TRANSIENT CAPILLARY PUMPED LOOP …...1 Division Mécanique Thermique Energétique 15th European Workshop on Thermal & ECLS Software - 9-10 October 2001 - Noordwijk, NL TRANSIENT CAPILLARY

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Division Mécanique Thermique Energétique

15th European Workshop on Thermal & ECLS Software - 9-10 October 2001 - Noordwijk, NL

TRANSIENT CAPILLARY PUMPED LOOPMODELLING WITH

ESATAN/FHTS AND SINDA/FLUINT

Christian PUILLET, Hugo MAMEDE FIGUEIREDO

C.N.E.S.

Département Thermique

DTS / AE / MTE / TH18, avenue Edouard Belin, F-31401 TOULOUSE cedex 04, France

[email protected]

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CONTENTS

• CAPILLARY PUMPED LOOP PRESENTATION

• OBJECTIVES

• MODEL PRESENTATION

• MODELS WITH MECHANICAL PUMPS• MODELS WITH CAPILLARY PUMPS

• TEMPERATURE RESULTS

• INFLUENCE OF NUMBER OF NODES

• ANALYSIS

• CONCLUSION

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CNES/MMS 5kW AMMONIA CAPILLARY PUMPED LOOP

DEVELOPPED UNDER CNESCO-FUNDED R&D CONTRACT(1993-1994)

5 CAPILLARY EVAPORATORS 4 CONDENSERS (IN PARALLEL)1 VAPOUR LINE1 LIQUID LINE1 TWO-PHASE RESERVOIR

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CAPILLARY EVAPORATOR PRINCIPLE

LIQUID

10 to 40 mm

VAPOURCHANNEL

POROUSMATERIAL

LIQUIDINLET

VAPOUROUTLET

POROUS MATERIAL

0.05 to 0.5m

HEAT

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OBJECTIVES

• START-UP MODEL OF 1st EVAPORATOR FROM FULLY FLOADED LOOP. DEVELOPPED IN MID 90’s USING MECHANICAL PUMPS AND VALVES.

• MODEL CONVERTED IN ESATAN/FHTS IN 99, PRESENTED AT 13th EWTES.

• REMAINING ISSUES :• USE OF FHTS CAPILLARY ELEMENTS• COMPARISON WITH SINDA/FLUINT

• OBJECTIVE :• TO EVALUATE ESATAN/FHTS CAPILLARY ELEMENTS• TO GET A MODEL SIMPLER AND MORE PRACTICAL TO USE

• MAINS POINTS :• FLUID TIME CONSTANTS (little solid inertia)• EVAPORATORS CLEARING (EVAP. 2 TO 5)• VAPOUR FRONT DISPLACEMENT

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MODEL

MECH. EVAPORATORS

EVAPISOL.

ISOLATOR

CAPIL. EVAPORATORS

CAPILLARYEVAPORATOR

Pressuredrop EVAP.

OUTLET

VAPOUR LINE• Convective coupling with air• Global pressure drop

CONDENSER• Cooling loop @ 0°C

LIQUID LINE• Convective coupling with air

PRESSURISER• Heater with prop. regulation

MODEL GEOMETRY CORRECTEDMECHANICAL PUMPS MODELLING AS CLOSE AS POSSIBLE TO CAPILLARY PUMPS

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Débit massique Evaporateur1

-5,00E-03

0,00E+00

5,00E-03

1,00E-02

1,50E-02

2,00E-02

0,00E+00 1,00E+01 2,00E+01 3,00E+01 4,00E+01 5,00E+01

Temps (s)

Déb

it m

assi

qu

e (k

g/s

)

FR5002

FR5006

FR5007

FR5008

FR5009

FR5011

FR5012

Arrivée du front vapeurà l'élément VANNE2 (FR5011)

Arrivée du front vapeurà l'élément VANNE 1 (FR5009)

Arrivée du front vapeurà l'élément SORTIE (FR5012)

Début de production vapeurdans l'élément TUBE (FR5008)

Mass flow rate evaporator 1

SINDA/FLUINT WITH MECHANICAL PUMPS

PRESSURE OSCILLATIONSCAUSED BY VAPOUR FRONTENTERING EACH FLUID NODE

=> HIGH MASS FLOW RATE& PRESSURE PEAKS

Saut de pression pompe et conduite principale

-5,0E+02

0,0E+00

5,0E+02

1,0E+03

1,5E+03

2,0E+03

2,5E+03

3,0E+03

3,5E+03

4,0E+03

0 100 200 300 400

Temps (s)

