Optimization of enclosed aisle data centers with induced CRAH bypass

Hamza Salih Erden*, Mustafa Koz, Mehmet T. Yildirim, H. Ezzat Khalifa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Aisle containment systems reduce temperature nonuniformities in traditional air-cooled data centers and pave the way for higher cooling air temperature and more efficient operation of the cooling system and wider application of economizers. However, enclosing the aisle does not guarantee the lowest possible cooling infrastructure power. Enclosed air (EA) configurations require computer room air handler (CRAH) fans to provide the entire rack air flowthrough the perforated tiles, as well as the leakage flow that inherently exists in data centers. In this paper, we propose the installation of induction bypass (BP) fans beneath the cold aisle (CA) perforated tiles that draw air from the plenum, placing the latter under a slightly depressed pressure. In doing so, warm air from the hot aisle is drawn into the plenum, where it is mixed with a smaller amount of cold air from the CRAH. As a result, the CRAH fans operate at lower speeds and consume less power, but the air passing through the CRAH is cooled to a lower temperature so that the air supplied to the enclosed CA remains at or slightly below the server redline temperature (∼27 °C). Detailed optimization based on hour-by-hour annual energy simulations for seven U.S. cities has shown that the proposed induced CRAH BP scheme can reduce combined chiller and air-moving power consumption substantially in EA data centers with or without an airside economizer.

Original languageEnglish
Article number2760355
Pages (from-to)1981-1989
Number of pages9
JournalIEEE Transactions on Components, Packaging and Manufacturing Technology
Issue number12
Publication statusPublished - Dec 2017

Bibliographical note

Publisher Copyright:
© 2017 IEEE.


Manuscript received February 25, 2017; revised September 9, 2017; accepted October 3, 2017. Date of publication October 25, 2017; date of current version December 21, 2017. This work was supported by the New York State Energy Research and Development Authority under Grant 41202. Recommended for publication by Associate Editor Y. Joshi upon evaluation of reviewers’ comments. (Corresponding author: Hamza Salih Erden.) H. S. Erden is with the Applied Informatics Department, Istanbul Technical University, Istanbul 34469, Turkey (e-mail: [email protected]).

FundersFunder number
New York State Energy Research and Development Authority41202


    • Computer room air handler (CRAH) bypass (BP)
    • Containment
    • Data center
    • Flow network modeling (FNM)
    • Optimization
    • Thermodynamic modeling


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