Thermodynamic optimization of a vacuum multi-effect membrane distillation system for liquid desiccant regeneration

Q. Chen, M. Kum Ja, Y. Li, K. J. Chua*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

The regenerator is one of the key components in the liquid desiccant air-conditioning system, and improvement of the regenerator performance is key to promoting the overall system energy efficiency. This study entails the investigation of a vacuum multi-effect membrane distillation system (V-MEMD) for liquid desiccant regeneration. The V-MEMD regenerator possesses the merits of high energy efficiency and zero desiccant carry-over. A thermodynamic model has been developed to study the regeneration process based on the principles of heat and mass transfer and heat and mass balances. The model is validated with experimental data, and the discrepancies are observed to be within 10% and 5% for regeneration rate and brine concentration, respectively. Employing the developed and validated model, several V-MEMD configurations have been investigated and the effects of key operating parameters are evaluated. The regenerator performance is observed to degrade at higher feed concentrations, while a higher hot water temperature promotes regeneration rate and thermal efficiency. The proposed configurations expand the operation range of the V-MEMD regenerator to greater than 40 wt% under a heat source temperature of 70 °C. Compared with existing liquid desiccant regeneration systems, the specific energy consumption is reduced by 10–50%.

Original languageEnglish (US)
Pages (from-to)960-973
Number of pages14
JournalApplied Energy
Volume230
DOIs
StatePublished - Nov 15 2018

Keywords

  • Liquid desiccant regeneration
  • Thermodynamic optimization
  • Vacuum multi-effect membrane distillation

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering
  • General Energy
  • Management, Monitoring, Policy and Law

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