Sau

t d

e p

ress

ion

(P

a)

PL1005-PL1004 - Pompe

PL1009-PL1321 - Conduite principale

Loop pressure drop

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-5,00E-03

0,00E+00

5,00E-03

1,00E-02

1,50E-02

2,00E-02

0,00E+00 1,00E+01 2,00E+01 3,00E+01 4,00E+01 5,00E+01

Temps (s)

Déb

it m

assi

qu

e (k

g/s

) FR5002 - ISOL

FR5007 - Pompe - Tube

FR5008 - Tube - Vanne 1

FR5009 - Vanne 1 - 2

FR5011 - Vanne 2 - Sortie 1

FR5012 - Sortie 1Saut de pression pompe et conduite principale

-5,0E+02

0,0E+00

5,0E+02

1,0E+03

1,5E+03

2,0E+03

2,5E+03

3,0E+03

3,5E+03

4,0E+03

0 100 200 300 400

Temps (s)

Sau

t d

e p

ress

ion

(P

a)

PL1005-PL1004 - Pompe

PL1009-PL1321 - Conduite principale

ESATAN/FHTS WITH MECHANICAL PUMPS

SAME BEHAVIOUR

SMOOTHER

Loop pressure drop

Mass flow rate Evaporator 1

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SINDA/FLUINT WITH CAPILLARY PUMPS


-5,00E-03

0,00E+00

5,00E-03

1,00E-02

1,50E-02

2,00E-02

0,00E+00 1,00E+01 2,00E+01 3,00E+01 4,00E+01 5,00E+01

Temps (s)

Déb

it m

assi

qu

e (k

g/s

)

ISOL

Après injection de puissance

Cannelures - Vanne 1

Vanne 1 - 2

Vanne 2 - Sortie 1

Sortie 1

Avant injection de puissance


-3,5E+03

-2,5E+03

-1,5E+03

-5,0E+02

5,0E+02

1,5E+03

2,5E+03

3,5E+03

0 100 200 300 400 500 600 700

Temps (s)

Sau

t d

e p

ress

ion

(P

a)Evaporateur capillaire

Conduite principale


Loop pressure drop

OSCILLATIONS MORE SEVERETHAN WITH MECHANICAL PUMPS

SAME GLOBAL BEHAVIOUR

(blue line : cap. evap. plotted as negative)

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ESATAN/FHTS WITH CAPILLARY PUMPS


-5,00E-03

0,00E+00

5,00E-03

1,00E-02

1,50E-02

2,00E-02

2,50E-02

3,00E-02

0,00E+00 1,00E+01 2,00E+01 3,00E+01 4,00E+01 5,00E+01

Temps (s)

Déb

it m

assi

qu

e (k

g/s

) FR5002 - ISOL

FR5007 - Pompe - Tube

FR5008 - Tube - Vanne 1

FR5009 - Vanne 1 - 2

FR5011 - Vanne 2 - Sortie 1

FR5012 - Sortie 1


-5,0E+02

0,0E+00

5,0E+02

1,0E+03

1,5E+03

2,0E+03

2,5E+03

3,0E+03

3,5E+03

4,0E+03

0 100 200 300 400

Temps (s)

Sau

t d

e p

ress

ion

(P

a)

Evaporateur capillaire

Conduite principale

SAME CONCLUSION AS WITHSINDA/FLUINT


Loop pressure drop

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TEMPERATURE (MECHANICAL PUMPS)

Comparaison des Température à divers endroits de la boucle

0,0E+00

5,0E+00

1,0E+01

1,5E+01

2,0E+01

2,5E+01

3,0E+01

3,5E+01

0 100 200 300 400 500 600 700 800 900

Temps (s)

Tem

pér

atu

re (

°C)

FHTS - Fin tube vapeur

FHTS- Début tube liquide

FHTS - Fin tube liquide

Essais - Fin tube vapeur

Essais - Début tube liquide

Essais - Fin tube liquide

FLUINT - Fin tube vapeur

FLUINT - Début tube liquide

FLUINT - Fin tube liquide

VAPOUR FRONT MOVES TOO FAST

Temperature : end of vapour line, beginning & end of liquid lineresults vs. test measurement

end of vapour (test)

end of liquid (test)

beg. of liquid (test)

