SPRAY MODEL VALIDATION ON SINGLE DROPLET HEAT AND MASS TRANSFERS FOR CONTAINMENT APPLICATIONS – SARNET-2 BENCHMARK J. Malet 1, T. Gelain 1, S. Mimouni

SPRAY MODEL VALIDATION ON SINGLE DROPLET

HEAT AND MASS TRANSFERS FOR CONTAINMENT

APPLICATIONS – SARNET-2 BENCHMARK

J. Malet1, T. Gelain1, S. Mimouni2, G. Manzini3, S. Arndt4, W. Klein-Hessling4, Z. Xu5, M. Povilaitis6, L. Kubisova7, Z. Parduba8,

S. Paci9, N.B. Siccama10, M.H. Stempniewicz10

1 IRSN, PSN-RES/SCA, Saclay, France2 Electricité de France, EDF R&D, Chatou, France3 RSE, Milano, Italy4 GRS, Berlin/Köln, Germany5 IKET, KIT, Karlsruhe, Germany6 LEI, Kaunas, Lithuania7 UJD SR, Bratislava, Slovakia8 UJV Rez, Czech Republic, 9 DIMNP, Pisa University, Pisa, Italy10 NRG, Safety & Power, the Netherlands

ERMSAR 2012, Cologne, Germany, March 21 – 23, 2012

Content

IntroductionPresentation of the experimentsPresentation of the benchmark participantsCode-experiment comparison exerciseResults analysisConclusions

Content


- 4

Introduction

PTR

Pump

Reactor enclosure

Spray nozzles

PTR

Pump

Reactor enclosure

Spray nozzles

Context •Severe accident •Mitigation •Spray systems in the containment vessel

Spray nozzles•~ 500 nozzles•4 different rings/ramps•Flow rate: 280 kg/s per ramp•Temperature : 20° - 60°C

Spray systems – main effects

- 5

Fissionproductswash-outHydrogen

mixing

SPRAYSYSTEMS

Pressurereduction

Spray systems – follow-up of SARNET activities separate effect tests in SARNET-2

- 6

Fissionproductswash-outHydrogen

mixing

SPRAYSYSTEMS

Pressurereduction

Condensation on droplet

Benchmark #1

Gas mixture entrainment by

sprays

Benchmark #2

SARNET-2 WP7 :

ContainmentWP7-2, Task 1:

Spray activities

- 7

Synthesis of the activities

•Specification•Nov. 2009: Delivery of the specifications•Dec. 2009: Specification meeting

•Calculations•Feb. To June 2010: Delivery of the blind and later open calculations (10 institutions, 10 codes, 15 contributions)

•Benchmark analysis•July 2010: Code-experiment comparison meeting•July 2010: Delivery of the code-experiment comparison report•Final diffusion: March 2011•Presentation at the NURETH 2011 conference

Content


- 9

1st Elementary benchmark - HMT on droplets

•Single droplet fall (monodisperse size distribution)

–Injected droplets:- 300 - 700 µm- 2 - 5 m/s- 20 - 40°C

•Air-steam homogeneous and steady mixture

–1 - 5 bar

–20 - 140°C

–3 - 90%

Vd

DdTd

Vd_Z2

Dd_z2Td_z2

Vd_Z1

Dd_z1Td_z1

Z2

Z1

Initial

TgP

RHat rest

Content


- 11

Benchmark participantsInstitution Code name Institution Code name

KIT KIT specific spray model GRS COCOSYS v.2.4 IVO

EDF NEPTUNE_CFD v. 1.0.7 GRS COCOSYS v.2.4 MARCH

ERSE (RSE) ECART - standard model 4W UJV MELCOR v. 1.8.6 YV

ECART -"ad hoc" model 4W* UJD COCOSYS v. 2.3v24

NRG ANSYS FLUENT v. 6.4.11 UJD ASTEC v. 2.0

NRG SPECTRA LEI COCOSYS v. 2.3IRSN ANSYS CFX v. 12 UNIPI FUMO

IRSN ASTEC CPA v. 1.3 rev3

10 institutions, 10 codes, 15 contributions

Content


Overall code-experiment comparison

- 13

SARNET-2 - Elementary spray benchmark on single droplet HMTIRSN experiments

Z = 2.51 m - OPEN exercise

-20%

-15%

-10%

-5%

0%

5%

10%

15%

20%

EVAP

3

EVAP

13

EVAP

18

EVAP

21

EVAP

24

COND

1

COND

2

COND

7

COND

10

TEST

Rel

ativ

e er

ror

on d

ropl

et

dia

met

er (%)

