scholarly journals Enhancement of the air gap membrane distillation system performance by using the water gap module

2020 ◽  
Vol 20 (7) ◽  
pp. 2884-2902
Author(s):  
Mostafa Abd El-Rady Abu-Zeid ◽  
Xiaolong Lu ◽  
Shaozhe Zhang
Keyword(s):  
Membrane Distillation ◽  
Air Gap ◽  
Operating Conditions ◽  
Coolant Temperature ◽  
Concentration Boundary ◽  
Air Gap Membrane Distillation ◽  
Distillation System ◽  
Negative Effect ◽  
In Series ◽  
Output Ratio

Abstract The negative effect of an air gap layer presented between the membrane and cooling plate on air gap membrane distillation (AGMD) performance was diminished largely by inserting a water gap membrane distillation (WGMD) module in series. The new design of air-gap–water-gap membrane distillation (AG-WG)MD was evaluated experimentally by comparing with an AGMD system under different operating conditions. In theory, mass and heat transfer in the new (AG-WG)MD and imitative AGMD systems were analyzed. Experimental outcomes showed that a new (AG-WG)MD design profoundly enhanced flux (Pd) and gained output ratio (GOR), and greatly decreased energy consumption (STEC) and heat input (EH.I). At a concentration of 5,000 mg/L, coolant temperature of 20 °C, and flow rate of 18 L/h, Pd was promoted by 76.26%, 40.84%, 35.45%, 30.91%, and GOR by 46.38%, 33.46%, 31.27%, 26.65%, in addition to STEC being reduced about 55.63%, 46.81%, 43.66%, 38.30%, and EH.I around 31.31%, 25.84%, 23.53%, 20.55%, from the AGMD to (AG-WG)MD system at feed temperatures of 50 °C, 60 °C, 70 °C, and 80 °C, respectively. The outcomes proved that the AGMD performance could be significantly promoted by integrating with WGMD in a combined MD system. This combination increased the temperature difference across the membrane and decreased thermal-concentration boundary layers for the AGMD system.

Experimental Study and Numerical Simulation of the Air Gap Membrane Distillation (AGMD) Process

2016 ◽  
Vol 11 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Ehsan Karbasi ◽  
Javad Karimi-Sabet ◽  
J. Mohammadi Roshandeh ◽  
M. A. Moosavian ◽  
H. Ahadi
Keyword(s):  
Numerical Simulation ◽  
Membrane Surface ◽  
Membrane Distillation ◽  
Air Gap ◽  
Operating Conditions ◽  
Permeate Flux ◽  
Air Gap Membrane Distillation ◽  
Temperature Polarization ◽  
Output Ratio ◽  
Cfd Method

Abstract Some challenges, including inappropriate distribution of currents on the membrane surface, poor hydrodynamics and existing severe temperature polarization (TP) phenomenon in MD modules, impede industrialization of MD process. Computational fluid dynamics (CFD) method was used for numerical simulation of hydrodynamics in air gap membrane distillation modules. One of two simulated modules in this work is a novel developed one in which heat and mass transfer data was compared with available literature data. Moreover, the effect of using baffles in module was investigated. Comparison between the novel module and conventional module indicates higher trans-membrane mass flux and gained output ratio (GOR) coefficient by 7% and 15%, respectively. Moreover, the effects of different operating conditions including feed temperatures and feed flow rates on permeate flux were investigated.

scholarly journals Experimental analysis of a novel helical air gap membrane distillation system

2021 ◽  
Author(s):  
Vandita T. Shahu ◽  
S. B. Thombre
Keyword(s):  
Flow Rate ◽  
Experimental Analysis ◽  
Membrane Distillation ◽  
Air Gap ◽  
Operating Conditions ◽  
Coolant Temperature ◽  
Feed Water ◽  
Air Gap Membrane Distillation ◽  
Feasible Solutions ◽  
Water Problems

Abstract Membrane distillation presents one of the feasible solutions to fresh water problems. The present study aims to develop an innovative Helical Air Gap Membrane Distillation (HAGMD) system and to analyze its behavior under different operating conditions. In this design the condenser is made up of a cylindrical copper tube with continuous helical fins over it, that increases the total available condensation area by almost 45% and enhances the overall heat transfer throughout the module. The presence of fins in the gap also reduces the total air gap width by almost 64%and therefore improves the flux production. A detailed experimental analysis is carried out for a better understanding of the underlying phenomenon. The effect of feed water temperature, feed flow rate, cold flow rate, coolant temperature and feed salinity on the performance of HAGMD is investigated experimentally. The analysis shows that the finned condenser results in very high flux. The maximum flux obtained from the system was 20 kg/m2 hr with feed of 5gm/liter salinity and a diving force temperature difference of 45 °C.

