Comparative analyses of transient batch operations of hollow-fiber DCMD and WGMD desalination systems at high salinity levels

Mahmoud B. Elsheniti*, Mohamed O. Elbessomy, Ahmed Rezk, Ahmed Fouly, Samy M. Elsherbiny, Osama A. Elsamni

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This study explores hollow-fiber membrane distillation (HFMD) as an alternative for treating high-salinity RO brines using a recirculating batch process. Water gap (WG) MD offers thermal and practical benefits that need to be compared with direct contact (DC) MD during the batch operation. A novel integrated, fully coupled transient CFD model for both HFMD configurations, HF-DCMD and HF-WGMD modules, with a zero-dimensional model for the feed tank is introduced. The model is validated against experimental data with a wide range of salinities and exhibits high accuracy with deviations lower than ±5 %. The results showed that the HF-WGMD module is more energy efficient than the HF-DCMD module despite having lower freshwater productivity and requiring longer batch operating times. At 70°C feed temperature and during the brine concentration from 70,000 to 100,000 and 233,333 ppm to get a pure water recovery ratio of 30% and 70%, the cumulative specific thermal energy consumption of the HF-WGMD module is lower than that of the HF-DCMD module by 12% and 8.2%, respectively. This is affected by an average reduction of 33.3 % in conduction heat loss with the option of a water gap during the batch process, providing an efficient means to treat concentrated brine.

Original languageEnglish
Article number118492
Number of pages21
JournalDesalination
Volume600
Early online date26 Dec 2024
DOIs
Publication statusE-pub ahead of print - 26 Dec 2024

Keywords

  • High salinity
  • Hollow fiber
  • Membrane distillation
  • Transient batch operation
  • Water gap

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