Performance improvement of countercurrent-flow direct contact membrane distillation in seawater desalination systems

2013 ◽  
Vol 51 (25-27) ◽  
pp. 5113-5120 ◽  
Author(s):  
Chii-Dong Ho ◽  
Tz-Jin Yang ◽  
Yu-Chuan Chuang
Keyword(s):  
Performance Improvement ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Countercurrent Flow ◽  
Seawater Desalination ◽  
Direct Contact Membrane Distillation

scholarly journals Distillate Flux Enhancement of Direct Contact Membrane Distillation Modules with Inserting Cross-Diagonal Carbon-Fiber Spacers

Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 973
Author(s):  
Chii-Dong Ho ◽  
Luke Chen ◽  
Jun-Wei Lim ◽  
Po-Hung Lin ◽  
Pin-Tsen Lu
Keyword(s):  
Carbon Fiber ◽  
Direct Contact ◽  
Pure Water ◽  
Water Productivity ◽  
Membrane Distillation ◽  
Design Parameters ◽  
Countercurrent Flow ◽  
Flux Enhancement ◽  
Direct Contact Membrane Distillation ◽  
Theoretical Predictions

A new design of direct-contact membrane distillation (DCMD) modules with cross-diagonal carbon-fiber spacers of various hydrodynamic angles in flow channels to promote turbulence intensity was proposed to enhance pure water productivity. Attempts to reduce the temperature polarization coefficient were achieved by inserting cross-diagonal carbon-fiber spacers in channels, which create wakes and eddies in both heat and mass transfer behaviors to enhance the permeate flux enhancement. A simplified equation was formulated to obtain the theoretical predictions of heat transfer coefficients in the current DCMD device. The permeate fluxes and temperature distributions of both hot and cold feed streams are represented graphically with the inlet volumetric flow rate and inlet temperature of the hot saline feed stream as parameters. The higher distillate flux of countercurrent-flow operations for saline water desalination was accomplished as compared to the concurrent-flow operations of various hydrodynamic angles. The results show that the agreement between the theoretical predictions and experimental results is reasonably good. The effects of countercurrent-flow operations and inserting carbon fiber spacers have confirmed technical feasibility and device performance enhancement of up to 45%. The influences of operating and design parameters on the pure water productivity with the expense of energy consumption are also discussed.

scholarly journals Seawater Desalination Based on a Bubbling and Vacuum-Enhanced Direct Contact Membrane Distillation

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Guangfu Cao ◽  
Qingfen Ma ◽  
Jingru Li ◽  
Shenghui Wang ◽  
Chengpeng Wang ◽  
...  
Keyword(s):  
Production Rate ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Published Data ◽  
Water Production ◽  
Permeate Flux ◽  
Seawater Desalination ◽  
Noncondensable Gas ◽  
Direct Contact Membrane Distillation ◽  
Water Production Rate

A Bubbling and Vacuum-enhanced direct contact membrane distillation (BVDCMD) is proposed to improve the water production rate of the direct contact membrane distillation (DCMD-)based seawater desalination process. Its heat and mass transfer mechanism are theoretically analyzed, and a CFD model is established, which is verified by the published data. Four types of the noncondensable gas, “O2,” “air,” “N2,” and “H2,” are adopted as the bubbling gas, and their process enhancements under different pressure of permeate side, temperature, and NaCl concentration of feed side and flow velocities are investigated. The results show that the permeate flux increased remarkably with the decrease in the viscosity of the bubbling gas, and hence, “H2” is the best option for the bubbling gas, with the permeate flux being enhanced by 144.11% and the effective heat consumption being increased by 20.81% on average. The effective water production rate of BVDCMD is predicted to be 42.38% more than that of DCMD, proving its feasibility in the seawater desalination.

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