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TEMPERATURE ESATAN/FHTSmechanical vs. capillary

Température à divers endroits de la boucle

0,0E+00

5,0E+00

1,0E+01

1,5E+01

2,0E+01

2,5E+01

3,0E+01

3,5E+01

0 100 200 300 400 500 600 700

Temps (s)

Tem

pér

atu

re (

°C)

FHTS Capil - Fin tube vapeur

FHTS Capil - Début tube liquide

FHTS Capil- Fin tube liquide

FHTS Non capil - Fin tube vapeur

FHTS Non capil - Début tube liquide

FHTS Non capil - Fin tube liquide

Temperature : end of vapour line, beginning & end of liquid line

THE VAPOUR FRONT MOVES EVEN FASTER WITH CAPILLARY PUMPS

(NO CONTROL ON MASS FLOW RATE FOR FIRST BUBBLES GENERATION INTHE CAPILLARY PUMP)

mech.

capil.

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INFLUENCE OF NUMBER OF NODESQ < 0

Q < 0

Isolator

INITIAL STEADY-STATE :

THEN THE HEAT EXTRACTION IS REMOVED ON THE UPPER LINE

FINAL STEADY-STATE :

Q < 0

INFLUENCE OF NUMBER OF NODES ON MASS FLOW RATE WITHIN ISOLATOR ?

vapour liquid

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CONVERGENCE IN TIME STEPMASS FLOW RATE IN ISOLATOR

CPU: 0.02 s / 42 s, 0.004 s / 81 s, 0.0008 s / 146 s

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INFLUENCE OF NUMBER OF NODES

1) CONVERGENCE REQUIRESA VERY HIGH NUMBER

OF NODES

2) FRONT MOVES FASTER

CPU: 16 / 1mn21s, 28 / 2mn19s, 52 / 5mn12s, 100 / 10mn6s, 196 / 21mn4s, 388 / 60mn6s

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ANALYSIS

• ABILITY TO SOLVE START-UP FROM FULLY FLOADED LOOP WITH PARALLEL LINES

• TYPICAL CPU TIME : ESATAN/FHTS SINDA/FLUINT MECH. PUMPS 120 mn 10 mn CAPIL. PUMPS 180 mn 50 mn

• LARGE INFLUENCE OF PRESSURE DROPS ON RESULTS• NUMERICAL DIFFICULTIES TO SOLVE IF VAPOUR FRONT IS BLOCKED BY EVAPORATORS BEFORE IT REACHES THE CONDENSER• VERY SMALL TIME STEPS

• HOWEVER, QUESTIONS ABOUT COHERENCE OF PHYSICS MODELLED WITH REALITY• LUMPED PARAMETER METHOD• HOMOGENEOUS MODEL

• => MORE ANALYTICAL AND EXPERIMENTAL WORK WOULD BE REQUIRED ON A SIMPLER LOOP (1 EVAPORATOR , 1 CONDENSER) TO GET CONFIRMATION

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CONCLUSION

THE ESATAN/FHTS CAPILLARY ELEMENTS WORK PROPERLY WITHINTHE LIMITATION OF THE PHYSICAL MODEL

CAPILLARY ELEMENTS SIMPLIFY THE WORK OF THE USER

THE MODELLING OF START-UP IS POSSIBLE

HOWEVER, MAYBE IT SHOULD BE LIMITED TO MODELS IN WHICHFLUID TRANSIENT IS NEGLIGIBLE

• MORE QUESTIONS THAN ANSWERS AT THE END OF THE WORK

• DOUBT ON THE POSSIBILITY TO GET A SIMPLER AND MORE PRACTICAL MODEL FOR FLUID START-UP

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TRANSIENT CAPILLARY PUMPED LOOPMODELLING WITH

ESATAN/FHTS AND SINDA/FLUINT

Christian PUILLET, Hugo MAMEDE FIGUEIREDO

C.N.E.S.

Département Thermique

DTS / AE / MTE / TH18, avenue Edouard Belin, F-31401 TOULOUSE cedex 04, France

[email protected]

TRANSIENT CAPILLARY PUMPED LOOP …...1 Division Mécanique Thermique Energétique 15th European Workshop on Thermal & ECLS Software - 9-10 October 2001 - Noordwijk, NL TRANSIENT CAPILLARY

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