Pressure drop, void fraction and wave behavior in two-phase non-Newtonian churn flow

2017 ◽  
Vol 174 ◽  
pp. 82-92 ◽  
Author(s):  
Ke Wang ◽  
Fan Jiang ◽  
Bofeng Bai ◽  
Teck Neng Wong ◽  
Fei Duan ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase ◽  
Churn Flow

Flow Pattern, Void Fraction and Pressure Drop During Adiabatic Two-Phase Gas-Liquid Flow in Vertical Micro-Channel

2012 ◽  
Author(s):  
Sira Saisorn ◽  
Somchai Wongwises
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Void Fraction ◽  
Test Section ◽  
Annular Flow ◽  
Fused Silica ◽  
Working Fluid ◽  
Micro Channel ◽  
Two Phase ◽  
Churn Flow

The experimental investigation is performed to study two-phase flow pattern, void fraction and pressure drop characteristics in a vertical micro-channel. The test section is a fused silica tube with a diameter of 0.53 mm and a length of 320 mm. Air and water are used as working fluid which is introduced to the test section in vertical upward direction. The test runs are done at superficial velocities of gas and liquid ranging respectively from 0.375 to 21.187 m/s and 0.004 to 2.436 m/s. Stereozoom microscope mounted together with camera are employed to conduct flow visualization from which slug flow, throat-annular flow, churn flow, annular flow and annular-rivulet flow are observed. Based on image analysis, void fraction data are obtained and found to be linear relationship with volumetric quality. The frictional pressure drop is relatively high when the formation of churn flow is established. Besides, the two-phase frictional multiplier is found to be strongly dependent on both mass flux and flow pattern.

scholarly journals Pressure drop and average void fraction measurements for two-phase flow through highly permeable porous media

2016 ◽  
Vol 94 ◽  
pp. 422-432 ◽  
Author(s):  
N. Chikhi ◽  
R. Clavier ◽  
J.-P. Laurent ◽  
F. Fichot ◽  
M. Quintard
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through

scholarly journals Frictional Pressure Drop and Liquid Holdup of Churn Flow in Vertical Pipes with Different Viscosities

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zilong Liu ◽  
Yubin Su ◽  
Ming Lu ◽  
Zilong Zheng ◽  
Ruiquan Liao
Keyword(s):  
Pressure Drop ◽  
Liquid Velocity ◽  
Gas Velocity ◽  
Liquid Holdup ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Viscous Oil ◽  
Predicted Values ◽  
Superficial Gas Velocity ◽  
Churn Flow

Churn flow commonly exists in the pipe of heavy oil, and the characteristics of churn flow should be widely understood. In this paper, we carried out air and viscous oil two-phase flow experiments, and the diameter of the test section is 60 mm. The viscosity range of the oil was 100~480 mPa·s. Based on the measured liquid holdup and pressure drop data of churn flow, it can be concluded that, due to the existence of liquid film backflow, positive and negative frictional pressure drop can be found and the change of frictional pressure drop with the superficial gas velocity is related to superficial liquid velocity. With the increase of viscosity, the change rate of frictional pressure drop increases with the increase of the superficial gas velocity. Combining our previous work and the Taitel model, we proposed a new pressure drop model for viscous oil-air two-phase churn flow in vertical pipes. By comparing the predicted values of existing models with the measured pressure drop data, the proposed model has better performance in predicting the pressure drop.

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.

Two-Phase Void Fraction and Pressure Drop in Horizontal Crossflow Across a Tube Bundle

1998 ◽  
Vol 120 (1) ◽  
pp. 140-145 ◽  
Author(s):  
G. P. Xu ◽  
K. W. Tou ◽  
C. P. Tso
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Mass Velocity ◽  
Flow Model ◽  
Tube Bundle ◽  
Diameter Ratio ◽  
Two Phase ◽  
Friction Pressure ◽  
Oil Flow ◽  
Friction Pressure Drop

Void fraction and friction pressure drop measurements were made for an adiabatic, horizontal two-phase flow of air-water, air-oil across a horizontal in-line, 5 × 20 tube bundle with pitch-to-diameter ratio, P/D, of 1.28. For both air-water and air-oil flow, the experimental results showed that the average void fraction were less than the values predicted by a homogenous flow model, but were well correlated with the Martinelli parameter Xtt and liquid-only Froude number FrLO. The two-phase friction multiplier data exhibited an effect of flow pattern and mass velocity, and they could be well-correlated with the Martinelli parameter.

INVESTIGATION ON VOID FRACTION FOR TWO-PHASE FLOW PRESSURE DROP OF EVAPORATIVE R-290 IN HORIZONTAL TUBE

2016 ◽  
Vol 78 (8-4) ◽  
Author(s):  
Agus Sunjarianto Pamitran ◽  
Sentot Novianto ◽  
Normah Mohd-Ghazali ◽  
Nasruddin Nasruddin ◽  
Raldi Koestoer
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Homogeneous Model ◽  
Saturation Temperature ◽  
Horizontal Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Experimental Conditions

Two-phase flow boiling pressure drop experiment was conducted to observe its characteristics and to develop a new correlation of void fraction based on the separated model. Investigation is completed on the natural refrigerant R-290 (propane) in a horizontal circular tube with a 7.6 mm inner diameter under experimental conditions of 3.7 to 9.6 °C saturation temperature, 10 to 25 kW/m2 heat flux, and 185 to 445 kg/m2s mass flux. The present experimental data was used to obtain the calculated void fraction which then was compared to the predicted void fraction with 31 existing correlations. A new void fraction correlation for predicting two-phase flow boiling pressure drop, as a function of Reynolds numbers, was proposed. The measured pressure drop was compared to the predicted pressure drop with some existing pressure drop models that use the newly developed void fraction model. The homogeneous model of void fraction showed the best prediction with 2% deviation

Comparative Study in the Stability Analysis Code of LAPUR5.2 and LAPUR6.0 for the Kuosheng NPP

2012 ◽  
Author(s):  
Chang-Lung Hsieh ◽  
Guan-Yu Chen ◽  
Chunkuan Shih ◽  
Jong-Rong Wang ◽  
Hao-Tzu Lin
Keyword(s):  
Stability Analysis ◽  
Pressure Drop ◽  
Void Fraction ◽  
Boiling Water ◽  
Boiling Water Reactors ◽  
Two Phase ◽  
Flow Area ◽  
Comparison Results ◽  
Fuel Assemblies ◽  
Water Reactors

Under certain conditions, boiling water reactors (BWRs) would be susceptible to couple neutron-thermalhydraulic instability. It is important to predict such potential problems as early as possible and prevent the core instability from happening. In each BWR reload core design, fuel vendors are required to provide instability boundaries on power/flow map to assure safety operation of the nuclear reactor. In Taiwan, a LAPUR5.2 methodology had been adapted to build up the remarkable analysis mode for different types BWRs to verify vendor’s results. However, with upgrading nuclear safety technology, most of boiling water reactors has been adopting partial length fuel assemblies to reduce two-phase pressure drop and void fraction, to improve reactor stability. The question is that LAPUR5.2 methodology cannot precisely analysis stability characteristics from the variation of flow area in fuel assemblies. From the reasons of upgrading stability analysis, a LAPUR6.0 methodology had built to do the related researches. This research was based on a comparison study between LAPUR5.2 and LAPUR6.0 to realize the major differences and their effects on stability characteristics. According to the comparison results for Kuosheng Nuclear Power Plant Unit 2 Cycle 21 reload design, it shows that LAPUR6.0 can completely present pressure drop, void fraction and density reactivity coefficient from the changing of flow area and fuel spacers.

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