Energy Consumption for Brine Solution Recovery in Direct Contact Membrane Distillation

2014 ◽  
Vol 931-932 ◽  
pp. 256-260
Author(s):  
Sothyreak Chhun ◽  
Watsa Khongnakorn ◽  
Wirote Youravong

Direct contact membrane distillation (DCMD) process was applied for brine solution recovery. The energy consumption of the process was evaluated as varying feed temperature and cross flow velocity (CFV). The evaporation efficiency and energy consumption were also studied. The experiments was carried out using a hollow fiber PVDF membrane with pore size of 0.1 μm and NaCl 3.5 %wt as feed solution. The operating feed temperature and CFV were in range of 40 °C-70 °C and 0.14-0.42 m/s (laminar and transition flow region), respectively. The temperature and CFV of permeate were fixed at 20 °C and 1.97 m/s respectively. It was found that the flux rate was in function with the temperature, CFV and temperature polarization coefficient (TPC). The best result in terms of energy consumption and evaporation efficiency were obtained at CFV and temperature of 0.28 m/s and 70 °C about 188.6 W and 41.1 %, respectively.

2018 ◽  
Vol 24 (11) ◽  
pp. 18
Author(s):  
Asrar Abdullah Hassan ◽  
Ahmed Khalid Mohammed Reda

Desalination is a process where fresh water produces from high salinity solutions, many ways used for this purpose and one of the most important processes is membrane distillation (MD). Direct contact membrane distillation (DCMD) can be considered as the most prominent type from MD types according to ease of design and modus operandi. This work studies the efficiency of using DCMD operation for desalination brine with different concentration (1.75, 3.5, 5 wt. % NaCl). Frame and plate cell was used with flat sheet PTFE hydrophobic type membrane. The study proves that MD is an effective process for desalination brines with feed temperature less than 60˚C especially for feed with low TDS. 37˚C, 47˚C, and 57˚C was feed temperature and 17, 22, 27˚C as permeate temperatures used in study, temperature in both sides of membrane are recorded and TDS for permeate collected to assure that there is no penetration of brine to permeate side, the results took every 30 min for time experiment of 180 min. From results, the flux increases with increasing feed temperature and flow rate, and decreasing with increasing feed concentration, experiment time, and permeate temperature.     


Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 493
Author(s):  
Amine Charfi ◽  
Fida Tibi ◽  
Jeonghwan Kim ◽  
Jin Hur ◽  
Jinwoo Cho

This study aims to investigate the effect of operational conditions on organic fouling occurring in a direct contact membrane distillation (DCMD) system used to treat wastewater. A mixed solution of sodium alginate (SA) and bovine serum albumin (BSA) was used as a feed solution to simulate polysaccharides and proteins, respectively, assumed as the main organic foulants. The permeate flux was observed at two feed temperatures 35 and 50 °C, as well as three feed solution pH 4, 6, and 8. Higher permeate flux was observed for higher feed temperature, which allows higher vapor pressure. At higher pH, a smaller particle size was detected with lower permeate flux. A mathematical model based on mass balance was developed to simulate permeate flux with time by assuming (i) the cake formation controlled by attachment and detachment of foulant materials and (ii) the increase in specific cake resistance, the function of the cake porosity, as the main mechanisms controlling membrane fouling to investigate the fouling mechanism responsible of permeate flux decline. The model fitted well with the experimental data with R2 superior to 0.9. High specific cake resistance fostered by small particle size would be responsible for the low permeate flux observed at pH 8.


Author(s):  
Danielle Park ◽  
Elnaz Norouzi ◽  
Chanwoo Park

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.


Desalination ◽  
2017 ◽  
Vol 423 ◽  
pp. 149-156 ◽  
Author(s):  
Zhongsen Yan ◽  
Haiyang Yang ◽  
Fangshu Qu ◽  
Huarong Yu ◽  
Heng Liang ◽  
...  

Author(s):  
Mohamed R. Elmarghany ◽  
A. H. El-Shazly ◽  
Ali Radwan ◽  
Essam M. Abo-Zahhad ◽  
Norhan Nady ◽  
...  

Abstract In the present work, the performance of different cell designs used for the membrane distillation (MD) process was investigated. Three distinctive cell designs were proposed and compared. A numerical simulation using ANSYS Fluent 19 was used to study the performance of the cells. The effects of changing inlet Reynolds number on pressure drop, salt concentration and velocity contours with in the different cell deigns were investigated. Results show that the pressure drop is minimum across the first design, and the salt concentration decreases as Reynolds number increases. At Reynolds number = 125, the results show an enhanced velocity distribution compared to Reynolds number = 250 and 50. One of the proposed cell designs was then fabricated to study the effect of fluid flow on the performance in a direct contact membrane distillation system. Energy parameters were calculated to evaluate the performance of the cell. An evacuated tube solar collector was used to provide the system with hot water. System thermal efficiency, gained output ratio, and specific energy consumption analysis were performed for the system. The increase in the feed flow rate almost doubled the system thermal efficiency and the gained output ratio was increased from 0.31 to 0.60, while the specific energy consumption decreased from 2064 to 1037 kWh/m3.


Author(s):  
Anas M. Alwatban ◽  
Ahmed M. Alshwairekh ◽  
Umar F. Alqsair ◽  
Robert Krysko ◽  
Abdullah A. Alghafis ◽  
...  

Abstract Computational fluid dynamics simulations are used to model the effect of the inlet feed temperature in direct contact membrane distillation modules. Embedded spacers are used as a local mixing promoter tool. Net-type spacers of angle 45° are used as spacers. The presence of the spacers will mitigate the temperature and concentration polarization effects. The calculation of the vapor flux through the membrane is based on the Dusty-Gas model. The membrane is considered as a functional surface, and the embedded spacers are treated as impermeable surfaces. The vapor flux equation couples the variation of the vapor flux in the feed and the permeate channel with the variation of the feed concentration along the membrane. The flow is considered turbulent in channels containing embedded spacers. The k–ω SST turbulent model is used to characterize the steady-state turbulent structures inside the flow channels. The flow rate in the feed and the permeate channels is fixed. The membrane properties are also fixed. The inlet feed temperature is varying while fixing the inlet permeate temperature. The results indicate that the embedded spacers increase the vapor flux permeation while the temperature and concentration polarizations are mitigated. As the inlet feed temperature is increased, the effect of the embedded spacers becomes more significant.


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