Study on Natural Stratified Cooling Release Characteristics of Micro-Encapsulated Phase Change Material Suspension

To enhance the operational efficiency and energy performance of data center cooling systems, this study introduces the micro-encapsulated phase change material suspension (MPCMS) into a naturally stratified cold storage system, leveraging its high latent heat, elevated specific heat capacity, and favorable flowability. A three-dimensional unsteady numerical model is developed to systematically investigate the thermal stratification behavior of MPCMS during the cold energy discharge process. The effects of flow rate, MPCMS mass fraction, and key structural parameters of the cold storage tank—such as aspect ratio, perforation ratio, installation height, and hole diameter of the uniform flow orifice plate—are examined to assess their impact on discharge performance. The results demonstrate that MPCMS exhibits superior suppression of mixing and a more stable thermocline structure compared to water, leading to improved energy efficiency, reduced flow rate requirements, and lower pumping power. Stratification performance is significantly enhanced as MPCMS mass fraction increases and flow rate decreases. From a tank design perspective, maintaining an aspect ratio between 2~4 is optimal for achieving favorable thermal stratification. A uniform flow orifice plate with a perforation ratio of 10%, a hole diameter of 20 mm, and an installation height of 1.25% of the tank height effectively mitigates thermal disturbances and stabilizes the thermocline. This study offers valuable theoretical insights and practical recommendations for the structural optimization and engineering application of MPCMS in naturally stratified cold storage systems.