Sealing Gaps Under IT Racks: A Technical Report from Upsite

CFD Analysis Reveals Significant Savings Potential

Upsite's Executive Summary:

Often overlooked, the small space between the bottom of an IT rack or cabinet and the raised floor or slab can have a significant impact on IT inlet temperatures. Such spaces are common, as casters and leveling feet under IT cabinets creates gaps from half an inch up to two or more inches between the floor and the bottom of the cabinet. However, this space allows the hot air from the IT equipment exhaust at the rear of the rack to flow under the rack and back into the IT equipment air inlets at the front of the rack. This recirculation of exhaust air increases the IT inlet temperatures, contributes to hot spots, and can ultimately lead to increased failure rates of IT equipment. This study examined the impact of sealing these small gaps.*

The Computational Fluid Dynamics (CFD) analysis revealed the impact of sealing these small gaps, which reduced temperatures as a result of eliminating the exhaust air recirculation under the rack. Sealing the gaps under the rack created opportunities to improve the overall airflow management in the data center. This, in return, improved the efficiency of the cooling system by allowing an increase in the cooling unit temperature set points and a reduction in cooling unit fan speeds. A more subtle, but important benefit, of optimizing the cooling unit operational conditions was releasing stranded capacity in the overall cooling system. The released capacity can be used to support increased IT loads and defer or eliminate capital expenses for new or upgraded cooling units. 

To read more, download the technical report below. 

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