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Views: 81 Author: Site Editor Publish Time: 2022-06-21 Origin: Site
The key factors in a data center cooling system. How these factors come together in a data center. How to describe the pros and cons of a plant cooling system to a customer. Computer Room Air Conditioning (CRAC)
Computer Room Air ConditionerComputer Room Air Conditioner (CRAC) is a large air conditioning unit used to transfer large amounts of heat out of a data center and return large amounts of cool air back to the data center. Cooling of the server room is accomplished by blowing air through cooling coils filled with refrigerant. In general, CRAC units are self-contained, thus allowing a single unit to fail without affecting other CRACs in the facility. self-contained units also allow capacity to be easily increased, however, CRACs lack the efficiency of scale that many large unified cooling systems have. Therefore, data centers using CRACs typically have higher PUEs.
CRAC consists of an indoor unit and an outdoor unit. The main components in the indoor unit are the electronic expansion valve, evaporator, compressor, and indoor fan; the main components in the outdoor unit are the condenser and outdoor fan. The refrigerant temperature in the evaporator is low, the hot air from the server drawn by the indoor fan is heat exchanged with the evaporator and becomes low temperature air suitable for the entrance of the server, the refrigerant after heat absorption is discharged to the outdoor condenser through the compression of the compressor and the absorbed heat is dissipated to the environment, the refrigerant after heat dissipation is returned to the indoor unit and becomes low temperature refrigerant through the throttling effect of the expansion valve and continues to absorb the hot air from the service hot air, thus completing the refrigeration cycle of CRAC.
In this cooling process, by providing electrical energy to compressors, fans and other components, the purpose of moving the heat dissipated by the server from the indoor side to the outdoor side is achieved, but the energy consumption of this part makes the CRAC data center have a higher PUE value. In addition, N+1 or N+2 redundancy schemes are usually configured to improve the reliability of the cooling system.
The cooling capacity of CRACs, however, has the potential to condense water vapor in the air into water. Therefore, data centers utilizing CRACs must install a leak detection system under the unit to detect any liquid released from the cooling method. This is often overlooked, which is why humidity control features should also be considered.
