A Study on Flow Patterns and Pressure Drop in Adiabatic Two-Phase Flow Across a Bank of Micro Pin Fins

2007 ◽  
Author(s):  
Santosh Krishnamurthy ◽  
Yoav Peles
Keyword(s):  
Pressure Drop ◽  
Mass Flux ◽  
Slug Flow ◽  
Flow Patterns ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Pin Fin ◽  
Scale Models ◽  
Pin Fins ◽  
Micro Pin Fins

Flow patterns, void fraction and pressure drop in adiabatic nitrogen-water two phase flows across a bank of micro pin fin were experimentally investigated for Reynolds number ranging from 5 to 50. Staggered cylindrical shaped micro pin fins with diameter and height of 100 μm were micro-fabricated into 1 cm long, 1.8 mm microchannel. Flow patterns were determined by flow visualization and classified as bubbly-slug flow, gas-slug flow, bridged flow and annular flow. The applicability of conventional scale models to predict two-phase frictional pressure drop was also assessed. The two-phase frictional multiplier was found to be a strong function of mass flux and flow patterns unlike the previous results observed in the microchannel studies. It was observed that models from conventional scale systems did not adequately predict the two-phase frictional multiplier at micro-scale and thus, a modified model accounting for mass flux and flow patterns have been developed in this work.

Experimental Study of Adiabatic Water Liquid-Vapor Two-Phase Pressure Drop Across an Array of Staggered Micro-Pin-Fins

2008 ◽  
Author(s):  
Christopher A. Konishi ◽  
Weilin Qu ◽  
Ben Jasperson ◽  
Frank E. Pfefferkorn ◽  
Kevin T. Turner
Keyword(s):  
Pressure Drop ◽  
Maximum Mass ◽  
Two Phase ◽  
Pin Fin ◽  
Pin Fins ◽  
Micro Pin Fins ◽  
Pin Fin Array ◽  
Test Module ◽  
Phase Pressure ◽  
Liquid Vapor

This study concerns pressure drop of adiabatic water liquid-vapor two-phase flow across an array of 1950 staggered square micro-pin-fins having a 200×200 micron cross-section by a 670 micron height. The ratios of longitudinal pitch and transverse pitch to pin-fin equivalent diameter are equal to 2. An inline immersion heater upstream of the micro-pin-fin test module was employed to produce liquid-vapor two-phase mixture, which flowed across the micro-pin-fin array. The test module was well insulated to maintain an adiabatic condition. Four maximum mass velocities of 184, 235, 337, and 391 kg/m2s, and a range of vapor qualities for each maximum mass velocity were tested. Measured pressure drop increases drastically with increasing vapor quality. Nine existing two-phase pressure drop models and correlations were assessed. The Lockhart-Martinelli correlation for laminar liquid-laminar vapor combination in conjunction with a single-phase friction factor correlation proposed for the present micro-pin-fin array provided the best agreement with the data.

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.

Numerical Study of the Endwall Effects on Water Single-Phase Pressure Drop Across a Circular Micro-Pin-Fin Array

2011 ◽  
Author(s):  
Jonathan R. Mita ◽  
Weilin Qu ◽  
Frank E. Pfefferkorn
Keyword(s):  
Pressure Drop ◽  
Single Phase ◽  
Numerical Study ◽  
Circular Cross Section ◽  
Reynolds Numbers ◽  
Pin Fin ◽  
Pin Fins ◽  
Micron Diameter ◽  
Micro Pin Fins ◽  
Pin Fin Array

This paper presents a numerical study of pressure drop associated with water liquid single-phase flow across an array of staggered micro-pin-fins having circular cross-section. The numerical simulations were validated against previously obtained experimental results using an array of staggered circular micro-pin-fins having the following dimensions: 180 micron diameter and 683 micron height. The longitudinal pitch and transverse pitch of the micro-pin-fins are equal to 399 microns. The effects of endwalls on pressure drop characteristics were then explored numerically. Six different micro-pin-fin height to diameter ratios were studied with seven different Reynolds numbers. All simulations were performed at room temperature (23°C). It was seen that for any given Reynolds number, as the pin height to diameter ratio increased, the pressure drop and resulting non-dimensional friction factor decreased.

Frictional Pressure Drop of Gas-Newtonian and Gas-Non Newtonian Slug Flow in Vertical Pipe

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Subrata Kumar Majumder ◽  
Sandip Ghosh ◽  
Gautam Kundu ◽  
Arun Kumar Mitra
Keyword(s):  
Pressure Drop ◽  
Slug Flow ◽  
Amyl Alcohol ◽  
Newtonian Liquid ◽  
Vertical Pipe ◽  
Two Phase ◽  
Vertical Column ◽  
Frictional Pressure Drop ◽  
Liquid Systems ◽  
Phase Pressure

Experimental study on two-phase pressure drop in a vertical pipe with air-Newtonian and non-Newtonian liquid in slug flow regime has been carried out within a range of gas and liquid flowrate of 0.5×10-4 to 1.92×10-4 m-3/s and 1.6×10-4 to 6.7×10-4 m3/s respectively. In the present study air and four types of liquids such as water, amyl alcohol, glycerin (two different concentrations), and CMC (Sodium Carboxymethyl Cellulose) are used. The present data were analyzed by two-phase friction method. To predict the two-phase pressure drop, correlations have been developed with Newtonian and non-Newtonian liquid. A general correlation was also developed to predict the two-phase pressure drop in a vertical column of diameter 0.01905 m and 3.4 m height combining both the Newtonian and non-Newtonian liquid systems.

