Two-Phase Flow through Corrugated U-Tube

2010 ◽  
Vol 224 (11) ◽  
pp. 2408-2417 ◽  
Author(s):  
B Shannak ◽  
R Damseh ◽  
M Al-Odat ◽  
M Al-Shannag ◽  
A Azzi
Keyword(s):  
Pressure Drop ◽  
Friction Factor ◽  
Two Phase Flow ◽  
Complex Geometry ◽  
Geometrical Parameters ◽  
Phase Flow ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
System Pressure ◽  
Inner Diameter

New measurements of the frictional pressure drop of air—water two-phase flow in a flexible corrugated U-tube have been carried out. Experiments were performed under the following conditions of two-phase parameters: mass flux of 300—800 kg/m2 s, gas quality of 1—60 per cent, and system pressure of 3—7 bar. The inner diameter of the U-tubes tested was 40 mm, with a ratio of curvature radius to inner diameter varying from 3 to 7.5. The results demonstrate that the two-phase flow resistance, energy dissipation, friction losses, and interaction of the two phases in flexible corrugated U-tubes are perceptible about two to five times greater than those in smooth U-tubes. Hence, the two-phase friction factor of such tubes increases from 0.65 to 1.4, depending on the influencing flow and geometrical parameters. The available correlations in the open literature present a similar trend and behaviour. However, they predict the data presented poorly because of the complex geometry of the flexible corrugated U-tube. Based on the energy balance and the presented experimental results, a new model has been developed to calculate the frictional two-phase pressure drop and hence the friction factor of the flexible U-tube. The model includes the relevant primary parameter, fits the experimental data well, and is sufficiently accurate for engineering purposes. The standard deviation of the data is less than 7 per cent. The reported results enable a practical design with standard products and optimization of the geometry of the flexible corrugated U-tube for specific conditions.

MODELING OF THE MINIMIZED TWO-PHASE FLOW FRICTIONAL PRESSURE DROP IN A SMALL TUBE WITH DIFFERENT CORRELATIONS

2016 ◽  
Vol 78 (6-11) ◽  
Author(s):  
Qais Abid Yousif ◽  
Normah Mohd-Ghazali ◽  
Nor Atiqah Zolpakar ◽  
Sentot Novianto ◽  
Agus Sujiantro Pamitran ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Friction Factor ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Frictional Pressure Drop

The major parameters of interest in heat transfer research are the refrigerant charge, pressure drop, and heat transfer capacity. Smaller channels reduce the refrigerant charge with higher heat transfer capability due to the increased in surface area to volume ratio but at the expense of a higher pressure drop. Differences between the predicted and experimental frictional pressure drop of two-phase flow in small tubes have frequently been discussed. Factors that could have contributed to that effect have been attributed to the correlations used to model the flow, some being modified from the originals developed for a macro system. Experimental test-rigs have varied in channel geometry, refrigerant type, and flow conditions. Thousands of data have been collected to find a common point among the differences. This paper reports an investigation of four different two-phase friction factor correlations used in the modeling of the frictional two-phase flow pressure drop of refrigerant R-22. One had been specifically developed for laminar flow in a smooth channel, another was modified from a laminar flow in a smooth pipe to be used for a rough channel, and two correlations are specific for turbulent flow that consider internal pipe surface roughness. Genetic algorithm, an optimization scheme, is used to search for the minimum friction factor and minimum frictional pressure drop under optimized conditions of the mass flux and vapor quality. The results show that a larger pressure drop does come with a smaller channel. A large discrepancy exists between the correlations investigated; between the ones that does not consider surface roughness and that which does, as well as between flow under laminar and turbulent flow conditions.

Analysis of Friction Factor of Two-Phase Flow in Helically Coiled Tubes

2021 ◽  
Author(s):  
Baihui Jiang ◽  
Zhiwei Zhou ◽  
Yu Ji
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Friction Factor ◽  
Single Phase ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Steam Generators ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Applicable Range

Abstract With compact structure and enhanced heat transfer capacity, helical-coiled once through steam generators (HTSGs) are widely used in the small modular reactors (SMRs). Nevertheless, the inside centrifugal forces make the flow more complicated, and increase the frictional pressure drop, which is closely related to the dual test of alternating thermal stress and flow instability. Therefore, the analysis of the friction factor in helically coiled tubes is significant to the efficient and safe operation of HTSGs. While the friction factor of single-phase flow in helically coiled tubes was fully studied and extensive correlations have been validated by a large amount of experimental data, the friction factor of two-phase flow still lacks feasible prediction due to its much more complexity. The existed correlations of two-phase flow in helically coiled tubes are mostly based on specified experimental parameters, so the applicable range is limited. Few scholars have tried to extend these correlations to broader applicability, but the trivial applicable range is unsuitable for program development or engineering design, which needs an accurate prediction of friction factor in a wider range. In this paper, existing frictional pressure drop correlations are investigated. The accuracy of single-phase frictional pressure drop correlations is verified through the comparison of calculation results. Since the known experimental data cannot cover a wide range of parameters, two assumptions are proposed, and the rationality is verified through the existing experimental data and calculation analysis. Based on the two assumptions and calculation, a set of calculation correlations for frictional pressure drop of two-phase flow in helically coiled tubes are proposed. The accuracy of this calculation model is validated by experimental data. The scope of application of this model is: D / d = 15–100, P = 0.12–6.3MPa, G = 200–1500kg / m2s, which is sufficient to support the design and operation of steam generators and the development of the simulation programs.