scholarly journals Enhanced production from an Air Gap Membrane Distillation Desalination system by varying the feed entry angle

2021 ◽  
Vol 945 (1) ◽  
pp. 012026
Author(s):  
Rubina Bahar ◽  
Mohammad Jabed Perves Bappy
Keyword(s):  
Membrane Distillation ◽  
Air Gap ◽  
Coolant Temperature ◽  
Entry Angle ◽  
Hydrophobic Membrane ◽  
Flow Angle ◽  
Enhanced Production ◽  
Air Gap Membrane Distillation ◽  
Scale Unit ◽  
Feed Temperature

Abstract The membrane distillation (MD) process is an evaporative metho driven by the partial pressure difference between two different temperature solutions, namely the hot feed and the coolant. The hot feed evaporates, and the vapour gets condensed to the cooler side. A hydrophobic membrane maintains the evaporating surface. Air Gap Membrane Distillation(AGMD) separates the hot feed from the coolant by a narrow air gap and a coolant plate. The condensate forms on the coolant plate, and the air gap works as an insulation for the heat loss through the membrane. The salient parameters like feed temperature, coolant temperature, and air gap thickness have already been identified through research in previous years. In this study, an innovative technique has been tested to minimize the polarization and increase the production from an AGMD lab-scale unit. The effect of the feed flow entry angle has been investigated. Also, the combined effect of inclined flow entry and a finned coolant surface has been studied. It has been found from the experiments that with a feed flow entry angle of 60°, the system shows an average of 10% to 14% boost in performance. When 60° inlet flow angle and finned coolant plate work in combination, an average of 69% to 78% increase of distillate flux was observed with the same energy input.

Modeling and optimization of air gap membrane distillation system for desalination

Desalination ◽  
2014 ◽  
Vol 354 ◽  
pp. 68-75 ◽  
Author(s):  
Qingfeng He ◽  
Pingli Li ◽  
Hongxin Geng ◽  
Chunyao Zhang ◽  
Juan Wang ◽  
...  
Keyword(s):  
Membrane Distillation ◽  
Air Gap ◽  
Modeling And Optimization ◽  
Air Gap Membrane Distillation ◽  
Distillation System

Heuristic Optimization Techniques for Air Gap Membrane Distillation System

2017 ◽  
Vol 42 (5) ◽  
pp. 1951-1965 ◽  
Author(s):  
Atia E. Khalifa ◽  
Binash A. Imteyaz ◽  
Dahiru U. Lawal ◽  
Mohamed A. Abido
Keyword(s):  
Membrane Distillation ◽  
Air Gap ◽  
Optimization Techniques ◽  
Heuristic Optimization ◽  
Air Gap Membrane Distillation ◽  
Distillation System

Experimental Study on a Multi-stage Air Gap Membrane Distillation (AGMD) Unit

2014 ◽  
Vol 69 (9) ◽  
Author(s):  
Rubina Bahar ◽  
M. N. A. Hawlader ◽  
K. C. Ng ◽  
Yee Jiun Haw
Keyword(s):  
Polyvinylidene Fluoride ◽  
Energy Use ◽  
Membrane Distillation ◽  
Air Gap ◽  
Coolant Temperature ◽  
Hydrophobic Membrane ◽  
Operating Variables ◽  
Water Power ◽  
Air Gap Membrane Distillation ◽  
Multi Stage

Membrane distillation (MD) is a separation process that involves vapour transport through a hydrophobic membrane. The evaporation is caused by the partial pressure difference between a hot fluid and cold fluid/surface. In this study, an air gap MD (AGMD) process is utilized to produce freshwater from saline solution. A multi-stage AGMD unit with 0.45 mm pore size Polyvinylidene Fluoride (PVDF) membranes is built and experiments have been carried out with different operating variables including feed temperature, coolant temperature, air gap width and feed inlet concentration.A maximum of 12.9 kg/m2 of distillate flux was obtained per kWh energy input from the multi-stage MD unit while for a previously built single-stage MD unit, the highest water/power ratio obtained was only 2.3 kg /m2 kWh. This variation indicates that multistaging is necessary for efficeint energy use in MD system. 

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