Thermal Control Strategies for Reliable and Energy-Efficient Data Centers

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Rehan Khalid ◽  
Aaron P. Wemhoff

Two self-developed control schemes, ON/OFF and supervisory control and data acquisition (SCADA), were applied on a hybrid evaporative and direct expansion (DX)-based model data center cooling system to assess the impact of controls on reliability and energy efficiency. These control schemes can be applied independently or collectively, thereby saving the energy spent on mechanical refrigeration by using airside economization and/or evaporative cooling. Various combinations of system-level controls and component-level controls are compared to a baseline no-controls case. The results show that reliability is consistently met by employing only sophisticated component-level controls. However, the recommended conditions are met approximately 50% of the simulated time by employing system-level controls only (i.e., SCADA) but with a reduction in data center cooling system power usage effectiveness (PUE) values from 3.76 to 1.42. Moreover, the recommended conditions are met at all averaged times with an even lower cooling system PUE of 1.13 by combining system-level controls only (SCADA and ON/OFF controls). Thus, the study introduces a simple method to compare control schemes for reliable and energy-efficient data center operation. The work also highlights a potential source of capital expenses and operating expenses savings for data center owners by switching from expensive built-in component-based controls to inexpensive, yet effective, system-based controls that can easily be imbedded into existing data center infrastructure systems management.

Author(s):  
James W. VanGilder ◽  
Roger R. Schmidt

The maximum equipment power density (e.g. in power/rack or power/area) that may be deployed in a typical raised-floor data center is limited by perforated tile airflow. In the design of a data center cooling system, a simple estimate of mean airflow per perforated tile is typically made based on the number of CRAC’s and number of perforated tiles (and possibly a leakage airflow estimate). However, in practice, many perforated tiles may deliver substantially more or less than the mean, resulting in, at best, inefficiencies and, at worst, equipment failure due to inadequate cooling. Consequently, the data center designer needs to estimate the magnitude of variations in perforated tile airflow prior to construction or renovation. In this paper, over 240 CFD models are analyzed to determine the impact of data-center design parameters on perforated tile airflow uniformity. The CFD models are based on actual data center floor plans and the CFD model is verified by comparison to experimental test data. Perforated tile type and the presence of plenum obstructions have the greatest potential influence on airflow uniformity. Floor plan, plenum depth, and airflow leakage rate have modest effect on uniformity and total airflow rate (or average plenum pressure) has virtually no effect. Good uniformity may be realized by using more restrictive (e.g. 25%-open) perforated tiles, minimizing obstructions and leakage airflow, using deeper plenums, and using rectangular floor plans with standard hot aisle/cold aisle arrangements.


2019 ◽  
Vol 1304 ◽  
pp. 012022
Author(s):  
Jianwen Huang ◽  
Cheng Chen ◽  
Guiyang Guo ◽  
Zhang Zhang ◽  
Zhen Li

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Ruben Gielen ◽  
Martine Baelmans

This work focuses on a comparison of second law based component design on one hand and second law based system design on the other within the context of electronics cooling. Typical electronics cooling components such as a heat sink and a heat exchanger are modeled and designed towards minimum entropy generation on individual level and on system level. A comparison of these levels allows us to qualify and quantify the influences among components induced by a system. Simultaneously, this article endeavors to be an illustrated assessment of the usefulness of efficiency criteria on component level. It turns out that the results of this work reveal a substantial influence of system dependencies on the optimal component design. As such a note of caution is raised about second law based component design which does not take into account the system in which a component has to operate.


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