Efficient thermal management for batteries 3 rd International Conference Thermal Management for EV/HEV 25. June 2013 Dr. Dirk Neumeister 1
Motivation: Thermal management of Li-Ion batteries - 20 C 0 C 20 C 40 C 60 C Available < 50% <70% 100% 100% 0% capacity: very high R ic high R ic by BMS Durability: aging in case useable perfect aging of charging temperature thermal runaway Heating Cooling Charge Discharge 2
Motivation: Thermal management of Li-Ion batteries Electric energy Warm air Plate heating Warm water Li-Ion battery 0 C < T < 40 C T between cells 5K T in cells = 5-10K Cold air Refrigerant Coolant Electric energy y: System Integration AC-loop 3
Measurement Example with real battery in a coolant chiller - system 4
Downsizing battery coolant cooling loop Method: Examination of all components and numerical optimisation on system level Cooling plate Electric water pump Quelle: Pierburg Chiller Tubes and expansion tank LT Radiator 5
Downsizing battery coolant cooling loop Method: Examination of all components and numerical optimisation on system level > 1Millionen combinations 6
Optimized Thermal Interface Standard solution Downsizing Downsizing + V V V T Coolant homogeneous TIM T Coolant homogeneous TIM T Coolant T Battery T Battery T Battery 7
Optimized Thermal Interface Validation Downsizing with LATHIN vs. Downsizing without LATHIN Cell with max temp. 1,8 K Cell with min temp. Temperature [ C] Cell with max temp. 5,6 K Cell with min temp. Time [sec] 8
Battery heating solution: heating foil One secondary loop heater for battery (and cabin) Two separate secondary loop heaters for battery (and cabin) Battery heating included in plate (and air PTC heater for cabin) Battery H 2 O-PTC or Fuel Battery Battery H 2 O-PTC or Fuel Cabin heater core H 2 O-PTC or Fuel Cabin heater core Cabin PTC heater Main features: Low package Low weight High heating dynamic Low heating losses Control easily integrable into BMS 9
Battery thermal management systems solutions Refrigerant Air Coolant 10
Behr battery thermal management solutions Coolant solutions Refrigerant solutions Coolant plate Heating-/ coolant plate Chiller Liquid-liquid heat exchanger Refrigerant plate Refrigerant module Air solutions Heating-/ refrigerant plate PTC Heater VAC module Fluid heater core 11
Battery thermal management systems solutions Refrigerant Air Coolant TE heat exchanger TE-battery-plate 12
Thermoelectricity for battery heating & cooling Tools & main workflow analytic equations & numerical procedures Matlab/Simulink Simulation of Peltier effect First estimations for applications Behr Integrated System Simulation (BISS) System Level Cabin comfort Thermal management validation physical properties dimensioning design fin spacing material Test bench (elements, small assemblies & components) Peltier effect->supplier validation Heat transfer of layers& bonding FEM Mechanical stress Optimal heat transfer Design of heat exchanger Prototype of thermoelectric heater/cooler 13
General challenges on heat exchanger design Main challenge: Heat transfer Peltierelement Heatfluxpath 1 Heatfluxpath 2 T coolant T max T target application Very progessive corellation between COP and T, underruns Carnot law by far due to unwanted heat flux into wrong direction. example: cooling 14
General challenges on heat exchanger design Additional challenges Homogeneous heat distribution Avoid local high temperature gradient on Peltier element Mechanical stress due to temperature difference Pulling tests show high statistic dispersion of maximal shear load on Peltier elements. =>mechanical stress has to be reduced by design of application. tensile specimen Peltier element 15
Thermoelectricity for battery heating & cooling: Example Simulation of dynamic cooling cycle control strategy 100 2000 1000 Thermal interface Cold plate Heat source: Thermal operating cycle Upper surface Peltier element Element T [ C] 80 60 40 20 0-20 800 1500 600 1000 400 500 200 0-200 -500-400 -1000-600 -1500-800 Q [W] cooling power Liquid channels 0 500 1000 1500 2000 t [s] -2000-1000 Dynamic cycle can be served well both cooling & heating mode 16
Thermoelectricity for heating & cooling at Behr: Example Example of thermoelectric thermal managemant battery plate Max-Temp-Cell [ C] 40 30 20 time Q Bat =150W T Ambient = 35 C LT-Radiator Thermoelectric Chiller 17
Battery thermal management systems solutions Refrigerant Air Coolant TE heat exchanger TE-battery-plate 18
Motivation: Thermal management of Li-Ion Batteries Electric energy Warm air Plate heating Warm water Li-Ion battery 0 C < T < 40 C T between cells 5K T in cells = 5-10K Cold air Refrigerant Coolant Electric energy y: System Integration AC-loop TE heating TE cooling Electric energy 19
Efficient thermal management for batteries 3 rd International Conference Thermal Management for EV/HEV 25. June 2013 For questions and further informations: Dr. Dirk Neumeister Behr GmbH & Co. KG Heilbronner Strasse 393 70469 Stuttgart, Germany Dirk.Neumeister@behrgroup.com 20