A Flow Model for Two-Phase Slug Flow in Horizontal Tubes

1961 ◽  
Vol 83 (4) ◽  
pp. 613-618 ◽  
Author(s):  
E. S. Kordyban
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Slug Flow ◽  
Flow Model ◽  
Simplified Model ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Horizontal Tubes

The paper presents a construction of a simplified model approximating the actual observed flow pattern. The resulting expressions for frictional pressure drop are found to agree fairly well with the author’s data for steam and water and the data for air and water of other investigators. The similarity with a portion of the Chenoweth-Martin correlation appears to present a logical explanation for the applicability of that correlation to slug flow.

The Visualization of Flow Boiling in a Uniformly Heated Micro Capillary Tube

2006 ◽  
Author(s):  
X. H. Yan ◽  
J. Z. Xu ◽  
D. W. Tang
Keyword(s):  
Pressure Drop ◽  
Slug Flow ◽  
Annular Flow ◽  
Capillary Tube ◽  
Flow Boiling ◽  
Bubbly Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Inner Diameter

This work presents experiments on the visualization of flow boiling of water in a horizontally placed and uniformly heated micro capillary tube. Three micro capillary tubes of quartz glass with inner diameters of 520, 315 and 242 μm are prepared. Experiments are performed with deionized water over a mass flux range from 39.3 to 362.5kg/m2s, and the inlet temperatures of 30, 45, and 60 °C respectively. By a video system with microscope and high-speed camera, the vapor-water two-phase flow’s patterns are recorded and analyzed. It has been found that periodic change of two-phase flow patterns and dramatic fluctuations of pressure drop occur in the micro capillary tubes. A new arch flow pattern, liquid film evaporating, and liquid droplet have been observed firstly. Bubbly flow has not been observed during our visual experiments for the inner diameter of 242 μm, the flow patterns are only made up of single liquid phase flow and two-phase elongate slug flow. The main flow regimes in these micro-tubes are single-liquid flow, slug flow, and annular flow with liquid film surrounded in the micro-tube with inner diameter of 520 and 315μm. Trends of pressure drop and flow patterns’ transition are compared and the results show that the increasing process of pressure drop is approximately in the single-liquid flow and bubbly flow, while the decreasing process of pressure drop is in the state of annular flow.

Flow Patterns and Frictional Pressure Drop of Gas-Liquid Two-Phase Flow in Microchannels

2016 ◽  
Vol 2016 (0) ◽  
pp. J0540102
Author(s):  
Hideo IDE ◽  
Takayuki UMENO ◽  
Eiji KINOSHITA ◽  
Takeshi OhTAKA ◽  
Ryo KUROSHIMA
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Frictional Pressure Drop

Flow Characteristics and Frictional Pressure Drops of Gas-Liquid Two-Phase Flow in Mini-Micro Pipes and at Vena Contract and Expansion

2007 ◽  
Author(s):  
Hiroyasu Ohtake ◽  
Hideyasu Ohtaki ◽  
Yasuo Koizumi
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Liquid Velocity ◽  
Flow Patterns ◽  
Experimental Results ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Frictional Pressure Drop

The frictional pressure drops and two-phase flow patterns of gas-liquid two-phase flow in mini-micro pipes and at vena contract and expansion were investigated experimentally. Test liquid was water; test gas was argon. The diameter of the test mini-pipe was 0.5, 0.25 and 0.12 mm, respectively. The pressure drop data and the flow pattern were collected over 2.1 < Ug < 92.5 m/s for the superficial gas velocity and 0.03 < Ul < 10 m/s for the superficial liquid velocity. The experimental results show that the flow patterns were slug, churn, ring and annular flows; pure bubbly flow pattern was not observed in a range of the present experimental conditions. The two-phase friction multiplier data for D > 0.5 mm showed to be in good agreement with the conventional correlations. On the other hand, the two-phase friction multiplier data for D < 0.25 mm differed from the calculated values by the conventional correlations. Then, thickness of liquid film around a gas plug and size of gas core were estimated and the effect of frictional pressure drop on channel size was discussed through Knudsen Number of gas and instability on liquid-gas interface. The coefficients of sudden enlargement and sudden contraction in mini-pipes for the gas-water two-phase flow were modified from the present experimental results.

Two-Phase Pressure Drop of CO2 in Mini Tubes and Microchannels

2003 ◽  
Author(s):  
R. Yun ◽  
Y. Kim
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Large Diameter ◽  
Two Phase ◽  
Heating Method ◽  
Pressure Drops ◽  
Direct Heating ◽  
Frictional Pressure Drop ◽  
Phase Pressure

Two-phase pressure drops of CO2 are investigated in mini tubes with inner diameters of 2.0 and 0.98 mm and in microchannels with hydraulic diameters from 1.08 to 1.54 mm. For the mini tubes, the tests were conducted with a variation of mass flux from 500 to 3570 kg/m2s, heat flux from 7 to 48 kW/m2, while maintaining saturation temperatures at 0°C, 5°C and 10°C. For the microchannels, mass flux was varied from 100 to 400 kg/m2s, and heat flux was altered from 5 to 20 kW/m2. A direct heating method was used to provide heat into the refrigerants. The pressure drop of CO2 in mini tubes shows very similar trends with that in large diameter tubes. Although the microchannel has a small hydraulic diameter, two-phase effects on frictional pressure drop are significant. The Chisholm parameter of the Lockhart and Martinelli correlation is modified by considering diameter effects on the two-phase frictional multiplier.

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