Numerical simulation of horizontal tube bundle falling film flow pattern transformation

Chen, Jingdong; Zhang, Ruihang; Niu, Runping

doi:10.1016/j.renene.2014.08.007

Cited by 50 publications

(11 citation statements)

References 6 publications

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“…Figure a displays the falling-film flow state on the horizontal tube. Considering the liquid inlet and flow pattern and referring to the relevant literature, , it is assumed that the calculation model is symmetrical. Therefore, the spreading range of the liquid flow under the single spray inlet is intercepted as the flow range studied in this paper.…”

Section: Numerical Modelmentioning

confidence: 99%

“…Various experiments and investigations were carried out to investigate the influences of the liquid properties, tube diameter, flow rate, and tube spacing on the flow state and falling-film thickness on the horizontal smooth tubes. ,− However, due to the limitation of sensor resolution and accuracy, some details of the microscopic flow characteristics during the falling-film process, such as the velocity distributions, local film distribution, and so on, may not be fully revealed through experimental studies . As an effective auxiliary means, computational fluid dynamics (CFD) can intuitively provide the complex flow behavior that is difficult to be presented in experimental research. , For example, some researchers have established CFD models based on the volume of fluid (VOF) method to study the transient thin film flow on solid substrates and identified different wetting patterns that may appear. − Furthermore, many researchers ,− conducted CFD studies on the flow characteristics of horizontal smooth tubes during falling-film evaporation. For example, Lin used a three-dimensional coordinate axis to explore the film thickness distribution of the smooth tube.…”

Section: Introductionmentioning

confidence: 99%

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Three-Dimensional Flow Behavior of a Falling Film on Horizontal Tubes: A Comparative Study on Smooth and Finned Tubes

Cao

Xie

et al. 2022

Ind. Eng. Chem. Res.

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In this work, the two-phase flow behavior of a falling film on horizontal smooth and finned tube systems was investigated and compared using a three-dimensional computational fluid dynamics model based on the volume of fluid method. The model was established to capture the microscopic gas–liquid interface of the falling film for smooth and finned tubes. The three-dimensional flow behavior of the falling film, including the liquid film spreading, the film thickness, the velocity distribution, and the effect of Reynolds number (Re) on the film distribution, was investigated systematically. The results show that the liquid film spreads on the smooth tube rapidly and forms a film thickness distribution of “crest-stable-crest”, while the axial spreading of the liquid film is significantly restricted and hindered by the fins on the finned tubes. The falling films of the smooth tube and the finned tube present a staggered column flow and an in-line column flow, respectively. Besides, the axial liquid film spreading on the smooth tube is more sensitive to the Re compared with the finned tubes. The finned tube with a lower fin density achieves better axial spreading, and the finned tube is completely covered by the liquid film at Re = 521 with an optimized liquid column spacing.

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Section: Numerical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Flow Behavior of a Falling Film on Horizontal Tubes: A Comparative Study on Smooth and Finned Tubes

Cao

Xie

et al. 2022

Ind. Eng. Chem. Res.

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“…The existing literature has revealed the following principal flow modes between the horizontal tubes, including the droplet mode, column flow pattern, sheet flow mode and intermediate flow regimes are droplet-column mode, column-sheet mode [13,14]. Chen et al [15] investigated computationally and experimentally to examine the different flow regime transformations between the horizontal tubes. Kandukuri et al [16] experimentally investigated the different phases in the column flow regime as well as examined flow parameters such as axial film thickness and jet diameter using image analysis approach.…”

Section: State Of Artmentioning

confidence: 99%

A 2-D numerical study of contact angle effect on transient falling-film flow over horizontal tubes

Kandukuri¹,

Deshmukh²,

Katiresan³

2022

Preprint

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The coverage of the liquid film over the horizontal tubes, particularly the wetting ratio, is important for heat transfer mechanism of gravity-driven evaporators and absorbers. A 2D, two-phase CFD model was developed to examine the falling-film hydrodynamics and transient flow mechanism for Reynolds numbers ranging from 100-500, contact angles spanning from 0°/30°/60°/90°, and inter tube spacing of 10 mm. The VOF method is used in this article to capture the gas-liquid interface. The findings showed that the complete spreading of the liquid film is difficult at low Reynolds numbers and high contact angles. The formation of dry regions on the tube wall as a result of insufficient liquid supply, liquid film breakage, and liquid film shrinkage. Furthermore, as the Reynolds number increases and contact angle decrease, the wetting ratio over the tube surface increases. It was worth noting that each contact angle must have a minimum Reynolds number in order to keep the surface completely wet. The research also found that for higher Reynolds numbers, the influence of contact angle on wettability of tube wall can be ignored. The liquid propagation time required to wet the tube surface increases as the contact angle value increases for the same Reynolds number. Fouling over the tubes can be aided by the formation of air voids near the lower stagnation zone.

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“…Their observation is that the film thickness plays a major role in formation of dry patches and strongly affects the coefficient of heat transfer in falling film heat transfer process. Chen et al (2015) simulated the pattern of falling film on a horizontal tube bundle of falling film evaporator. A Volume of Fluid (VOF) technique was used by them for tracking the free surface of two phase flow.…”

Section: Fig 2 Mechanism Of Flowmentioning

confidence: 99%

Numerical Study of Liquid Film Formation around Tubes of Horizontal Falling Film Evaporator

2021

JAFM

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Falling film evaporative heat exchangers are extensively used in processing industries; broad areas of application being refrigeration, desalination and food processing industries. The fundamental aspect of this type of heat transfer process is to extract the process heat in the form of latent heat by liquid which is sprayed over the surface of the process tubes. Formation of liquid film over a fully wetted horizontal round tube of falling film evaporator has been numerically simulated here. Two numerical approaches, Volume of Fluid (VOF) technique and the Eulerian multiphase model are applied to compare their results. The effect of varying flow and geometrical parameters on the film thickness is investigated. Two horizontal tubes of diameter 19.05mm and 25.04mm with three different uniform spacing have been selected for simulation. Film Reynolds numbers 650, 950 and 1250 are considered for the above set of parameters. Ii is observed that the geometrical and flow parameters considerably influence the film thickness. Transient analysis of the film formation has been carried out and parameters like pathline of liquid film and the velocity profile have been obtained for understanding the flow behavior in a better manner. All the simulated results agree well with the published data.

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Numerical simulation of horizontal tube bundle falling film flow pattern transformation

Cited by 50 publications

References 6 publications

Three-Dimensional Flow Behavior of a Falling Film on Horizontal Tubes: A Comparative Study on Smooth and Finned Tubes

Three-Dimensional Flow Behavior of a Falling Film on Horizontal Tubes: A Comparative Study on Smooth and Finned Tubes

A 2-D numerical study of contact angle effect on transient falling-film flow over horizontal tubes

Numerical Study of Liquid Film Formation around Tubes of Horizontal Falling Film Evaporator

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