vol 7-1-041 055 azridjal aziz, distribution of two-phase flow in a distributor

7/28/2019 Vol 7-1-041 055 Azridjal Aziz, DISTRIBUTION OF TWO-PHASE FLOW IN A DISTRIBUTOR

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JournalofEngineeringScienceandTechnologyVol.7,No.1(2012)41-55SchoolofEngineering,TaylorsUniversity

41

DISTRIBUTIONOFTWO-PHASEFLOWINADISTRIBUTOR

AZRIDJALAZIZ1,2

,AKIOMIYARA1,

*,FUMIAKISUGINO1

1DepartmentofMechanicalEngineering,SagaUniversity,

1Honjomachi,Saga-shi,8408502,Japan2DepartmentofMechanicalEngineering,RiauUniversity

KampusBinaWidya,Km12,5,Sp.Baru,Panam,Pekanbaru,28293,Indonesia

*CorrespondingAuthor:[email protected]

Abstract

The flow configuration and distribution behavior of two-phase flow in a

distributormadeofacrylicresinhavebeeninvestigatedexperimentally.In this

study, air and water were used as two-phase flow working fluids. The

distributor consistsofone inlet andtwo outlets,which are set asupper and

lower,respectively.Theflowvisualizationatthedistributorwasmadebyusing

a highspeedcamera. The flow rates of air and water flowing out from the

upperandloweroutletbranchesweremeasured.Effectsofinclinationangleof

the distributor were investigated. By changing the inclination angle from

verticaltohorizontal,unevendistributionswerealsoobserved.Thedistribution

of two-phase flow through distributor tends even flow distribution on the

vertical position and tends uneven distribution on inclined and horizontal

positions. It is shown that even distribution could be achieved at high

superficialvelocitiesofbothairandwater.

Keywords:Two-phaseflow,Distributor,Distribution,Visualization,Angle.

1.Introduction

Flowmal-distributionoftwo-phaseflowmixturesinheatexchangerswithparallel

flowcircuitsreducethethermalperformancewheretheheattransferoccurs.Often,flowratesthroughthechannelsarenotuniformandintheextremecase,almostno

flowthroughsomeofthem,whichexhibitsapoorheatexchangingperformance.

The situation becomesmorecomplicatedespeciallywith two-phase flows [1]. In

evaporators,uniformdistributionisessentialtoavoiddry-outphenomenonandthe

resulting poor heat exchange performance. In condensers, uneven distributionof

liquidcouldcreatezonesofreducedheattransferduetohighliquidloading.Thus,


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42A.Azizetal.

JournalofEngineeringScienceandTechnologyFebruary2012,Vol.7(1)

Nomenclatures

A Area,m2

Q Volumetricflowrate,L/min

R Deviationratio

U Superficialvelocity,m/s

Subscripts

1 Outlet1

2 Outlet2

G Gasphase,airL Liquidphase,water

in the design and optimization of compact heat exchangers with parallel flow

technologies, understanding of two phase distribution in themanifolds aregreat

importance[2-4].

Tae and Cho [5] have investigated two-phase flow distribution and phase

separationthroughvarioustypesofbranchtubesinsingleT-junction.Wenetal.

[6] investigated how to improving two-phase refrigerant distribution in themanifoldoftherefrigerationsystemwiththreedifferentdistributorconfiguration.

Manyvariablesaffectthedistributionoftwo-phasemixtures,includinggeometric

factors(manifoldcross-sectiondesign,branchcouplings,location,andorientation

of the tubes) and onthe inlet flowconditions (flowrate, flowstructure, vapor

fraction, and heat load on the tubes). Due to this complexity, no general

physically basedmethodhasbeendevelopedto describetheflowconditions in

heat exchangermanifolds andpredict thetwo-phase flowdistribution.Kimand

Sin[7]studiedairandwatertwo-phaseflowdistributioninaparallelflowheat

exchanger.Duetocomplexity,onlyalimitednumberofstudieshaveinvestigated

thephenomenonthatoccursintwo-phaseflowdistributors.