EDF - NEPTUNE

NRG - FLUENT

IRSN - CFX

KIT - Dev. Model

ERSE - ECART Ad hoc model

UNIPI - FUMO

GRS - COCOSYS - IVO model

UJD - COCOSYS

LEI - COCOSYS

UJV - MELCOR

UJD - ASTEC/CPA

IRSN - ASTEC/CPA

- 14

Code-experiment comparison – CFD codesHMT on IRSN single droplet testsEDF - NEPTUNE V.1.0.7 - BLIND

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800

Measured droplet diameter (µm) (I. C. 95%)

Cal

cula

ted

drop

let

diam

eter

(µm

)

Z = 4.39 mY = X+/-10%

HMT on single droplet testsIRSN - CFX

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800


Cal

cula

ted

drop

let

diam

eter

(µm

)

Z = 4.39 mY = X+/-10%

HMT on IRSN single droplet testsNRG - FLUENT

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800


Cal

cula

ted

drop

let

diam

eter

(µm

)

Z = 4.39 m BLINDZ = 4.39 m OPENY = X+/-10%

HMT on IRSN single droplet testsKIT - Model under development

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800


Cal

cula

ted

drop

let

diam

eter

(µm

)


- 15

Code-experiment comparison – ECART, FUMO, MELCOR codes

HMT on IRSN single droplet testsERSE - ECART - "ad hoc"

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800


Cal

cula

ted

drop

let

diam

eter

(µm

)


HMT on IRSN single droplet testsUNIPI - FUMO - BLIND

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800


Cal

cula

ted

drop

let di

amet

er (µm

)

Z = 4.39 mY = X+/-10%

HMT on IRSN single droplet testsUJV - MELCOR

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800


Cal

cula

ted

dro

ple

t dia

met

er (µm

)

Z = 4.39 m - BLINDZ = 4.39 m - OPENY = X+/-10%

- 16

Code-experiment comparison COCOSYS and ASTEC codes

HMT on IRSN single droplet testsGRS - COCOSYS - EVO Model

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800


Cal

cula

ted

drop

let

diam

eter

(µm

)


HMT on IRSN single droplet testsUJD - ASTEC V. 2.0

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800


Cal

cula

ted

dro

ple

t dia

met

er (µm

)


0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800

Cal

cula

ted

drop

let

diam

eter

(µ

m)


HMT on IRSN single droplet testsIRSN - ASTEC/CPA

Z = 4.39 mY = X+/-10%

- 17

Main conclusions of code-experiment comparion

1.Low user-effect

2.A general good agreement between codes and experiments, but...

3.… large differences obtained for some specific tests

4. To undersand these differences detailed look on the mass transfer expressions next section

Content


- 19

Mass flux expressions – detailed look

bd

d

drefmd

masss D

ShTDDQ

2

mref

n

refdd TScTBASh Re

Diffusion coefficient

Reference temperature

« density term »

In all codes, the droplet mass flux expression can be expressed with the same general expression below

… but different « detailed » choices are made

- 20

« Density term » : different expressions in codes

For the ASTEC code, the expression is given by:

ds

dsbulksfilmmsbd TX

TXXTcM

1,

2

where 2

2filmpg

filmm TR

PTc (so-called average molar concentration in ASTEC).

And P

TPTX dsatds

F o r t h e M E L C O R c o d e , t h e e x p r e s s i o n i s g i v e n b y :

1

1ln ,

ds

dsbulksbulkmbd TY

TYYT

W h e r e bulkabulksbulkm TTT ( s o - c a l l e d d e n s i t y o f t h e a t m o s p h e r e i n M E L C O R ) .

For the UNIPI code, this expression is given by:

ds

bulksfilmmsbd TX

XTcM

1

1ln ,

1

where 1

1filmpg

filmm TR

PTc (so-called the “film” mixture molar concentration in the code).

For the COCOSYS code (IVO model), this expression is given by:

dsbulksfilmmbd TYYT ,

where 2

dsatbulksfilmm

TTT

(so-called the average steam density in COCOSYS).

