Experimental assessment of flow distributors for falling-films over horizontal tube banks

Bustamante, John G.; Garimella, Srinivas

doi:10.1016/j.ijrefrig.2019.02.025

Cited by 19 publications

(4 citation statements)

References 21 publications

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“…Due to thin film and violent perturbation of the gas–liquid interface, the mass transfer reactor of the falling film over the horizontal tube has been widely applied in the field of mass transfer. − Recently, several studies have focused on the evolution of intertube flow patterns, film thickness, motion features of the film, , heat, and mass transfer performance, , and enhancement mechanism of micro-mass transfer through experiments, , numerical simulations, , and theoretical tests of the horizontal falling film absorber …”

Section: Introductionmentioning

confidence: 99%

Motion Evolution Mechanism of Falling Film over Horizontal Tube at Low-Spray Density

Zheng

Zhao

Wang

et al. 2022

Ind. Eng. Chem. Res.

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Horizontal falling film absorber has been widely applied in petroleum, chemical industry, and toxic gas disposal due to its advantages of large fluctuation of gas–liquid interface, accurately controlled interface, easy separation of gas–liquid interface, and low-pressure drop. The study of the velocity evolution of the liquid film at low-spray density is essential to understand the micro-mass transfer mechanism of the reactor and strengthen the absorption. The present study first deciphered the subregion features of the falling film motion over a horizontal tube with varied flow patterns and the parameters, such as spray density, spray height, and salinity that affects the velocity distribution of the falling film at low-spray density for the superhydrophilic surface, were also investigated using the modified PIV method. The result indicated that the velocity distribution of the film renders a typical subregion effect, i.e., nonimpact zone and impact zone for droplet mode, while, for jet mode, the film between the adjacent columns exists in the form of mutual repetition, and the velocity of the film will be slightly higher than that of the body motion region at the interaction ring. It was also found that the spray density and spray height had a positive effect on the average velocity of falling film over the horizontal tube for droplet mode and jet mode. However, for the droplet mode, the spray density increases the velocity of the film by increasing the frequency of the droplet impact. In addition, the average velocity of the film decreases with the increase in the salinity (viscosity).

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Section: Introductionmentioning

confidence: 99%

Motion Evolution Mechanism of Falling Film over Horizontal Tube at Low-Spray Density

Zheng

Zhao

Wang

et al. 2022

Ind. Eng. Chem. Res.

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“…Horizontal tubes are often chosen as the structure type of falling film evaporators in the desalination and refrigeration fields. John et al [5] compared the performance of eight liquid distributors for the film flow over horizontal tube banks. By using the chromatic confocal displacement sensor, Chen et al [6] measured the film thickness on the horizontal tube under the droplet and sheet flow.…”

Section: Introductionmentioning

confidence: 99%

“…The working fluids studied in the existing literature are mainly concentrated in pure water [5][6][7][8]10,11,13,19,23,25], seawater [3], oil sewage [15,16], LiBr solution [17], freon refrigerant [9,20,22], ethylene glycol aqueous solution [14], potassium formate aqueous solution [24], ionic fluid [21,22]. For the cryogenic liquid, Pavlenko et al [26] measured the film flow of cryogenic liquid nitrogen on the surfaces with complex geometry, and found the microstructure has a significant influence on the film spreading progress.…”

Section: Introductionmentioning

confidence: 99%

Falling Film Flow and Heat Transfer of Cryogenic Liquid Oxygen on Different Structural Surfaces

et al. 2022

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The accurate prediction of the falling film characteristics of cryogenic liquids is necessary to ensure good evaporation performance, due to their special physical properties. In this study, the film flow and heat transfer characteristics on four different structures were investigated, and the performance of the cryogenic liquid oxygen was compared with other fluids with higher temperatures, which demonstrates the influence of structures and liquid mediums. The VOF model was used to capture the film surface in the simulation model. The results show that for the four structures, liquids with higher kinematic viscosity tend to have greater film thickness, and the sensible heat transfer coefficients are inversely related to the nominal thermal resistance of falling film flow. Both on the smooth plate and the corrugated plate, the film wettability depends on the kinematic viscosity, rather than the dynamic viscosity, and the effect of kinematic viscosity is greater than that of surface tension. Both the local heat transfer coefficient and its fluctuation amplitude decrease gradually along the flow direction on the triangular corrugated plate, and the vortices are easier to produce at the wall troughs when the film viscosity is higher. At the bottom of the horizontal tube, the increases in local film thickness of the liquid oxygen are less than those of the water and the seawater. More liquid tends to accumulate at the bottom of the round tube, while it easily detaches from the film surface of the elliptical tube. For the horizontal tubes, the local heat transfer coefficients decrease rapidly when θ = 0–5°, and increase sharply at θ = 175–180°.

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“…Censi and Padovan (2019) compared experimental heat transfer performance of hybrid film evaporator and flooded evaporator and reported that measured total pressure drop in the evaporator and global heat transfer coefficient is better in case of hybrid film evaporator also refrigerant charge requirement is around 36% less than the flooded evaporator. Bustamante and Garimella (2019) experimented with eight different distributors where the boxbased distributer performed better than the tube-based distributor. Yan et al (2019) reported that nozzle distance above the tube bundle is key to better fluid flow performance.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on the effect of liquid phase and vapor phase separation over performance of falling film evaporator

Anjankar

Lakade

Padalkar

et al. 2022

Environmental Quality Mgmt

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Energy, cost, and environmental concerns play a vital role in understanding governing parameters of distributor design in falling film evaporators. Distributor design is a hidden parameter in many experimental papers. The uniform distribution of liquid refrigerant over the tube bundle mostly depends on two‐phase liquid refrigerant and vapor refrigerant. This work conducted experiments with two distribution systems with and without separation of liquid‐vapor refrigerant after expansion valve for the same evaporator capacity with R134a as a refrigerant. Results reveal that; separating vapor refrigerant has a positive impact on the approach of the evaporator with an open system distributor arrangement. The highest delta T and lowest practice are found at a heat flux of 13.97 kW/m2 with an available system distributor compared to a closed system with a heat flux of 14.25 kW/m2. The open system arrangement in the distributor is the novel parameter for distributor design, ensuring uniform distribution with minimum pressure drop and dry suction. An open system distributor has an average 16.1% capacity increase over a closed system. The experimental analysis helps to understand different parameters for the design of distributors in falling film evaporators for uniform distribution.

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Experimental assessment of flow distributors for falling-films over horizontal tube banks

Cited by 19 publications

References 21 publications

Motion Evolution Mechanism of Falling Film over Horizontal Tube at Low-Spray Density

Motion Evolution Mechanism of Falling Film over Horizontal Tube at Low-Spray Density

Falling Film Flow and Heat Transfer of Cryogenic Liquid Oxygen on Different Structural Surfaces

Experimental investigation on the effect of liquid phase and vapor phase separation over performance of falling film evaporator

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