scholarly journals Experimental Investigation on Floating Solar-Driven Membrane Distillation Desalination Modules

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 304
Author(s):  
Qingxiu Miao ◽  
Yaoling Zhang ◽  
Shuo Cong ◽  
Fei Guo
Keyword(s):  
Power Source ◽  
Membrane Distillation ◽  
Small Scale ◽  
Sea Waves ◽  
Permeate Flux ◽  
Practical Application ◽  
Rejection Ratio ◽  
Cold Source ◽  
Mild Temperature ◽  
Feed Temperature

Membrane distillation (MD) processes need a relatively mild temperature gradient as the driving force for desalination. In the field, it is reasonable to utilize solar energy as the heat source for the feed, and seawater as the infinite cold source for condensation. Solar-driven MD provides a route for the practical application of seawater desalination at a small scale. In this work, we focus on floating MD modules with a solar heating bag as the power source, and perform proof-of-principle experiments on the MD performance under various conditioning parameters, including feed flow rate, feed temperature, salinity, air gap, and sea waves. The results indicate that floating solar-driven MD modules are feasible in terms of permeate flux and salt rejection ratio, and the upward evaporation MD configuration leads to a better performance in terms of permeate flux. The simulation and experiments also show that the natural sea waves disturb the heating bag and the MD module floating on the surface of seawater, and effectively enhance the feed circulation and transport in the system.

scholarly journals A Comparison Study of Brine Desalination using Direct Contact and Air Gap Membrane Distillation

2019 ◽  
Vol 25 (11) ◽  
pp. 47-54
Author(s):  
Ahmed Shamil Khalaf ◽  
Asrar Abdullah Hassan
Keyword(s):  
Flow Rate ◽  
Direct Contact ◽  
Polyvinylidene Fluoride ◽  
Membrane Distillation ◽  
Air Gap ◽  
Feed Flow Rate ◽  
Permeate Flux ◽  
Air Gap Membrane Distillation ◽  
Flat Sheet ◽  
Feed Temperature

Membrane distillation (MD) is a hopeful desalination technique for brine (salty) water. In this research, Direct Contact Membrane Distillation (DCMD) and  Air Gap Membrane Distillation (AGMD) will be used. The sample used is from Shat Al –Arab water (TDS=2430 mg/l). A polyvinylidene fluoride (PVDF) flat sheet membrane was used as a flat sheet form with a plate and frame cell. Several parameters were studied, such as; operation time, feed temperature, permeate temperature, feed flow rate. The results showed that with time, the flux decreases because of the accumulated fouling and scaling on the membrane surface. Feed temperature and feed flow rate had a positive effect on the permeate flux, while permeate temperature had a reverse effect on permeate flux. It is noticeable that the flux in DCMD is greater than AGMD, at the same conditions. The flux in DCMD is 10.95LMH, and that in AGMD is 7.14 LMH.  In AGMD, the air gap layer made a high resistance. Here the temperature transport reduces in the permeate side of AGMD due to the air gap resistance. The heat needed for AGMD is lower than DCMD, this leads to low permeate flux because the temperature difference between the two sides is very small, so the driving force (vapor pressure) is low.                                                                                               

scholarly journals Performance Investigation of O-Ring Vacuum Membrane Distillation Module for Water Desalination

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Adnan Alhathal Alanezi ◽  
H. Abdallah ◽  
E. El-Zanati ◽  
Adnan Ahmad ◽  
Adel O. Sharif
Keyword(s):  
Flow Rate ◽  
Membrane Distillation ◽  
Membrane Module ◽  
Water Desalination ◽  
Feed Flow Rate ◽  
Permeate Flux ◽  
Vacuum Degree ◽  
Flat Sheet ◽  
Vacuum Membrane Distillation ◽  
Feed Temperature

