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Numerical investigation on a high-temperature data center cooled by combined liquid-cooling and free-cooling - a comprehensive case study

Author

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  • Wang, Zi-Xing
  • Xue, Ke
  • Chen, Jun-Yu
  • Li, Nan
  • Tao, Wen-Quan

Abstract

A high-performance cooling system is crucial for data center (DC) energy saving. This paper aims to model and analyze the cooling performance of a novel liquid-cooling and free-cooling combined cooling scheme proposed for high-temperature DC. The air-cooling and liquid-cooling combined servers (ALCS) and free-cooling air handling units (AHU) are combined in the DC. There is still no such study on the ALCS and AHU combined DC cooling performance at the complete DC system level. In this paper, the ANSYS Fluent and MATLAB SIMULINK are used to carry out the CFD simulation and the system-level simulation. For the studied DC in Xi'an, the effects of fans rotation speed (FRS) on IT room cooling performance are first investigated. When FRS is constant, under the inlet air/water temperature of 45 °C, the minimum FRS is 850 rad·s−1 to ensure the safe server operation, while the total rack fans power is 83.68 W. By adjusting the FRS in different ALCSs, a modified FRS working condition is obtained with better cooling performance and lower rack fans power (81.36 W). Then, the free-cooling performance of twelve AHU designs is tested. All AHU designs can meet the cooling requirement when the environment temperature is 15 °C, and the highest COP of AHU (COPAHU) reaches 28. But when the environment temperature is as high as 40 °C, the highest COPAHU is only 3.94. The optimized AHU design with the highest ten-year averaged COPAHU of 17.54 for the studied DC in Xi'an is obtained. The studied DC exhibits effective cooling and energy consumption performance. For the ten-year period, the PUE and COP of DC are respectively 1.18 and 7.64. The COP of the free-cooling part has reached 2.2 times of the COP of the water-cooling part, which indicates that the application of AHU can effectively improve the cooling efficiency.

Suggested Citation

  • Wang, Zi-Xing & Xue, Ke & Chen, Jun-Yu & Li, Nan & Tao, Wen-Quan, 2026. "Numerical investigation on a high-temperature data center cooled by combined liquid-cooling and free-cooling - a comprehensive case study," Applied Energy, Elsevier, vol. 404(C).
    • Handle: RePEc:eee:appene:v:404:y:2026:i:c:s0306261925018847
    DOI: 10.1016/j.apenergy.2025.127154
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    References listed on IDEAS

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