Simulation results showed that the optimum permeation flux obtained through the desalination unit is relatively higher in Ghardaïa than in Bouzaréah, with a flow exceeding 30 kg/h.m2. The permeation flux and the power to load reached their maximum values with the charge of solar irradiation 48 kg/h.m2 and 6300 kJ/h, respectively, for Ghardaïa at the sun irradiation value 800 W/m2 and temperature of 34 °C. Results showed that Ghardaïa had a higher GOR value than Bouzaréah over the year (10.947 vs. 8.3389). Moreover, both locations recorded thermal recovery ratio values exceeding 1, indicating the high efficiency of the desalination unit.

Superhydrophobic electrospun FPI/PTFE nanofiber membranes for robust vacuum membrane distillation

In this study, we firstly proposed a fluorinated polyimide (FPI) /polytetrafluoroethylene (PTFE) nanofiber membrane for vacuum membrane distillation (VMD) by electrospinning FPI and double eletcrospraying PTFE particles. The resultant FPI /PTFE nanofiber membrane possessed desirable superhydrophobicity (water contact angle (WCA) of 155.3°), anti-wettability and durability due to the rough micro/nano structure of the membrane surface. The surface morphology and chemical composition of obtained FPI nanofiber membranes were characterized by SEM, FTIR, XRD and XPS, and the effects of PTFE content on the VMD performance were investigated. Results showed that the liquid entry pressure (LEP) of FPI/PTFE nanofiber membranes increased significantly after PTFE particles were introduced (LEP of 158 kPa). In the VMD process, the FPI/PTFE nanofiber membrane showed stable MD flux (33.49 L·m2·h−1) and excellent salt rejection (99.96%). Furthermore, the FPI/PTFE nanofiber membrane maintained its favorable performance, resulting in stable MD flux (30.21 L·m2·h−1) and salt rejection (99.96%) after the 120 h continuous long-term operation. It shows a promising future for VMD of FPI/PTFE nanofiber membranes.

Application of vacuum membrane distillation process for lithium recovery in spent lithium ion batteries (LIBs) recycling process

The feasibility of using vacuum membrane distillation (VMD) for lithium recovery by concentrating the discharged leachate from spent lithium ion batteries (LIBs) recycling process was evaluated. The performance of VMD was compared with that of direct contact membrane distillation (DCMD) in terms of water flux, concentration rate, membrane wetting, and economic feasibility. VMD achieved a higher volume concentration factor (VCF) of 45 compared to the VCF of 25 achieved by DCMD in the LiCl feed solution. In the Li2SO4 feed solution, VMD and DCMD were concentrated to VCF15 and VCF 17, respectively, before wetting occurred. The stability of the MD process was verified using feed solutions containing nickel and manganese, which are cathode materials that can cause scaling even at low concentrations. Low concentrations of nickel and manganese did not significantly affect the maximum VCF or wetting; however, high concentrations of nickel and manganese affected the stability of the MD process. VMD exhibited a higher flux and 32 % lower thermal energy consumption than DCMD. Furthermore, the expected cost of Li2CO3 production with VMD for leachate concentration was $8.31–10.65/kg. The VMD concentration process is a feasible option for recovering lithium from the discharged leachate from spent LIBs recycling process.

Prediction of sulfuric acid solution in the vacuum membrane distillation process using Artificial Neural Network

This paper presented an effective approach utilizing Artificial Neural Network (ANN) to predict the vacuum membrane distillation (VMD) process of sulfuric acid solution. Firstly, mathematical models have been developed and the influence mechanisms of critical parameters on the transfer resistance in the VMD process were explored via a simulation process. Furthermore, an ANN model from the experimental data under actual working conditions, was developed and applied to simulate the effects of critical parameters on the VMD process performance including membrane flux and gained output ratio (GOR). The simulation results revealed that decreasing feed concentration or vacuum side pressure and increasing feed temperature or feed velocity would contribute to the reduction of total transfer resistance. Then, the operation data at multiple working conditions using actual sulfuric acid solution was divided into three sets (training, validation and test) to develop the ANN model. The trained ANN model was subsequently observed to have good agreement between the predicted and experimental data. From the subsequent simulations with various variable controls, increasing feed concentration or vacuum side pressure led to the declines of membrane flux and GOR, while increasing feed temperature or feed flow rate were helpful to improve membrane flux and GOR. Obviously, the developed ANN model performed well to predict the VMD process performance with minimum error, which could be effectively utilized to predict and optimize the VMD system for industrial wastewater treatment without performing a complicated, expensive and dangerous experimental test.

