TY - JOUR
T1 - Numerical study of desalination by vacuum membrane distillation – Transient three-dimensional analysis
AU - Anqi, Ali E.
AU - Usta, Mustafa
AU - Krysko, Robert
AU - Lee, Jung Gil
AU - Ghaffour, NorEddine
AU - Oztekin, Alparslan
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The co-author Ali E. Anqi extends his appreciation to the Deanship of Scientific Research at King Khalid University for the support he received through General Research Project under the grant number (R.G.P.1/120/40). The research reported in this paper was also supported by King Abdullah University of Science and Technology (KAUST), Saudi Arabia.
PY - 2019/10/25
Y1 - 2019/10/25
N2 - The performance of vacuum membrane distillation (VMD) modules can be optimized through careful selection of design parameters. The present study examines how the addition of cylindrical filaments in the feed channel increases momentum mixing and the overall performance of VMD modules under different operating inlet conditions. Three-dimensional transient Computational Fluid Dynamics (CFD) simulations are conducted using Wall-Adapting Local Eddy-Viscosity (WALE) subgrid-scale Large Eddy Simulation (LES) turbulence model. Local concentration, temperature, and flux are coupled at the membrane surface to predict the rate of water vapor diffused through the membrane by Knudsen and viscous diffusion mechanisms. The predicted and measured vapor flux agrees reasonably well; validating the employed model. The small-scale eddies induced by the presence of spacer filaments promote mixing in the module, thus the temperature and concentration polarization is alleviated and the water vapor flux is immensely improved. The insertions of filaments in the feed channel increase the water permeate rate by more than 50% at higher feed flow rates and inlet temperatures. The pressure drop by the spacer reduces the allowable module length by one order of magnitude, but the module length increases two folds at feed temperature 80℃. Even though the power consumption of the module containing the filaments is increased, the addition of filaments is strongly recommended since the required power for the process could be supplied from readily available low-grade heat source.
AB - The performance of vacuum membrane distillation (VMD) modules can be optimized through careful selection of design parameters. The present study examines how the addition of cylindrical filaments in the feed channel increases momentum mixing and the overall performance of VMD modules under different operating inlet conditions. Three-dimensional transient Computational Fluid Dynamics (CFD) simulations are conducted using Wall-Adapting Local Eddy-Viscosity (WALE) subgrid-scale Large Eddy Simulation (LES) turbulence model. Local concentration, temperature, and flux are coupled at the membrane surface to predict the rate of water vapor diffused through the membrane by Knudsen and viscous diffusion mechanisms. The predicted and measured vapor flux agrees reasonably well; validating the employed model. The small-scale eddies induced by the presence of spacer filaments promote mixing in the module, thus the temperature and concentration polarization is alleviated and the water vapor flux is immensely improved. The insertions of filaments in the feed channel increase the water permeate rate by more than 50% at higher feed flow rates and inlet temperatures. The pressure drop by the spacer reduces the allowable module length by one order of magnitude, but the module length increases two folds at feed temperature 80℃. Even though the power consumption of the module containing the filaments is increased, the addition of filaments is strongly recommended since the required power for the process could be supplied from readily available low-grade heat source.
UR - http://hdl.handle.net/10754/659229
UR - https://linkinghub.elsevier.com/retrieve/pii/S0376738819305319
UR - http://www.scopus.com/inward/record.url?scp=85075397839&partnerID=8YFLogxK
U2 - 10.1016/j.memsci.2019.117609
DO - 10.1016/j.memsci.2019.117609
M3 - Article
SN - 0376-7388
SP - 117609
JO - Journal of Membrane Science
JF - Journal of Membrane Science
ER -