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Liebert XD System™ Reduces Energy to Cool Data Centers by 31%
Data center facilities operate continuously 24/7/365 and cost the US $2.7 billion in total electrical energy utilization in 2005. The Liebert XD System™ has the potential to save $155 million of this energy cost compared with traditional Computer Room Air-Conditioning units. The energy required to cool the heat-generating servers and other computer related equipment accounts for 37% of the total energy used by the data centers ($1 billion). More than 32% of the cooling load is attributed to the air moving devices that transfer the heat load from the data center space to an external building chilled water system. The Liebert XD System™ offers an innovative alternative to this heat removal process by incorporating a pumped two-phase fluid to transfer this heat from the data center space to the external building chilled water system. The remaining 68% of the cooling load is attributed to the building chilled water system. An additional innovation of the Liebert XD system is that the system is entirely sensible cooling, rather than the combination of latent cooling and sensible cooling inherent with traditional cooling systems.
The Liebert XD cooling system consists of a pumping module, multiple distributed cooling modules, and refrigerant fluid in a piping circuit. The Liebert XD cooling modules are located in close proximity to the heat load generated by the server racks. The system design allows for the use of high efficiency prop fans to circulate air to the server racks and transfer the heat from the racks to the pumped refrigerant circuit, which is then exchanged with the traditional building chilled water system. Significant energy savings are realized with the system compared with traditional Computer Room Air-Conditioning units which are located along the perimeter of the room and force large volumes of air throughout the data center space via a higher static floor plenum. In addition to moving air only in a small, localized area, the Liebert XD System leverages the phase change efficiency of the pumped refrigerant fluid which allows for lower fluid volumes and pumping power loads than a single phase fluid such as water.
As a result of these differences, the Liebert XD System yields a 61% energy savings for transferring data center heat load to the building chilled water system compared with traditional Computer Room Air-Conditioning units. The reduction in latent cooling with the Liebert XD System reduces the heat load on the building chilled water system by 17%. Combining these two energy savings factors, the Liebert XD System lowers the heat load on the building chilled water system for a data center by 31%. With more than 300 sites in operation globally, the Liebert XD System has repeatedly demonstrated this performance advantage and has achieved an annual saving of $17 million in energy costs. With more than 50% of the global data centers suitable for deployment of the Liebert XD System, the achievable potential is $155 million.
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