Recently,theuseofsmalldiametertubeisbecomingofinterestinimproving

the heat exchanger performance,but a largepressuredropwillbe occurin thesmalltubeand itwould bedecrease the heat transferperformance. Inorder to

reduce the pressure drop and to obtain a higher heat transfer coefficient of

refrigerant flow, the flowmust bedistributed into severalchannels byusinga

distributor.Therefrigerantdistributorwilldistributerefrigerantflowequallyfrom

thethermostaticexpansionvalveintoeachevaporatorchannel.

To keep the heat exchanger performance, refrigerant should be distributed

equally througheachpipe.However,the refrigerantflowthroughdistributoris

noteasyflowdividedequally,andthedriftconditionoftherefrigerantflowwill

beinfluencedbytheshapeandpositionofthedistributor.Sometimes,itcouldbe

leadto decreaseof heat exchangerperformance. It isnecessarytomaintainthe

performance of the heat exchanger by minimizing this drift condition. In air

conditioners,vaporandliquidofarefrigerantflowthroughdistributor.Although

air andwater flow in the distributor issomewhat different from the two-phaserefrigerantflow,experimentsofthedistributionofair-watertwo-phaseflowgive

valuableinformation.Flowobservationsarepossibleonlyforairandwaterflow.

Inthisstudy,experimentalresearchisaimedtoclarifygeneralcharacteristics

offlowanddeviationofair-watertwo-phaseflowsthroughthedistributor.The


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DistributionofTwo-phaseFlowinaDistributor43


flowratesofeachphaseflowingintheoutletafterdistributorbranchesupperand

lower were measured. To understand the two-phase flow behavior in the

distributor,flowdistribution patternsofairandwaterhavebeen observedbya

high-speedcamera.Effectsof inclinationangleofthedistributoronflowpattern

andflowrateofairandwaterwerealsoinvestigated.

2.Experiments

2.1.Experimentalapparatusandprocedure

Figure 1 illustrates the experimental apparatus. The experimental apparatus

consistsofairandwatersupplysystem,mergingsection,distributortestsection,

twogas-liquid separator, airmeasuring bath, andwatermeasuring cylinder.Air

flowrateandwaterflowratebeforeenteringtotestsectionaresetupusingaflowmeterandair-waterwillmixinthemergingsection.

The test section consistsof anentrance tubewithdiameter of8 mm and a

distributorwithtwooutlet tubes,upper and lowerwith diameter of5mm.The

entrancetubehas400mmtubelengthfromthedistributorinlettoensureafully

developedflow.Thedistributorwasmachinedand polished forma rectangular

block of acrylic resin. The transparent block facilitates flow visualization

observation.To investigatetheslopeeffectofthedistributor,theangledirectionof the test sectioncan changed toother angle. The whole test section and the

detailofthedistributorareshowninFigs.2and3,respectively.Inthisstudyair

and water wereused as two-phaseflowworking fluid.Waterwas suppliedby

water source in laboratory. Air was supplied by air-compressor with set up

pressure regulator. Both the air and water flow rate were controlled by using

calibrated rotameter before entering the merging section. The accuracy of the

rotameteris6%.

Theexperimentswere conducted indifferentslopesof thedistributorin 0,45and90withvaryingairandwaterflowrates.Theinclinationangle0isused

for horizontal position, 45 for inclined position and 90 is used for vertical

position.Themeasurementsofairandwaterflowratesateachexitofdistributor

weretakenafterthegas-liquidseparator.Airflowratewasmeasuredbytheair

measuringbath andwater flowrate bythewatermeasuringcylinder.The flow

Fig.1.ExperimentalApparatus.


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44A.Azizetal.


visualizationandphotographs of flow patternswere capturedusing highspeed

videocamera(KeyenceMotionAnalyzingVW-6000)atshutterspeed1/30.000

second,frameratepersecond(fps)at500fps,andreproductionspeedat15 fps.

Duringthewholeseriesoftests,severalrunsweremadetochecktherepeatability

of the data. The data presented are average values of ten measurements. The

errorsoftheairandwaterflowratemeasurementsareconsideredtobeacceptable

andtheyareevaluatedas6.14%and5.19%,respectively.

TheuncertaintieswereestimatedusingthemethodsuggestedbyBell[8]and

Moffat[9].Themeasurementuncertaintiesoftheairandwaterflowrateswere4.0%and1.9%,respectively.

