Che 503 Fluid Flow - Lec 9 (1)

8/19/2019 Che 503 Fluid Flow - Lec 9 (1)

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Le!" P#$"

Discussed Topics Course Outcome Course Learnin(Students should be a

Chapter 4Two-phase fow• Flow regimes and

fow patterns or

horizontal andvertical fow• Hold-up• Pressure,

momentum andenergy relations

• Practical methodsor evaluatingpressure drop

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Flow patterns — the ways in which the phases are distribut

cross section !, *.e ie ! +/*7 I" +ei8"& i* i "e/e$ *! )e $)#e *! predict pressure dro

$##& +ee"+ "!* !"# !" *.e ! $**e"& )* $#! !" *.ee#!/i* !, *.e .$e *.i slip velocity will infuence the holraction o the pipe volume .i/. i !//ie+ ) $ $*i/#$

Se/i$# $**e"*i!" i *.ee,!e ,!/e+ !" *.ee $e/* !, *.e

*.ee /!6#e@ 6i@*e7%1' T.e ! $**e"7

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%3' T.e e#$*i!".i )e*ee" ee 8$+ie"* i" $ ie $"!$*e $"+ .i/$# !e*ie !, *.e .$e


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T.e +i>ee"/e i" +e"i* )e*ee" *.e .$e i i6!

+e*e6i"i"8 ! $**e"7 8$ 8$D#ii+ #i #iD!#i+ !#i+ !ertical upward fow

#i8.*e .$e i## ie 6!e i/# *.$" *.e +e"e .$ee#!/i*7

Horizontal fow ! $**e" 6!e /!6#e@

8$i*$*i!"$# ,!/e i## $/* ee"+i/#$ *! *.e ie $@i& *.e +i

+e"e /!6!"e"* *! ! e,ee"*i$## "e$e *.e )!**!6ie7


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Two-phase "as #!apour$ - %iFlow T.e !i)#e comination !, *! .$e ! $e

gas'li&uid gas'solid li&uid'solid

Be/$e !, *.e ee"/e !, *.e *! .$e& *.ee $e /!"i+e$)#e com+e/i)i"8 $"+ $"*i,i"8 *.e "$*e !, *.e !

I" 6!* /$e *.e 8$ .$e& .i/. 6$ )e !i"8 i*. $ much great*.$" *.e #ii+& /!"*i"!# $//e#e$*e *.e #ii+ *. i"!#i"8 $ *$"

Ei*.e .$e 6$ )e i" streamline ! i" turbulent fow, though the most imporin which both phases are *)#e"*7

I, *.ee i "! .e$* *$",e *! *.e !i"8 6i@*e& *.e 6$ $*e !, ! !, e$/. .$e e6$i" )*$"*i$## /!"*$"*

!#6e*i/ !$*e %$"+ e#!/i*ie' i"/e$e !8eie# $ *.e 8$ e@$"+ee7


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Two-phase "as #!apour$ - %iFlow I" $ )!i#e ! e$!$*!=

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*! $!i+ ei! +$6$8e *! ei6e"*7


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Flow (egimes and Flow Patt

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Hi8. #ii+-8$ $*i!& *.e #ii+

,!6 *.e /!"*i"! .$e

L! $#e i* ,!6 *.e +iee.$e


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+iii!" $e !"# $!@i6$*e Pe$e+ ) CHHABRA $"+

RiCHAR;SON )$e+ !" *.!eei!# ee"*e+ ) MAN;HANE etal $"+ WEISMAN et $#7


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Vertical fow

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I" 8e"e$#& *.e ! $**e"6$ i $#! $#i/$)#e *!e*i/$# !


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LOCHART $"+ MARTINELLI = e@ee+ .!#+- i" *e6 !, $ $$6e*e J& /.*.e e#$*ie !$*e !, #ii+ $"+ 8$& +e


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Pee& M!6e"*6& $"+ E"e8 Re#$

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I" *.e separated fow model

the phases are "rst considered to fow separately

their /!6)i"e+ e>e/* i *.e" e@$6i"e+7

T.e *!*$# ee 8$+ie"* i" $ .!i:!"*$# ie& #- dP$P% & dl '& /!"

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.ee 'dP$P% T!*$# ee +! ,! *! .$e !

-dP Pee +! +e *! ,i/*i!"

