two-phase flow patterns for zeotropic mixtures of

Two-phase Flow Patterns for Zeotropic Mixtures

of Tetrafluoromethane/ethane in a Horizontal

Smooth Tube

Song Q.L., Gong M.Q., Wang H.C., etc.

Key Laboratory of Cryogenics,

Technical Institute of Physics and Chemistry (TIPC),

Chinese Academy of Sciences, Beijing, China

24, July, 2019 Hartford, USA

Summary

Experiment apparatus

Adiabatic flow patterns

Condensation flow patterns

Introduction

Main Content

Introduction3/26

Aerospace

BioengineeringEnergy

Health care

A wide range of demand

Mixed-refrigerant Joule-Thomson

refrigeration (MJTR)

0

K

230

80

Single stage compression:

Higher pressure (30-50MPa)

Two/three stage cascade:

Complicated structure

Gas regenerative, Gas expansion:

Expensive, low efficiency

➢ Low pressure (2MPa)

➢ Low cost

➢ Simple structure

➢ non-moving parts at low

temperature parts

50 100 150 200 250 300 3500

5

10

15

20

25

He

Ne

N2

CH4

CF4

C2H

6

C3H

8

iC4H

10

iC5H

12ph=2.0 MPa

pl=0.1 MPa

h (

kJ/

mol)

T (K)

Mixed-refrigerants

Tetrafluoromethane (R14) and ethane

(R170) are the essential components in

the mixed-refrigerants.

➢ Pure fluids with different boiling points

➢ Zeotropic mixture

➢ Temperature relayTemperature relay

MJTR system

4/26Introduction

Two phase

Two phaseGas

From evaporator

High pressure Liquid To throttle

GasTo compressor

➢ Physical mechanism of two-phase heat transfer and pressure drop is closely related to flow patterns.

Heat exchangers

◆Aim of this work

A comprehensive presentation of the experimental studies on

➢ Adiabatic and condensation flow patterns for R14/R170 mixtures

5/26Introduction

Summary




Introduction

Main Content

T T T TSight glass Sight glass

Heat flux

T

T T T T

C

T T

p

TT

Vacuum pump

Vacuum chamberCooling

loop 2

Cooling

loop 1 Heat

exchanger

Magnetic-

driven pump

Throttling

valve

Reservoir

DC Regulator

Preheater Sight glass Sight glass

Heat transfer section

p

Entrance effect

eliminated section

Experiment Apparatus

View glass - flow

pattern

Vacuum insulation

High speed camera

31

1 1

3

i ii

i i i

copper

T T

d dq

+

= +

−

− =

1

2

copper

Sq q

S=

Temperature distribution one-dimension Fourier Law

7/26

Experimental uncertainties

Parameters Instruments Range Uncertainties

T Pt100 80-300 K 0.1 K

p Pressure sensor 0-4 MPa 0.02%

G Mass flow meter 0–108 kg h-1 0.1%

◆Experiment conditions and uncertainties

Experimental conditions

Fluids Composition p(MPa) ∆Tbd(K) q(kW m-2) G(kg m-2 s-1) x D (mm)

R14/R170

0.19/0.81,

0.44/0.56,

0.63/0.37

0.8/0.2

1.5-2.5 3.6-30.7 8.4-42.2 100-350 0-1 4

8/26Experiment Apparatus

(b)

(c) (d)

(e)

(a)

Intermittent flow Transition flow

Wavy-annular flow Smooth-annular flow

Wavy-stratified flow

Intermittent: intermittent vapor slug with liquid bridge;

Transition: thick liquid layer in bottom with liquid waves can flap the tube top;

Wavy-annular: liquid film has discernable interfacial waves, can’t flap the tube top;

Smooth-annular: thin and fairly smooth liquid film along the entire tube perimeter;

Wavy-stratified: separate liquid and vapor layers with soft liquid waves.

9/26Experiment Apparatus

Summary




Introduction

Main Content

0.0 0.2 0.4 0.6 0.8 1.0

100

150

200

250

300

350

p=2 MPa, R14:R170=0.632:0.368

Intermittent Transition Wavy-Annular

Smooth-Annular Wavy-Stratified

G (

kg

m-2

s-1

)

x

(b)

◆Effect of mass flux


➢ Transition vapor qualities decrease with mass flux

➢ Wavy-stratified flow occur at lower mass flux

0.0 0.2 0.4 0.6 0.8 1.0

100

150

200

250

300

350

p=2 MPa, R14:R170=0.437:0.563



G (

kg

m-2

s-1

)

x

(a)

11/26

◆Effect of saturation pressure

➢ Transition vapor qualities increase with saturation pressure

0.0 0.2 0.4 0.6 0.8 1.0

1500

2000

2500

G=200 kg m-2 s

-1, R14:R170=0.193:0.807


Smooth-Annular

P (

kP

a)

x

(a)

0.0 0.2 0.4 0.6 0.8 1.0

1500

2000

2500

G=200 kg m-2 s

-1, R14:R170=0.437:0.563


Smooth-Annular

P (

kP

a)

x

(b)

pv

lv

lThermodynamic properties

12/26Adiabatic flow patterns

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0

G=200 kg m-2 s

-1, p=1.5 MPa


Smooth-Annular

X R

14

x

(a)

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0

G=350 kg m-2 s

-1, p=2 MPa


Smooth-Annular

X R

14

x

(b)

◆Effect of concentration

➢ Transition vapor qualities increase with the concentration of R14

Concentration Thermodynamic properties


◆ Comparison with existing flow pattern maps

➢ Breber et al. and Tandon et al.: well predict the majority of

annular flow.

