What are the Advantages of Using DC Aisle Containment Systems? Do they improve Energy Efficiency?
In the early days of computing, "System Rooms" relied on cold air underneath the raised floor to cool down the equipment. The cabinets had sealed doors, ventilation grills at the bottom, and fans on top to regulate the temperature inside. The rack density used to be around 1 to 2 kW per rack. Years went by quickly.?
As technology evolves, so do data centers. Nowadays, most of the data centers have hundreds of cabinets that occupy 1000 m2 white spaces and consume more than 10 kW of power each. The Rack Aisle Containment System is a key component in these data centers. It helps to optimize cooling and energy efficiency. Rack manufacturers provide not only standardized solutions but also automated ones.
How does the Cooling Air Cycle function in White Space?
In the White Space, the air cycle directs the heat to the cooling indoor units so they can transfer it from the inside to the atmosphere. The air cycle consists of two types of fan groups. The first group is the fans of the cooling indoor units. The second is the fans of the active equipment located in various sections (in racks) of the white space. Ignoring the effects of this second type of fan group leads to major design and operational problems. The first and second groups of fans must work in harmony.
Fans in active devices are in charge of exhausting the heat inside the equipment from the back. As the hot air flows through the device, it removes heat from the components that need to be cooled. The hot air is expelled from the back. If there is not enough fresh cold air coming in from the front, the hot air from the back can flow back to the front due to the pressure difference. This can cause the heated air to continuously circulate, leading to the formation of "hot spots" and a temperature rise that can damage the equipment.
The indoor units are to ensure that there is adequate airflow to the front of the active equipment. The IT equipment's internal fans then draw as much air as needed to transfer the internal heat to the outgoing air. Since IT equipment is placed in rows of cabinets in the white space, the cooler's total airflow distribution must be sufficient to provide the necessary flow that all equipment requires. That is the critical point to maintain the environmental conditions of the IT equipment.
Before implementing aisle containment, it is crucial to arrange the cabinets into hot and cold aisles. This prevents hot air exhaust by servers from being sucked in by another server.
How Do Rack Aisle Containment Systems Benefit?
To prevent hot and cold air from mixing during flow, the next step is to apply a barrier. This involves closing the aisles with hot air and connecting them to the return of the indoor units with ducts, which is known as Hot Aisle Containment. On the other hand, Cold Aisle Containment refers to the closure of the front of the server racks to trap cold air in front of the IT equipment. The cold air is then directed to the equipment through ventilated tiles on a raised floor.
The containment system allows the airflow to be directed in the intended direction. It is an effective solution that ensures the proper airflow level and distribution within IT equipment. This prevents an increase in inlet temperatures caused by mixing hot and cold air. However, if the positive pressure differential from front to back is not supported, the containment method may not eliminate the issues. Instead, it may only delay their occurrence or reduce their impact.
Can the Use of an Aisle Containment System Improve Energy Efficiency?
Aisle containment systems are designed to maintain cooling environmental conditions for high availability and offer the potential to increase energy efficiency as well. These systems manage the rack density distribution and adequate airflow respectively. Aisle containment systems also prevent the loss of cooling efficiency caused by deviation from ideal conditions. Once this fundamental requirement is fulfilled, maximizing efficiency by operating at a higher set point becomes feasible.
When the aisle containment system is not in place, the airflows are not regulated properly. This leads to a mixture of cold air from indoor units and hot air being exhausted at the inlet of one or more IT equipment. If the temperature exceeds certain limits, it can cause harm to IT equipment by shortening its lifespan, increasing the risk of thermal shutdown and downtime.
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To avoid the risk of environmental instability and increase predictability, it's common to lower the set points of indoor units. However, this action can cause problems with the capacity and efficiency of data center infrastructure.
Lowering the return temperature set point of the indoor cooling unit can cause inefficiency due to condensing water on the evaporator and reduce the COP of the compressor. When the COP of compressors decreases, the capacity of the cooling unit also decreases. Both increase power consumption and risk exceeding electrical current requirements, compared to the base of electrical design.
Reduced cooling capacity in the white space could lead to a loss of redundancy and require you to invest in additional cooling devices. However, adding more indoor units may decrease energy efficiency due to increased fan consumption and require more electrical capacity.
Conclusion
Data Center Cooling Optimization Series
Regional Engineering Manager- Wells Fargo at Jones Lang Lasalle
10 个月I'll say this about aisle containment: do your homework. Different AHJs will have different requirements, particularly where Fire Suppression is involved. Some folks are OK with fusible links for the roof panels, others want an electronic means of release/monitoring, still others will demand suppression be brought into the contained space. While those aspects can affect how difficult/expensive the project is, it's still a very worthwhile pursuit and a very useful tactic for driving down PUE.
Data Center Design and Operations Engineer, ATD, AOS
10 个月Your article provides a clear and concise overview of the key concepts and benefits of aisle containment systems. I especially agree with your emphasis on the importance of separating hot and cold air flows. This is a critical step in improving cooling efficiency in data centers.