-dPa Pee +! +e *! *.e $//e#e$*i!"

dl

dP

dl

dP

dl

dP a f TPF −+

−

=−


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Pee& M!6e"*6& $"+ E"e8 Re#$

T.e .e$ $* *.e $## i !!*i!"$# *! *.e *!*$# $*e !, 6!6e"*6

$ii"8 ,!6 riction and acceleration& ! *.$* *.e *!*$# +! i" is given by(

-∆P TPF = ( -∆P f ) + (-∆P a )

T.e ee +! +e *! acceleration i i6!*$"* i" *!-.$e

*.e 8$ i "!6$## !i"8 6/. ,$*e *.$" *.e #ii+& $"+ *.ee,!e@$"+ *.e #ii+ .$e i## $//e#e$*e i*. /!"ee"* transer

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$//e#e$*i!" #!e


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Pee& M!6e"*6& $"+ E"e8 Re#$

M!6e"*6 )$#$"/e $"+ $" e"e8 )$#$"/e - i**e" i" e@$

*! i"8#e-.$e i+ !7 C$""!* )e e+ i" $/*i/e i"/e *.e i"+ii+$# .$e e#!/i*ie $

+e"i*ie $e "!* "!"7

S!6e i6#i


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Pee& M!6e"*6& $"+ E"e8 Re#$

Me*.!+ ,! e*i6$*i"8 *.e +! i" ee +e *! ,i/*i!" ) LOC

MARTINELLI $"+ #$*e 6!+ie/* ,!6#$*e+7

T.e *!-.$e ee +! +e *! ,i/*i!" -∆P TPF i *$e" $ *.

+! -∆P L ! -∆P G *.$* !#+ $ie ,! ei*.e .$e !i"8 $#!"e

*.e *$*e+ $*e& 6#*i#ie+ ) !6e ,$/*! 2G ! 2

L 7

F"/*i!" !, *.e $*i! !, *.e i"+ii+$# i"8#e-.$e ee +!7

2

G

G

TPF

P

P Φ=

∆−

∆− 2 L

L

TPF

P

P Φ=

∆−

∆−


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P$/*i/$# Me*.!+ ,! E$#$*i"8 Pe

T.e e#$*i!" )e*ee" G $"+

L $"+ ' %igure ).* Se$$*e /e - $//!+i"8 *!

*.e "$*e !, *.e ! !, *.e*! .$e7

F! 6$ !$*e e "i* $e$!, L! and G+ or the liuid and

gas, ee/*ie#& Re"!#+"6)e eL #L! d& L / and eG

#G+d & G / may be used as

criteria ,! +e


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Ci*i/$# !

C!6ei)#e i+ C!"+i*i!" !, !"i/ e#!/i* 6$ )e e$/.e+ Li6i*i"8 *.e 6$@i66 !$*e ,! $ 8ie" *e

ee7

C$" $#! !// i*. *!-.$e !&

S!6e*i6e )e e$/.e+ i*. $ +! i" ee !, e /e"* !, *.e i"#e* ee7


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E@$6#e

S*e$6 $"+ $*e ! *.!8. $ Q5 66 i7+7 i

!$*e !, 0705 $"+ 175 8 ee/*ie#7 I, **e6e$*e $"+ ee $e 330 $"+ 120 .$* i *.e ee +! e "i* #e"8*. !, i$6i"8 $+i$)$*i/ /!"+i*i!"


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S!#*i!"


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S!#*i!"


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)ummary

M#*i.$e F#!

;EFINITIONS

IMPORTANCES

GAS LIKUI;FLOW

-M$*ei$# i*. +i>ee"/*$*e ! .$e

-M$*ei$# i*. +i>ee"*

/.e6i/$# !e*ie )**.e $6e *$*e ! .$e

-;i*i##$*i!"& A)!*i!E$!$*i!"&C!"+e"$*i!"&S!#e"* e@*$/*i!"

17 T.e fow patterns.27 T.e hold-up !, *.e i"+ii+$# .$e

$"+ *.ei e#$*ie e#!/i*ie737 T.e e#$*i!".i )e*ee" pressure gradient i" $ie

$"+ *.e !$*e $"+ .i/$# !e*ie !, *.e


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T*!i$#

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Che 503 Fluid Flow - Lec 9 (1)

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