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Research Papers

Steady State and Transient Experimentally Validated Analysis of Hybrid Data Centers

[+] Author and Article Information
Tianyi Gao

Binghamton University-SUNY,
Binghamton, NY 13902
e-mail: Tgao1@binghamton.edu

Bahgat Sammakia, Emad Samadiani

Binghamton University-SUNY,
Binghamton, NY 13902

Roger Schmidt

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 April 7, 2014; final manuscript received November 12, 2014; published online January 19, 2015. Assoc. Editor: Mehmet Arik.

J. Electron. Packag 137(2), 021007 (Jun 01, 2015) (12 pages) Paper No: EP-14-1041; doi: 10.1115/1.4029163 History: Received April 07, 2014; Revised November 12, 2014; Online January 19, 2015

Data centers consume a considerable amount of energy which is estimated to be about 2% of the total electrical energy consumed in the U.S. in the year 2010, and this number continues to increase every year. Thermal management is becoming increasingly important in the effort to improve the energy efficiency and reliability of data centers. The goal is to keep the information technologies (IT) equipment temperature within the allowable range in high power density data centers while reducing the energy used for cooling. In this regard, liquid and hybrid air/water cooling systems are alternatives to traditional air cooling. In particular, these options offer advantages for localized cooling higher power racks which may not be manageable using the room level air cooling system without requiring significantly more energy. In this paper, a hybrid cooling system in data centers is investigated. In addition to traditional raised floor, cold aisle-hot aisle configuration, a liquid–air heat exchanger attached to the back of racks is considered. First of all, the paper presents a review of literature of the study of this heat exchanger strategy in the thermal management of a data center. The discussion focus on rear door heat exchanger (RDHx) performance, both the steady state and transient impact are analyzed. The studies show that under some circumstances, this hybrid approach could be a viable alternative to meet the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) recommended inlet air temperatures, while at the same time reducing the overall energy consumption in high density data centers. The hybrid design approach can also significantly improve the dynamic performance during rack power increases or computer room air conditioner (CRAC) unit failure. And then, additional parametric steady state and dynamic analyses, are presented in detail for the different scenarios.

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References

Figures

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Fig. 5

Effectiveness of heat exchanger [24]

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Fig. 6

Typical performance of a rear door heat exchanger (numerical results compared with experimental data [36]; percentage heat removal as function of water temperature and flow rate) [35]

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Fig. 4

Average inlet and outlet temperatures of rack A [34]

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Fig. 3

Representative CFD model of data center

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Fig. 2

Rack layout for data center used for study—plan view

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Fig. 1

Underfloor air supply configuration [1]

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Fig. 15

Rack A average inlet temperature [35]

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Fig. 7

Surface map showing effectiveness

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Fig. 8

Rack inlet air temperature versus distance from raised floor for baseline performance comparison: (a) rack with rear door heat exchanger enhancement and (b) rack without cooling enhancement [24].

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Fig. 9

Summary of data center impact of using rear cover heat exchanger [24]

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Fig. 10

Impact of hybrid solution on data center with 2 and 3 ft underfloor plenum [40]

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Fig. 11

Average inlet temperature of racks A and D [42]

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Fig. 12

Average inlet temperature of racks A and D [42]

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Fig. 13

Energy consumption of each operation conditions [42]

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Fig. 14

Rack A average inlet temperature [35]

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Fig. 16

Rack A average inlet temperature [35]

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Fig. 17

Rack A average inlet temperature [35]

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Fig. 31

Water and air increase pattern

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Fig. 29

Response time study results of rack B1 [48]

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Fig. 30

Response time study results of rack B1 [48]

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Fig. 21

Power changing profile with time [42]

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Fig. 22

Average Inlet temperature of rack A [42]

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Fig. 23

Average Inlet temperature of rack A [42]

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Fig. 24

Water and air increase pattern [48]

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Fig. 32

(a) Average inlet temperature of row A racks versus time for CRAC 1 and CRAC 4 failure combination and (b) average inlet temperature of row D racks versus time for CRAC 1 and CRAC 4 failure combination

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Fig. 33

(a) Average inlet temperature of row A racks versus time for CRAC 2 and CRAC 3 failure combination and (b) average inlet temperature of row D racks versus time for CRAC 2 and CRAC 3 failure combination

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Fig. 34

(a) Average inlet temperature of row A racks versus time for CRAC 3 and CRAC 4 failure combination and (b) average inlet temperature of row D racks versus time for CRAC 3 and CRAC 4 failure combination

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Fig. 18

Airflow profile due to CRAC failure with time [42]

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Fig. 19

(a) Inlet temperature of rack B1 [42] and (b) inlet temperature of rack D1 [42]

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Fig. 20

(a) Inlet temperature of rack B1 [42] and (b) inlet temperature of rack D1 [42]

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Fig. 35

CRAC-less cooling solution design

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Fig. 25

(a) Average inlet temperature of row B racks [48] and (b) average inlet temperature of row D racks [48]

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Fig. 26

(a) Average inlet temperature of row B racks [48] and (b) average inlet temperature of row D racks [48]

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Fig. 27

Inlet temperature of rack D1 [48]

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Fig. 28

Inlet temperature of rack D1 [48]

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