2.2.Datareduction

Theair-watervolumetricflowratewastakenafterflowout fromthegas-liquidseparator.Thevolumetricflowratesofairinoutlet1andoutlet2areQ

G1andQ

G2

and the volumetric flow rates of water are QL1 and QL2, respectively. The

deviation ratioR defined withEqs. (1) and (2). Theair deviation ratio isRG,

andthewaterdeviationratioisRL.Where,subscriptGisforairandsubscriptL

forwater.

( ) ( )2121 GGGGG QQQQR += (1)

( ) ( )2121 LLLLL QQQQR += (2)

R=1statesthatallfluidflowoutfromtheupperoutlet,R=0statesthatthere

isnodeviation,andR=-1statesthatallfluidflowoutfromtheloweroutlet.

ThesuperficialvelocitiesUofeachfluidaredefinedwithEqs.(3)and(4).UG

istheairsuperficialvelocityandUListhewatersuperficialvelocity.

AQUGG

= (3)

AQU LL = (4)

whereAisflowareaofinlettube.

400mm

70mm

Fig.2.TestSection.

Distributor

88mmmm55mmmm

55mmmm

InletOutlet1

Outlet2

Fig.3.Distributor.


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3.ResultsandDiscussion

TheexperimentalconditionsareplottedonflowpatternmapsasshowninFigs.

4(a)and4(b),whichareMandhanemapforhorizontalflowandSekoguchimap

forverticalflow.InFig.4(a),solidlinesindicatecriteriaofMandhaneetal.[10]

anddashedlinesindicatecriteriaofBaker[11].TheSekoguchimap[12]isfor

upward and concurrent vertical flow. Three types of symbols mean different

inclination,suchasblackcirclefor0,squarefor45,andtrianglefor90.

The experiment was carried out on the condition of the water superficial

velocityUL isconstant with changingconditionsof air superficialvelocityUG

Fig.4.ExperimentalConditionsonFlowPatternMaps.

101

100

101

102

101

100

SuperficialGasvelocity[m/s]

SuperficialLiquidVelocity[m/s]

Bubbleflow

Slugflow

Frothflow

Annularflow

B S6

B F10

S F10

S F6

F A10

F A6

(c) (d) (e)

(h) (i) (j)

(m)(n)

(o)

(r) (s) (t)

(w) (x) (y)

(b)

(g)

(l)

(q)

(v)

(a)

(f)

(k)

(p)

(u)

(z)

(aa)

(ab)

(ac)

(ad)

(ad)

(b)Sekoguchi[12]MapforVerticalFlow.

101

100

101

102

101

100

Dispersedflow

BubbleElongated

Bubbleflow

Stratifiedflow

Slugflow

Waveflow

AnnularAnnularMistflow

SuperficialGasVelocity[m/s]


(c) (d) (e)

(h) (i) (j)

(m)(n) (o)

(r) (s) (t)

(w) (x) (y)

(b)

(g)

(l)

(q)

(v)

(a)

(f)

(k)

(p)

(u)

(z)

(aa)

(ab)

(ac)

(ad)

(ad)

(a)Mandhane[10]andBaker[11]MapsforHorizontalFlow.


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46A.Azizetal.


fromlowtohighorviceversa.Experimentaldatahavebeenobtainedunderthe

conditionsof superficialvelocities of air andwater, which are 0.06,0.15,0.7,

3.31,17.92m/sforairand0.03,0.06,0.33,0.82,3.54m/sforwater,respectively.

In the present experiment, developed two-phase flows,which are achieved

beforethedistributor,agreetotheseflowpatternmapsforboththeconditionsof

horizontal and vertical. The experiments cover stratified flow, wavy flow,

elongatedbubbleflow,dispersedflow,slugflow,bubbleflow,andannularflow.

Identificationoftheflowpatternswerecarriedoutusingflowpatternssuggested

byMassoud [13]andGhiaasiaan [14].Theexperimentsof differentdistributorinclination angle at 0, 45 and 90 were conducted under same superficial

velocitycondition,thoughtheyaresomediscrepancies.

