COLUMN DATA CENTERS uid is circulated directly to the electronics for cooling with no other heat transfer mechanisms (e.g., air cooling). FIGURE 1 Datacom cooling system overview. Building Many Liquid Cooling Loops Datacom Equipment Center Facilities Water Even these definitions are subject to a broad interRack System (FWS) Direct CDU Load Datacom Cooling pretation and do not account for the numerous liquid Chiller Equipment Tower Cooling System cooling loops that can exist in a data center cooling sys(DECS) tem. Figure 1 provides a good overview of a liquid cooling arrangement that contains multiple liquid cooling loops. Condenser Water Technology Cooling Four separate liquid cooling systems or loops are System (CWS) Systems (TCS) shown in Figure 1. Not all four necessarily exist in a given liquid cooling system, but this arrangement represents the most TABLE 1 ASHRAE liquid cooling classes from liquid cooling for datacom equipment centers. complete liquid cooling system. TYPICAL INFRASTRUCTURE DESIGN LIQUID FACILITY SUPPLY COOLING * The condenser water system WATER TEMPERATURE MAIN COOLING EQUIPMENT SUPPLEMENTAL COOLING EQUIPMENT CLASSES (CWS) is very typical to many water W1 36°F to 63°F Water-Side Economizer Chiller/Cooling Tower cooled chilled water cooling systems (Cooling Tower or Drycooler) W2 36°F to 81°F between the exterior heat rejection W3 Cooling Tower Chiller 36°F to 90°F equipment (in this case, the cooling Water-side Economizer W4 N/A 36°F to 113°F (Cooling Tower or Drycooler) tower) and the chiller. W5 Building Heating System Cooling Tower >113°F * The facilities water system (FWS) www.info.hotims.com/49809-6 O CT O B E R 2 0 1 4 ashrae.org ASHRAE JOURNAL 83