As established in part 2 of this series, effective thermal management of batteries is critical to maximise performance & durability. Engineering battery packs where the fluid has direct access to the cell surface, enables improved heat transfer and temperature uniformity within the cells. The benefits include faster charging, faster warm-up (in cold environments) and extended cell longevity. Castrol thermal management fluids are used to improve heat transfer in a wide range of electrically sensitive applications such as data centre cooling (direct contact with circuit boards), electric motor cooling and battery thermal management. The process of evaluating the performance of heat transfer fluids includes experimental testing on thermal rigs and Computational Simulation. In this final part we will cover the conclusions to this study but first a quick recap. Castrol ON Thermal Rig The Castrol ON Thermal Rig has been developed entirely in-house and is shown in Figure 1. It allows for interchangeable battery modules, enabling production or 3D printed development parts to be easily integrated and tested. Heated Representative Cells This project used Heated Representative Cells (HRCs) that are designed to emulate real cells. Calibrated with six thermal sensors on the surface, HRCs can repeatably generate heat as required by the charge-discharge cycle. HRCs are not susceptible to long-term performance drift, do not require cell balancing or pose the safety risks associated with actual lithium ion cells. Further advantages to this approach include, • Removing the effects of cell-to-cell manufacturing variability. • Desired test conditions can be held indefinitely aiding measurement stability. • Increased ease of adding instrumentation. Simulating the Castrol ON Thermal Rig A 1D system-level model of the rig was developed for improving transient drive cycle simulation. Correlating the 1D model to the rig revealed insights into the performance of the dielectric fluid through other rig components. Advanced techniques for selection of battery thermal management fluids Advertising feature Why Direct Thermal Management? Figure 1 – Castrol ON Thermal Rig in temperature-controlled test chamber Figure 2 – Heated representative cells Figure 3 – Castrol ON Thermal Rig: System-Level 1D Model
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