➢ Barbieri et al.: accurately predict the transition tendency

from intermittent flow to annular flow.

➢ Zhuang et al.: accurately predict the intermittent flow.

0.01 0.1 1 10

0.1

1

10Mist&Annular

Wavy-Stratified

Plug&Slug

Bubble

T

T



J v*

Xtt

Transition

T

(a)

0.01 0.1 1 10

0.01

0.1

1

10



J v

(1-)/

Mist

Annular&

Semi-Annular

Wavy

Slug

Plug

(b)

0.01 0.1 1 10

1E-3

0.01

0.1

1

10

Intermittent

Annular

FrL=3.75X

2.4

tt



Fr l

Xtt

(c)

0.01 0.1 1 101

10

IntermittentTransition

Wavy-Annular

Smooth-Annular



We*

Xtt

(d)


◆ New flow pattern map

0.15 0.1

v lS Fr Bd Ca− −=

Inertia

force

Gravity

force

Surface

tension

Viscous

force

0.2

tt22 12.5S X −

1.71

tt21.45S X=

1.62

tt83.4S X=

1.52

tt360.6S X=

WS:

I to T:

T to WA:

WA to SA:

Song Q.L., Gong M.Q., et al. Int. J. Heat & Mass Transfer. 127, 2018, 910-924

0.01 0.1 1 10

10

100



S

Xtt


Summary




Introduction

Main Content

◆Effect of mass flux and saturation pressure


➢ Transition vapor qualities decrease with mass flux

➢ Transition vapor qualities increase with saturation pressure

0.0 0.2 0.4 0.6 0.8 1.0

1500

2000

2500

G=200 kg m-2 s

-1, q=26.0 kW m

-2

R14:R170=0.437:0.563


Smooth-Annular

P (

kP

a)

x

(b)

0.0 0.2 0.4 0.6 0.8 1.0

100

150

200

250

300

350

p=2 MPa, q=26.0 kW m-2, R14:R170=0.437:0.563



G (

kg

m-2

s-1

)

x

(a)

17/26

◆Effect of heat flux

➢ Transition vapor qualities decrease with heat flux

➢ The effect of heat flux is more pronounced at higher R14 concentration (Fig. (b))

0.0 0.2 0.4 0.6 0.8 1.0

0

10

20

30

40

G=200 kg m-2 s

-1, p=2 MPa, R14:R170=0.193:0.807


Smooth-Annular

q (

kW

m-2

)

x

(a)

0.0 0.2 0.4 0.6 0.8 1.0

0

10

20

30

40


Smooth-Annular

q (

kW

m-2

)

x

G=200 kg m-2 s

-1, p=2 MPa, R14:R170=0.632:0.368

(b)

lv,R170 lv,R14H H

18/26Condensation flow patterns

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0

G=200 kg m-2 s

-1, p=2 MPa, q=26.0 kW m

-2



X R

14

x

(a)

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0

G=350 kg m-2 s

-1, p=2 MPa, q=26.0 kW m

-2


Smooth-Annular

X R

14

x

(b)

◆Effect of concentration

➢ Transition vapor qualities increase first and then decrease

lv,R170 lv,R14H Hl,R14 l,R170 v,R14 v,R170,

Dynamic influence Thermodynamic influence

x x


0.0 0.2 0.4 0.6 0.8 1.0

210

220

230

240

250

260

270

Subcooled liquid

p = 2 MPa

3l3

5

4

3v

1

Bubble point line

Dew point line

T (

K)

XR14

2

Superheated vapor

Two-phase

R170 R14

R14/R170 phase diagram at p = 2 MPaMass transfer influence


G

Vapor mixture

Liquid mixture

Vapor-liquid interfaceDiffusion layer

Tube wallHeat fluxMass flux

YR14

XR14

R14 R170

◆Compared with adiabatic flow

➢ Condensation transition vapor qualities increase first and then decrease

➢ While adiabatic transition vapor qualities increase unchangeably

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0

Adiabatic, G=350 kg m-2 s

-1, p=2 MPa


Smooth-Annular

X R

14

x

(b)

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0

Condensation, G=350 kg m-2 s

-1, p=2 MPa


Smooth-Annular

X R

14

x

(a)



Nonequilibrium characteristics

Boiling number

Bo

Heat flux

q

Vapor and liquid

concentration difference

Y-X

Mass flux

G

Latent

heat Hlv

Mass transfer resistance of

zeotropic mixture

tttt 5 2 0.4

( , , ( ))1 8 10 1 ( )

Xf X Bo Y X

Bo Y X− =

+ + −



0.2

tt22 12.5 ( )S f X −

1.71

tt21.45 ( )S f X=

1.62

tt83.4 ( )S f X=

1.52

tt360.6 ( )S f X=

WS:

I to T:

T to WA:

WA to SA:

0.1 1 10

10

100



S

f(Xtt, Bo, (Y-X))

tttt 5 2 0.4

( , , ( ))1 8 10 1 ( )

Xf X Bo Y X

Bo Y X− =

+ + −


Summary




Introduction

Main Content

➢ Flow visualization experiments of R14/R170 mixtures under

adiabatic and condensation conditions were presented.

➢ The effects of mass flux, saturation pressure, concentration

and heat flux on flow pattern transitions were analyzed.

➢ Both modified adiabatic and condensation flow pattern map

were developed.

Summary 25/26

Thanks for your attention!

Email: [email protected]

two-phase flow patterns for zeotropic mixtures of

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