As the demand for high-performance computing grows, traditional air cooling methods struggle to manage the heat produced by next-generation AI and HPC chips, which often exceed 1000 W Thermal Design Power (TDP). To address this challenge, Google has introduced Brazos, a closed-loop liquid-to-air cooling system designed for easy integration into existing air-cooled environments.
Brazos is now generally available, allowing for the deployment of high-density, liquid-cooled equipment without the need for extensive facility retrofitting. This innovative system supports simple, one-rack-at-a-time installations, significantly reducing the time and capital typically required for data center upgrades.
Figure 1: Brazos OCP ORV3 Sidecar Configuration showing three units providing cooling to an adjacent IT rack.
Functioning as a self-contained liquid ecosystem, Brazos captures heat at the component level and efficiently rejects it into the data center's hot aisle using advanced liquid-to-air heat exchangers. This plug-and-play architecture can be quickly installed in any legacy facility equipped with adequate power and standard air handling systems.
Figure 2: Photograph of three Brazos modular units in a sidecar rack.
System Design and Specifications
Brazos consists of a modular system featuring three cooling units and integrated rack manifolds, designed for high reliability. Each modular chassis occupies 11 Open Units (OU) of rack height and is compatible with standard Open Compute Project (OCP) ORv3 form-factor racks. Key specifications include:
- Rack thermal capacity: Supports a 60 kW nominal thermal load per rack across three modular units.
- Coolant compatibility: Operates using either deionized (DI) water or a 25% propylene glycol mixture (PG25).
- Power delivery: Functions on a 40–60 V DC input, connecting directly with standard rack busbars.
- Safety features: Complies with UL/CSA/IEC 62368-1 standards, including built-in leak detection and pressure relief valves.
- Control plane: Local monitoring through a built-in human-machine interface (HMI) and remote management via Modbus over TCP.
The design emphasizes field serviceability, featuring low-friction slides for easy access to components. Key parts such as pumps and fans are designed to be hot-swappable, minimizing downtime for repairs.
Rapid Deployment and Industry Engagement
In the coming months, Google plans to open-source the technical specifications and design principles of Brazos through industry forums. This initiative is part of a broader strategy to enhance the open hardware ecosystem, promoting collaboration among system architects, manufacturers, and thermal engineers to scale liquid cooling solutions for future computing demands.
Next Steps for Data Center Optimization
Data center operators interested in optimizing their infrastructure for liquid cooling should stay tuned for upcoming open-source design submissions through the Open Compute Project forum.
