Two-phase frictional pressure drop and water film thickness in a thin hydrophilic microchannel

2018 ◽  
Vol 127 ◽  
pp. 813-828 ◽  
Author(s):  
James M. Lewis ◽  
Yun Wang
Keyword(s):  
Pressure Drop ◽  
Film Thickness ◽  
Water Film ◽  
Two Phase ◽  
Water Film Thickness ◽  
Frictional Pressure Drop

Measuring Water Film Thickness in a Wet Gas Compressor Diffuser: Design, Calibration, and Testing of Electromagnetic Probes

2017 ◽  
Author(s):  
Craig Nolen ◽  
Melissa Poerner
Keyword(s):  
Film Thickness ◽  
Water Level ◽  
Water Film ◽  
Probe Design ◽  
Two Phase ◽  
Water Film Thickness ◽  
Wet Gas ◽  
Flow Phenomena ◽  
In Series ◽  
Electromagnetic Probes

The distribution of water in the diffuser of a wet gas compressor is not well understood. Measurements of water film thickness across the diffuser surface would improve the understanding of two-phase flow phenomena in wet gas compressors. Electromagnetic probes were designed in order to measure water film thickness in the diffuser of a SwRI-designed wet gas compressor. The probes consisted of two electrode foils plated on a thin insulating substrate, allowing them to be bonded in place without drilling through the diffuser. An AC signal was passed between the electrodes, and the voltage across a resistor in series with the electrodes was recorded. As the water level covering the electrodes increased, the recorded voltage increased. A method of calibrating the probes was developed and used prior to installation in the diffuser. Testing showed the probes to be effective at detecting the presence of water in the diffuser and indicating the general water level. Improvements in probe design, calibration, and installation are needed to provide more precise water film thickness data.

An Improved Correlation for Two-Phase Frictional Pressure Drop in Boiling and Adiabatic Downflow in the Annular Flow Regime

1991 ◽  
Vol 205 (5) ◽  
pp. 317-328 ◽  
Author(s):  
J F Klausner ◽  
B T Chao ◽  
S L Soo
Keyword(s):  
Pressure Drop ◽  
Film Thickness ◽  
Flow Regime ◽  
Annular Flow ◽  
Volume Fraction ◽  
Interfacial Shear Stress ◽  
Published Data ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Wide Range

An improved correlation is presented for annular two-phase frictional pressure drop data for vertical downflow. An ideal dimensionless film thickness based on the vapour volume fraction, a characteristic friction factor based on the two-phase frictional pressure gradient and a Weber number relevant for the interfacial capillary wave structure are the correlating parameters. The proposed new correlating scheme is tested against a wide range of data obtained in this investigation for refrigerant R11 in forced convection boiling and in adiabatic test sections of 19 mm cylindrical cross-section as well as published data for air-water and air-glycerine solution mixtures in the annular flow regime. Over 80 per cent of the measured values fall within ±30 per cent of those predicted from the correlation. Due to the wide range of liquid film thickness covered, 0.05–2.9 mm, its validity extends past the range where previously reported downflow pressure drop correlations fail. A paradox connected with previously reported annular downflow pressure drop correlations based on the liquid-vapour interfacial shear stress is pointed out. Upflow frictional pressure drop data in the annular flow regime can also be correlated by the proposed scheme.

Measuring Water Film Thickness in a Wet Gas Compressor Diffuser—Design, Calibration, and Testing of Electromagnetic Probes

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Craig Nolen ◽  
Melissa Poerner
Keyword(s):  
Film Thickness ◽  
Water Level ◽  
Water Film ◽  
Probe Design ◽  
Two Phase ◽  
Water Film Thickness ◽  
Wet Gas ◽  
Flow Phenomena ◽  
In Series ◽  
Electromagnetic Probes

The distribution of water in the diffuser of a wet gas compressor is not well understood. Measurements of water film thickness across the diffuser surface would improve the understanding of two-phase flow phenomena in wet gas compressors. Electromagnetic probes were designed in order to measure water film thickness in the diffuser of a SwRI-designed wet gas compressor. The probes consisted of two electrode foils plated on a thin insulating substrate, allowing them to be bonded in place without drilling through the diffuser. An AC signal was passed between the electrodes, and the voltage across a resistor in series with the electrodes was recorded. As the water level covering the electrodes increased, the recorded voltage increased. A method of calibrating the probes was developed and used prior to installation in the diffuser. Testing showed the probes to be effective at detecting the presence of water in the diffuser and indicating the general water level. Improvements in probe design, calibration, and installation are needed to provide more precise water film thickness data.

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.

Influence of Ground Slag on the Rheology of Mortar

2013 ◽  
Vol 438-439 ◽  
pp. 67-71
Author(s):  
Qian Qian Zhang ◽  
Jian Zhong Liu ◽  
Jia Ping Liu
Keyword(s):  
Film Thickness ◽  
Specific Surface ◽  
Yield Stress ◽  
Surface Area ◽  
Specific Surface Area ◽  
Water Film ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Water Film Thickness ◽  
Binder Ratio

The effects of ground slag with different specific surface area on the rheology of mortar at water-binder ratio of 0.25, 0.28 and 0.30 were investigated, and the combined effects of packing density and solid surface area on the rheology of mortar were evaluated in terms of the water film thickness. The results show that with the increasing of specific surface area of slag (220 m2/kg-784 m2/kg), plastic viscosity and yield stress decrease. The correlations of yield stress and plastic viscosity to the water film thickness are basically linear with high correlation R2 values. The action of the ground slag on the rheology of mortar can be characterized by water film thickness, and with the increasing of water film thickness the rheological parameters decrease.

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