Typicalphotographsoftheobservedflowpatternsfordistributorposition0o

(horizontal)areshowninTable1thatcorrespondingwithpointa,b,c,d,ande,

wheretheairsuperficialvelocityisvariedfromlowtohigh(0.06m/sto19.57

m/s)andwatersuperficialvelocityiskeptathighvelocity,around3.54m/s.

Table1.ObservedFlowPatternforPointofa,b,c,d,andeatHigh

SuperficialVelocitiesofWaterrelativelyConstantandvariesofAir

fromLowtoHighatDistributorPosition0o.

FlowPatternImage PointSuperficial

Velocity

Deviation

Ratio

a UG=0.06m/s

UL=3.85m/s

RG=0.198

RL=-0.041

b UG=0.14m/s

UL=3.80m/s

RG=0.036

RL=-0.059

c UG=0.70m/s

UL=3.66m/s

RG=0.255

RL=-0.018

d UG=2.46m/s

UL=3.58m/s

RG=0.486

RL=-0.075

e UG=19.57m/s

UL=2.83m/s

RG=0.091

RL=-0.023

Dispersedbubblyflow

Dispersedbubblyflow

Dispersedbubblyflow

Annulardispersedflow



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Fortheallconditions,thewaterdeviationratiosRLarenegativethoughthey

areclosetozeroasshowninTable1. Itshowedthattheevenlydistributionofwateronthedistributorinupperoutletandloweroutletcouldachievedatthehigh

watersuperficialvelocitywithincreasingoftheairsuperficialvelocity.

Ontheotherhand,theairdeviationratiosRGarepositiveanditisnotsimple

variation.Increasingtheairsuperficialvelocity,RGdecreasesfirst,increases,and

decreasesagain.Theflowpatternoftheseconditionsisvariedasfollows.Atthe

pointsaandb,smallbubblesareuniformlydistributedthoughthepointbismore

uniform.However,theflowpatternbecomestheannulardispersedflowatpointdwheretheairslugtendstoflowupperpartofthetube.Increasingairvelocity,the

flow ismoredisturbed and air isevenlydistributed. Inthehighwater velocity

region,thewaterflowisdominantandtheairvelocityhasinsignificanteffect.

Theflowpatternidentificationbyvisualobservationisquitesubjective,itis

necessarytodefinetheassociatedflowpatternindetails.Thedescriptionofflow

patternonMandhane [10] and Baker [11] flow patternmap givenin Fig. 4(a)agreewiththeflowpatternimageasshowninTable1.

Thisflowpatterncoverdispersedbubblyflowandannulardispersedflowfor

highliquidsuperficialvelocityand it isagreewithflowpattern fromMassoud

[13]andGhiaasiaan[14].Itcanbeconcludedthattheequalliquiddistribution,

whichisrequiredtokeephighperformanceofevaporator,isonlyaccomplished

undertheconditionofhighvaporandliquidvelocities.

Theexperimentalresultswithtypicalphotographforpointofy,t,o,j,andeat

distributor position 0o (horizontal) are shown in Table 2. The air superficial

velocityiskeptathighvelocity,around18m/s,andwatersuperficialvelocityis

variedfrom0.03m/sto2.83m/s.TheairdeviationratiosRGarepositiveforall

theconditions,thoughtheyareratherclosetozeroasshowninTable2.

Itindicatedthatevenifthehighairsuperficialvelocity,theairflowslightly

driftsto upperoutlet independently ofwater flow rate.On the otherhand, the

waterdeviationratiosRLarenegativethoughthevalueisapproachingzerowitha

gradualincreasingofwatersuperficialvelocity.Thevisualizedflowregime(seeTable2)canbefurtherclassifiedintoannular

flow, annularmist flow, and annular dispersed flow. It can be confirmedwith

Mandhane[10]andBaker[11]flowpatternmapasshowninFig.4(a).Itcanbe

explainedthatfromTable2theuniformdistributionofairwasobtainedathigher

air velocity, where at these conditionRG approaches zero. The more uniform

distributionforwatercanbeachievedwithincreasingwatervelocity.

Figure5showstheexperimentalresultsofdistributorposition0o(horizontal)

withdeviationratioonsuperficialvelocitiesofairandwaterwhichare0.06,0.15,0.7, 3.31, 17.92 m/s for air and 0.03, 0.06, 0.33, 0.82, 3.54 m/s for water,

respectively.Figure5(b)showstheflowpatternmapofMandhane[10]andBaker

[11]forhorizontalpositionwithcirclemarkforexperimentalresults.