A new O-ring flat sheet membrane module design was used to investigate the performance of Vacuum Membrane Distillation (VMD) for water desalination using two commercial polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) flat sheet hydrophobic membranes. The design of the membrane module proved its applicability for achieving a high heat transfer coefficient of the order of 103 (W/m2 K) and a high Reynolds number (Re). VMD experiments were conducted to measure the heat and mass transfer coefficients within the membrane module. The effects of the process parameters, such as the feed temperature, feed flow rate, vacuum degree, and feed concentration, on the permeate flux have been investigated. The feed temperature, feed flow rate, and vacuum degree play an important role in enhancing the performance of the VMD process; therefore, optimizing all of these parameters is the best way to achieve a high permeate flux. The PTFE membrane showed better performance than the PVDF membrane in VMD desalination. The obtained water flux is relatively high compared to that reported in the literature, reaching 43.8 and 52.6 (kg/m2 h) for PVDF and PTFE, respectively. The salt rejection of NaCl was higher than 99% for both membranes.

Experimental and Numerical Study of Water Distillation Performance of Small-Scale Direct Contact Membrane Distillation System

2017 ◽  
Author(s):  
Danielle Park ◽  
Elnaz Norouzi ◽  
Chanwoo Park
Keyword(s):  
Water Temperature ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Small Scale ◽  
Feed Water ◽  
Water Production ◽  
Water Distillation ◽  
Direct Contact Membrane Distillation ◽  
Feed Temperature ◽  
Feed Water Temperature

A small-scale Direct Contact Membrane Distillation (DCMD) system was built to investigate its water distillation performance for varying inlet temperatures and flow rates of feed and permeate streams, and salinity. A counterflow configuration between the feed and permeate streams was used to achieve an efficient heat exchange. A two-dimensional Computational Fluid Dynamics (CFD) model was developed and validated using the experimental results. The numerical results were compared with the experiments and found to be in good agreement. From this study, the most desirable conditions for distilled water production were found to be a higher feed water temperature, lower permeate temperature, higher flow rate and less salinity. The feed water temperature had a greater impact on the water production than the permeate water temperature. The numerical simulation showed that the water mass flux was maximum at the inlet of the feed stream where the feed temperature was the highest and rapidly decreased as the feed temperature decreased.

scholarly journals Performances of air gap and water gap MD desalination modules

2018 ◽  
Vol 13 (1) ◽  
pp. 200-209 ◽  
Author(s):  
Atia E. Khalifa
Keyword(s):  
Specific Energy Consumption ◽  
Membrane Distillation ◽  
Air Gap ◽  
Dominant Factor ◽  
Feed Water ◽  
Permeate Flux ◽  
Hydrophobic Membrane ◽  
Air Gap Membrane Distillation ◽  
Gap Width ◽  
Feed Temperature

Abstract Membrane distillation (MD) is a promising thermally-driven membrane separation technology for water desalination. In MD, water vapor is being separated from the hot feed water solution using a micro-porous hydrophobic membrane, due to the difference in vapor pressures across the membrane. In the present work, experiments are conducted to compare the performance of water gap membrane distillation (WGMD) and air gap membrane distillation (AGMD) modules under the main operating and design conditions including the feed and coolant temperatures, membrane material and pore sizes, and the gap width. Results showed that the WGMD module produced higher fluxes as compared to the AGMD module, for all test conditions. The feed temperature is the dominant factor affecting the system flux. The permeate flux increases with reducing the gap width for both water and air gap modules. However, WGMD module was found to be less sensitive to the change in the gap width compared to the AGMD module. The PTFE membrane produced higher permeate flux as compared to the PVDF membrane. Bigger mean pore diameter enhanced the permeate flux, however, this enhancement is marginal at high feed temperatures. With increasing the feed temperature, the GOR values increase and the specific energy consumption decreases.

scholarly journals Kapok Fibre as Membrane Distillation for Humic Acid Wastewater Treatment

2019 ◽  
Vol 8 (11) ◽  
pp. 786-789
Keyword(s):  
Wastewater Treatment ◽  
Humic Acid ◽  
Physical Properties ◽  
Pure Water ◽  
Membrane Distillation ◽  
Absorption Test ◽  
Permeate Flux ◽  
Hydrophobic Properties ◽  
Thermal Desalination ◽  
Feed Temperature