F o r t h e C F X c o d e , t h i s e x p r e s s i o n i s g i v e n b y :

bulks

dsbulkm

bulkm

sbd X

TXT

M

M

,, 1

1ln

W h e r e bulkpg

bulkmbulkm TR

PMT ,

A n d sbulksabulkabulkm MXMXM ,,,

- 21

Differences in « density terms »

SARNET-2 - Elementary benchmark on HMT on single droplets Relative difference between the different codes results and the ASTEC results on the Gamma term (so-called "density term" in the mass flow-rate expression)

- Z = 0 m

-120

-100

-80

-60

-40

-20

0

20

40

60

80

E3 E13 E18 E21 E24 C1 C2 C7 C10

Test

Rela

tive

diff

eren

ce

[(co

de-A

STEC

)/AST

EC]

[%]

MELCORUNIPICOCOSYS (with correction)CFX

From to -100% to + 60% relative differencesbetween the participants

« density terms »

- 22

Diffusion coefficient

SARNET-2 - Elementary benchmark on HMT on single dropletsRelative difference between diffusion coefficients given by two participants

and different expressions calculated independently on the basis of the experimental results

-40%

-20%

0%

20%

40%

60%

80%

100%

Test

Rela

tive

diff

eren

ces

UNIPI/ FULLER_TBULKCOCOSYS/ UNIPIUNIPI/ WILKE_LEE_TBULKUNIPI/ FULLER_TFILM1

From -20% to over 100%differences between

participantsfor the steam diffusion

coefficient in the mixture

- 23


Reference temperature in the participants codes

-droplet temperature Td, -bulk temperature Tbulk, -the mean value Tfilm1 between droplet and bulk temperature, -so-called 1/3 law temperature Tfilm2, i.e. a value pondered by 1/3 of the bulk temperature and 2/3 of the droplet temperature.

- 24


Overall differences on the mass flux over the droplet due to the choice of the reference temperature used in diffusion coefficient - at Z = 0 m

-100%

-50%

0%

50%

100%

150%

200%

E3 E13 E18 E21 E24 C1 C2 C7 C10

Test

Rela

tive

diff

eren

ce (

%)

Tbulk/ Tfilm2

Tfilm1/ Tfilm2

Td/ Tfilm2

Overall differences on the mass flux over the droplet due to the choice of the reference temperature used in kinematic viscosity in the Schmidt number - at

Z = 0 m

-10%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

E3 E13 E18 E21 E24 C1 C2 C7 C10

Test

Rela

tive

diff

eren

ce (

%)

Tbulk/ Td

Tfilm1/ Td

Tfilm2/ Td

From -20% to over 100%differences between

participantsDepending on the way the reference temperature is

calculated

- 25

Analysis of benchmark differences between codes/tests

The different parameters in the mass flux expressions lead to several « errors » that can

compensate together or be enhanced

Can we find the reason why these « errors » are small in some tests, and largers in other

tests ?

The post-processing of partners data has shown 2 relevant parameters (next slide)

- 26

Relevant parameters

VdDdTdInitial conditions

Droplet residence time

Relative mass variation

compared to droplet mass

Table 1: Average residence time of the droplet and associated standard deviation at Z = 2.51 m(average value calculated from MELCOR, UNIPI, COCOSYS and ASTEC/ CPA calculations) ; ASTEC mass

flux at Z = 0 divided by the initial droplet mass md

Test Mean residence time (s) at Z =2.51 m

Associated standarddeviation (s)

Qsmass

/ md (Z = 0)

EVAP3 0.914 0.05 0.058EVAP13 1.716 0.069 0.605EVAP18 2.116 0.035 2.722EVAP21 3.036 0.361 1.991EVAP24 4.813 0.712 4.07COND1 2.09 0.259 0.942COND2 2.166 0.24 0.717COND7 1.485 0.044 0.112COND10 0.99 0.031 0.115

- 27

SARNET-2 - Elementary spray benchmark on single droplet HMTIRSN experiments

Z = 2.51 m - OPEN exercise

-20%

-15%

-10%

-5%

0%

5%

10%

15%

20%

TEST

Rela

tive

err

or o

n d

ropl

et

dia

met

er (

%)

EDF - NEPTUNE

NRG - FLUENT

IRSN - CFX

KIT - Dev. Model

ERSE - ECART Ad hoc model

UNIPI - FUMO

GRS - COCOSYS - IVO model

UJ D - COCOSYS

LEI - COCOSYS

UJ V - MELCOR

UJ D - ASTEC/CPA

IRSN - ASTEC/CPAFor tests with drops having larger residence timein case of larger mass flux compared to the droplet mass, « errors » in the code expressions are seen more clearly

Explanation of the large differences between codes for some tests

Content


- 29

Main conclusion

Differences obtained in some specific tests are due to many different choices done by the code developer for the modelling

And are clearly observed for tests with: Higher droplet residence time Higher mass transfer rate/compared to droplet mass

ratio

Be aware of having validating your model under different conditions if you want to increase your code predictability

1 test is not enough to validate one phenomenon, a range of tests improves the code validation on this phenomena

Consequences for spray calculations in containment analysis

• It is difficult to say in advance what will be the main effects if wrong choices are made in the droplet HMT modelling, since phenomena are coupled, but…

• Possible larger errors, if wrong parameters are used in the mass flux expressions, can be assumed :- In case severe accident Thy conditions AND for small droplets

- In case of droplet evaporation (H2 when spraying is activated)

- In case of larger residence times if saturation is not reached (allowing changes in the droplet size due to mass transfer)

- 30

How far is this benchmark from reactor applications ?

