Views: 0 Author: Site Editor Publish Time: 2026-01-23 Origin: Site
In a data center dry cooler system, free cooling refers to operating the cooling system by using low ambient outdoor air temperature to reject heat without running mechanical refrigeration (chillers or compressors).
Warm water or glycol from IT liquid cooling loops (direct-to-chip, RDHx, CDU, or immersion systems) flows to the dry cooler
When the outdoor air temperature is lower than the return liquid temperature, the dry cooler can dissipate heat directly
Fans modulate to maintain the required supply temperature
No compressors are used—only pumps and fans operate
“Free” does not mean zero energy use, but:
No compressor power consumption
Significantly lower electrical load compared to chiller operation
Energy use is limited to fans and circulation pumps
This leads to major reductions in operating cost and PUE.
Lower energy consumption and operating costs
Improved PUE (Power Usage Effectiveness)
Extended equipment life due to reduced mechanical stress
Environmentally friendly (lower CO₂ emissions)
Water-free cooling when using dry coolers
Free cooling performance improves when:
The data center operates with higher liquid temperatures (e.g. 30–45°C supply)
The site is located in cool or moderate climates
High-density racks use liquid cooling instead of traditional air cooling
Many modern data centers achieve 70–90% annual free cooling hours using dry coolers.
Full free cooling: Dry cooler alone meets the entire cooling load
Partial free cooling: Dry cooler handles part of the load, with chillers assisting during peak ambient temperatures
Free cooling in a data center dry cooler system is a highly efficient operating mode where ambient air replaces mechanical refrigeration, delivering substantial energy savings, improved sustainability, and lower total cost of ownership.