Membrane distillation (MD) is a process of combining membrane with thermal desalination where it operates at two different temperatures which are hot and cold. A vapour pressure resulted between the temperature differences of two sides of the membrane is called permeate flux. In this study, kapok fibre, which provides hydrophobic properties, has been chosen as an alternative solution for synthetic membrane in the MD process. Therefore, the primary purpose of this research is to investigate the effect of feed temperature ranging from 40 to 70℃ towards the separation of pure water from humic acid (HA) wastewater. An experimental investigation for the performance of vacuum membrane distillation (VMD) system was performed to treat the HA wastewater to produce pure water. The experimental set up of VMD was set with kapok fibre acting as a barrier that separates the collected pure water from HA wastewater, which is conducted for four hours. Based on this study, the increase in the amount of calculated permeate flux correlates to the increase of feed temperature. The calculated permeate flux is 0.237 kgh-1m -2 at the temperature of 40℃. The amount of calculated flux increases steadily to 0.4 and 0.6 kgh-1m -2 respectively for every 10℃ increments. Furthermore, the physical properties of kapok fibre were analysed by using a scanning electron microscope (SEM). Surface morphology of the kapok fibre at the condition of before and after the MD process were studied without subjecting any chemical treatment on it. Accordingly, the physical properties of the kapok fibre were seen different after the MD process conducted. Additionally, the hydrophobic properties of the kapok fibre were evaluated by using an absorption test. The absorption test was conducted at varies temperature, which results in the highest percentage of absorptivity 4.823 % at 60℃. The hydrophobic kapok fibre has shown excellent properties that can be applied in the MD process and utilised in wastewater treatment.

scholarly journals A Numerical Simulation of Membrane Distillation Treatment of Mine Drainage by Computational Fluid Dynamics

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3403
Author(s):  
Ji Qi ◽  
Jiafeng Lv ◽  
Zhen Li ◽  
Wei Bian ◽  
Jingfeng Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mine Water ◽  
Membrane Distillation ◽  
Transfer Efficiency ◽  
Permeate Flux ◽  
Heat Transfer Efficiency ◽  
Temperature Polarization ◽  
Feed Temperature

Membrane distillation (MD) is a promising technology to treat mine water. This work aims to investigate the change in mass and heat transfer in reverse osmosis mine water treatment by vacuum membrane distillation (VMD). A 3D computational fluid dynamics (CFD) model was carried out using COMSOL Multiphysics and verified by the experimental results. Then, response Surface Methodology (RSM) was used to explore the effects of various parameters on the permeate flux and heat transfer efficiency. In terms of the influence degree on the permeation flux, the vacuum pressure > feed temperature > membrane length > feed temperature membrane length, and the membrane length has a negative correlation with the membrane flux. Increasing the feed temperature can also increase the convective heat transfer at the feed side, which will affect the heat transfer efficiency. Furthermore, the feed temperature also has a critical effect on the temperature polarization phenomenon. The temperature polarization becomes more notable at high temperatures.

scholarly journals Direct Contact Membrane Distillation for Separation of Hcl From A Mixture of Acids

2018 ◽  
Vol 24 (6) ◽  
pp. 41
Author(s):  
Assrar Abdullah Hassan ◽  
Hala Adel Jabbar
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Polyvinylidene Fluoride ◽  
Sulfuric Acid Concentration ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Feed Concentration ◽  
Flux Increase ◽  
Hcl Concentration ◽  
Feed Temperature

