Due to the increase in computer rack equipment power in recent years, thermal management of data centers has become a challenging problem. Data center facilities with raised floor plenums are the most popular configuration from a thermal management perspective. Considerable ongoing research efforts focus on optimizing the room layouts and equipment design in order to achieve the desired cooling. However, the detrimental impact of under floor blockages, which occur widely, is seldom addressed. These blockages often take the form of chiller pipes, cabling, and wires. They impede the flow of cold air from the air conditioning units and yield unpredictable air flow patterns. This results in highly maldistributed tile flow rates which can create additional hot spots above the raised floors. In this paper the effect of such under floor blockages on data center performance is characterized in detail. A representative data center is modeled using commercial CFD code, with typical under floor blockages. Blockages are shown to have a significant impact on tile flow rates and rack inlet temperatures. A detailed parametric study is presented, to identify the locations under the floor, where blockages if installed, have minimal effect on data center performance. Case studies are presented to show that blockages, if installed with prior consideration, have a positive effect on overall data center performance. Finally guidelines are presented on how to rearrange existing blockages or to install new blockages, and still achieve an improvement in thermal performance, without any change to the room layout or cold air supply.

Volume Subject Area:
Heat Transfer
Topics:
Data centers, Flow (Dynamics), Thermal management, Tiles, Air conditioning, Air flow, Computational fluid dynamics, Computers, Cooling, Design, Pipes, Temperature, Wire
1.
S. Bhopte, B. Sammakia, R. Schmidt, M. Iyengar and D. Agonafer, “Effect of Under Floor Blockages on Data Center Performance”, Inter-Society Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm), San Diego, California, June 2006.
2.
Karki
K. C.
,
Radmehr
A.
and
Patankar
S. V.
, “
Use of Computational Fluid Dynamics for Calculating Flow Rates through Perforated Tiles in Raised Floor Data Centers
”,
International Journal of Heating, Ventilation, Air Conditioning, and Refrigeration Research
, Volume
9
, Number
2
, April
2003
, pp.
153
–
166
.
3.
K.C. Karki, S.V. Patankar and A. Radmehr, “Techniques for Controlling Airflow Distributions in Raised Floor Data Centers”, Paper No., IPACK2003–35282, Proceedings of IPACK’03, The Pacific Rim/ASME International Electronic Packaging Technical Conference and Exhibition, July 6-11, 2003, Maui, Hawaii, USA.
4.
S. Bhopte, D. Agonafer, R. Schmidt and B. Sammakia, “Optimization of Data Center Room Layout to Minimize Rack Inlet Air Temperature”, Paper No., IPACK2005–73027, Proceedings of IPACK’05, The Pacific Rim/ASME International Electronic Packaging Technical Conference and Exhibition, July 17-22, 2005, San Francisco, California, USA.
5.
R. Schmidt and E. Cruz, “Raised Floor Computer Data Center: Effect on Rack Inlet Temperatures of Chilled Air Exiting both the Hot and Cold Aisles”, ITHERM Conference, San Diego, California, USA, June 2002, pp. 580–594
6.
R. Schmidt, “Effect of Data Center Characteristics on Data Center Processing Equipment Inlet Temperatures”, Paper No., IPACK2001–15870, Proceedings of IPACK’01, The Pacific Rim/ASME International Electronic Packaging Technical Conference and Exhibition, July 8-13, 2005, Kauai, Hawaii, USA.
7.
R.K. Sharma, B.E. Cullen and C.D. Patel, “Dimensionless Parameters for Evaluation of Thermal Design and Performance of Large Scale Data Centers”, Paper No. AIAA 2002-3091, American Institute of Aeronautics and Astronautics Conference, 2002.
8.
Personal Communication, Madhusudan K. Iyengar and Roger Schmidt, Advanced Thermal Laboratory, IBM Systems and Technology Group, Poughkeepsie, New York, 12601, USA.
9.
Flotherm 5.1, Flomerics Ltd., U.K.
10.
Flotherm User Manual, Flomerics Ltd., U.K.
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