Datacenter Cooling System Design

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Chilldyne can help design your liquid cooled data center. In the air-cooled data center, all the heat goes into the air, if you have a 300 kW data center, you need 300kW (85 tons of air cooling) This could be supplied by a system of 3x 50 ton air conditioners, so that there is redundancy if one of the air conditioners goes down. In general, the load on the air conditioners due to humidity and sunlight is low, as the computers don’t sweat and the data center doesn’t have many windows.

In a liquid cooled data center, some heat goes into the air and some goes into the water-cooling system. The nice thing about direct to chip liquid cooling is that the water flow is directed exactly where it is needed, so hot spots due to airflow problems are less likely to occur.

The servers use less power due to slower fans and less leakage current. The heat that goes into the air is 20-30% of the total heat and 70-80% ends up in the water. The data center can run warmer, less fans are required and chillers are often not needed. Chilldyne can recommend designs for cooling systems that include dry coolers, cooling towers or chillers. We can predict how much heat goes into each system and help determine the required cooling system hardware. We would need to know the local climate and the following parameter, (typical numbers for a dual Milan AMD system.

  • CPU power 240 watt x 2 per node
  • Maximum design Core temperature 75 °C
  • Total server DC power 680 watts nominal, 750 watts maximum
  • Cooling water maximum temperature 83.5 °F (29 °C)
  • Cold aisle maximum temperature 95 °F (35 °C)
  • Hot aisle maximum temperature 106 °F (41 °C) with 14 °F (-10 °C) minimum dewpoint per ASHRAE
  • Maximum wet bulb temperature as per OSHA is 89 °F (32 °C) for light work in the hot aisle. (comfort limit)

With these numbers we can determine the heat capture ratio (how much of the heat goes into the water). The system power the CPU temperature. We can advise on tradeoffs between comfort, performance and efficiency.