CFD SIMULATION OF AIRFLOW AND COOLING IN A DATA CENTER

There is a strong need to improve our current capabilities in thermal management and electronic cooling, since estimates indicate that IC power density level could reach 500 W/cm2 in near future. This paper presents several possible closed and open loop cooling schemes for thermal management of electronic equipment in data centers. To be able to identify the overall energy consumption impact, a thermodynamics coefficient of performance (COP) analysis for a data center under each one of the proposed schemes is presented. A limited condition condition 2nd law of thermodynamics thermal efficiency (ηII) analysis of the proposed open-loop schemes is also presented. Using available performance data, the overall data center COP of open and closed-loop cooling schemes is evaluated. Also, the 2nd law efficiency of open-loop schemes is evaluated. To properly design and size the components of a liquid or refrigeration-assisted open or closed-loop cooling scheme requires heat exchanger modeling that need to be incorporated in existing CFD simulation models. For that, analytical modeling of two kinds of direct expansion refrigeration cooling evaporator and a secondary liquid cooling fan coil heat exchanger in conjunction with a computational fluid dynamics (CFD) model to analyze a refrigeration cooled high heat density electronic and computer data center installed on a raised floor is presented. Both models incorporate an accurate tube-by-tube thermal hydraulic modeling of the heat exchanger. The refrigeration coil analysis incorporates a multi region heat exchanger analysis for a more precise modeling of two phase refrigerant flow in the evaporator. The single phase secondary loop fan coil heat exchanger modeling uses an effectiveness method for regional modeling of the spot-cooling coil. Using an iterative method, results of the heat exchanger modeling is simultaneously incorporated in the CFD model and an optimal design of spot cooling heat exchanger is developed. The presented cooling schemes, theoretical thermodynamics analysis along with the detailed thermal-hydraulic heat exchanger simulation in conjunction with the state-of-the-art CFD simulation code should enable data center designers to be able to handle expected increased in heat density of the future data centers.

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Perforated tile models for improving data center CFD simulation

13th InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems ◽

10.1109/itherm.2012.6231414 ◽

2012 ◽

Cited By ~ 9

Author(s):

Waleed A. Abdelmaksoud ◽

Thong Q. Dang ◽

H. Ezzat Khalifa ◽

Roger R. Schmidt ◽

Madhusudan Iyengar

Keyword(s):

Data Center ◽

Cfd Simulation

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Investigation of Airflow Pattern of a Typical Data Center by CFD Simulation

Energy Procedia ◽

10.1016/j.egypro.2015.11.350 ◽

2015 ◽

Vol 78 ◽

pp. 2687-2693 ◽

Cited By ~ 8

Author(s):

Caifeng Gao ◽

Zhen Yu ◽

Jianlin Wu

Keyword(s):

Data Center ◽

Cfd Simulation ◽

Airflow Pattern ◽

Typical Data

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Improving Prediction Accuracy Concerning the Thermal Environment of a Data Center by Using Design of Experiments

Energies ◽

10.3390/en13184595 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4595

Author(s):

Naoki Futawatari ◽

Yosuke Udagawa ◽

Taro Mori ◽

Hirofumi Hayama

Keyword(s):

Design Of Experiments ◽

Data Center ◽

Prediction Accuracy ◽

Data Centers ◽

Cfd Simulation ◽

Thermal Environment ◽

Parameter Tuning ◽

Inlet Temperature ◽

Cfd Model ◽

Ventilation Efficiency

In data centers, heating, ventilation, and air-conditioning (HVAC) consumes 30–40% of total energy consumption. Of that portion, 26% is attributed to fan power, the ventilation efficiency of which should thus be improved. As an alternative method for experimentations, computational fluid dynamics (CFD) is used. In this study, “parameter tuning”—which aims to improve the prediction accuracy of CFD simulation—is implemented by using the method known as “design of experiments”. Moreover, it is attempted to improve the thermal environment by using a CFD model after parameter tuning. As a result of the parameter tuning, the difference between the result of experimental-measurement results and simulation results for average inlet temperature of information-technology equipment (ITE) installed in the ventilation room of a test data center was within 0.2 °C at maximum. After tuning, the CFD model was used to verify the effect of advanced insulation such as raised-floor fixed panels and show the possibility of reducing fan power by 26% while keeping the recirculation ratio constant. Improving heat-insulation performance is a different approach from the conventional approach (namely, segregating cold/hot airflow) to improving ventilation efficiency, and it is a possible solution to deal with excessive heat generated in data centers.

