Phase change materials (PCMs) are widely recognized as an effective solution for thermal energy storage and have been extensively adopted in battery thermal management systems for electric vehicles. Their application to data-center thermal management, however, remains comparatively underexplored despite the growing importance of cooling systems in modern digital infrastructure. This thesis investigates a PCM-based cold thermal energy storage device originally proposed by Liang et al. and introduces an alternative design strategy based on auxiliary cross-flow heat exchange channels. The proposed approach aims to mitigate the limitations associated with the low thermal conductivity of PCMs by reducing the characteristic heat conduction distance within the storage medium and enhancing heat extraction from thermally disadvantaged regions.