Review on CFD analysis of horizontal falling film evaporators in multi-effect desalination plants

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Abstract

Desalination is a sustainable solution for water stressed countries. Among thermal desalination technologies, multi-effect desalination (MED) offers lower specific energy consumption. Falling film evaporators are extensively used in MED plants. This type of evaporator can achieve higher overall heat transfer coefficient and requires low liquid charge. The major challenges in these evaporators are (i) attaining uniform liquid load over tube bundle to avoid dry patches and scale formation, and (ii) achieving higher overall heat transfer coefficient. Although, experiments can characterize on a macroscopic scale, for microscopic understanding detailed numerical analyses is needed. This study focuses on critically analyzing the CFD works for MED falling film evaporator available in the literature. CFD modeling and methodologies have been presented followed by identification of key research gaps based on comprehensive discussion on hydrodynamics and heat/mass transfer aspects of falling film evaporators. The effects of thermophysical properties variation for broadening the operating range of MED plants, scale formation, CO2 release, liquid load maldistribution outside tubes, uneven vapor flow inside vapor box and vapor flow in co-current/cross direction need more insight. Addressing these research gaps could assist in the development of optimum evaporator design with higher overall heat transfer coefficient, improved wettability and less susceptibility to scale formation can guarantee the evaporator performance.

Original languageEnglish
Pages (from-to)296-320
Number of pages25
JournalDesalination and Water Treatment
Volume166
DOIs
Publication statusPublished - Oct 2019

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Keywords

  • CFD
  • Desalination
  • Evaporator
  • Falling film
  • MED

ASJC Scopus subject areas

  • Water Science and Technology
  • Ocean Engineering
  • Pollution

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