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Energy-Efficient Improvement Approaches through Numerical Simulation and Field Measurement for a Data Center

Energies ◽

10.3390/en12142757 ◽

2019 ◽

Vol 12 (14) ◽

pp. 2757 ◽

Cited By ~ 1

Author(s):

Fujen Wang ◽

Yishun Huang ◽

BowoYuli Prasetyo

Keyword(s):

Numerical Simulation ◽

Data Center ◽

Cfd Simulation ◽

Field Measurements ◽

Heat Index ◽

Temperature Index ◽

Performance Indexes ◽

Airflow Distribution ◽

Computational Fluid Dynamics Cfd ◽

Simulation Results

The power density of electronic equipment increased dramatically recently. Data center and data processing and telecommunication facilities are facing the exceptionally high sensible heat loads which result in a large amount of energy consumption. In this study, a numerical simulation using computational fluid dynamics (CFD) was conducted to investigate the influence of alternative approaches to avoid bypassing and recirculation for air distribution in a full-scale data center. Field measurements were extensively conducted to validate the simulation results. Various performance indexes were adopted to enhance the evaluation of the thermal performance of the data center. The simulation results revealed that the practice with hot aisle enclosure and the installation of blocking panels for the unoccupied racks can provide satisfactory airflow distribution and thermal management under low load conditions. The return temperature index (RTI) can be improved by 3% through CFD simulation through installation of the blank panels, which reveals the reduction of recirculation airflow. The return heat index (RHI) increases by 8%, which presents a reduction of bypass airflow. A practical experiment using physical air curtains was conducted to enclose the hot aisle in the data center, which also reveals an 8% improvement for bypass airflow. Higher cooling performance can be achieved via reduction of recirculation and bypass airflow in the data center. Through the simulation of different improvement approaches in the data center, the optimum practice for cooling airflow arrangement can be identified accordingly.

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A Hybrid Flow Network-CFD Method for Achieving Any Desired Flow Partitioning Through Floor Tiles of a Raised-Floor Data Center

2003 International Electronic Packaging Technical Conference and Exhibition, Volume 2 ◽

10.1115/ipack2003-35171 ◽

2003 ◽

Cited By ~ 4

Author(s):

James W. VanGilder ◽

Ted Lee

Keyword(s):

Data Center ◽

Flow Resistance ◽

Cfd Simulation ◽

Floor Tile ◽

Electrical Circuit ◽

Trial And Error ◽

Flow Network ◽

Floor Tiles ◽

Circuit Analogy ◽

Cfd Method

A technique is presented which allows a data center designer or operator to achieve any desired partitioning of available airflow among the floor tiles of a raised-floor data center without resorting to trial-and-error. The output from the analysis is a tile-by-tile prescription of flow resistance characteristics (e.g., damper settings), which accomplishes the desired partitioning. The technique is derived from an electrical-circuit analogy of the airflow in the data. Each circuit branch represents one path that air may follow from the CRAC unit supply, through a particular floor tile, and ultimately back to the CRAC return. Any desired flow partitioning through tiles can be achieved by proper adjustment of tile resistances in each circuit; however, by itself, the flow network has too many unknowns to be solvable. A CFD simulation of the entire data center, in which the desired flow partitioning is specified, provides the pressure distribution above (in the room) and below (in the plenum) the floor tiles. The method is illustrated in step-by-step fashion with a simple example case.

