Turbulent heat transfer in spacer-filled channels: Experimental and computational study and selection of turbulence models

Ciofalo, Michele; Liberto, Massimiliano Di; Cerva, Mariagiorgia La; Tamburini, Alessandro

doi:10.1016/j.ijthermalsci.2019.106040

Cited by 14 publications

(8 citation statements)

References 24 publications

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“…This technique had been used by many researchers for the evaluation of heat transfer coefficients by recorded isoline (selected hue interval from the color map) using color image processing techniques [6,7,13,21].…”

Section: Steady State Analysis By the Constant Heat Flux Methodsmentioning

confidence: 99%

“…More information on turbulence models and calculation methods can be obtained in the ANSYS Fluent package [37] and A. Stasiek's doctoral dissertation [28]. Numerical modeling of turbulent flows is also presented in the works [5,13,21,28]. The k-ε model proposed in 1974 by Launder and Spalding [41] and CFD FLUENT software by ANSYS Inc (Southpointe 2600 Ansys Drive Canonsburg, PA 15317 USA) was The displacement of the moving marker particles is determined by correlating the fragments of two images recorded at a known time interval.…”

Section: Computational Fluids Dynamics-cfdmentioning

confidence: 99%

“…Numerical modeling of turbulent flows is also presented in the works [5,13,21,28]. The k-ε model proposed in 1974 by Launder and Spalding [41] and CFD FLUENT software by ANSYS Inc. (Southpointe 2600 Ansys Drive Canonsburg, PA 15317, USA) was selected to verify the thermographic measurements of the model heat exchanger (flat duct with rib-shaped mechanical turbulators).…”

Section: Computational Fluids Dynamics-cfdmentioning

confidence: 99%

“…or, after transformation: 𝑓 = 8 • ℎ 𝑐 • 𝜌 • 𝑢 (13) where f-friction factor, Pr-Prandtl number, cp-specific heat, ρ-air density, u0 -flow inlet velocity. The obtained results may suggest that the transition region (the region between two regimes of flow: laminar and turbulent) is significantly shifted above the Reynolds number of 10,000, which is consistent with the Moody and Pigott's work [43,44].…”

Section: Friction Factormentioning

confidence: 99%

“…Furthermore, liquid crystal thermography assisted by particle image velocimetry is an excellent and recognized measurement method used in the study of advanced thermal-flow processes in major world-wide research centers [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

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Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators

2021

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The main goal of the research presented in this paper was the experimental and numerical analysis of heat enhancement and aerodynamic phenomena during air flow in a channel equipped with flow turbulators in the form of properly configured ribs. The use of ribs intensifies the heat transfer and at the same time increases not only the flow resistance but also the energy costs. Therefore, designing modern heat exchangers with optimal thermal and flow parameters requires the knowledge of the theory of heat exchangers as well as measurement methods and numerical calculations. Bearing in mind the above, the liquid crystal techniques (LCT), particle image velocimetry (PIV) and digital image processing (DIP) for temperature, velocity, friction factor and heat transfer coefficient measurements are presented herein. These three optical tools (using desktop computers) create an extremely powerful and advanced measuring technique that has not been available anywhere before. Brief histories of these measurement methods and techniques are discussed and some examples are presented. In order to assess and select the value of the measurement technique, local and average distributions of Nusselt numbers (in the measurement section) obtained by the transit analysis method on the inter-rib regions of a plate coated by thermochromics liquid crystal and heated by air as an alternative to the steady-state analysis. In the parallel, numerical calculation was performed with the use of the ANSYS Fluent software code and supported by laser anemometry-computed turbulence intensity of air flow. Comparison of the Nusselt number distributions was determined by three methods, i.e., steady state, the transient method and CFD simulation. Up to three-fold enhancement of the local heat transfer capability was observed. Failure to take into account the surface of the ribs in heat transfer causes differences in the obtained results of the Nusselt number depending on the method used. Apart from the heat transfer data, the pressure drop in the form of friction factors is also presented. On the basis of the conducted research, it can be stated that both qualitative and quantitative coherence was obtained between the experimental and computational studies.

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Section: Steady State Analysis By the Constant Heat Flux Methodsmentioning

confidence: 99%

Section: Computational Fluids Dynamics-cfdmentioning

confidence: 99%

Section: Computational Fluids Dynamics-cfdmentioning

confidence: 99%

Section: Friction Factormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators

2021

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Multilayered membrane spacer: does it enhance solution mixing?

Al‐Amshawee

Yunus

Dakhil

2023

J of Chemical Tech & Biotech

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The present review systematically investigates and illustrates the effect of multilayered membrane spacers on the features of fluid dynamics that influence all performance metrics. Multilayer spacers are frequently composed of three sets of filaments (i.e., top, middle, and bottom layers), which has the benefit of increasing mass transfer and decreasing membrane surface fouling when compared to ordinary monolayer (e.g., extruded spacer) and two‐layer spacers. The review found that the multilayer spacer's middle layer disperses primary flow to the thin side spacers placed near the membrane's surfaces. The thin side spacers will then form narrow passageways to keep the solution in situ for as long as mass transfer is achievable. The employment of thin spacers close to the membranes at satisfactory operational conditions (e.g., adequate flow velocity) results in swirling flows and incorporation of transverse and longitudinal eddies near to the membranes, reducing the boundary layer's width and making the associated ion concentration domain at the membranes much more consistent. The concept and implementation of multilayer geometry in feed channels appears to be promising, since a multilayered spacer can function at a lower maximum flow velocity than normal two‐layer spacers, saving operational energy while minimizing concentration gradients at the membrane surfaces. Furthermore, the multilayer structure's durability and mechanical strength may help to reduce membrane deformation and maintain long processes. Future studies might look at significantly reducing spacer thickness for industrial uses. © 2023 Society of Chemical Industry (SCI).

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Ion exchange membrane electrodialysis for water and wastewater processing: application of ladder-type membrane spacers to impact solution concentration and flow dynamics

Al‐Amshawee

Yunus

Dakhil

2023

Environ Sci Pollut Res

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Turbulent heat transfer in spacer-filled channels: Experimental and computational study and selection of turbulence models

Cited by 14 publications

References 24 publications

Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators

Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators

Multilayered membrane spacer: does it enhance solution mixing?

Ion exchange membrane electrodialysis for water and wastewater processing: application of ladder-type membrane spacers to impact solution concentration and flow dynamics

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