Cooling Systems in Data Centers: Keeping the Core Cool

Published on: April 2025 | By: Racktales.com

Modern data centers rely heavily on advanced cooling systems for operational efficiency.

1. Raised Floor and CRAC Units

CRAC (Computer Room Air Conditioning) units use refrigerant-based cooling. Cold air is delivered through raised floors while hot air is removed from rear server racks using aisle containment strategies.

A traditional CRAC unit with hot/cold aisle setup.

2. CRAH Units (Computer Room Air Handlers)

Unlike CRAC, CRAH units use chilled water coils to cool air and require external chillers. They're common in high-density environments for their efficiency and control.

3. In-Row Cooling

In-row cooling places cooling units between server racks to handle hot air immediately as it exits, reducing airflow inefficiencies and energy use.

4. Liquid Cooling

Liquid cooling solutions like direct-to-chip and immersion cooling are rising in popularity for high-performance compute (HPC) workloads.

Immersion cooling: Servers submerged in dielectric fluid.

5. Rear Door Heat Exchangers (RDHx)

These units cool the hot exhaust air directly at the back of server racks using chilled water heat exchangers, ideal for dense legacy systems.

6. Evaporative/Adiabatic Cooling

Evaporative systems cool incoming air using water mist and are often used in climates where ambient air is dry and cooler.

7. Free Cooling

Free cooling uses outside air or water-side heat exchangers when ambient temperatures allow, reducing the need for mechanical cooling.

Conclusion

Data center cooling continues to evolve, with hybrid systems becoming the norm. Choosing the right solution requires a balance of performance, density, energy efficiency, and location.

Written by Racktales.com — Unracking the Future of IT