Flow distribution and turbulent heat transfer in a ... · LBE Loop Thesys 2 Technology for He avy...

1 Karsten Litfin, FR09, 08.12.2009KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)

KArlsruhe Liquid metal LAboratoryKALLA

Flow distribution and turbulent heat transfer in ahexagonal rod bundle experiment

K. Litfin, A. Batta, A. G. Class,T. Wetzel, R. Stieglitz

Karlsruhe Institute of TechnologyInstitute for Nuclear and Energy Technologies

[email protected]



Introduction Liquid metal cooled reactors (ADS)Motivation• Minimization of radiotoxicity of long lived

fission products (Am,Cu,Np,..)

Realisation options• Accelerator Driven Systems• Fast critical reactors

Heavy liquid metal (Pb or LBE) as coolant• High neutron production rate• low reactivity

Open issues• Turbulent liquid heat transfer of HLM

along fuel pins and bundles

Sketch of ADS



Experimental overview:Experimental campaign at KALLA in the framework of IP-EUROTRANS:• LBE single rod experiment

• Heat transfer for forced, mixed and buoyant convection• Test of heater performance• Validation and qualification of measurement techniques

• Water rod bundle experiment• Pressure drop in subchannels / rod bundle area• Fluid-structure-interaction (flow induced vibrations)• Validation and qualification of measurement techniques• 2dim flow distribution in sub channels (turbulent mixing)

• LBE rod bundle experiment• Pressure drop in subchannels / rod bundle area• Temperature distribution of the rod bundle in the forced convection regime• Heat transfer of the hexagonal rod bundle geometry



ADS Fuel assembly design

FootHead

Flow equilizer & straightenerTest section

FootUpper plenum

InletFuel pin

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1 6 2

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68

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Parameter PDS-XADS Experiment MYRRAHDesign of FA hexagonal hexagonal hexagonalTotal Power 0.775 MW 0.43 MW 1.466 MWNumber of fuel pins 90 19 91Pin diameter 8.5 mm 8.2 mm 6.55 mmPitch 13.41 mm 11.48 mm 8.55 mmP/D ratio 1.57 1.4 1.3Pin length 1272 mm 1272 mm 1200 mmActive height 870 mm 870 mm 600 mmNr. of grid spacers 3 3 3coolant mean velocity 0.42 m/s 2 m/s 2.5 m/smass flow ~ 40 kg/s ~ 26 kg/s ~ 71 kg/ssub channel area 9330 mm² 1260 mm² 2760 mm²mean heat flux 38 W/cm² 100 W/cm² 131 W/cm²Inlet temperature ~ 300 °C ~ 300 °C ~ 200 °Coutlet temperature ~ 400 °C ~ 415 °C ~ 337 °C



LBE Single rod experimentExperiment carried out atLBE Loop Thesys 2

Technology forHeavy Liquid MetalSystems 2nd Version

• Medium: Pb45Bi55• Inventory: 222 l• Flow rate: 2 - 14 m³/h• Diameter: 60 mm • 4 different flowmeterAccuracy + 0,5%

• Oxygen control



• Single rod layout:• Total power 22,4 kW• heated length 870 mm• Power density 100 W/cm²• Rod diameter dr 8,2 mm• Tube diameter D 60 mm

• Measurement Range:• Temperature 200°C - 400°C• Velocity 0 -1.6 m/s• Prantl 0,016 - 0,03• Reynolds 5·104 - 5,6·105

Results will be presented in Talk 6-16 "Turbulent liquid metal heat transfer along a heated rod within an annular cavity"

Thermocouplespacer

LBE Single rod experiment



Water rod bundle experiment

Technical details:• Temperature 20°C - 100°C • Flow rate 130 m³/h• Pressure 14,7 bar• H2O inventory 8 m³

• Water rod bundle design identical with LBE rod bundle except for PMMA in active Zone needed for LDA measurements

• Isothermal experiment• Measurement Range:

Velocity: 0.1 - 10 m/s Reynolds: 103 - 9·104

Experiment carried out atKALLA water loop



Pressure measurements• Fast pressure sensors Pa to Pg for component specific pressure loss, flow metering and vibration measurements

Temperature measurements• Static temperature sensors T1 and T2 for overall temperature change

LDA velocity measurements• LDA1 downstream venturi nozzle for inlet conditions• LDA2 upstream fist spacer for lateral flow distribution

due to the bundle• LDA3 downstream 2nd spacer for lateral redistribution

UDV velocity measurements• Measurement in each sub Channel type


InletOutlet

FootHead Flow equilizer & straightenerTest sectionPg

Pa

Pd,c,b

Pf,e

spacer positionLDA3 LDA1LDA2

UDV

T1T2

u0

u0

u0

g

Sensor instrumentation:



0,0

0,5

1,0

1,5

2,0

2,5

0 20.000 40.000 60.000 80.000 100.000Re

Loss

coe

fficie

nt CD

Measured Spacer Loss CoefficientCalculated Spacer loss coefficient

Water rod bundle experimentMeasurements of pressure loss Pa to Pg in different configurations to characterize loss coefficient of • Inlet section with foot and riser• Flow straightener• Test section• Spacer

2.58 bar0.38 bar0.66 bar0.60 barExp Pressure loss

5.70.78----Loss coefficient

SpacerFlow straightner

Test section

Inlet section

Experimental results of pressure loss measurementsat max velocity of 10m/s (Re 88.000)

