A parametric CFD study of computer room air handling bypass in air-cooled data centers

Vahid Ebrahimpour Ahmadi, Hamza Salih Erden*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Computer room air handling (CRAH) bypass (BP) method is an application that reduces the total fan power in air-cooled data centers by lowering CRAH fan speed. BP fans supply the complementary fraction of server airflow from warmer room air through lower-resistance floor openings into the plenum. Hence, chillers need to operate at lower temperatures less efficiently, which poses an optimization problem. The reduced-order modeling tools in the literature adequately predict fan power. However, they assume well-mixed temperature at rack inlets to deal with this optimization problem and fail to quantify the impact of ignoring temperature non-uniformities. This study includes an experimental verification of computational fluid dynamics (CFD) modeling for CRAH BP method in predicting temperatures in a data center test-cell. The subsequent parametric study uses both CFD and reduced-order modeling tools on a more representative quadrant of a large data center to investigate induced and forced CRAH BP in both enclosed and open aisle configurations as well as comparing various plenum heights, IT load and server airflow rate. Results indicate where reduced-order modeling tools perform reasonably well and where the need for CFD emerges and identify various favorable data center designs and operating conditions for CRAH BP method.

Original languageEnglish
Article number114685
JournalApplied Thermal Engineering
Volume166
DOIs
Publication statusPublished - 5 Feb 2020

Bibliographical note

Publisher Copyright:
© 2019 Elsevier Ltd

Keywords

  • Computational fluid dynamics
  • CRAH bypass method
  • Data centers
  • Optimization
  • Reduced-order modeling

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