Experimental and numerical study on the thermal performance of microencapsulated phase change material slurry (MEPCS) for closed-loop thermosyphon cooling in a data center

Liquid cooling with microencapsulated phase change material slurry (MEPCS) provides high energy-efficiency for data center thermal management. However, existing models lack the capacity to accurately capture the phase-change dynamics within intricate systems. To tackle this, the multiscale additional heat source (MAHS) model was developed. Validation against experimental data demonstrates that it achieves remarkable prediction accuracy, with average errors of 1.62 % for pressure drop and 0.42 % for temperature. Results reveal that the concentration has a “double-edged sword” effect. Low-concentration MEPCS (0.1–2 %) enhances heat transfer effectiveness by 1.01–1.05 times via latent heat and micro-convection, while high concentrations (e.g. 15 %) degrade performance due to high-viscosity-induced flow resistance. For a system with 0.1 % MEPCS, the reduction in thermal resistance per unit heating-power increase (1.7–4.3) is significantly greater than that per unit cooling-temperature increase (1.1–2.0). Under critical conditions (26 °C cooling, 20W heating), of the thermosiphon system with 0.1–2 % MEPCS has the thermal resistance as the pure carrier fluid. At higher powers (>20 W), MEPCS shows better chip-cooling heat-flux adaptability due to latent heat and energy density advantages. This study proposes the first validated framework for passive MEPCS-driven cooling, advancing energy-efficient thermal management in high-density computing infrastructures.