CFD simulation on membrane distillation of NaCl solution

Xu, Zhaoguang; Pan, Yanqiu; Yu, Y.-L.

doi:10.1007/s11705-009-0204-7

Cited by 37 publications

(13 citation statements)

References 8 publications

(7 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed some very well focused experiments were presented in this work in which it was already highlighted the influence that geometrical parameters such as flow cross section and channel's characteristic length could have on the formation of T-polarisation, showing in particular how, even at low Reynolds numbers, small channel equivalent diameters could reduce dramatically polarisation, thus without significantly enhancing pressure drops and energy losses. CFD tools have been adopted by Cipollina et al to simulate the thermo fluid dynamic inside spacer filled channels [15] or, by Xu et al, in tubular MD channels [16], finding in both cases that higher velocities reduce temperature polarisation by enhancing the heat transfer coefficients. In particular the former study underlined how in asymmetrical spacers, temperature polarisation is increased by transversal filaments, which create calm zones behind them.…”

Section: Cfd Modelling Of Spacer-filled Channelsmentioning

confidence: 99%

Membrane distillation heat transfer enhancement by CFD analysis of internal module geometry

Cipollina¹,

Micale²,

Rizzuti³

2011

Desalination and Water Treatment

View full text Add to dashboard Cite

Module geometry optimisation can be a crucial matter in all separation processes using selective or hydrophobic membranes, e.g. Reverse Osmosis (RO), Membrane Distillation (MD). In fact the choice of suitable channel shape and size can dramatically affect the performance of the process. With reference to the membrane distillation process, temperature polarization phenomena and pressure drops along the channels largely affect the process efficiency (i.e. the efficient use of temperature driving force for the passage of vapour through the membrane) as well as pressure distribution, module mechanical resistance and pumping costs.Several works have been presented so far in literature on the fluid flow characterization of spacer-filled channels for the case of Reverse Osmosis modules, but only few works deal with the problem of MD modules optimization.The present work aims at the CFD simulation of the fluid flow and temperature fields within spacer-filled MD module channels for a variety of spacer geometries. Both commercial and custom made geometries have been simulated in order to identify the most important parameters affecting process efficiency. The commercial CFD code ANSYS CFX11.0 has been adopted to perform simulations.Results provide valuable information to identify the main features which an optimised spacer should possess in order to minimise T-polarization and pressure drops along the channel.

show abstract

Section: Cfd Modelling Of Spacer-filled Channelsmentioning

confidence: 99%

Membrane distillation heat transfer enhancement by CFD analysis of internal module geometry

Cipollina¹,

Micale²,

Rizzuti³

2011

Desalination and Water Treatment

View full text Add to dashboard Cite

show abstract

“…However, the heat-transfer model developed in this study was over-simplified being based on non-porous and rigid shell and tube heat exchangers, which are not coupled with the mass transfer and phase changes. Moreover, these prior simulation studies only focused on mass-and/or heat-transfer improvement by designing better flow channels or incorporating spacers for both non-MD and MD flat sheet or spiral wound membrane modules [37][38][39][40][41][42]. Thus far, CFD analysis for process modeling in hollow fiber MD modules has been limited to our previous work [33,43].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations

Yang

Wang

et al. 2012

Journal of Membrane Science

View full text Add to dashboard Cite

As an extended exploration of process enhancing strategies, nine modified hollow fiber modules with various turbulence promoters were designed and modeled using a two dimensional computational fluid dynamic (CFD) heat-transfer model to investigate their potential in improving heat transfer and module performance for a shell-side feed direct contact membrane distillation (DCMD) system.With the aids of turbulence promoters, the feed heat-transfer coefficient h f of the modified modules generally showed much slower decreasing trends along the fiber length compared to the original (unmodified) module. A 6-fold h f enhancement could be achieved by a modified module with annular baffles and floating round spacers. Consistently, the temperature polarization coefficient (TPC) and mass flux distribution curves of these modified modules presented increasing trends and gained an optimal improvement of 57% and 74%, respectively.With the local flow fields and temperature profiles visualized in CFD simulations, it was confirmed that an appropriate selection of turbulence promoters could promote intense secondary flows and radial mixing to improve the shell-side hydrodynamics and enhance heat transfer. Moreover, an increase of flow velocity was used and compared as a conventional approach to improve hydrodynamics. It was found that a well-designed module could bring more significant enhancement for a liquid-boundary layer dominant heat-transfer process.Finally, the hydraulic energy consumption (HEC) caused by the insertion of turbulence promoters or the increase of circulating velocity was compared. Configurations with attached quad spacers or floating round spacers achieved a good compromise between enhanced permeation fluxes and modest HECs. Overall, the TPC decreases with increasing MD coefficient (C) values and operating temperatures; while the thermal efficiency increases dramatically with increasing C and operating temperatures in a MD system.

show abstract

“…26,27 Recently, computational fluid dynamics (CFD) has grown to be an important simulation tool with which to study the heat, mass and momentum transport phenomena in complicated designs. 4,28,29 Many researchers [30][31][32][33] have claimed that CFD is helpful not only for designing various processes by reducing the cost and extent of experiments, but also in determining processes or operating parameters that are not feasible in the experiments.…”

Section: Introductionmentioning

confidence: 99%

Experimental and mathematical study of air gap membrane distillation for aqueous HCl azeotropic separation

Kalla

Upadhyaya

Singh

et al. 2018

J of Chemical Tech & Biotech

View full text Add to dashboard Cite

BACKGROUND In the present study, the feasibility of air gap membrane distillation (AGMD) process is investigated for breaking an azeotropic mixture. A test cell AGMD module with hydrophobic PTFE membrane was fabricated and HCl/H2O azeotrope (20.2 wt% HCl) was taken as feed. A mathematical model based on Stefan diffusion multicomponent molecular‐Knudsen mass transfer approach has been developed and validated with experimental data. The effects of different process parameters on total permeate flux, on selectivity and on breaking an HCl/H2O azeotrope mixture also have been studied. The feed side membrane surface temperature and membrane side condensing surface temperature were estimated by CFD modelling. RESULTS The HCl selectivity obtained in the permeate was <1, which indicates that permeate flux is leveraged with water and a higher HCl concentration in the retentate was achieved relative to the permeate. The permeate flux decreased from 36 to 17 kg m−2 h−1 upon increasing the air gap from 3 mm to 11 mm at 50 °C feed temperature. The permeate flux increased from 4 to 28.5 kg m−2 h−1 upon increasing the feed temperature from 30 to 50 °C at 5 mm air gap. CONCLUSION With azeotropic feed, the maximum concentration of HCl achieved in the retentate was 30.8 wt% HCl (i.e. a hyperazeotropic solution) and in permeate was found to be 15.29 wt% HCl (i.e. hypoazeotropic solution). This indicates a strong possibility of using AGMD for azeotropic mixture separation. It also was observed that the permeate flux is affected mainly by feed temperature and air gap width. © 2018 Society of Chemical Industry

show abstract

CFD simulation on membrane distillation of NaCl solution

Cited by 37 publications

References 8 publications

Membrane distillation heat transfer enhancement by CFD analysis of internal module geometry

Membrane distillation heat transfer enhancement by CFD analysis of internal module geometry

Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations

Experimental and mathematical study of air gap membrane distillation for aqueous HCl azeotropic separation

Contact Info

Product

Resources

About