Simulation Driven Solution to Coolant Filling Strategy in an Electric Truck

<div class="section abstract"><div class="htmlview paragraph">Thermal management of an electric vehicle plays a vital role for optimum performance and utilization of the available energy. Coolant circuits forms an important module in the overall vehicle architecture to achieve this. It is highly necessary to ensure that required quantity of the coolant is filled in the coolant loop. However, coolant deficit due to trapped air in the circuit might pose operational risks and system failure due to inadequate cooling. In this regard, CFD simulation approaches are proven to have an edge in visualizing the flow field, thereby, identifying the root cause of problem in coolant filling process.</div><div class="htmlview paragraph">Using commercial CFD software Star-CCM+ as a tool, current work addressed the issue of removing trapped air inside the circuits by systematic filling approach. Studies have been carried out to understand the coolant filling fractions achieved with traditional filling method on battery loop. Different ways of filling the coolant followed by de-aeration was simulated to recreate the actual coolant filling sequence followed in the test bench. Different strategies like gravity and pump filling, cycles of pump on-off scenarios, filling by system tilt, one-sided filling, with different pump speeds, have been explored to identify and recommend the best coolant filling strategy.</div><div class="htmlview paragraph">Testing correlation is established on a standalone battery component before scaling to entire cooling loop. Good correlation with test data on vulnerable air pocket locations and fill volume is observed. Testing and simulation team worked together in formulizing iterative CFD studies. Final coolant fill strategy is arrived by considering cyclic Pump ON & OFF after traditional gravity filling. The learnings are applied on combined battery, eDrive (powertrain) and dash heat loop to achieve maximum fill percentage.</div></div>