Numerical simulation of the flow in a plane-channel containing a periodic array of cylindrical turbulence promoters

Koutsou, C.P.; Yiantsios, S.G.; Karabelas, A.J.

doi:10.1016/j.memsci.2003.11.005

Cited by 112 publications

(84 citation statements)

References 13 publications

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“…Furthermore, studies of fine flow structures in small independent cells and their impact on neighboring cells has not been reported in details. Recently, Koutsou et al [14] reported a 2D flow simulation in a rectangular channel in the presence of cylindrical turbulence promoters similar to a case reported by Schwinge et al [8,9]. They concluded that more realistic 3D simulations are needed for optimization of spacers.…”

Section: Introductionmentioning

confidence: 69%

See 1 more Smart Citation

Fluid dynamics of spacer filled rectangular and curvilinear channels

Ranade

Kumar

2006

Journal of Membrane Science

125

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Section: Introductionmentioning

confidence: 69%

“…It is well known that symmetry of a flow over a single cylinder breaks when Reynolds number increases beyond a critical Reynolds number of 60 [14]. The unit cell approach is not valid for cases where periodic symmetry of flow is absent despite the symmetric and periodic geometry.…”

Section: Unit Cell Approachmentioning

confidence: 99%

Fluid dynamics of spacer filled rectangular and curvilinear channels

Ranade

Kumar

2006

Journal of Membrane Science

125

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“…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

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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.

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“…Koutsou et al [41] for instance identified a critical Reynolds number of Re crit ≈ 60 in case of an blockage ratio of D s /H = 2 and a separation distance of L s /D s = 6. This value is slightly lower compared to the single cylinder where Re crit ≈ 83.…”

Section: Influence Of Temporally Oscillating Flow Conditionsmentioning

confidence: 99%

Entrance length effects on Graetz number scaling in laminar duct flows with periodic obstructions: Transport number correlations for spacer-filled membrane channel flows

Rohlfs

Lienhard

2016

International Journal of Heat and Mass Transfer

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Self-similarity and scaling laws are powerful tools in engineering and thus useful for the design of apparatus. This self-similarity is well understood for the heat and mass transfer in laminar empty channel flows, including the fully developed region as well as inlet length effects in the developing region (Graetz problem). In this study, we examine the validity of the scaling behavior arising from the Graetz solution for channel flows disturbed by periodic obstructions. Simulation results show that entrance length effects and scaling laws do not change due to the presence of obstructions if the flow field remains steady in time and the dimensionless inlet length is given by X T /D h ≈ C inl. ·Re·Pr, where C inl. ≈ 0.01 for the local and C inl. ≈ 0.03 for the average Nusselt number. The Nusselt number in the inlet region for an internal flow scales by Nu = (Re · Pr) 1/3 , similar to the empty channel flow (Shah and London, 1978). If the analogy between heat and mass transfer holds, same conclusions and relations are valid for the Sherwood number, Sh ∝ (Re · Sc) 1/3 , where Sc denotes the Schmidt number. In the fully developed region, the Nusselt number depends slightly on the Reynolds and Prandtl numbers owing to the loss in self-similarity of the velocity field (contrary to the empty channel flow). The limit of the classical self-similarity is the onset of temporal oscillations (instability) in the flow field. Beyond this limit, the length of the thermal entrance region is strongly reduced. Furthermore, a strong dependency of the Nusselt number in the fully developed region on the Prandtl number is found.

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Numerical simulation of the flow in a plane-channel containing a periodic array of cylindrical turbulence promoters

Cited by 112 publications

References 13 publications

Fluid dynamics of spacer filled rectangular and curvilinear channels

Fluid dynamics of spacer filled rectangular and curvilinear channels

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

Entrance length effects on Graetz number scaling in laminar duct flows with periodic obstructions: Transport number correlations for spacer-filled membrane channel flows

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