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Research Papers

Improved Computational Fluid Dynamics Model for Open-Aisle Air-Cooled Data Center Simulations

[+] Author and Article Information
Waleed A. Abdelmaksoud

Research Assistant
e-mail: wamarouf@syr.edu

Thong Q. Dang

Professor

H. Ezzat Khalifa

NYSTAR Distinguished Professor
Fellow ASME
Department of Mechanical and Aerospace Engineering,
Syracuse University,
Syracuse, NY 13244

Roger R. Schmidt

IBM Fellow and Chief Engineer
Fellow ASME
Data Center Energy Efficiency,
IBM Corporation,
Poughkeepsie, NY 12601

1Corresponding author.

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the Journal of Electronic Packaging. Manuscript received January 10, 2012; final manuscript received June 3, 2013; published online July 24, 2013. Assoc. Editor: Yogendra Joshi.

J. Electron. Packag 135(3), 030901 (Jul 24, 2013) (13 pages) Paper No: EP-12-1089; doi: 10.1115/1.4024766 History: Received January 10, 2012; Revised June 03, 2013

There is a need in the IT industry for CFD models that are capable of accurately predicting the thermal distributions in high power density open-aisle air-cooled data centers for use in the design of these facilities with reduced cooling needs. A recent detailed evaluation of a small data center cell equipped with one high power rack using current CFD practice showed that the CFD results were not accurate. The simulation results exhibited pronounced hot/cold spots in the data center while the test data were much more diffused, indicating that the CFD model under-predicted the mixing process between the cold tile flow and the hot rack exhaust flow with the warm room air. In this study, a parametric study was carried out to identify CFD modeling issues that contributed to this error. Through a combined experimental and computational investigation, it was found that the boundary condition imposed at the perforated surfaces (e.g., perforated tiles and rack exhaust door) as fully open surfaces was the main source of error. This method enforces the correct mass flux but the initial jet momentum is under-specified. A momentum source model proposed for these perforated surfaces is found to improve the CFD results significantly. Another CFD modeling refinement shown to improve CFD predictions is the inclusion of some large-scale geometrical features of the perforated surfaces (e.g., lands/gaps) in the CFD model, but this refinement requires the use of grids finer than those typically used in practice.

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References

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Figures

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Fig. 1

Top view of the DC/RL facility (dimensions in meters)

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Fig. 2

Field measurement technique of temperature in DC/RL facility

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Fig. 3

Photograph of temperature poles placed on one row intersects rack 3

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Fig. 4

Simulated chassis design layout (dimensions in millimeters)

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Fig. 5

Perforated tile used in the DC/RL

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Fig. 6

Rack models with and without gaps

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Fig. 7

Comparison of temperature profiles 0.3 m in front and 0.3 m behind racks (symbols: test data; thin dashed line: baseline CFD; dotted line: improved CFD; solid line: detailed CFD)

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Fig. 8

Comparison of temperature profiles along center of edge tiles (symbols: test data; thin dashed line: baseline CFD; dotted line: improved CFD; solid line: detailed CFD)

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Fig. 9

Comparison of temperature contours in vertical plane bisecting rack 1

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Fig. 10

Comparison of temperature contours in vertical plane 0.3 m in front of racks

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Fig. 11

Contours of chassis inlet temperature (T–Ttile) distribution

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Fig. 12

Comparison of pathlines released from perforated tiles

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