Performance Assessment of Coupled Concentrated Photovoltaic-Thermal and Vacuum Membrane Distillation (CPVT-VMD) System for Water Desalination

Numerical simulations were carried out to assess the technical and economic feasibility of a solar water desalination system that has a novel hybrid Concentrating Photovoltaic Thermal (CPVT) collector coupled with a Vacuum Membrane Distillation (VMD) process. A special characteristic of this CPVT is its triangular receiver with PV cells facing the reflecting surface. This type of receiver has the advantage of generating more electricity with less PV surface area and great potential to be used to hybridize conventional parabolic thermal collectors. TRNSYS was employed to analyze the annual performance of the CPVT-VMD system evaluating parameters such as solar fraction, specific permeate production and specific energy production for different coastal cities. In the dynamic simulations, local annual weather data and specific information about the characteristics and operating conditions of a real CPVT collector and a VMD module were considered. From the parametric analysis the optimal surface area of collectors and the input temperature of the VDM module were determined. A maximum specific permeate of 218.410 m 3/m2VMD for Acapulco, MX, and a minimum of 170.365 m 3/m2VMD for Singapore, SG, were achieved for the proposed CPVT-VMD system of four solar collectors with an operating set temperature of 55 °C. An economic profit was found after 7 years for Acapulco city, which showed great potential to use solar energy from hybrid CPVT collectors for a VMD process to provide freshwater in coastal cities.

Preparation of nano-porous poly(ether ether ketone) hollow fiber membrane and its performance for desalination in vacuum membrane distillation

Nano-porous poly(ether ether ketone) (PEEK) hollow fiber membranes were successfully fabricated from PEEK/polyetherimide (PEI) blends via thermally-induced phase separation (TIPS) followed by chemical extraction of PEI method. The gas permeation rates, morphologies and mechanical properties of membranes were systematically investigated under different spinning conditions. The content of PEEK in blends substantially determined the gas permeation rates following the order: PEEK30/PEI70 (~9000 GPU) > PEEK40/PEI60 (~5100 GPU) > PEEK50/PEI50 (~1700 GPU) > PEEK60/PEI40 (~300 GPU) > PEEK70/PEI30 (below 1.0 GPU). Faster winding rates and bigger N2 bore fluid flow rates would result in bigger pores, higher porosity and larger gas permeation rates, while would cause lower mechanical strength. Furthermore, the silane-grafted hydrophobic PEEK hollow fiber membranes were successfully prepared via one-step reduction followed by silane modification. The performance of virgin and modified membranes was evaluated by treating saline feed containing 3.5 wt% sodium chloride in vacuum membrane distillation (VMD) process. Compared with virgin PEEK membrane, the modified membranes exhibited a more stable flux and higher salt rejection over 99.9 % for 33 h, indicating the significant improvement in the anti-wetting property caused by silane modification. The application attempt expands the research direction of PEEK membranes and promotes its further application potential in VMD process.

Study on the synergistic heat transfer of double boundary layers in the jacketed vacuum membrane distillation process

During the process of membrane distillation (MD) heat recovery, due to the adverse effects of the heat exchange boundary layer and membrane surface boundary layer, the latent heat is hindered in its transfer and ultimately leading to the loss of heat recovery and mass transfer capacity of the system. In this study, a novel type of jacketed hollow fiber vacuum membrane distillation module (J-HF-VMD-M) has been successfully developed. It has the dual functions of “feed evaporation” and “vapor condensation”, which is helpful in reducing the volume and complexity of the system. Based on the structural characteristics of the jacketed module, a “Synergistic heat transfer model of double boundary layers” (SHT-DBL Model) is proposed for the first time. Compared with the previous “independent heat transfer” method between boundary layers, the “synergistic heat transfer” can overcome the above challenges more effectively. Compared with the non-heat recovery process in experimental range, the equivalent membrane distillation flux of the jacketed-type heat recovery process increased by 246.1 %, especially the gain output ratio increased by 145.1 %, and the corresponding increment is more significant than that of the traditional heat recovery process.

Improved performance of vacuum membrane distillation process

Improved performance of vacuum membrane distillation process