Google open-sources Brazos liquid cooling for air-cooled data centers

Google has introduced Brazos, a liquid cooling solution that allows data centers to support next-generation AI and high-performance computing (HPC) hardware without requiring extensive facility retrofits. The system targets operators facing thermal challenges from chips exceeding 1,000 watts of thermal design power (TDP), which traditional air cooling cannot efficiently manage. Brazos offers a modular, rack-level approach to liquid cooling, avoiding the capital and time costs of full data center overhauls involving chilled water loops.

How Brazos works

Brazos is a closed-loop, liquid-to-air cooling system that integrates directly into existing air-cooled environments. The design consists of three modular cooling units mounted alongside standard Open Compute Project (OCP) ORv3 racks. Each unit captures heat at the component level via liquid coolant and rejects it into the data center’s hot aisle using high-efficiency heat exchangers. The system operates independently of facility water supplies, using either deionized water or a propylene glycol mixture (PG25) as coolant.

The system supports a nominal thermal load of 60 kW per rack and is powered by 40–60 V DC inputs, compatible with standard rack busbars. Built-in safety features include leak detection, pressure relief valves, and compliance with UL/CSA/IEC 62368-1 standards. Local monitoring is available via a built-in human-machine interface (HMI), while remote management uses Modbus over TCP. The design prioritizes serviceability, with hot-swappable pumps and fans and low-friction slides for easy access to components.

Why it matters for data center operators

Retrofitting data centers for liquid cooling typically requires significant capital expenditure and months of facility updates. Brazos eliminates this barrier by enabling incremental adoption—operators can deploy liquid cooling one rack at a time, reducing upfront costs and operational disruption. The system’s plug-and-play architecture allows it to be installed in any legacy facility with sufficient power and standard air handling, making it accessible to a broader range of operators.

Google’s decision to open-source the Brazos design through the Open Compute Project (OCP) could accelerate industry adoption. By releasing technical specifications, design principles, and visual assets, Google aims to standardize rack-mounted liquid cooling solutions for high-power computing demands. This move aligns with broader industry trends toward modular, scalable infrastructure, particularly as AI and HPC workloads drive demand for higher-density deployments.

What’s next

Google plans to formally open-source the Brazos design in the coming months, inviting system architects, manufacturers, and thermal engineers to evaluate and scale the technology. The company will submit the design through the Open Compute Project forum, where it will join other open hardware innovations. For data center operators, this presents an opportunity to future-proof facilities for high-power computing without committing to full-scale liquid cooling retrofits.