Experiments in free falling and downward cocurrent annular flows – Characterization of liquid films and interfacial waves

Rivera, Yago; Berna, C.; Muñoz-Cobo, J.L.; Escrivá, A.; Córdova, Yaisel

doi:10.1016/j.nucengdes.2022.111769

Cited by 20 publications

(18 citation statements)

References 51 publications

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“…The empirical correlation generally used to predict the average film thickness of a free-falling annular flow is [13,36,37]:…”

Section: Film Thicknessmentioning

confidence: 99%

“…To cover a wide range of flow conditions, a comprehensive analysis was conducted by combining previous experimental data obtained from the developed flow region with the current results. These data [11,12,15,18,33,[36][37][38][39][40][41] were then compared with Nusselt's theoretical solution and two recently proposed empirical predictions [36,37]. The comparison, as shown in Fig.…”

Section: Film Thicknessmentioning

confidence: 99%

“…As a result, the gas velocity or Weber number may have a negligible impact on the entrainment process. In some prior studies exploring two-phase annular flow [18,37], the gas input was intentionally set to zero to simulate the free-falling film annular flow. While this represents a similar scenario to our current study, where air is drawn into the air core, it is essential to recognise that there might still be variations in flow properties due to the presence of the air core.…”

Section: Annular Inletmentioning

confidence: 99%

See 2 more Smart Citations

Experimental Study of Developing Free-Falling Annular Flow in a Large Scale Vertical Pipe

Xue¹,

Stewart²,

Kelly³

et al. 2023

Preprint

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“…The empirical correlation generally used to predict the average film thickness of a free-falling annular flow is [13,36,37]:…”

Section: Film Thicknessmentioning

confidence: 99%

Section: Film Thicknessmentioning

confidence: 99%

Section: Annular Inletmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Study of Developing Free-Falling Annular Flow in a Large Scale Vertical Pipe

Xue¹,

Stewart²,

Kelly³

et al. 2023

Preprint

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“…Measurement of the liquid film thickness by inserting electrodes or parallel wire probes into the pipes is widely used in the field due to its simplicity and low cost [23,24,. With no induced disturbance to the flow, the embedded electrodes can be grouped as parallel strip electrodes, concentric circle electrodes, circular rod electrodes, ring-shaped electrodes, and so on [12,36,39,40,[110][111][112][113][114][115][116][117][118][119][120][121][122][123][124][125][126][127][128]. The conductance probe is capable of measuring the void fraction of the annular flow.…”

Section: Conductance Sensormentioning

confidence: 99%

Two-Phase Annular Flow in Vertical Pipes: A Critical Review of Current Research Techniques and Progress

Xue¹,

Stewart

Kelly

et al. 2022

Water

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Two-phase annular flow in vertical pipes is one of the most common and important flow regimes in fluid mechanics, particularly in the field of building drainage systems where discharges to the vertical pipe are random and the flow is unsteady. With the development of experimental techniques and analytical methods, the understanding of the fundamental mechanism of the annular two-phase flow has been significantly advanced, such as liquid film development, evolution of the disturbance wave, and droplet entrainment mechanism. Despite the hundreds of papers published so far, the mechanism of annular flow remains incompletely understood. Therefore, this paper summarizes the research on two-phase annular flow in vertical pipes mainly in the last two decades. The review is mainly divided into two parts, i.e., the investigation methodologies and the advancement of knowledge. Different experimental techniques and numerical simulations are compared to highlight their advantages and challenges. Advanced underpinning physics of the mechanism is summarized in several groups including the wavy liquid film, droplet behaviour, entrainment and void fraction. Challenges and recommendations are summarized based on the literature cited in this review.

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“…Conversely, in counter-current flow, it leads to an increase in the average film thickness [7]. Regarding interfacial waves, high vapor Reynolds numbers tend to decrease their amplitude in co-current flow [8] while in counter-current flows, they lead to an increase [9], contributing to the flooding phenomenon [10].…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of a confined falling liquid film sheared by a gas flow in a plate heat exchanger of an NH₃/H₂0 absorption chiller

Sleiman,

Collignon,

Phan

et al. 2024

J. Phys.: Conf. Ser.

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In recent years, the demand for cooling has seen a substantial increase, primarily due to rising summertime temperatures. Conventional mechanical compression air conditioners have played a predominant role in fulfilling this demand, albeit at the cost of significant electricity consumption. In response, absorption chillers have emerged as an eco-friendly alternative, powered by sustainable heat sources like solar energy or industrial waste heat. The present work is conducted within the framework of developing compact absorption chillers incorporating plate heat exchangers. It builds upon prior research by improving an existing numerical model for falling film plate heat exchangers within an NH3/H2O absorption chiller. This former numerical model evaluates the coupled heat and mass transfer between the liquid film and the vapor flow while excluding hydrodynamic interactions at the liquid-vapor interface. The current investigation aims to address compactness and cost-efficiency limitations in absorption chillers. The consequences of operation within confined spaces were numerically evaluated. An innovative analytical model was developed to quantify the influence of the interactions at the liquid-vapor interface. Shear stress and interfacial perturbations were considered compared to the classical Nusselt model, enabling the evaluation of the changes in the average film thickness and the flooding phenomenon. This analytical model was then added to the previously developed heat and mass transfer model. The numerical model was applied to both the desorber and absorber units. The results show that increased confinement has minimal effects on the transfer coefficients. Additionally, an approach is suggested for estimating flooding in confined spaces and the results are compared with various correlations available in the literature.

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Experiments in free falling and downward cocurrent annular flows – Characterization of liquid films and interfacial waves

Cited by 20 publications

References 51 publications

Experimental Study of Developing Free-Falling Annular Flow in a Large Scale Vertical Pipe

Experimental Study of Developing Free-Falling Annular Flow in a Large Scale Vertical Pipe

Two-Phase Annular Flow in Vertical Pipes: A Critical Review of Current Research Techniques and Progress

Numerical modeling of a confined falling liquid film sheared by a gas flow in a plate heat exchanger of an NH₃/H₂0 absorption chiller

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Experiments in free falling and downward cocurrent annular flows – Characterization of liquid films and interfacial waves

Cited by 20 publications

References 51 publications

Experimental Study of Developing Free-Falling Annular Flow in a Large Scale Vertical Pipe

Experimental Study of Developing Free-Falling Annular Flow in a Large Scale Vertical Pipe

Two-Phase Annular Flow in Vertical Pipes: A Critical Review of Current Research Techniques and Progress

Numerical modeling of a confined falling liquid film sheared by a gas flow in a plate heat exchanger of an NH3/H20 absorption chiller

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Numerical modeling of a confined falling liquid film sheared by a gas flow in a plate heat exchanger of an NH₃/H₂0 absorption chiller