An investigation and comparative study of the pressure drop in air-water two-phase flow in vertical helicoidal pipes

Xin, R. C.; Awwad, A.; Dong, Zhe; Ebadian, M. A.; Soliman, H.M.

doi:10.1016/0017-9310(95)00164-6

Cited by 118 publications

(53 citation statements)

References 15 publications

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“…It is evident that the available pressure drop data in usable form on water-steam flows through helically coiled tubes are rather limited, so that more experimental studies are clearly welcome. Since the present study is specifically targeting water-steam two-phase flows, available data generated with fluids other than water-steam [7,9,10,[14][15][16][17][18]21] are not taken into account.…”

Section: Experimental Pressure Drop Databankmentioning

confidence: 99%

“…Available void fraction measurements in helical coils [7,9,10,14,16,18] suggest that curvature effects on the void fraction are small and negligible, so that straight tube void fraction prediction methods can be extrapolated to helically coiled tubes, at least in first approximation. Therefore, the void fraction prediction method of Woldesemayat and Ghajar [51] was used here, as this is one of the most accurate general purpose void fraction correlations currently available for straight tubes [50].…”

Section: Comparison With Existing Correlationsmentioning

confidence: 99%

“…Due to its practical relevance, two-phase flow pressure drop in helically coiled tubes has been investigated quite extensively [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Notably, several authors found straight tube prediction methods appropriate to predict the pressure drop in helical coils.…”

Section: Introductionmentioning

confidence: 99%

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Two-phase pressure drop prediction in helically coiled steam generators for nuclear power applications

Cioncolini

Santini

2016

International Journal of Heat and Mass Transfer

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This study considers the prediction of the pressure gradient with water-steam two-phase flows through helically coiled steam generator tubes, focusing in particular on the operating conditions of low-medium pressure, low mass flux and low heat flux typical of once-through steam generators with in-tube boiling adopted in small modular nuclear reactor systems. Twenty-five widely used empirical correlations have been tested against an experimental pressure drop databank drawn together in this study containing 980 data points. Since no existing correlation is capable of collapsing and satisfactorily fitting the collected databank, a new pressure drop prediction method for helically coiled tubes is proposed. This new prediction method is very simple to implement, as it is based on the homogeneous flow model, is asymptotically consistent with straight tube twophase flows and is largely superior in accuracy to existing prediction methods (mean absolute error of 7.3%, and 9 points out of 10 captured to within ±15%). The new prediction method is applicable for operating pressures in the range of 0.75-9.0 MPa, mass fluxes from 400 kg/m 2 s to 1191 kg/m 2 s, heat fluxes up to 750 kW/m 2 , tube diameters within 5-20 mm and coil to tube diameter ratio above 32.4. Curvature effects on the pressure gradient in helical coil two-phase flows can be significant, particularly with high velocity flows in tight curvature coils where the centrifugal force is intense.2

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Section: Experimental Pressure Drop Databankmentioning

confidence: 99%

Section: Comparison With Existing Correlationsmentioning

confidence: 99%

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Two-phase pressure drop prediction in helically coiled steam generators for nuclear power applications

Cioncolini

Santini

2016

International Journal of Heat and Mass Transfer

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“…The helix angle has almost no effect on pressure drop, even though coil diameter has certain effects at low flow rates. Xin et al (1996) measured the pressure drop and void fraction for an air-water mixture flowing through vertical helicoidal pipes. In their later work, Xin et al (1997) investigated the effect of coil geometries and flow rates of air and water on two-phase flow pressure drop in annular vertical and horizontal helical pipes.…”

Section: Heat Transfer In Single-phase Flowmentioning

confidence: 99%

“…Due to the compact structure and high heat transfer coefficient, helical coil heat exchangers find extensive use in industrial applications such as power generation, nuclear industry, process plants, heat recovery systems, refrigeration, food industry, etc. (Abdulla 1994; Bai et al 1999;Futagami and Aoyama 1988;Jensen and Bergles 1981;Patankar et al 1974;Xin et al, 1996). Heat exchanger with helical coils is used for residual heat removal systems in islanded or barge mounted nuclear reactor systems, wherein nuclear energy is utilised for desalination of seawater (Manna et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Helically Coiled Heat Exchangers

Jayakumar¹

2012

Heat Exchangers - Basics Design Applications

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Flow pattern transition, frictional pressure drop, and holdup of gas non‐Newtonian fluid flow in helical tube

Thandlam

Mandal

Majumder

2015

Asia-Pacific J Chem Eng

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An investigation on flow pattern, pressure drop, and holdup of cocurrent upward two-phase flow in a vertical helical coil tube has been carried out with Newtonian and non-Newtonian fluids. The flow patterns observed in the present study are divided into three main regimes, i.e. plug flow, slug flow, and stratified flow. Lockhart-Martinelli parameter (X) was used to predict the friction factor and frictional pressure drop of two-phase flow. Correlations for the frictional pressure drop were developed to interpret the observed flow patterns with various operating variables. The effect of geometrical parameters on flow pattern, pressure drop, and holdup are enunciated. Based on the experimental data, a correlation was proposed to predict the flow transitions of flow patterns (i.e. plug-slug flow and slug-stratified flow) by dimensional analysis. Probabilistic neural network model has also been developed to predict the flow patterns of two-phase flow. Figure 5. Effect of coil diameter (D c ) on flow regime of non-Newtonian fluids at constant tube diameter d t = 0.015 m, SCMC concentration = 1.0 kg/m 3 and pitch difference (p/D c ) = 1.0. Asia-Pacific Journal of Chemical Engineering FLOW PATTERNS OF GAS NON-NEWTONIAN FLUID FLOW 429 R 2 , correlation coefficient; SE, standard error.Figure 11. Effect of different variables [(a) superficial liquid velocity at d t = 0.02 m; D c = 0.2 m; P/D c = 1.0; SCMC-1.5 kg/m 3 , (b) coil diameter at d t = 0.02 m; P/D c = 0.5; Usl = 1.238 m/s; SCMC-3.0 kg/m 3 , (c) tube diameter at D c = 0.075 m; P/D c = 1.0; SCMC-3.0kg/m 3 and (d) pitch difference at d t = 0.15 m; D c = 0.117 m; SCMC-3.0 kg/m 3 ] on frictional pressure drop.

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An investigation and comparative study of the pressure drop in air-water two-phase flow in vertical helicoidal pipes

Cited by 118 publications

References 15 publications

Two-phase pressure drop prediction in helically coiled steam generators for nuclear power applications

Two-phase pressure drop prediction in helically coiled steam generators for nuclear power applications

Helically Coiled Heat Exchangers

Flow pattern transition, frictional pressure drop, and holdup of gas non‐Newtonian fluid flow in helical tube

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