NUMERICAL STUDY OF VACUUM-AIDED SPRAY FLASH DESALINATION

Document Type

Conference Proceeding

Publication Date

1-1-2021

Abstract

Spray flash desalination is an advanced distillation method by space flash evaporation of over-saturated multi-component droplets and/or ligaments to generate the distilled condensable vapor. Vacuum-aided spray flash is spraying the superheated and atomized droplets into a depressurized chamber whose low pressure is maintained by a continued vacuum extraction of vapors, a process of high thermal non-equilibrium and of high non-uniformity in phase changes and transport. This study presents a CFD numerical simulation to quantify some of the non-equilibrium and non-uniformity characteristics in vacuum-aided spray flash distillation, especially on the temperature difference and the thermal re-equilibrium tendency between vapor and liquid residue. Since ANSYS Fluent lacks the mathematic model of self-heat supplied evaporation in discrete phase modeling (DPM), a pressure-driven flash evaporation model is proposed and implemented into CFD via User-defined functions (UDF). Preliminary results meet a good agreement with experiments. It revealed the non-uniformed characteristics of the vapor phase (i.e., distributions of temperature and velocity), as well as the thermal non-equilibrium between the two phases. It also suggests that the salt fraction within droplets will result in negative impacts on evaporating efficiency and evaporating rate during the process.

Identifier

85113318239 (Scopus)

ISBN

[9781567005172]

Publication Title

Proceedings of the Thermal and Fluids Engineering Summer Conference

External Full Text Location

https://doi.org/10.1615/TFEC2021.cnd.36274

e-ISSN

23791748

First Page

777

Last Page

787

Volume

2021-May

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