Liquid Cooling Solutions for Data Center Energy Efficiency: Bilibili's Practice

The rapid development of big data and artificial intelligence has increased the demand for high‑performance data centers. Traditional air‑cooling reaches its limit (≈50 °C) and brings noise and energy‑consumption issues, prompting the adoption of liquid‑cooling technologies.

This article introduces the cooling system of Bilibili's next‑generation customized data center. It first reviews conventional air‑cooling architectures, including server components, fan and duct designs, and the national design standard GB50174‑2017. The cooling chain is divided into the refrigeration source, cold‑water transport, and terminal heat‑exchange units, with typical solutions such as water‑cooled chillers, air‑cooled chillers, and indirect evaporative coolers.

Data center energy efficiency is evaluated by the Power Usage Effectiveness (PUE) metric. According to GB 40879‑2021, a reduction of 0.1 in PUE can save millions of yuan annually for a 10 MW IT load.

Liquid cooling, which uses high‑heat‑capacity liquids, overcomes the thermal limits of air. It can be classified into direct contact (immersion and spray) and non‑contact (cold‑plate) solutions. Liquid cooling enables higher inlet temperatures (>45 °C), allowing the elimination of traditional chillers and achieving PUE values below 1.15 in many regions.

Bilibili's implementation combines water‑cooled chillers, indirect evaporative cooling, and high‑efficiency magnetic‑levitation fluorine pumps. The cold‑plate liquid‑cooling rooms are designed with careful consideration of flow resistance, leak detection, connector selection, and redundancy. Testing includes custom liquid‑load simulators and verification of cooling capacity, temperature uniformity, and system stability.

The project has completed construction, testing, and delivery of the first phase liquid‑cooling rooms, with over 30 POC and gray‑scale tests performed. Bilibili also contributed to industry standards, co‑authoring the "Liquid‑Cooling Cold‑Plate Specification for Electronic Equipment" and participating in the 2023 China Data Center Liquid‑Cooling Technology Summit.

Overall, liquid cooling offers a path to greener, lower‑cost data centers by reducing fan power, enabling higher coolant temperatures, and improving overall PUE, while presenting challenges in multi‑disciplinary integration, standardization, and cost reduction.