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Alternative Layouts for Air Distribution Improvement of a Computing Data Center

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.677.282 ◽

2013 ◽

Vol 677 ◽

pp. 282-285

Author(s):

F.J. Wang ◽

C.M. Lai ◽

Y.S. Huang ◽

J.S. Huang

Keyword(s):

Data Center ◽

Best Practice ◽

Cfd Simulation ◽

Numerical Study ◽

Cost Effective ◽

Distribution Patterns ◽

Air Distribution ◽

Cooling Performance ◽

Airflow Distribution ◽

Computational Fluid Dynamics Cfd

In this study, numerical simulation by using computational fluid dynamics (CFD) codes were conducted to investigate the influence of alternative layouts for air distribution in a full scale newly constructed data center. Through the simulation of different airflow distribution patterns in the data center, the optimum practice for cooling airflow arrangement can be identified easily. The simulation results also revealed that the best practice with a vertical under floor cooling architecture can provide satisfactory airflow distribution and thermal management. Higher cooling performance can be achieved by providing better separation of cold and hot aisle stream. Rack cooling index (RCI) has been used to evaluate the cooling performance of environmental conditions for the data center facility. Numerical study through CFD simulation can not only identify the best practice for airflow distribution, but also provide the energy-efficient and cost-effective HVAC system specific for data center facility.

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Effect of Rack Models and Buoyancy Forces on a Small Data Center Facility

ASME 2019 Heat Transfer Summer Conference ◽

10.1115/ht2019-3709 ◽

2019 ◽

Author(s):

Beichao Hu ◽

Long Phan ◽

Cheng-Xian Lin

Keyword(s):

Data Center ◽

Buoyancy Force ◽

Data Centers ◽

Cfd Simulation ◽

Early Stage ◽

Black Box ◽

Ease Of Use ◽

Box Model ◽

Small Data ◽

Buoyancy Forces

Abstract Due to the rapid growth of the power density in data centers, the thermal management of the data center has become more and more important. Computational Fluid Dynamics has been proven to be one of the most effective tools in the design and analysis in data centers due to its ease of use and fast prediction in data centers. Due to the large size of a data center facility, one of the most challenging tasks in the data center CFD simulation is to establish simplified models to provide a fast but accurate prediction for both the temperature and flow field in data centers. In the past few years, people have proposed many tile models specifically to simulate the jet effect of the perforated tile. However, other aspects of the simulation were still in the early stage, e.g. rack models and the effect of buoyancy forces. This paper mainly studied the effect of the three rack models, which were Black Box Model, Modified Black Box Model, and Volumetric Heat Model. The effects of the buoyancy force were also studied. The result showed that buoyancy force had a huge impact on the simulation result, while the three rack models investigated had little difference.

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Validation and Evaluation of Turbulence Models in Thermal Predictions of a Small Data Center Facility

Volume 8A: Heat Transfer and Thermal Engineering ◽

10.1115/imece2018-87479 ◽

2018 ◽

Author(s):

Beichao Hu ◽

Long Phan ◽

Cheng-Xian Lin

Keyword(s):

Turbulence Model ◽

Data Center ◽

Data Centers ◽

Cfd Simulation ◽

Turbulence Models ◽

Equation Model ◽

Computational Time ◽

Small Data ◽

Resource Requirements ◽

The Difference

Thermal management in data centers has become more and more important due to the rapid growth in power density in modern data centers. Computational fluid dynamics (CFD) is proved to be a very useful tool in data center design and analysis. However, the previous papers always utilize k-epsilon model, and has never studied on the effect of other turbulence models. This paper will demonstrate the difference between various turbulence models in terms of accuracy and computational time. The data center investigated in this paper has a floor area of 900 ft2 and comprises one rack, one CRAC unit, and several perforated tiles. This paper mainly investigates the effect of various turbulence models on CFD simulation in data center. The Turbulence model is believed to be a possible factor to improve the CFD results. The most suitable turbulence model will be identified based on a balance in both accuracy and computing resource requirements. Four turbulence models were investigated in this paper. The present investigation suggested that A&S 1-equation model yield the best accuracy and required the least computational time. Hence, 1-eqaution model should be the preferable turbulence model for CFD simulation in data center in the future.

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