Effect of vibration on the thermal performance of a hybrid thermal management system with liquid cooling and phase change material

Despite the widespread presence of vibrations in real-world applications, their influence on phase change material (PCM)-integrated liquid cooling battery thermal management systems (BTMS) remains inadequately explored. Through a validated numerical model, it is revealed that vibrations-specifically at 10 Hz with a 10 mm amplitude-play a pivotal role in regulating both thermal safety and PCM utilization. In the absence of vibration, the baseline system breaches the critical 45 degrees C safety threshold within just 5 min under a 4C discharge rate. However, when subjected to Z-axis vibration, peak temperatures are reduced to 35-36 degrees C, while maximum temperature gradients are constrained to approximately 5 degrees C, showcasing the profound impact of mechanical excitation. The direction of vibration emerges as a decisive factor in determining PCM activation efficiency. Y-axis vibration demonstrates superior performance, achieving 60 % PCM utilization through periodic fluctuations in liquid fraction (0.17-0.6) with oscillation periods of 88 similar to 107 s under segmented heating conditions. This markedly outperforms X-axis vibration, which achieves only 13 % utilization, and Z-axis vibration, which lags further behind at 4.5 %. Interestingly, while Y-axis vibration generates the highest flow velocity (0.61 m/s), Z-axis vibration enhances heat dissipation by fostering uniform flow fields interspersed with densely distributed small vortices, despite its comparatively lower PCM usage. This intricate interplay between vibration direction, vortex dynamics, and segmented heating unveils distinct operational advantages: Z-axis vibration optimizes temperature uniformity, whereas Y-axis vibration maximizes PCM efficiency. These findings underscore the critical importance of vibration characteristics as a design parameter for hybrid BTMS, particularly in off-road vehicle applications where robust thermal management is imperative under extreme mechanical disturbances.