Thermal Analysis on Module Level in an Automotive Battery ... · Thermal Analysis on Module Level...
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© FH AACHEN UNIVERSITY OF APPLIED SCIENCES | LES Lehrgebiet Energiespeichersysteme | COMSOL CONFERENCE 2016 MUNICH 13.10.2016 | 1
Thermal Analysis on Module Level in an Automotive Battery Package
Ziyi Wu M.Sc. 13.10.2016
© FH AACHEN UNIVERSITY OF APPLIED SCIENCES | LES Lehrgebiet Energiespeichersysteme | COMSOL CONFERENCE 2016 MUNICH 13.10.2016 | 2
Content
Thermal Analysis on Module Level in an Automotive Battery Package
Motivation
Ground Model
Internal Cooling Fin
External Water Cooling
Summary
© FH AACHEN UNIVERSITY OF APPLIED SCIENCES | LES Lehrgebiet Energiespeichersysteme | COMSOL CONFERENCE 2016 MUNICH 13.10.2016 | 3
Motivation
Thermal Analysis on Module Level in an Automotive Battery Package
Individual batteries have their own
operational temperature ranges
Many Li-Ion cells do not function
well above 60 °C
A good understanding of the
thermal behavior of the batteries
has its significance during designing
safe and robust battery packages
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0 100 200 300 400 500 600 700 800
100 °C
Capacity Retention (%)
Cycle Numbers
25 °C
60 °C
80 °C
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-3
-2
-1
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Time (s)
C-Rate
[Source: Linden‘s Handbook of Batteries] [Source: photo, ebaracus.com]
AHR18700M1Ultra graphite/LiFePO4
cell from A123 Systems
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Ground Model - Battery Module
Thermal Analysis on Module Level in an Automotive Battery Package
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Current Conductor
Cover
Case
Cell
Mandrel
- Pole
Gap between + Pole and active material
Spacer
+ Pole
48 V battery module with a least number of cells
15 identical cells High capacity power
cell from K2 Energy - K218650P01
[Source: K2 ENERGY]
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SPECIFICATION
Nominal Capacity @ C/5 (Ah) 1.25
Average Operating Voltage @ C/5 (V) 3.2
Internal Impedance @ 1kHz, AC (mΩ) <19
RECOMMENDED OPERATING CONDITIONS
Continuous Discharge (A) 5.0
Charge Current (A) ≤1.25
High Operating Temp (°C) 60
Low Operating Temp (°C) -20
MAXIMUM OPERATING CONDITIONS
Continuous Discharge (A) 21
Charge Current (A) 2.4
High Operating Temp (°C) 85
Low Operating Temp (°C) -40
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-12.5
-7.5
-2.5
2.5
Time (s)
Current [A] SOC [%]
Ground Model - Load Profile
Thermal Analysis on Module Level in an Automotive Battery Package
Load profile is derived from the technical data
Charging at 2 C-rate
Discharging at 8 C-rate
Cell Heating: 𝑄𝐶𝑒𝑙𝑙 = 𝐼2 ∙ 𝑅
Simulation duration: 20 ∙ 103 𝑠𝑒𝑐𝑜𝑛𝑑
[Source: K2 ENERGY]
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∆T (K)
Time (s)
Temperature - 𝑇𝑒𝑥𝑡 = 𝑇0 = 20 °𝐶
Convective Heat Flux - 𝑞0 = ℎ ∙ 𝑇𝑒𝑥𝑡 − 𝑇
Constant htc = 20 𝑊 (𝑚2 ∙ 𝐾)
Objective 1: 𝑇𝐶𝑒𝑙𝑙 ≤ 𝑇𝑟𝑒𝑐𝑜𝑚𝑚𝑒𝑛𝑑𝑒𝑑 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑜𝑛
Objective 2: 𝑇𝐶𝑒𝑙𝑙_𝑀𝑎𝑥 − 𝑇𝐶𝑒𝑙𝑙𝑀𝑖𝑛≤ 3 𝐾
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∆T (K)
Time (s)
ICF_0
Temperature Gain of Hottest Cell
∆T between Hottest and Coldest Cell
Ground model – Results
Thermal Analysis on Module Level in an Automotive Battery Package
316.3
320.7 330.6
322.4
332.6
323.6
XY-Cross Section ICF_0 @ 20000 s (K)
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ICF_1 ICF_2 ICF_3 ICF_4 ICF_5 ICF_6
Internal Cooling Fin (ICF) Concepts
XY-Cross Section (mm2) 11.95 12.00 12.00 12.00 12.00 12.01
Circumference (mm) 12.25 25.13 16.00 19.00 26.00 23.50
Internal Cooling Fin - Concept
Thermal Analysis on Module Level in an Automotive Battery Package
Temperature: 𝑇𝑒𝑥𝑡 = 𝑇0 = 20 °𝐶
Convective Heat Flux: 𝑞0 = ℎ ∙ (𝑇𝑒𝑥𝑡 − 𝑇)
Constant htc = 20 𝑊 (𝑚2∙𝐾)
