Void fractions for condensing refrigerant flow in small channels. Part II: Void fraction measurement and modeling

2012 ◽  
Vol 35 (2) ◽  
pp. 246-262 ◽  
Author(s):  
Julian Winkler ◽  
Jesse Killion ◽  
Srinivas Garimella
Keyword(s):  
Void Fraction ◽  
Void Fractions ◽  
Small Channels ◽  
Fraction Measurement

scholarly journals A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels

Sensors ◽  
2016 ◽  
Vol 16 (2) ◽  
pp. 159 ◽  
Author(s):  
Huajun Li ◽  
Haifeng Ji ◽  
Zhiyao Huang ◽  
Baoliang Wang ◽  
Haiqing Li ◽  
...  
Keyword(s):  
Void Fraction ◽  
Measurement Method ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Small Channels ◽  
Fraction Measurement

Measurement of Void Fraction in Dispersed Bubbly Flow With Constant Electric Current Method

2012 ◽  
Author(s):  
Shin-ichiro Uesawa ◽  
Akiko Kaneko ◽  
Yutaka Abe
Keyword(s):  
Electric Current ◽  
Void Fraction ◽  
Bubbly Flow ◽  
Three Dimensional ◽  
Current Method ◽  
Electrical Current ◽  
Measurement Methods ◽  
Polarization Method ◽  
Void Fractions ◽  
Fraction Measurement

Void fraction is one of important physical values for gas-liquid two-phase flow in nuclear power plants, and it is an essential parameter for designs and performance evaluations of devices, including a core of BWR and so on. Therefore void fraction measurement with real time, high temporal resolution and high spatial resolution has been needed. In several void fraction measurement methods, electric measurement methods of void fraction can realize real-time measurement. In previous studies, conductance methods capacitance methods, wire mesh methods and tomography techniques have been studied. In the present study, we research on a constant electric current method. This method can measure void fraction with higher temporal resolution and simpler systems. In previous study, the constant electrical current method has been applied in annular flow mainly. However, the method cannot be applied to three dimensional dispersed bubbly flow. This is because void fraction is estimated by cross-section ratio of gas and liquid phases in this method. In the present study, Maxwell’s theory and polarization method are applied to calculation method of void fraction from voltage measured by constant electrical current method, and we try to measure void fraction in dispersed bubbly flow. Maxwell’s theory is a calculation of a mixture with two materials of different conductivity. The polarization method proposed in this study assumes bubbles to be dielectric bodies and void fraction is estimated by the polarization electric field of the bubbles. In the experimental results, the void fractions in the three dimensional dispersed bubbly flow can be estimated with Maxwell’s theory and the polarization method. The void fractions estimated with these methods are more accurately than the previous method. Furthermore, it is experimentally clarified that the present proposed method can follow highly temporal void fluctuations of bubbly and froth flows. In addition, effects of intervals between electrodes and structures of electrodes are experimentally investigated.

A method for void fraction measurement of bubble/slug flow in small channels based on contactless impedance detection

2021 ◽  
Vol 92 (10) ◽  
pp. 105006
Author(s):  
Junchao Huang ◽  
Ziwei Guo ◽  
Xiao-Yu Tang ◽  
Haifeng Ji ◽  
Baoliang Wang ◽  
...  
Keyword(s):  
Void Fraction ◽  
Slug Flow ◽  
Small Channels ◽  
Fraction Measurement

Void Fraction Measurement of Cryogenic Multiphase Flow in Microgravity

2018 ◽  
Vol 66 (6) ◽  
pp. 147-152
Author(s):  
Hiroaki Kobayashi ◽  
Yuki Sakamoto ◽  
Kiyoshi Kinefuchi ◽  
Tetsuya Sato
Keyword(s):  
Multiphase Flow ◽  
Void Fraction ◽  
Fraction Measurement

Two-Phase Friction Factor Obtained From Various Void Fraction Models During Condensation of R134A in Vertical Downward Flow at High Mass Flux

2008 ◽  
Author(s):  
Ahmet Selim Dalkilic ◽  
Suriyan Laohalertdecha ◽  
Somchai Wongwises
Keyword(s):  
Void Fraction ◽  
Annular Flow ◽  
Smooth Tube ◽  
High Mass ◽  
Two Phase ◽  
Void Fractions ◽  
Mass Fluxes ◽  
Friction Factors ◽  
Flow Void ◽  
Fraction Models

Void fractions are determined in vertical downward annular two-phase flow of R134a inside 8.1 mm i.d. smooth tube. The experiments are done at average saturated condensing temperatures of 40 and 50°C. The average qualities are between 0.84–0.94. The mass fluxes are around 515 kg m−2s−1. The experimental setup is explained elaborately. Comparisons between the void fraction determined from 35 void fraction correlations are done. According to the use of various horizontal and vertical annular flow void fraction models together with the present experimental condensation heat transfer data, similar void fraction results were obtained mostly for the smooth tube. The experimental friction factors obtained from void fraction correlations are compared with the friction factors determined from graphical information provided by Bergelin et. al. Effect of void fraction alteration on the momentum pressure drop is also presented.

Void fraction measurement by X-ray absorption

2002 ◽  
Vol 25 (8) ◽  
pp. 615-621 ◽  
Author(s):  
Abdullah Abbas Kendoush ◽  
Zareh Azat Sarkis
Keyword(s):  
Void Fraction ◽  
X Ray ◽  
Fraction Measurement ◽  
X Ray Absorption

Void fraction measurement of the air-water two-phase flow in the sub-channel of a rod bundle geometry based on an impedance meter

2018 ◽  
Vol 115 ◽  
pp. 480-486 ◽  
Author(s):  
Bin Yu ◽  
Wenxiong Zhou ◽  
Liangming Pan ◽  
Hang Liu ◽  
Quanyao Ren ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Rod Bundle ◽  
Fraction Measurement ◽  
Impedance Meter

Void fraction measurements in breaking waves

2007 ◽  
Vol 463 (2088) ◽  
pp. 3151-3170 ◽  
Author(s):  
C.E Blenkinsopp ◽  
J.R Chaplin
Keyword(s):  
Void Fraction ◽  
Wave Breaking ◽  
Breaking Waves ◽  
Phase Detection ◽  
Bubble Plume ◽  
Two Phase ◽  
Void Fractions ◽  
Highly Sensitive ◽  
Energy Dissipated ◽  
Degree Of Similarity

This paper describes detailed measurements and analysis of the time-varying distribution of void fractions in three different breaking waves under laboratory conditions. The measurements were made with highly sensitive optical fibre phase detection probes and document the rapid spatial and temporal evolutions of both the bubble plume generated beneath the free surface and the splashes above. Integral properties of the measured void fraction fields reveal a remarkable degree of similarity between characteristics of the two-phase flow in different breaker types as they evolve with time. Depending on the breaker type, the energy expended in entraining air and generating splash accounts for a minimum of between 6.5 and 14% of the total energy dissipated during wave breaking.

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