Improvement of the 1D CFD method for Thermal management of a Battery Electric Vehicle

Abstract: Electrification of vehicles is necessary to combat greenhouse gas emissions, whichcauses global warming and climate change. There has been a demand in the use ofBattery Electric Vehicles due to this increased awareness of sustainability. However,they have been beset with issues such as range and conservation of energy. A partof the solution could be an energy-efficient thermal management system. A 1-Dimensional (1-D) complete vehicle thermal model in GT-SUITE is used topredict the energy efficiency of the vehicle at the conceptual stage. The model helpspredict results quickly and is used for complete system-level simulations. This thesisfocuses on optimizing the method for predicting the realistic and accurate energyconsumption of the thermal management system in the vehicle at the 1-D level. TheCompact Modular Architecture (CMA) platform, which is the vehicle platform usedin current production cars by Volvo Cars will be used for the study and all studiesare performed using a standardized drive cycle. Initial sensitivity studies with afully open grille are performed to understand the operating points of the variouscomponents of interest to investigate. The mass flow rate, ambient temperature,battery temperature, and cooling fan speed are varied.The Active Grille Shutters (AGS) which provides aerodynamic benefit at high speedis implemented in the existing thermal model which could previously accommodateonly the fully open grille. This allows the grille shutters to vary at different anglesbased on cooling demand. The previous existing thermal model method also neededto be optimized to accommodate the AGS. The cooling fan control logic needed tobe improved for better accuracy and energy consumption prediction. Furthermore,the grille shutters and cooling fan speed is needed to regulate the amount of air flowthrough the heat exchangers for the model to behave as close to a real productionvehicle. A code was developed which generated fan speed and grille shutter anglesbased on mass flow rate values to input in the model.Further investigations were made with the optimized thermal model with AGS tostudy the influence of additional mass flow rate on the mass power consumptionof the thermal management system components of interest. It was observed in the initial sensitivity studies that the additional mass flow rate saw significant power savings. However, with the implementation of AGS and additional mass airflowinto the system, the power due to the variation of shutters is taken into account.The results indicate that the total power consumption gradually decreases with theincreasing mass flow rate. But, this is up to a certain extent where the energyconsumption due to the shutter opening takes over the overall power consumptionof the vehicle and overcomes the savings seen by other components in the system causing the total power to increase.