Water-side economization
Water-side economization uses a cooling tower as either the primary or supplementary means of cooling the chilled water supply for an air conditioning system. In a typical data center application (Figure 5), a cooling tower cools water in the condenser circuit, which in turn cools the chilled water in a common heat exchanger. The purpose of the external heat exchanger is to take the load off the CRAH, which can consume significant energy if the cooling load is high.
Figure 5: Water-side free cooling
ITE racks
(cooling load)
CRAH
Heat
exchanger
Condenser
pump
Figure 5 shows water-side free cooling for a data center using cold-aisle containment. Water-side free cooling can also be used to supplement other cooling configurations.
Benefits and disadvantages of free air cooling
By using outside air to avoid or limit CRAH use, free-air cooling can significantly reduce a data center’s energy requirements. However, free-air cooling systems require full integration with the facility system and must be carefully designed and adjusted to the data center’s regional location.
Air containment strategies
Air containment strategies separate cold supply air from warm return air to maximize air handler efficiency. Selecting an air containment strategy generally depends on whether there is a raised floor or dropped ceiling, and/or the ability to meet fire codes. You can use one of two containment strategies:
•Cold-aisle containment
•Hot-aisle containment
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