Thermal Fluids Analysis WorkshopAugust 22 2008August 22, 2008

HIGH-HEAT SHIELD DESIGN

CONCEPTUAL STUDY USING

PHASE CHANGE MATERIALS

by

Amin H DjamshidpourAmin H Djamshidpour

Advisor: Dr. Periklis PapadopoulosExpert Industry Advisor: Dr. Boris Yendler, Comsat Technical

Services/Lockheed Martin CorporationServices/Lockheed Martin Corporation

PRESENTATION OUTLINEPRESENTATION OUTLINE

I d iIntroductionObjectiveMethodologyBenchmark CasesBenchmark CasesModel SetupR lResultsOptimizationConclusionQuestionsQuestions

8/22/2008 2

OBJECTIVEOBJECTIVE

D i h h i l b d hi ldDesign a phase change material based shield which can sustain high-heat loads for aerospace applications

Absorbing the thermal energy coming from external stream frictionRe-usable system

Using the absorbed energy for internal spacecraft usageUsing the absorbed energy for internal spacecraft usage

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INTRODUCTIONINTRODUCTION

Ph Ch M i l (PCM )Ph Ch M i l (PCM )Phase Change Materials (PCMs)Phase Change Materials (PCMs)Having high heats of fusion

Absorbing energy during melting while temperature remains constant

Remain the temperature constant during phase changeRemain the temperature constant during phase change

Making it is useful for keeping the subject at a steady temperature for a long timep g

Importance of absorbing Thermal EnergyImportance of absorbing Thermal EnergyThermally shield vehicle’s Outer Mold Line (OML)Converting the energy to electrical propulsionUsing the converted energy for internal Spacecraft usageUsing the converted energy for internal Spacecraft usage

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METHODOLOGYMETHODOLOGY

SINDA/ FLUINT for simulating the internal heat transferSINDA/ FLUINT for simulating the internal heat transfer

CFD codes for the externals heat fluxUsed exciting data

Ideal simulation include combination of both methodsdea s u at o c ude co b at o o bot et ods

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MODEL SETUP / BENCHMARK CASESMODEL SETUP / BENCHMARK CASES

G lG lGoalsGoalsModel validation against experimental data

Benchmark CasesBenchmark CasesThermal Energy Storage System (TES)Thermal Energy Storage System (TES)Thermal Management System (TMS)

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TES Case TMS Case

TES CASETES CASE

PCM b d th l t tPCM-based thermal energy storage systemWater freezing was studied Initial Temperature of 0 3 °CInitial Temperature of 0.3 CBronze finned tube – cold sourceEthyl Alcohol as a coolant is flowing inside the tube

At a temperature range of -20°C to -10°C

M d l f th l t t

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Model of thermal energy storage system

TES CASE RESULTS 1TES CASE – RESULTS – 1

C i d A l iComparison and Analysis

Water solidification next to finned tube after 2 hour

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Water solidification next to finned tube after 2 hour

TES CASE RESULTS 2TES CASE – RESULTS – 2

C i d A l iComparison and Analysis3

2.5

N FRON

T

1 5

2

LESS SOL

IDIFICA

TION

Benchmark Results

t = 1 hr

1

1.5

DIMEN

SIONL t = 2 hrs

0.5

10 11 12 13 14 15 16 17 18 19 20

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DIMENSIONLESS AXIAL DIRECTION

solidification front propagation

TMS CASE

PCM b d li t

TMS CASE

PCM-based cooling arrangement built of aluminum fins PCM AristowaxPCM - AristowaxConsidered convective cooling of

h c = 50 W/m2-ºC on the topc

Applied study heat load ofq in = 20 kW/m2 to the bottom

A simple schematic of the device

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TMS CASE RESULTS 1 TMS CASE – RESULTS – 1

C i d A l iComparison and Analysis

time(s)1390990590590

Propagation of the melt-front into the PCM with time

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TMS CASE RESULTS 2TMS CASE – RESULTS – 2

C i d A l iComparison and Analysis140

100

120

60

80

Tempreture (ºC)

at heat source y=0 cm

b/m results at y=0 cm

at center of PCM y=6.35 cm

b/m results at y=6.35 cm

40

at heat sink y=12.7 cm

b/m results at y=12.7 cm

0

20

0 160 320 480 640 800 960 1120 1280 1440 1600

Time (S)

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Time (S)

Compared results between benchmark and new simulation

CASE STUDY CONCLUSIONCASE STUDY CONCLUSION

I TES CI TES CIn TES CaseIn TES CasePCM solidified around the finned tubeModel verified

In TMS CaseIn TMS CaseSimulation results match benchmark resultsSlightly different in the beginning but converged to the endAcceptable error, about 5-10 %

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APPLICATION BACKGROUND APPLICATION – BACKGROUND

I f d i i h l hi ldImportance of designing thermal shield

U d b b d h lUsed to absorb and to store thermal energy

Convert the thermal energy into electrical powerConvert the thermal energy into electrical power

Maintain the temperature of the heat shield below lti i tmelting point

Used as a main component for controlling vehicle temperature

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MATERIAL SELECTIONMATERIAL SELECTION

f l iImportant Parameters for PCM selection:Density, Heat of fusion, Heat Capacity, Melting Pt.,

iliBoiling Pt.

