How Does A Dry Cooler Work in A Datacenter?

In a data center, a dry cooler plays a critical role in dissipating heat from the cooling system. Unlike traditional water-cooled systems (which use cooling towers and water evaporation), dry coolers rely entirely on airflow to transfer heat from a fluid (e.g., water, glycol-water mixture) to the ambient environment.

How a Dry Cooler Works in a Data Center

1. Heat Collection from IT Equipment

Air Cooling Systems:

Hot air from servers is captured by computer room air conditioners (CRACs/CRAHs), which use refrigerants to cool the air. The heated refrigerant then flows to the dry cooler’s condenser coils (in split-system designs).

Liquid Cooling Systems:

A fluid (e.g., water, dielectric fluid) absorbs heat from servers (via cold plates, racks, or direct-to-chip cooling). The heated fluid is pumped to the dry cooler’s heat exchanger coils.

2. Heat Transfer in the Dry Cooler

Step 1: Fluid-to-Air Heat Exchange:

The heated fluid flows through the dry cooler’s coils.

Fans draw ambient air across the finned coils, transferring heat from the fluid to the air via conduction and convection.

The cooled fluid (now ready to absorb more heat) is pumped back into the data center’s cooling loop.

Step 2: Heat Dissipation to the Environment:

The warmed air is discharged into the atmosphere (e.g., via rooftop or outdoor dry coolers), completing the heat rejection process.

3. Key Operational Modes

Normal Cooling Mode:

Fans operate continuously to maintain fluid temperature within target limits (e.g., 25–35°C for water glycol).

Free Cooling Mode (in Cool Climates):

In cold weather, the dry cooler can act as an air-side economizer:

Ambient air is cool enough to directly cool the fluid without mechanical refrigeration (e.g., chillers are bypassed), reducing energy use.

Hybrid Systems (with Cooling Towers):

In some setups, dry coolers work alongside cooling towers:

Dry coolers are used in cool seasons to save water.

Cooling towers take over in hot seasons for more efficient heat rejection (via water evaporation).

Advantages of Dry Coolers in Data Centers

Water Efficiency:

No water evaporation (unlike cooling towers), making them ideal for water-scarce regions.

Reduced Maintenance:

No risk of waterborne contaminants (e.g., Legionella), scaling, or corrosion in the cooling loop.

Simplified Design:

Eliminates the need for water treatment systems, pumps, and storage tanks associated with cooling towers.

Scalability:

Easy to add more dry coolers (e.g., on rooftops) as cooling demands grow.