Objective 1: 𝑇𝐶𝑒𝑙𝑙 ≤ 𝑇𝑟𝑒𝑐𝑜𝑚𝑚𝑒𝑛𝑑𝑒𝑑 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑜𝑛
Objective 2: 𝑇𝐶𝑒𝑙𝑙_𝑀𝑎𝑥 − 𝑇𝐶𝑒𝑙𝑙_𝑀𝑖𝑛 < 3 𝐾
4 * Internal Cooling Fin
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∆T (K)
Time (s)
Internal Cooling Fin - Results
Thermal Analysis on Module Level in an Automotive Battery Package
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∆T (K)
Time (s)
Temperature Gain of Hottest Cell
∆T between Hottest and Coldest Cell
315.8
319.8 326.1
320.2
325.4
319.9
XY-Cross Section ICF_1_1 @ 20000 s (K)
ICF_0
ICF_1_1
ICF_3_1ICF_4_1ICF_5_1ICF_6_1
ICF_2_1
ICF_1 ICF_2 ICF_3 ICF_4 ICF_5 ICF_6
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Thermal Analysis on Module Level in an Automotive Battery Package
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∆T (K)
Time (s)
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∆T (K)
Time (s)
ICF_0
ICF_1_1
ICF_3_1ICF_4_1ICF_5_1ICF_6_1
ICF_1_2
ICF_3_2
ICF_4_2ICF_5_2ICF_6_2
ICF_2_1
Temperature Gain of Hottest Cell
∆T between Hottest and Coldest Cell
314.2
316.7 320.9
317.3
321.6
317.9
XY-Cross Section ICF_4_2 @ 20000 s (K)
Internal Cooling Fin - Results
8 * Internal Cooling Fin
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∆T (K)
Time (s)
Thermal Analysis on Module Level in an Automotive Battery Package
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∆T (K)
Time (s)
Internal Cooling Fin - Results
Temperature Gain of Hottest Cell
∆T between Hottest and Coldest Cell
312.5
313.6 314.4
313.9
314.5
314.1
XY-Cross Section ICF_2_2 @ 20000 s (K)
ICF_0
ICF_1_1
ICF_3_1ICF_4_1ICF_5_1ICF_6_1
ICF_1_2
ICF_3_2
ICF_4_2ICF_5_2ICF_6_2
ICF_2_1
ICF_2_2
ICF_1 ICF_2 ICF_3 ICF_4 ICF_5 ICF_6
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Thermal Analysis on Module Level in an Automotive Battery Package
ICF & External Water Cooling
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∆T (K)
Time (s)
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∆T (K)
Time (s)
Temperature Gain of Hottest Cell
∆T between Hottest and Coldest Cell
ICF_2_2
ICF_2_2-3
External Water Cooling
8 * ICF_2
Temperature -
𝑇𝑒𝑥𝑡 = 𝑇0 = 20 °𝐶
Velocity: 𝑈𝑊 = 1 𝑚 𝑠
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Thermal Analysis on Module Level in an Automotive Battery Package
ICF & External Water Cooling
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∆T (K)
Time (s)
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∆T (K)
Time (s)
Temperature Gain of Hottest Cell
∆T between Hottest and Coldest Cell
ICF_2_2
ICF_2_2-3
ICF_2_2-5
External Water Cooling
8 * ICF_2
Temperature -
𝑇𝑒𝑥𝑡 = 𝑇0 = 20 °𝐶
Velocity: 𝑈𝑊 = 1 𝑚 𝑠
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Thermal Analysis on Module Level in an Automotive Battery Package
Summary
Simulative thermal analysis contributes in gaining knowledge of the cell heating during
operational conditions
a helpful step before conducting actual tests
The simulation results show, the temperature distribution in the ground model of the battery
module is greatly uneven
differences in cell cycle life within the same battery module
a shortened cycle life of the entire module
Cooling systems for the battery module shall be considered as an indispensable component in
battery systems for automotive applications
Combine systems with different cooling principle shall be involved for large battery module
a homogenous temperature distribution
ensure the function of all cells
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Thank you!Thank you!
FH Aachen University of Applied SciencesFaculty of Aerospace Engineering - Energy Storage Systems
Ziyi Wu M.Sc.Hohenstaufenallee 652064 Aachen | Germany
T +49.241.6009 52880F +49.241.6009 [email protected]
Prof. Dipl.-Ing. Hans KemperHohenstaufenallee 652064 Aachen | Germany
T +49.241.6009 52485F +49.241.6009 [email protected]