Evaluation Analysis of Prediction Methods for Two-Phase Flow Pressure Drop in Mini-Channels

2008 ◽  
Author(s):  
Licheng Sun ◽  
Kaichiro Mishima
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Turbulent Region ◽  
Frictional Pressure Drop ◽  
New Correlation ◽  
Mini Channels ◽  
Flow Pressure ◽  
Better Than

2092 data of two-phase flow pressure drop were collected from 18 published papers of which the working fluids include R123, R134a, R22, R236ea, R245fa, R404a, R407C, R410a, R507, CO2, water and air. The hydraulic diameter ranges from 0.506 to 12mm; Relo from 10 to 37000, and Rego from 3 to 4×105. 11 correlations and models for calculating the two-phase frictional pressure drop were evaluated based upon these data. The results show that the accuracy of the Lockhart-Martinelli method, Mishima and Hibiki correlation, Zhang and Mishima correlation and Lee and Mudawar correalion in the laminar region is very close to each other, while the Muller-Steinhagen and Heck correlation is the best among the evaluated correlations in the turbulent region. A modified Chisholm correlation was proposed, which is better than all of the evaluated correlations in the turbulent region and its mean relative error is about 29%. For refrigerants only, the new correlation and Muller-Steinhagen and Heck correlation are very close to each other and give better agreement than the other evaluated correlations.

Two-Phase Flow Through Square and Circular Microchannels—Effects of Channel Geometry

2004 ◽  
Vol 126 (4) ◽  
pp. 546-552 ◽  
Author(s):  
Peter M.-Y. Chung ◽  
Masahiro Kawaji ◽  
Akimaro Kawahara ◽  
Yuichi Shibata
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Separated Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Channel Geometry ◽  
Frictional Pressure Drop ◽  
Channel Shape

An adiabatic experiment was conducted to investigate the effect of channel geometry on gas-liquid two-phase flow characteristics in horizontal microchannels. A water-nitrogen gas mixture was pumped through a 96 μm square microchannel and the resulting flow pattern, void fraction and frictional pressure drop data were compared with those previously reported by the authors for a 100 μm circular microchannel. The pressure drop data were best estimated using a separated-flow model and the void fraction increased non-linearly with volumetric quality, regardless of the channel shape. However, the flow maps exhibited transition boundaries that were shifted depending on the channel shape.

Experimental Investigation on Flow Patterns and Frictional Pressure Drop of Downward Air-Water Two-Phase Flow in Vertical Pipes

2013 ◽  
Author(s):  
Yuqing Xue ◽  
Huixiong Li ◽  
Tianyou Sheng ◽  
Changjiang Liao
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Oil Recovery ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Vertical Pipe ◽  
Two Phase Flows ◽  
Two Phase ◽  
Frictional Pressure Drop

A large amount of air need be transported into the reservoir in the deep stratum to supply oxygen to some microbes in Microbial Enhanced Oil Recovery (MEOR). Air-water two-phase flows downward along vertical pipeline during the air transportation. Base on the experiment data described in this paper, the characteristics of air-water two phase flow patterns were investigated. The flow pattern map of air-water two phase flows in the pipe with inner diameter of 65 mm was drawn, criterions of flow pattern transition were discussed, and the dynamic signals of the pressure and the differential pressure of the two phase flow were recorded to characterize the three basic flow regimes indirectly. The frictional pressure drop of downward flow in vertical pipe must not be disregarded contrast with upward two phase flow in the vertical pipe because the buoyancy must be overcame when the gas flows downward along pipe, and there would be a maximum value of frictional when the flow pattern translated from slug flow to churn flow.

Correlations of the Holdup and the Frictional Pressure Drop in Air-Water Two-Phase Flow in a Flat Capillary Rectangular Channel

2004 ◽  
Author(s):  
Hideo Ide ◽  
Tohru Fukano
Keyword(s):  
Pressure Drop ◽  
Aspect Ratio ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena

Both vertical upward and horizontal gas-liquid two-phase flows in a flat capillary rectangular channel were studied to clarify the flow phenomena, the holdup and the frictional pressure drop. The dimension of the channel used was 9.9 mm × 1.1 mm. The orientations of the channel were with the wide side vertical and the wide side horizontal. The differences between the flow characteristics in such orientations were investigated. New correlations of holdup and frictional pressure drop for flat capillary channels are proposed, in which the effect of aspect ratio has been taken into consideration.

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