Numerical study of desalination by vacuum membrane distillation – Transient three-dimensional analysis

Anqi, Ali E.; Usta, Mustafa; Krysko, Robert; Lee, Jung Gil; Ghaffour, NorEddine; Oztekin, Alparslan

Numerical study of desalination by vacuum membrane distillation – Transient three-dimensional analysis

Files

Numerical study of spacer in VMD pre-proof.pdf (6.05 MB)

Embargo End Date

2021-10-25

Type

Article

Authors

Anqi, Ali E.
Usta, Mustafa
Krysko, Robert
Lee, Jung Gil
Ghaffour, NorEddine

Oztekin, Alparslan

KAUST Department

Water Desalination and Reuse Research Center (WDRC)
Environmental Science and Engineering Program
Biological and Environmental Sciences and Engineering (BESE) Division

Online Publication Date

2019-10-25

Print Publication Date

2019-10

Date

2019-10-25

Abstract

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.

Citation

Anqi, A. E., Usta, M., Krysko, R., Lee, J.-G., Ghaffour, N., & Oztekin, A. (2019). Numerical study of desalination by vacuum membrane distillation – Transient three-dimensional analysis. Journal of Membrane Science, 117609. doi:10.1016/j.memsci.2019.117609

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.