Potential materials: High and Low Temperature PCM candidates:

High Temperature PCMs Low Temperature PCMs

Material Melting point °C Material Melting point °C

LiF 848.2 AlBr3 97.5

LiBr3 552 GaI3 212

CuCl 430 TaCl5 216

CsNO3 414 BiBr3 218

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PARAMETERS OF THE MODEL PARAMETERS OF THE MODEL Fins

t fin(cm) t heat shield(cm) t PCM(cm) d_1 fin(cm)

Details of the initial designed model

PCM0.2 0.3 4.7 10

T outside(ºC) T initial(ºC) q in-peak(W/cm2

) d_2 fin(cm)

-150 0 119 5

PCM

P C b C b LiF

Properties of materials used in the design

Property Carbon-Carbon LiF

Density-solid, kg/m3 1800 2640

Density-liquid, kg/m3 --- 2640

Specific heat solid J/kg K 2102 96 1548 08Specific heat-solid, J/kg-K 2102.96 1548.08

Heat of fusion, kJ/kg --- 1044.4

Melt-temperature, ºC 3500 848.4

Conductivity-solid, W/m-K 250 11 3

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Conductivity solid, W/m K 250 11.3

HEAT LOADHEAT LOAD

120

140Considered only the maximum heat load

80

100

ATE W

/cm

^2Applied to stagnation

point only

20

40

60

HEAT RApoint only

Gaussian distribution

0

20

0 4 812

16

20

24

28

32

36

40

44

48

52

56

60

64

68

72

76

80

84

88

92

96

100

104

108

112

116

120

124

128

132

136

140

144

148

152

156

Time (sec)

of the heat load vs. time

Time (sec)

test case heating pulse

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MESHMESHApplied 

Heat Load

Skin

Fin

Grids generated in Thermal Desktop for the model with finPCM

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TEMPERATURE DISTRIBUTIONTEMPERATURE DISTRIBUTION

No Fin With Fins

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No Fin

RESULTS 1RESULTS – 1

1200

1400

1600

1000

1200

1400

1600

800

1000

ure (C°)

HS‐0.00(mm)

HS‐1.5

PCM‐3.0

PCM‐3.4

PCM‐4.0

PCM‐4.6200

400

600

800

400

600

Temperatu

PCM‐5.4

PCM‐6.2

PCM‐8.3

PCM‐11.0

PCM‐14.5

PCM‐25.2

‐200

0

110

19

28

37

46

55

64

73

82

0

200

0 4 812

16

20

24

28

32

36

40

44

48

52

56

60

64

68

72

76

80

84

88

92

96

100

104

108

112

116

120

124

128

132

136

140

144

148

152

156

160

PCM‐50.0

0

1.045

2.415

4.212

6.566

9.566

13.697

8.999

5.949

748

91

100

109

118

127

136

145

154

‐200Time  (sec)

1 18

25

40.

Temperature distribution at different depth into PCMfor model with no fin

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for model with no fin

RESULTS 2RESULTS – 2

1000

1200

1400

1600

1200

1400

1600

200

400

600

800

800

1000

re (C°)

HS‐0.0(mm)

HS‐1.5

PCM‐3.0

PCM‐3.4

PCM‐4.0

PCM‐4 6

‐200

0

110

19

28

37

46

55

64

73

2

400

600

Temperatu

PCM‐4.6

PCM‐5.4

PCM‐6.2

PCM‐8.3

PCM‐11.0

PCM‐14.5

PCM‐25.2

0

1.045

2.415

4.212

6.566

9.651

.697

999

49

48

82

91

100

109

118

127

136

145

154

0

200

0 4 812

16

20

24

28

32

36

40

44

48

52

56

60

64

68

72

76

80

84

88

92

96

100

104

108

112

116

120

124

128

132

136

140

144

148

152

156

160

PCM‐50.0

Temperature distribution at different depth into PCMdistance between fins 5 cm

9

13.

18.9

25.94

40.74 1

‐200Time (sec)

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distance between fins 5 cm

OPTIMIZATIONOPTIMIZATION

80% reduction of PCM thickness

1200

1400

1600

80% reduction of PCM thickness

600

800

1000

1200

‐200

0

200

400

18

152292

3643

5057

6471

78

85

92

99

106

13

0

1.18

7

2.47

3

4.22

9

5.76

5

11

120

127

134

141

148

155

8/22/2008 22

Demonstration of propagation of the temperature into PCM distance between fins 5 cm for optimized design

CONCLUSIONCONCLUSIONThe incident energy can be stored

Lithium Fluoride (LiF) was selected as PCM High latent heat of fusionHigh latent heat of fusion Enables it to absorb a significant amount of thermal energyThe total energy absorbed by the model: 33.593 kJ gy y

Total amount of energy absorbed by the PCM shielding: 91 3 MJ91.3 MJ

Equivalent to 25.36 kWh. Specific energy density of the typical Lithium-ion battery is aboutSpecific energy density of the typical Lithium ion battery is about 150-200 Wh/kg

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QUESTIONSQUESTIONS

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