Heat transfer characteristics of obliquely dispensed evaporating falling films on an elliptic tube

Lee, Yee-Ting; Hong, Sihui; Dang, Chaobin; Chien, Liang-Han; Chang, Li-Wang; Yang, An-Shik

doi:10.1016/j.ijheatmasstransfer.2018.12.031

Cited by 39 publications

(4 citation statements)

References 32 publications

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“…In their study, falling film heat transfer coefficients are measured with different heat fluxes. Lee et al (2019) studied the liquid film distribution on elliptical tube to get the heat transfer characteristics by varying the flow rate and dispense angle. They observed that at low flow rates the liquid is unable to envelop the entire tube surface.…”

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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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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“…Asbik et al [16] observed in their study that the decreasing ellipticity generates a noticeable reduction in the laminar sublayer and hence favors the turbulence regime. Lee et al [17] simulated the effect of obliquely dispensed angle on heat transfer of elliptical tube. They found that increasing the obliquely dispensed angle can result in angle thinner liquid films, lower interfacial velocities and worse heat transfer outcomes, also they think the reasonable obliquely dispensed angle is within 30°.…”

Section: Zhang Et Al / Desalination and Water Treatment 157 (2019mentioning

confidence: 99%

Study on liquid film thickness and flow characteristics of falling film outside an elliptical tube

Zhang¹,

Zhu²,

Q³

2019

Desalination and Water Treatment

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A three-dimensional model is applied to simulate the spreading process and thickness distribution of the liquid film outside an elliptical horizontal tube falling-film heat exchanger. Reynolds number (Re) is 187 and the counter-current air flow rates are 0, 0.1 and 0.5 m/s, respectively. The volume of fluid method is used to trace the gas-liquid interface. It is shown that falling film flow delays and the liquid film thickness increases as the gas flow rate increases. When the counter-current gas flow rate is increased to 0.5 m/s, the falling film distribution becomes uneven and local accumulation occurs. Along the circumferential direction, the liquid film velocity increases as the gas flow rate increases.

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“…Such falling film flow has been widely used in various chemical engineering, thermal energy engineering, mechanical engineering, and engineering thermo-physics and nuclear energy fields due to its excellent properties, such as the small flow rate, small temperature difference, simple structure, high heat- and mass-transfer coefficient, and low power consumption. Nowadays, the falling film evaporator, air conditioning refrigerator, horizontal falling film exchanger (HFFE), − and condenser have been widely used in various heat exchange systems.…”

Section: Introductionmentioning

confidence: 99%

Effect of Structural Optimization of Scrubbing Cooling Rings on Vertical Falling Film Flow Characteristics

Huang

Wang

et al. 2022

ACS Omega

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In order to study the influence of the structural optimization of the scrubbing cooling ring in the scrubbing cooling chamber on the flow characteristics of the vertical falling film, the flow characteristics of the turbulent falling film in the rising section of the development region at different internal platform heights of the scrubbing cooling ring and a high Reynolds number were studied by FLUENT software. First, the correctness of the model was verified by the maximum error of simulation and experimental results of no more than 9.836%. Then, the distribution of liquid film thickness (δ), velocity ( V ), and turbulence intensity ( I z ) at 0° of the tube in the axial direction x = 0–500 mm were calculated and obtained when the platform height ( H ) was 0–30 mm and the liquid film Reynolds number ( Re l ) = 1.1541 × 10 4 –3.4623 × 10 4 . The results showed that δ in the entrance region increased sharply due to the “jet” effect with solid wall constraints formed by the structure of the water inlet pipe and the scrubbing cooling ring. On the contrary, the liquid film in the fully developed region showed a stable fluctuation trend due to the weakening of the “jet” effect. When H = 30 mm, the change of δ was relatively stable and the change of I z was small, indicating that this platform height is conducive to the stable and uniform distribution of the liquid film. In addition, when Re l < 1.1541 × 10 4 , the liquid film was unstable due to the low flow rate and insufficient cohesion of the liquid film, but V increased slightly. In addition, with the increase of Re l , δ did not change significantly along the axial direction, that is, the Plateau–Rayleigh hindered the growth of δ. Finally, the empirical formula for δ applicable to Re l = 1.1541 × 10 4 –3.4623 × 10 4 at the axial fixed position was fitted for the first time.

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Heat transfer characteristics of obliquely dispensed evaporating falling films on an elliptic tube

Cited by 39 publications

References 32 publications

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

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

Study on liquid film thickness and flow characteristics of falling film outside an elliptical tube

Effect of Structural Optimization of Scrubbing Cooling Rings on Vertical Falling Film Flow Characteristics

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