Atwatersuperficialvelocityconstanton0.03,0.06,0.33,0.82,3.54m/swithair superficial velocity is varied from low to high (0.06m/s to 17.92m/s) asshowninFig.5(a),theflowdistributionofairinthedistributortendstoevenly

distributed at high air superficial velocity, the air deviation ratios RG in this

conditionispositivethoughtheyareratherclosetozero.


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48A.Azizetal.


Ontheotherhand,atairsuperficialvelocityconstanton0.06,0.15,0.7,3.31,

17.92m/swithwatersuperficialvelocityisvariedfromlowtohigh(0.03m/sto

3.54m/s)asshowninFig.5(a),theflowdistributionofwaterinthedistributor

tendstoevenlydistributedathighwatersuperficialvelocity.

ThewaterdeviationratiosRLinthisconditionisnegative,thoughthevalueis

approachingzerowithincreasingwater superficialvelocity.So itcanbestated

that the deviation ratios R are approaching zero or it tends evenly flow

distributionthroughthedistributorathighsuperficialvelocitiesofairandwater.

Table2.ObservedFlowPatternforPointofy,t,o,j,andeatHighSuperficialVelocitiesofAirrelativelyConstantandvariesin

WaterfromLowtoHighatDistributorPosition0o.


Velocity

Deviation

Ratio

yUG=17.90m/s

UL=0.03m/sRG=0.082

RL=-0.773

tUG=16.64m/sUL=0.06m/s

RG=0.114RL=-0.391

oUG=17.38m/s

UL=0.33m/s

RG=0.134

RL=-0.185

jUG=18.11m/s

UL=0.81m/s

RG=0.133

RL=-0.093

eUG=19.57m/s

UL=2.83m/s

RG=0.091

RL=-0.023

TheairdeviationratiosRG forpoint u, v andp arenegativefordistributorposition0o (horizontal) asshown inTable3 and Fig.5(a) witharrows sign.It

meansthatforthiscondition,bothairandwatertendtoflowoutatloweroutlet

(seeflowpatternimageinTable3),almostnofluidflowoutattheupperoutletinthiscondition.Whenthesuperficialvelocitybothairandwaterareverylow,most

oftheairaccompanieswiththewaterflowingoutfromtheloweroutlet.

Annularflow

Annularflow

Annularmistflow

Annularmistflow



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Figure6showstheexperimentalresultsofdistributorposition45o(inclined)

withdeviationratioonsuperficialvelocitiesofairandwaterwhichare0.06,0.7,

17.92m/s for air and 0.03,0.33, 3.54 m/s for water, respectively. Figure 6(a)

shows thesuperficial velocity forairandwater with deviationratio,where theexperimentalresultsmarkedwithacircle.

Deviationratioispositiveforair(RG)andnegativeforwater(RL).Figure6(b)showstheflowpatternmapofMandhane[10]andBaker[11]atinclinedposition

45owithcirclemarkforexperimentalresults.Thiscircleismatchwiththecircle

inFig6(a).Atwatersuperficialvelocityconstanton0.03,0.33,3.54m/swithair

superficialvelocityisvariedfrom0.06m/sto17.92m/s,theflowdistributionof

Fig.5.ExperimentalConditionsinCircleMark

onDeviationRatioandFlowPatternMapsfor0o.

101

100

101

102

101

100

Dispersedflow

BubbleElongated

Bubbleflow

Stratifiedflow

Slugflow

Waveflow




(c) (d) (e)

(h) (i) (j)

(m)(n) (o)

(r) (s) (t)

(w) (x) (y)

(b)

(g)

(l)

(q)

(v)

(a)

(f)

(k)

(p)

(u)

(z)

(aa)

(ab)

(ac)

(ad)

(b)Mandhane[10]andBaker[11]MapforHorizontalFlow.

