A comparison of homogenous and separated flow assumptions for adiabatic capillary flow

Furlong, Thomas W.; Schmidt, David P.

doi:10.1016/j.applthermaleng.2012.05.007

Cited by 17 publications

(4 citation statements)

References 36 publications

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“…A number of mathematical models of capillary tubes ( Garcia-Valladares, 2007 ;Wang et al, 2012 ;Seixlack and Barbazelli, 2009 ;Seixlack, 1996 ) that are based on the separated two-phase flow model where the flow is assumed to be heterogeneous can be found in the literature. The results reported in these studies agree slightly better with the experimental results compared to homogeneous models, but several studies ( Furlong and Schmidt, 2012 ;Wong and Ooi, 1996 ) point out that both two-phase models can be used to describe the flow of refrigerants in capillary tubes. Although homogeneous and separated flow models have been compared extensively with each other and against experimental data, no investigation, at least to the best of the authors' knowledge, has been made to experimentally determine the velocity ratio of the vapor and liquid phases, which is one of the key parameters that indicate the homogeneity of the flow.…”

Section: Introductionsupporting

confidence: 65%

Two-phase flow patterns in adiabatic refrigerant flow through capillary tubes

Lorbek

Kuhelj

Dular

et al. 2020

International Journal of Refrigeration

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This paper presents the results of an experimental study of the flow visualization of the refrigerant R600a through a capillary tube with an internal diameter of 0.8 mm made from a FEP (fluorinated ethylene propylene) polymer that was installed in a small-scale, vapor-compression refrigeration system. The main purpose of the study was to determine the flow patterns of the refrigerant flow in capillary tubes under different operating conditions and to verify whether the results obtained using a FEP tube are representative for the flow of a refrigerant in copper capillary tubes. The results of the study revealed that the two-phase refrigerant flow in the FEP capillary tubes consists predominantly of slug flow. These slugs continuously expand while traveling downstream. It was also found that different operating conditions can have a strong influence on the frequency of the vapor bubbles' formation and their growth. In addition, an experimental study of the effect of local or global imperfections on the inner surface of the FEP tube was performed. In some cases the imperfections increased the number of vapor-bubble inception points, which caused a homogenization of the two-phase flow.

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Section: Introductionsupporting

confidence: 65%

Two-phase flow patterns in adiabatic refrigerant flow through capillary tubes

Lorbek

Kuhelj

Dular

et al. 2020

International Journal of Refrigeration

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“…Two models, the separated flow model (SFM) and the homogeneous flow model (HFM), have been used by many investigators to classify two-phase flows in numerical analysis. [16][17][18][19][20] Based on the SFM, each phase can be considered as a region with its velocity and temperature fields; however, having the temperature and velocity distributions of both phases is necessary to solve the problem and some corrections also must be applied to the solution due to the interface between phases. Meanwhile, the same flow and temperature fields are assumed for two phases.…”

Section: Introductionmentioning

confidence: 99%

“…Agrawal and Bhattacharyya [17] compared both models in an adiabatic capillary circular tube and proved that the SFM predicted pressure distribution along the tube better than the HFM. Another comprehensive comparison between both models was performed by Furlong and Schmidt, [19] who found that the SFM shows a smaller error when determining the mass flow rate and has higher accuracy for simulations. However, there was a serious limitation with the SFM when the working fluid properties were near the critical point.…”

Section: Introductionmentioning

confidence: 99%

Liquid film thickness of two‐phase slug flows in capillary microchannels: A review paper

2021

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Two-phase Taylor flow has received considerable attention from researchers in recent decades due to its potential use in a wide variety of industrial and medical applications. A large number of experimental, analytical, and numerical efforts have been taken by researchers to understand the fundamental characteristics of two-phase flows and the relevant transport phenomena. This paper presents a comprehensive review of the hydrodynamics, flow pattern, and liquid film thickness in two-phase flows through mini-and microchannels with different cross-sectional geometry. This paper also reviews correlations that predict liquid film thickness in microchannels for gas-liquid and liquid-liquid flows. The variations of liquid film thickness are plotted over a wide range of capillary numbers for both experimental and computational studies. This study shows that the effects of cross-sectional area on the flow patterns and flow characteristics have not been sufficiently investigated by researchers, particularly for rectangular cross-sectional areas with different aspect ratios.

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“…Recent visualization studies (Lorbek et al, 2020;Tannert and Hesse, 2016) suggest that the two-phase flow in capillary tubes is predominantly a heterogeneous (separated) slug flow. However, models using the homogeneous two-phase flow assumption are proven to provide results with similar accuracy as separated models (Furlong and Schmidt, 2012).…”

Section: Introductionmentioning

confidence: 99%