Thermal management of a li-ion battery in a hybrid passenger car within the development process Dr. Florence Michel, Daimler AG 19.03.2013
Outline 1. Thermal management of HEV battery 2. Numerical process 3. STAR-CCM+ model validation 4. Thermal behavior of the battery under real conditions 2 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
HEV-battery, S-Class S400 Hybrid Heat sink and evaporating plate Lithium ion cells Battery Management System Inlet refrigerant Current plug Cell System Control 3 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Thermal Management of HEVs, PHEVs and EVs T [ C] T max operating temperature range T min t [s] time period use case HEV-battery in the S-Class S400 Hybrid Temperature in the engine comparment, Uphill drive 35 km/h T( C) 4 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Overview of the thermal management development process KICK OFF I H G F E D C B A Start dka data freeze DPT-1 data freeze DPT-2 data freeze DigEFzg data freeze DigBFzg dka DPT-1 DPT-2 DigEFzg DigBFzg review DPT-1 validation vehicle concept review DPT-2 validation serial capability ((optional)) review DigEFzg TAG development process Start hardware EFzg Validation EFzg ((optional)) Validation BFzg Start hardware BFzg Functional release 5 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Numerical process for thermal management of a battery Convection full vehicle CHT computation of battery Energy management full vehicle Conduction and radiation full vehicle Cell data from supplier Heat source, cool request VehEMent+ (Matlab-Simulink) STAR-CCM+ AC circuit full vehicle Model validation using measurement results Heat transfer refrigerant Dymola 6 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Direct coupling way vs. Tables Tables (indirect coupling way) 40 Driving cycle (e.g. uphill) Variation battery temperature Coolant inlet temperature Benefit: efficiency, reliability Offline P loss,batt / kw 30 20 10 0 0 500 1000 time / s Heat generation = f(cell temperature, time) T cool_inlet (t) STAR-CCM+ T cell (3D distribution) Q cell/ambiance (t) Q cell / cool t) VehEMent+ 1D/3D coupling STAR-CCM+ -VehEMent+ Benefit: Temp. distribution evaporating plate T cool_inlet (t) Variation heat losses (t, x i ) STAR-CCM+ T cell (3D distribution) Q cell/ambiance (t) Q cell / cool t) VehEMent+ 7 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Measurement in the powertrain test-rig The test-rig includes all moving parts and heat generating elements of a vehicle (except AC-system). The battery is cooled by coolant. The powertrain is operated following a city drive cycle with high electric loads during short-time acceleration and deceleration phases. The battery SOC is varying between 40 and 55%. Test-rig (fragmented) 8 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Boundary conditions for the computation The drive cycle is computed using VehEMent+ providing the transient heat losses. The coolant inlet conditions and heat losses are given as boundary conditions. Flow rate Mean heat losses Inlet temperature 1 L/min 170 Watts 10.5 C I (A) Vel. (km/h) 9 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Numerical model of the HEV battery Jellyroll resin container R-Jellyroll-container = 0.028 W/m²/K TIM 10 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Numerical results: temperature distribution Min Max 11 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Numerical results, transient computation Delta T = 3 C 12 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Measurement in a conditioning cabinet 14 1 35 1 25 Test conditions: Current pulse until constant temperatures 370W heat losses Coolant: water-glysantin 50-50% 10 C inlet temperature, 6l/min 30 C ambiance Pos1 Pos2 Pos3 Pos4 15mm 20mm 45mm 15mm Thermocouples in the battery 13 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Numerical results, steady state computation T( C) T 45 1 +25 Vergleich: T(sim)/T(exp) Comparison num. / exp. results T 1 +2040 T 35 1 +15 ( C) T 30 1 +10 T 1 +5 25 Pos1_Exp Pos2_Exp Pos3_Exp Pos4_Exp Pos1_Sim Pos2_Sim Pos3_Sim Pos4_Sim P4 Pos4 T20 1 Cell35 Cell28 Cell25 Cell14 Cell01 8 6 Vergleich: T(sim)-T(exp) Temperature difference num. / exp. results Pos3 P3 ( C) 4 2 0-2 -4-6 Pos1_DeltaT Pos2_DeltaT Pos3_DeltaT Pos4_DeltaT Pos2 P2 Pos1 P1-8 Cell35 Cell28 Cell25 Cell14 Cell01 14 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Numerical results, transient computation P4 Pos4 Pos3 P3 Pos2 P2 Pos1 P1 15 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Thermal behavior with temperature control Boundary conditions: 300W heat losses constant 10 C cooling plate temperature if cooling on Temperature control: - T > 32 C cooling on - T < 28 C cooling off T ( C) Thermal behavior (Jellyroll, cooling plate) T 1 +30 Jellyroll max. temperature Jellyroll min. temperature CAN signal temperature Cooling plate temperature T 1 +25 T 1 +20 T 1 +15 T 1 +10 T 1 +5 T 1 0 10 20 30 40 50 60 Time (min) Time period for cool down: 5-7min Cooling is on around 50% of total time Temperature difference between CAN signal for control and jellyroll between 6 and 8 C 16 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Effect of the ambient temperature Boundary conditions: 200W heat losses constant 10 C cooling plate temperature Ambience: 35 C or 90 C with a heat transfer coefficient of 120W/m².K ( C) 38 37 36 35 34 33 32 31 30 Maximum jellyroll temperature for ambient temperatures of 35 C or 90 C 0 10 20 30 40 50 60 Time (min) Ambience 35 C Ambience 90 C Temperature difference between T.amb = 35 C and T.amb = 90 C (after one hour): T, jellyroll = 31,8-30,8 = 1 C 17 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Effect of the ambient temperature Temperature distribution in the battery (z- and x-sections): 10 90 10 90 Negligeable effect of conduction through internal screws 18 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Conclusions Numerical methods have been developed in order to predict the transient temperature distribution of a refrigerant cooled battery. These methods can be applied to batteries cooled by water or air in HEVs, PHEVs and EVs. A conjugate heat transfer model has been created in STAR-CCM+. The comparison with experimental results shows a good agreement within 4K for the temperature of the cell can. The battery temperature is computed in transient under vehicle electrical and thermal loads. The effect of the vehicle ambient conditions on the battery cells' temperature is negligeable (less than 1K). 19 Thermal management of a li.ion battery in a hybrid passenger car, F. Michel, Daimler AG 19.03.2013
Thank you for your attention!!! 20