(a)SuperficialVelocityonDeviationRatio.

v

y,t,o,j,e

a,b,c,d,e

RL

RG

u,p


10/15

50A.Azizetal.


air tends to even distribution athigh air superficial velocity.Although the air

deviation ratioRG at pointe isbigger than the pointo andy, it isresulted of

inclined position45o and high air superficialvelocity; air tends to flowout at

upperoutletbecauseofgravity.

Table3.ExperimentalConditionsforPointofu,v,andpatvariesSuperficialVelocitiesofAirandWateratDistributorposition0

o(Horizontal).


Velocity

Deviation

Ratio

uUG=0.07m/s

UL=0.03m/s

RG=-0.464

RL=-0.753

vUG=0.16m/s

UL=0.03m/s

RG=-0.916

RL=-1

pUG=0.07m/s

UL=0.06m/s

RG=-0.462

RL=-0.891

For all conditions, the air deviation ratiosRG are positive though they are

ratherclosetozero,asshowninFig.6(a)witharrows(alsoseeTables4and5).

Ontheotherhand,wheretheairsuperficialvelocityiskeptconstanton0.06,0.7,

17.92m/sandwatersuperficialvelocityisvariedfrom0.03m/sto3.54m/s,the

waterdeviationratiosRLarenegativethoughthevaluesareapproachingzerowith

increasingwatersuperficialvelocity.Itmeansthattheflowdistributionofwater

tends to evenly distribution with increasing water superficial velocity. So it

showedthatequalflowdistributionthroughthedistributoratinclinedposition45o

occursathighsuperficialvelocitiesofairandwater.

The flow pattern image for point y, o and e at distributor position 45o

(inclined)areshowninTable4,wheretheairsuperficialvelocityiskeptathighvelocityaround17m/s,andwatersuperficialvelocityisvariedfrom0.03m/sto

2.97m/s.

At this condition, equal distribution of air achieved with decreasing water

superficialvelocity.ComparetoTable2,it showedthattheairflowdistribution

tendsmoreunevendistribution thanexperimental conditioninTable2. Onthe

other hand, the water deviation ratiosRL are negative, though the values are

approaching zero andmoreevenly distribution achievedwith increasing water

superficial velocity.These are similar to experimental results in Table 2.The

typicalphotographsofobservedflowpatternasshowninTable4,coverannular

flow, annular mist flow and annular dispersed flow, it can be confirmedwith

Mandhane[10]andBaker[11]flowpatternmapasshowninFig.6(b).

Stratifiedflow

Stratifiedflow

Stratifiedflow


11/15



Fig.6.ExperimentalConditionsinCircleMarkon

DeviationRatioandFlowPatternMapsfor45 o.

The flow pattern image for point a, c and e at distributor position 45o

(inclined) are shown inTable5 where the water superficial velocityis kept at

highvelocityaround3.54m/s,andairsuperficialvelocityisvariedfrom0.06m/s

to16.37m/s.

Inthiscondition,thevalueofwaterdeviationratiosRLisapproachingzeroand

evenly distributionachievedwithincreasingair superficialvelocity.On theother

hand,atwatersuperficialvelocityaround3.54m/s,theairdeviationratios RGareapproachingzerowithlittlediscrepancyat pointe,airtendstoflowoutatupper

outletbecauseofgravity.Thevisualized flow regimeasshown inTable5 cover

dispersedbubblyflowandannulardispersedflow;itcangivegoodagreementwith

Mandhane[10]andBaker[11]flowpatternmapasshowninFig.6(b).

(a)SuperficialVelocityonDeviationRatio.

o,y

e

RL

RG

a,c,e

101

100

101

102

101

100

Dispersedflow

BubbleElongated

Bubbleflow

Stratifiedflow

Slugflow

Waveflow



SuperficialLiquidVelocity

[m/s]

(c) (e)

(m) (o)

(w) (y)

(a)

(k)

(u)

(z)

(ac)

(ad)

(b)Map[10,11]forHorizontalFlow.


12/15

52A.Azizetal.


Table4.ExperimentalConditionsforPointofy,o,andeat

varyingSuperficialVelocitiesofWaterfromLowtoHighandAir

relativelyConstantatDistributorPosition45 o.

