Dell PowerEdge Rack Enclosure 4020S - Manual (Page 6)

Dell Inc. | Data Center Infrastructure 6
Cooling
The Dell 2420 and 4220 Rack Enclosures have been designed to provide the necessary thermal environment to help
reduce inefficiency at the rack level in cooling your rack mount equipment in the data center environment.
When it comes to cooling in the rack environment, the two key areas that need to be addressed are airflow into the
rack and management of the hot air exhaust inside the rack.
The air intake into the rack enclosure is a function of how much cool air is presented to the rack and the amount of
cool air that can make it through the perforations in the rack enclosure front door as well as how much hot air can be
expelled through the perforations in the rear doors of the rack enclosure.
The door perforation design of the 2420 and 4220 Rack Enclosure front and rear doors provide 80% open area for
greater airflow capability than many other comparable racks.
Figure 3: 80% Open Perforation on Front & Rear Doors
Although the size of perforations in the rack doors are not usually a key contributor to overheating in the rack and
data center environment, a more open door perforation design ensures adequate airflow at the rack level.
Incorrect airflow management inside the rack enclosure can cause inefficiencies in cooling your rack mount
equipment. In standard data center environments, IT equipment pulls cool air in through the front door of the rack
enclosure and expels hot air through the rear of the system, and then through the rear doors of the rack. This cycle
of air flow should be consistent and continuous.
Key to maintaining this airflow cycle is proper rack enclosure design and the use of best practices in configuring
your rackmount equipment. The design of the rack should be such that the airflow path inside the rack does not
allow hot air exhausting from the rear of systems to travel to the front of the equipment through the sides of the rack.
When hot air exhaust travels to the front of the rack, it can enter rackmount equipment and disrupt the cooling cycle
by introducing hot air into the systems, thereby decreasing the systems’ efficiency. See Figure 4.
It should be noted that the rack fan kit available from Dell for legacy rack enclosures will also install into the 4220
Rack Enclosure.