Ever wondered how data centres keep running without overheating? The answer isn’t just powerful cooling systems—it’s how that cooling reaches the server. That’s where a Coolant Distribution Unit (CDU) comes in—it acts as a bridge between a data centre's cooling infrastructure and the IT equipment, ensuring heat is effectively managed.

With the growing demand for AI computing and AI-powered tools, the need for data centres is expected to rise rapidly. This trend is reflected in market projections.

According to The Grand View Research, CDU systems for data centres accounted for a 36.7% market share in 2025, and the global CDU market size is projected to reach approx. 7.1 billion USD by 2033.

Design engineers can help OEMs, EPCs, and manufacturers by simplifying installation through seamless system integration, reducing project costs, and accelerating time-to-market with scalable solutions.

In this blog, we’ll explain why CDUs are becoming a critical component of AI data centre cooling and the design engineering process for building a reliable CDU system.

Liquid Cooling is no longer optional — and neither is CDU

Modern AI data centre infrastructure can consume 100+ kW of electricity per rack and generate far more heat than traditional (Central Processing Unit) CPUs.

Air cooling alone cannot remove heat effectively, especially in high-density racks. As they consume more energy, 60+ kW, and create hotspots, proving ineffective and impractical for large-scale data centres.

Imagine trying to cool a running engine with a hand fan instead of a coolant loop and a radiator. The fan moves air but can't carry heat away from the engine fast enough, as the air is concentrated in specific regions.

A fluid medium in direct contact with the hot equipment (engine) carries heat away from the source.

Water has a much higher capacity for absorbing heat. CDU data centres use water and fluid dynamics to convert heat into a liquid cooling loop.

The main functions of CDUs include:

Temperature Control

Maintains coolant at the appropriate temperature for (Graphics Processing Unit) GPUs. It adjusts flow and heat exchange and keeps the supply temperature stable despite server load changes.

Isolation

Protects IT equipment from fluctuations by keeping the building water loop separate from the server. A building’s chilled water system often contains rust particles, dissolved minerals, corrosion inhibitors, etc. that might damage server cooling circuits.

Heat Transfer

Removes heat using liquid instead of air. Since all electrical power converts into heat, it needs to be removed continuously for optimum server performance.

Pressure Control

Ensures sufficient pressure and flow inside the servers, making certain each server receives the cooling it requires. Both excessive and reduced flow may harm the server’s capacity and shorten component life.

What happens without proper CDU design

The CDU itself is usually designed by the manufacturer; however, a design engineer is responsible for integrating this design with the data centre’s mechanical, piping, structural, and control systems.

If key design considerations are overlooked during system integration, the following risks can lead to operational failures:

Inadequate Hydraulic Design

The CDU may not receive or deliver the required flow and pressure if the piping system design does not support the hydraulic requirements of the cooling loop.

  • Uneven flow distribution between racks
  • Excessive pressure drop across the piping network
  • Pump cavitation due to poor suction conditions

These conditions may cause the GPUs to overheat and lead to shutdown.

Improper Equipment Layout

Plant engineering designers need to determine where to install the CDU so that both the cooling plant and the IT equipment are within range. Poor layout can cause:

  • Long piping runs that increase pressure losses
  • Limited space for pump or heat exchanger replacement
  • Conflicts with other structural elements

Structural and Mechanical Issues

CDUs are heavy pieces of equipment, especially after being filled with coolant. Adequate structural integrity is essential to safely support their weight. But, without structural coordination:

  • Excessive vibration may affect pumps and piping
  • Thermal expansion may not be accommodated
  • Pipe supports might not fit into the CDU

Limited Scalability

AI data centres are in heavy demand with the possibility of expansion over time. Design engineers need to plan for such future growth and consider the problems that data centre operators may encounter.

  • Costly retrofits to support new AI racks
  • Inadequate utility connections
  • Insufficient piping capacity

Engineering a CDU: What it actually takes

A CDU may appear to be a simple mechanical enclosure at first glance, but internally it is a carefully designed process system, similar to a packaged industrial process skid.

Plant engineers use the same engineering principles for designing this unit as they do for industrial process skids. Each layer solves a distinct problem, missing any one of them compromises the whole system.

Process Design

It is the core design process establishing the functional parts of the CDU. The system transfers heat from the secondary coolant loop, flowing towards the IT equipment, to the primary facility water loop while maintaining required temperature and flow rates.

A piping design engineer undertakes the following responsibilities during process design:

  • Design pressure control strategies
  • Evaluate system efficiency under different load conditions
  • Perform pressure drop calculations across piping, heat exchangers, valves, and cold plates

Piping Design

CDUs and data centres contain sophisticated piping systems that help minimise hydraulic losses—pipe friction, fluid crash—while remaining serviceable. A well-designed piping system with flexibility improves system reliability.

  • Assess vibration fatigue from continuously running pumps, especially at welded and threaded joints
  • Design flexible connections at rack manifolds to absorb minor movements and avoid causing stress in the piping network
  • Verify pipe support spacing and anchoring for the added weight of the coolant-filled lines

Instrumentation & Controls

Modern CDUs are highly automated, requiring advanced monitoring and control. AI training workloads lead to rapid spikes in heat rejection. The unit needs to react and be responsive to these changing loads in real time, not just remain at a steady state.

  • Insert temperature sensors at both ends of the loop to verify heat exchanger performance.
  • Program control logic that modulates pumps and valves under variable loads instead of just on/off control
  • Use flow meters to detect blockages and pump degradation across rack branches

Skid Design and Layout

A CDU skid needs to be compact for the required data centre footprint and provide sufficient access for regular maintenance. It must also be structurally designed to support the fully loaded weight of the unit during operation and installation.

  • Plan filter changes, pump swaps, and valve servicing without needing to move the skid
  • Design the skid for differing data centre layouts to reduce custom rework time.
  • Reduce on-site installation time and risk by arranging factory assembly and testing before skid delivery

3D Modelling and Clash Detection

Quality check and verification are essential to ensure a CDU performs as intended before reaching a data centre. Using SolidWorks and Navisworks for possible multi-disciplinary clashes and design imperfections helps during the integration stage.

  • Validate maintenance access paths in the 3D model to ensure technicians can service the unit post-installation
  • Check for clashes against electrical containments and mechanical systems before fabrication
  • Model the skid, piping runs, and connection points against the required data centre footprint

Build for what’s next: Scalable CDU design for growing AI Infrastructure

Meet the cooling demands of your AI data centres with custom-engineered CDUs.

Sedin Engineering complements CDU manufacturers by providing detailed piping engineering expertise tailored to your facility. From process design and piping layouts to structural integration and fabrication drawings, we help transform standard CDU packages into fully engineered solutions.

Contact our sales team to learn how our piping engineering expertise can support your next AI data centre project.