FlowPatternImage PointSuperficialVelocity

DeviationRatio

y UG=17.76m/s

UL=0.03m/s

RG=0.097

RL=-0.519

o UG=16.52m/s

UL=0.32m/s

RG=0.112

RL=-0.144

e UG=16.37m/s

UL=2.97m/sRG=0.251

RL=-0.117

Table5.ExperimentalConditionsforPointofa,c,andeat

varyingSuperficialVelocitiesofAirfromLowtoHighandWater

relativelyConstantatDistributorPosition45 o.


Velocity

Deviation

Ratio

aUG=0.06m/s

UL=3.84m/s

RG=0.178

RL=-0.016

cUG=0.84m/s

UL=3.72m/s

RG=-0.042

RL=0.014

eUG=16.37m/s

UL=2.97m/s

RG=0.251

RL=-0.117

Experimentalresultsofdistributorpositionindifferentinclination(angle0o,

45oand90o)onsuperficialvelocitiesofairandwateratpoint z,c,ab,ac,andad

areshowninFig.7(a).TheflowpatternmapofMandhane[10]andBaker[11]in

Fig.7(b)showstheexperimentalconditionsinwhichtheyareindicatedthepoints

withcirclemark.In theseconditions,thedistributionof two-phaseflowthrough

Annularflow

Annularmistflow


Dispersedbubblyflow


Dispersedbubblyflow


13/15



distributor tends unevenly flow distribution on horizontal position and tends

evenlyflowdistributionontheverticalpositionasshowninFig.7(a)andTable6.

ThedeviationratiosRareapproachingzerobothforairandwaterwithchanging

inclination form horizontal (0o) to vertical (90

o). It can be concluded that the

equal fluid distribution both air and water, it is achieved by changing the

inclinationanglefromhorizontalpositiontoverticalposition.

(a)DistributorInclinationonDeviationRatio.

(b)SekoguchiMap[12]forVerticalFlow.

Fig.7.ExperimentalConditionsinCircleMarkonDeviationRatio

andFlowPatternMapsforDifferentInclination.

Theobservedflowpatternatpointz,c,ab,ac,andadatdistributorposition90o(vertical)showninTable6anditwasplottedonMandhaneBakermap[10,

11]andSekoguchimap[12]withcirclemarkfortestresults.Theexperimental

resultscoverslugflowwithsmallbubble,dispersedbubbleflow,frothflowandannular flow. It can be confirmed with Sekoguchi flow pattern map [12] for

verticalpipewithgoodagreementasshowninFig.4(b).


14/15

54A.Azizetal.


Table6.ObservedFlowPatternforPointofz,c,ab,ac,andad

atDistributorPosition90o.


Velocity

Deviation

Ratio

z UG=0.37m/sUL=0.31m/sRG=0.268RL=-0.169

cUG=0.95m/sUL=3.7m/s

RG=-0.173RL=0.029

abUG=1.62m/s

UL=0.17m/s

RG=-0.062

RL=0.029

acUG=3.46m/s

UL=0.83m/s

RG=-0.029

RL=0.04

adUG=4.71m/s

UL=0.02m/sRG=-0.002

RL=-0.077

4.Conclusions

Theexperimental studywas carried out to characterize the flowconfigurations

and to clarify the distribution characteristics of air and water two-phase flow

throughthedistributor.Theobservedflowpatternand thedistributiondeviation

of two-phase flow were explained and the conclusions of this study could be

drawnasfollow:

Attheinletofthedistributor, theobservedflowpatternsofhorizontal andverticaltwo-phaseflowsagreedwellwiththeMandhane-Bakerflowmapfor

horizontalflowandtheSekoguchimapforverticalflow,respectively.

Forhorizontalandinclinedconditions,theevendistributionoftwo-phaseflowinadistributorachievedonlyathighsuperficialvelocitiesofbothairandwater.

ThedeviationratiosRareapproachingzero(evendistribution)withincreasingairandwatersuperficialvelocitiesandbychangingtheinclinationanglefrom

horizontal toverticalposition.However, thereis someinexplicablebehavior

andcriteriaoftheevendistributionhavenotbeenfullyclarified.

Slugflow

Dispersedbubbleflow

Slugflowwithsmallbubble

Frothflow

Annularflow


15/15



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vol 7-1-041 055 azridjal aziz, distribution of two-phase flow in a distributor

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