droplet retention and velocity field in a steam generator...

ANS meeting, Anaheim, CA (2008)

Laboratory for Thermal HydraulicsNuclear Energy and Safety

Droplet retention and Velocity Field in a Steam Generator

Ralf Kapulla, Steffen Danner, Salih Güntay, Abdel Dehbi

2008 ANS Annual MeetingDisneyland Hotel

Anaheim, California, June 8-12, 2008



Overview

Phase VI: Droplet retention in separator and dryer

Test section

Droplet retention

Test A: Collected mass retained

Test B: Local droplet size

Velocity field

Summary



Test section & Measurement positions

Air in

Dryer

8 m

1.4 m

Upper sectionof separator

uv

r

Lower sectionof separator: Swirl vane unit

Dropletgeneration

MP1

MP2A

MP3A

MP4AMP4B

MP5

MP6

MP2B

MP3B



Drain positions & test matrix

8 m

1.4 m



Retention calculation

8 m

1.4 m

For a decontamination system inwhich one injects a certain amountof droplets (in) and another amountof droplets (out) leave the system,the amount of droplets retained canbe quantified with the retention coefficient (RET)

– For negligible retention it follows RET = 0,– if 90 % of the droplets are retained it follows RET = 0.9– and if all the droplets are retain RET = 1.



Whole test section retention

8 m

1.4 m

20 40 600.0

0.2

0.4

0.6

0.8

1.0

1.2

BF050

BF400 BF800 BF050

BF400BF800

BF100

BF010

path: D:\kapulla\SWP55\ARTIST\PRC5\origin\Ret_Calculation\RET_Calculations_Results_DEHS.OPJName: RGIntegralRET02Sing

inte

gral

RET

[-]

AMMD [μm]– Retention increases with increasing AMMD – for all gas mass flow rates.

– Lower retention as gas mass flow rates increases. Reason: Gravitational settling.



Swirl vane retention

8 m

1.4 m

– Retention of swirl vane similar to whole test section.

– Retention characteristic dominated by swirl vane.

20 40 600.0

0.2

0.4

0.6

0.8

1.0

1.2

BF400 BF800 BF050

BF050

BF400BF800

BF100

BF10

path: D:\kapulla\SWP55\ARTIST\PRC5\origin\Ret_Calculation\RET_Calculations_Results_DEHS.OPJName: RGSVRET02

swir

l van

e RE

T [-

]

AMMD [μm]



Droplet separator upper part retention

8 m

1.4 m

– Retention of droplet sep. upper part is weak.

– No clear correlation between RET and AMMD.

20 40 600.0

0.2

0.4

0.6

0.8

1.0

1.2

( )

BF10 BF050 BF100 BF400 BF800

path: D:\kapulla\SWP55\ARTIST\PRC5\origin\Ret_Calculation\RET_Calculations_Results_DEHS.OPJName: RGDropletSRET02

ds u

pper

par

t RET

[-]

AMMD [μm]

Please note: x-axis scale (AMMD) according to test section inlet. Not according droplet separator upper part inlet.



20 40 600.0

0.2

0.4

0.6

0.8

1.0

1.2

BF10 BF050 BF100 BF400 BF800

path: D:\kapulla\SWP55\ARTIST\PRC5\origin\Ret_Calculation\RET_Calculations_Results_DEHS.OPJName: RGDryerRET02

drye

r RET

[-]

AMMD [μm]

Dryer section retention

8 m

1.4 m

– Dryer is weakest component in retention chain.

– Retention small independent of gas mass flow rate and AMMD.

Please note: x-axis scale (AMMD) according to test section inlet. Not according droplet separator upper part inlet.



Inertial impaction

8 m

1.4 m

Stokes number approach for the dryer section:

– For the highest flow rate (BF800) inertial impaction starts at pd 10 m≈ μ



Local measurement positions & test matrix

8 m

1.4 m

To generate different droplet size spectra the DEHS mass flow rate was kept constant (1 l/h) and the nozzle gas mass flow rate was varied.

Higher air flow rates -> smaller droplets



0 20 40 60 80 1000

20

40

60

80

100

0 20 40 60 80 1000

20

40

60

80

100cw = 2 μm

x = 100 mm x = 160 mm x = 200 mm x = 220 mm

path: D:\kapulla\SWP55\ARTIST\PRC6\origin\.Droplets\MP3A_Tropfen_PDA_A_01.OPJName: PRC6_GBF100VCA10

BF100, A10

cum

mul

ativ

e vo

lum

e, %

diameter, μm

cw = 2 μm

x = 100 mm x = 160 mm x = 200 mm x = 220 mm

BF400, A10

cum

mul

ativ

e vo

lum

e, %

diameter, μm

Radial position dependence

8 m

1.4 m

Carrier gas mass flow rate 100 kg/h and 400 kg/h.

– Larger droplet content shows radial dependence. Larger large-droplet content as one moves radialy towards the wall.

– Radial dependence caused by rotational component of the flow field.

MP3A



Comparison: inlet & after swirl vane & after lid

8 m

1.4 m

0 20 40 60 80 100 120 1400

20

40

60

80

100cw = 2 μm

x = 250 mm (MP4A) x = 400 mm (MP4A) x = 450 mm (MP4A) x = 500 mm (MP4A)

---------------------------------------------- (MP2A) (MP3A)

path: D:\kapulla\SWP55\ARTIST\PRC6\origin\.Droplets\MP4A_Tropfen_PDA_A_01.OPJName: MP4ABF100VCA10

BF100, A10

cum

mul

ativ

e vo

lum

e, %

diameter, μm

Carrier gas mass flow rate 100 kg/h.

– Large droplet content is dramatically reduced.

– Weakly increasing larger droplet content for increasing radial position at after lid (MP4A)



Mean axial velocities: after swirl vane

8 m

1.4 m

-200 -100 0 100 2000.0

0.4

0.8

1.2

M12 BF800 BF600 BF400 BF200 BF100 BF050

MP3Apath: D:\kapulla\SWP55\ARTIST\PRC6\origin\.Velocities\MP3_Velocities_Vers_E_A_01.OPJName: M12_Axial_Vel

u [

m/s

]

radial distance [mm]– Low velocities in the core region (-100 < r < 100 mm) due to blockage by swirl vane.

– Increasing velocities outside the core flow for increasing carrier gas mass flow rates.



-200 -100 0 100 200-4

-3-2

-1

0

12

3

4 M12 BF800 BF600 BF400 BF200 BF100 BF050

MP3Apath: D:\kapulla\SWP55\ARTIST\PRC6\origin\.Velocities\MP3_Velocities_Vers_E_A_01.OPJName: M12_Radial_Vel

v [

m/s]

radial distance [mm]

Mean radial velocities: after swirl vane

8 m

1.4 m

– Swirl vane introduces strong transverse velocity component.

– Magnitude of transverse velocity above magnitude of axial velocity.



Centrifugal force after the swirl vane

8 m

1.4 m



Summary

8 m

1.4 m

- Retention increases with increasing AMMD.

- Due to gravitational settling low carrier mass flow rates have higher retention than high mass flow rates.

- Velocity field database is (i) available and ready for the (ii)comparison with CFD-calculations.

- Very promising, high quality droplet distribution database is (i) available and ready for the (ii) comparison with CFD-calculations.

droplet retention and velocity field in a steam generator...

Documents