TY - GEN
T1 - NUMERICAL STUDY OF VACUUM-AIDED SPRAY FLASH DESALINATION
AU - Guo, Guangyu
AU - Deng, Hongling
AU - Zhu, Chao
AU - Ji, Zhiming
N1 - Funding Information:
★ This work was supported by Science Foundation Ireland (Grant Number 05/IN/I886). Support from Cisco Systems and the Silicon Valley Community Foundation is gratefully acknowledged.
Publisher Copyright:
© 2021 Begell House Inc.. All rights reserved.
PY - 2021
Y1 - 2021
N2 - 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.
AB - 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.
KW - CFD
KW - multi-component evaporation
KW - non-equilibrium process
KW - spray flash desalination
KW - UDF
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U2 - 10.1615/TFEC2021.cnd.36274
DO - 10.1615/TFEC2021.cnd.36274
M3 - Conference contribution
AN - SCOPUS:85113318239
T3 - Proceedings of the Thermal and Fluids Engineering Summer Conference
SP - 777
EP - 787
BT - 5th-6th Thermal and Fluids Engineering Conference, TFEC 2021
PB - Begell House Inc.
T2 - 5th-6th Thermal and Fluids Engineering Conference, TFEC 2021
Y2 - 26 May 2021 through 28 May 2021
ER -