- same Thy conditions- same range of droplet sizes- no pressure variation, so different droplet

thermodynamical equilibrium

- different droplet velocities- no gas entrainment, so different droplet

dynamical equilibrium- no turbulence

Spray systems – SARNET-2 Benchmarks

- 32

Hydrogen mixing

SPRAYSYSTEMS

Pressurereduction

Condensation on droplet

Gas mixture entrainment by

sprays

Benchmark #1 Benchmark #2

SARNET-2 WP7 :

ContainmentWP7-2, Task 1 : Spray activities

- 33

Status of the next elementary benchmark

Tests in the IRSN CALIST facility Real PWR spray nozzle (2 m

« diameter » spray) Real-scale experiment for spray

entrainment

Benchmark specificaions: nov. 2011

Partners contributions received Received in February 2012 (FLUENT,

CFX, NEPTUNE, GASFLOW, ECART, FDS)

Last contributions until March 31st 2012

Synthesis report in 2012

After SARNET-2, we will be close to be able to calculate real size spray systems in a reactor using accurate CFD

tools or advanced spray LP modelling

Coupled phenomenaThe zone of droplet characterisitcs variation is « small »

compared to the size of the containment building BUT is the place of strong exchanges:

CFD calculations could bring some insights if the reactor meshed zone is reduced to few meters below the nozzles!

Hydrogen mixing

SPRAYSYSTEMS

Pressurereduction

Coupled phenomena

Thanks!

- 36

1st Elementary benchmark - HMT on droplets

Test P [bar] Tgas [°C] HR [%] Td [°C] Dd [µm] Ud [m/s] EVAP3 1.00 20.1 20.5 20.6 611+/-4 3.58

EVAP13 5.42 100.1 15.0 31.0 605+/-4 3.75 EVAP18 1.00 135.2 3.0 30.9 309+/-5 3.66 EVAP21 4.29 97.4 12.0 29.2 311+/-7 3.63 EVAP24 4.97 135.0 4.0 30.3 296+/-4 3.10 COND1 4.00 141.3 55.0 36.0 341+/-2 4.90 COND2 4.80 141.6 71.0 37.0 344+/-2 4.70 COND7 5.30 139.3 87.0 35.0 593+/-11 2.10

COND10 2.40 121.5 79.0 16.0 673+/-5 2.10

Main thermodynamical exchanges for spray occur in a small region:Vertical evolution of the droplet size and temperature

HMT ON SINGLE DROPLET - IRSN TEST - COND7

500

520

540

560

580

600

620

640

660

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Z (m)

Dd (µm

)

UNIPI LEI - COCOSYS UJV - MELCORERSE- ECART TRADI ERSE - ECART 1DROP NRG - FLUENTUJD - ASTEC IRSN - ASTEC UJD - COCOSYSGRS - COCOSYS MARCH GRS - COCOSYS IVO EDF - NEPTUNEKIT - Dev. model IRSN - CFX NRG - SPECTRA

HMT ON SINGLE DROPLET - IRSN TEST - COND7

0

20

40

60

80

100

120

140

160

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Z (m)

Td

(°C)

UNIPI LEI - COCOSYS UJV - MELCORERSE- ECART TRADI ERSE - ECART 1DROP NRG - FLUENTUJD - ASTEC IRSN - ASTEC UJD - COCOSYSGRS - COCOSYS MARCH GRS - COCOSYS IVO EDF - NEPTUNEKIT - Dev. model IRSN - CFX NRG - SPECTRA

Condensation

Evaporation

Equilibrium temperature

Increase of droplet

temperature

Main variations of droplet sizes due to HMT in the first meter of droplet fall

Documents

SPRAY MODEL VALIDATION ON SINGLE DROPLET HEAT AND MASS TRANSFERS FOR CONTAINMENT APPLICATIONS – SARNET-2 BENCHMARK J. Malet 1, T. Gelain 1, S. Mimouni