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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
8/22/2008 3
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
8/22/2008 4
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
8/22/2008 5
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)
8/22/2008 6
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
8/22/2008 7
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
8/22/2008 8
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
8/22/2008 9
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
8/22/2008 10
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
8/22/2008 11
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)
8/22/2008 12
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 %
8/22/2008 13
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
8/22/2008 14
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
8/22/2008 15
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
8/22/2008 16
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
8/22/2008 17
MESHMESHApplied
Heat Load
Skin
Fin
Grids generated in Thermal Desktop for the model with finPCM
8/22/2008 18
TEMPERATURE DISTRIBUTIONTEMPERATURE DISTRIBUTION
No Fin With Fins
8/22/2008 19
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
8/22/2008 20
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)
8/22/2008 21
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
8/22/2008 23
QUESTIONSQUESTIONS
8/22/2008 24