InletOutlet

FootHead

Flow equilizer Test section

Pg

Pa

Pd,c,b

Pf,e

spacer positionLDA

3LDA

1LDA

2

UDVT1

T2u0

u0u0

g

Loss coefficient of the test section

Loss coefficient of the spacer

3

4

5

6

7

8

9

10

11

0 20.000 40.000 60.000 80.000 100.000Re

Loss

coe

fficie

nt CD

Measured Test Section Loss CoefficientCalculated Test section loss coefficient



Water rod bundle experimentComparing experimental results: • Simple calculation of loss coefficient for used spacer given by average blockage ratio calculates a loss coefficient of 0.65

a

b

fe

d

g

25.0 upCD ⋅⋅

∆=ρ

2

7

⋅=AAC S

D

2.21 bar2.26 bar2.58 barTest section pressure loss 0.20 bar0.20 bar0.38 barSpacer pressure loss LBE Exp 300°CLBE Exp 200°CH2O Exp.

• Calculated pressure losses for water and lbe experiment:



Water rod bundle experimentCFD of the test section area

Calculated pressure loss of the spacer geometry agrees very well with measured pressure loss.

CFD 1/6 of the test section with modelled spacers(1.2M cells, kε model)

InletOutlet

FootHead

Flow equilizerTest section

Pg

Pa

Pd,c,b

Pf,e

spacer positionLDA

3LDA

1LDA

2

UDVT1

T2u0

u0u0

g

calculated pressure loss of the test section near a spacer

0.40 Bar




1,0E-10

1,0E-09

1,0E-08

1,0E-07

1,0E-06

1,0E-05

1,0E-04

0,1 1,0 10,0 100,0Frequency [Hz]

Amplitud

e

dp103

dg

Measurements of pressure loss on inlet and test section area with high time resolution:

• Negligible influence of flow induced vibrations onto the experimental setup.

FFT of the time resolved pressure of the test section

-0,1

0,0

0,1

0,2

0,3

-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0Time [s]

Amplitud

e

dp101 103

Cross correlation calculation of the time resolved pressure of the inlet and test section

ab dg

InletOutlet

FootHead

Flow equilizerTest section

Pg

Pa

Pd,c,b

Pf,e

spacer positionLDA

3LDA

1LDA

2

UDVT1

T2u0

u0u0

g




0,00

0,20

0,40

0,60

0,80

1,00

1,20

1,40

1,60

-1 -0,8 -0,6 -0,4 -0,2 0 0,2 0,4 0,6 0,8 1rel. distance

u/u m

ean

Re = 5.000Re = 8.000Re = 10.000Re =26.000

LDA

LDA Measurements of 1d velocity downstream the venturi nozzle at the end of the flow straightening section :

• Symmetric flow distribution, flow conditionning works more reliable compared to the single rod experiment.

Normalized velocity profile downstream the venturi nozzle at the end of the flow straightening section




LDA

CFD of the velocity profile at the end of the flow straightening section:

Velocity profile downstream the venturi nozzle at the end of the flow straightening section with Re 8000. (cfd with 960.000 cells , kεmodel)




LDA

• 1d Measurements of the velocity profile in the testsection area:

1d velocity profile at the beginning of the testsection (5m/s Re 38000)

• 2d Measurements of the velocity profile in the testsection area are planned.• Additional cfd planned.



16 Thomas Wetzel, Forschungszentrum Karlsruhe, 15.09.2009

LBE rod bundle experiment


Technical details:• Temperature 190°C - 450°C • Flow rate 47 m³/h• Pressure 5,9 bar• Test ports 3• Usable height 3405 mm• O2 Control �• LBE-Inventory 4 m³ (42 to)• Tube diameter 107mm

Experiment to be carried out atLBE Loop THEADES(THErmalhydraulics and Ads DESign)



17 Thomas Wetzel, Forschungszentrum Karlsruhe, 15.09.2009

Pressure measurements• Fast pressure sensors for component specific pressure loss, flow metering and vibration measurements.

• Pitot tube for pressure distribution in sub channels


InletOutlet

FootHead Flow equilizer & straightenerP P

Pd,c,b

P T

Tu0

u0

g

u0

Test section

moveable TC-SpacerTC-Spacer

spacer position

TC-Pinfixer

P P P

Sensor instrumentation:

Temperature measurements• Static temperature sensors T for overall temperature change

• Fast TC equipped spacer and Pinfixer for subchannel and rod surface temperature distribution



Conclusions• Single rod experiments show a large influence of buoyancy on the velocity profile even at relatively high Reynolds Numbers while the temperature field is less influenced. This yields to an enhanced heat removal.

• Currently used Nusselt correlations are rather conservative.

• Water rod bundle experiments show very good agreement of measured pres-sure loss with numerical predictions in the fully turbulent flow regime whereas in the transitional regime secondary flow leads to a rising loss coefficient

• Measurements show negligible flow induced vibrations onto the setup

• LBE rod bundle experiments will be conducted soon and hopefully give new insights onto the heat transfer.

Acknowlegement• The work is supported in the framework of the IP-EUROTRANS project; contract number FI6W-CT-2004-516520

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Flow distribution and turbulent heat transfer in a ... · LBE Loop Thesys 2 Technology for He avy...

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