HCl is separated from HCl –H2SO4  solution by membrane distillation process(MD). The flat –sheet membranes made from polyvinylidene fluoride (PVDF) and polypropylene (pp.). Plate and frame these types of membrane where used in the process. The feed is a mixture of HCl and H2SO4 acids compositions depended on metals treated object.HCl concentration increased in the permeate during the process but sulfuric acid increased gradually in the feed .During the concentration of solution acids concentrations in the feed at the beginning were 50 g/dm3 of sulfuric acid and 50 g/dm3 of hydrochloric acid at 333K feed temperature the permeate flux was 71 dm3/m2.d. At a higher  concentration of HCl  in the feed  111g /dm3  and 61 g/ dm3 of sulfuric acid  at the feed temperature 333K  volume permeate flux was 57 dm3/ m2.d . At a higher concentration of  sulfuric acid  in the feed 161 g/dm3 and 60 g/dm3 of HCl decrease the permeate flux from 71 to 35 dm3/m2.d at 333K . The permeate flux increase from 35 at 333K to 85 at 343 K increase the temperature caused an increase in permeate flux. Increases in sulfuric acid concentration from 50 to 161 g/dm3 decrease the volume permeate flux from 71 to 35 dm3 /m2.d, HCl concentration was achieved a higher value 9.1 g/dm3 during the process at the feed concentration 161g/dm3 of sulfuric acid and 60g/dm3 of hydrochloric acid at feed temperature 343K.  

scholarly journals A Systematic Framework for Optimizing a Sweeping Gas Membrane Distillation (SGMD)

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 254
Author(s):  
Nawras N. Safi ◽  
Salah. S. Ibrahim ◽  
Nasser Zouli ◽  
Hasan Shaker Majdi ◽  
Qusay F. Alsalhy ◽  
...  
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Membrane Distillation ◽  
Feed Flow Rate ◽  
Permeate Flux ◽  
Gas Flow Rate ◽  
Feed Concentration ◽  
Sweeping Gas ◽  
Feed Temperature ◽  
Systematic Framework

The present work has undertaken a meticulous glance on optimizing the performance of an SGMD configuration utilized a porous poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) membrane. This was carried out by conducting a systematic framework for investigating and optimizing the pertinent parameters such as sweeping gas flow rate, feed temperature, feed concentration and feed flow rate on the permeate flux. For this purpose, the Taguchi method and design of experiment techniques were harnessed to statistically determine optimum operational conditions. Besides that, a comprehensive surface and permeation characterization was conducted against the hand-made membranes. Results showcased that the membrane performance was ultimately controlled by the feed temperature and was nearly (~680) % higher when the temperature raised from 45 to 65 °C. Also, to a lesser extent, the system was dominated by the feed flow rate. As the adopted feed flow rate increases (from 0.2 to 0.6 L/min), around 47.5% increment was bestowed on water permeability characteristics. In contra, 34.5% flux decline was witnessed when higher saline feed concentration (100 g/L) was utilized. In the meantime, with raising the sweeping gas flow rate (from 120 to 300 L/h), the distillate was nearly 129% higher. Based on Taguchi design, the maximum permeate flux (17.3 and 17 kg/m2·h) was secured at 35 g/L, 0.4 L/min, 65 °C and 300 L/h, for both commercial and prepared membranes, respectively.

Experimental study of multi-effect membrane distillation (MEMD) for treatment of water containing inorganic salts

2016 ◽  
Vol 11 (4) ◽  
pp. 765-773 ◽  
Author(s):  
Bhausaheb L. Pangarkar ◽  
Samir K. Deshmukh ◽  
Prashant V. Thorat
Keyword(s):  
Flow Rate ◽  
Separation Efficiency ◽  
Operating Time ◽  
Specific Energy Consumption ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Carbonate Solutions ◽  
Inorganic Solutes ◽  
Latent Heat Of Vaporization ◽  
Feed Temperature

A novel multi-effect membrane distillation (MEMD) process has been implemented to treat water containing four different inorganic solutes. The 4-stage MEMD module was developed based on the air-gap configuration. The influence of operating parameters like concentration, feed temperature, flow rate and operating time on permeate fluxes of zinc sulfate, sodium fluoride, magnesium chloride and sodium carbonate solutions was observed. Concentration had negligible effect on the MEMD's permeate flux, while its performance increased with increasing feed temperature and flow rate. Its separation efficiency was stable at more than99.91% throughout the experiment. In addition, its specific energy consumption after the recovery of the latent heat of vaporization and sensible heat of brine was measured at different component concentrations and found to be independent of the type of component.

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