Title: Battery Electric Vehicle (BEV) Thermal Management 1D and 3D CFD Co-simulation
Increasing demands on BEV, such as higher range, faster charging time, increased power consumption of cabin comfort or entertainment systems make the thermal management of batteries more and more critical. The battery thermal management itself is crucial for the cell life, safety and everyday vehicle performance. Thus, comprehensive simulations of the thermal system at different operating conditions should be a vital component during a vehicle development.
Modeling vehicle thermal systems only via 1D comes with many simplifications (e.g. underhood cool pack flow uniformity, cabin interior flow and battery pack cooling), hence 1D and 3D co-simulation is preferable.
Battery cooling system is an example of such simplifications. As the cooling plate pressure drop can’t be assumed to be a quadratic function of the flow (either due to viscous forces in a thin plate or due to a cooling by an oil liquid), multiple re-runs of 3D CFD are necessary. However, the correct module pressure drop and temperature response is important and extrapolating can be inaccurate. This motivates co-simulation of 1D and 3D, leading to an accurate pressure drop and detailed temperature response of each module at multiple load cases.
The demonstrated pack evaluation approach exploits benefit of weak coupling. Siemens LMS Amesim 1D tool with 3D Simcenter STAR-CCM+ co-simulation allows to perform detailed 3D CFD when needed and feed the system level with accurate inputs and vice versa. Concretely, the 1D is used to balance pack coolant circuit via a PID regulator and furthermore to evaluate hydraulic power consumption. The 3D evaluates temperature response and pressure drop of a module. To handle the files with variables and perform 3D conjugate heat transfer analysis a java script within Simcenter STAR-CCM+ were developed. Additionally, results of 3D area stored within a performance table. The co-simulation then interpolates from the table if appropriate data available and thus significantly reduces the vehicle development time.
*BDS, BSM licenses are now tested, in the paper and current project we implement measured data for cell characteristics.