Coolant Distribution Units (CDUs) in Data Centre Liquid Cooling Systems

As data centre power densities continue to increase, traditional air-based cooling solutions are becoming insufficient for many applications. Liquid cooling has emerged as a key strategy for managing high thermal loads, particularly in high-performance computing (HPC) and AI-driven environments.

What Is a Coolant Distribution Unit (CDU)?

A Coolant Distribution Unit, or CDU, is a piece of equipment that manages how cooling liquid is supplied to IT equipment in a data centre.

You can think of a CDU as a control point between:

• The building’s cooling system, and

• The liquid cooling pipes connected to servers or racks

Its job is to make sure the cooling liquid is delivered at the right temperature, pressure, and flow, without putting IT equipment at risk.

What Does a CDU Actually Do?

A CDU typically performs several important functions:

Heat Transfer

The CDU removes heat from the liquid returning from IT equipment and transfers it to the building’s cooling system.

Flow and Pressure Control

It controls how fast the liquid flows and ensures pressure stays within safe limits, even when IT loads change.

Temperature Control

The CDU helps maintain consistent supply temperatures so IT equipment operates within safe limits at all times.

Monitoring and Protection

CDUs usually include sensors and alarms that monitor temperature, pressure, and flow. If something goes wrong, the system can alert operators or shut down safely.

How CDUs Fit into the Building Cooling System

From a building perspective, CDUs connect liquid-cooled IT equipment to:

• Chilled water or cooling plant

• Heat rejection systems (such as chillers or dry coolers)

• Monitoring and control systems

As data centres continue to evolve, CDUs play an important role in enabling higher performance, better efficiency, and reliable operation.