Optimization on jet‐induced ventilation to enhance the uniformity of airflow distribution in data center

Typical data center architectures utilize a raised floor; cooling airflow is pumped into an under-floor plenum and exits through perforated floor tiles located in front of IT equipment racks. The under-floor space is also a convenient place to locate critical building infrastructure, such as chilled-water piping and power and network cabling. Unfortunately, the presence of such objects can disrupt the distribution of cooling airflow. While the effects of other design parameters, such as room layout, plenum depth, perforated tile type, and leakage paths, have been systematically studied — and corresponding best-practices outlined, there is no specific advice in the literature with regard to the effect of under-floor infrastructure on airflow distribution. This paper studies the effects of such obstructions primarily through CFD analyses of several layouts based on actual facilities. Additionally, corresponding scenarios are analyzed using a Potential Flow Model (PFM), which includes a recently-proposed obstruction-modeling technique. It is found that under-floor obstructions significantly affect airflow distribution only when they are located very near perforated tiles and cooling units and occupy a substantial fraction of the total plenum depth.

Download Full-text

Analysis of Airflow Distribution Across a Front-to-Rear Server Rack

ASME 2007 InterPACK Conference, Volume 1 ◽

10.1115/ipack2007-33574 ◽

2007 ◽

Cited By ~ 9

Author(s):

Amir Radmehr ◽

Kailash C. Karki ◽

Suhas V. Patankar

Keyword(s):

Boundary Conditions ◽

Data Center ◽

High Velocity ◽

Critical Conditions ◽

Airflow Distribution ◽

Symmetrical Configuration ◽

Computational Fluid Dynamics Cfd ◽

Potential Failure ◽

Cooling Air ◽

Vertical Jet

The most common server racks in data centers are front-to-rear racks, which draw in the cooling air from the front side and discharge it from the backside. In a raised-floor data center the cooling air to these racks is provided by perforated tiles that are placed in front of them. In a high-density data center, these tiles discharge a considerable amount of airflow, which leads to a high-velocity vertical jet in front of the rack. Such a high-velocity jet may bypass the servers located at the bottom of the rack leading to their airflow starvation and potential failure. In this paper the effect of the high-velocity jet on the airflow taken by servers at various heights in the rack is studied. A computer model based on the Computational Fluid Dynamics (CFD) technique is used to predict the airflow distribution through servers stacked in the rack. Two cases are considered. In one case, the rack is placed in the middle of a row of racks in a prefect hot aisle-cold aisle arrangement. The boundary conditions around such a rack is symmetrical. In the other case, the rack is placed in a room with asymmetrical boundary conditions. The characteristics of the servers in the rack are taken from typical 1U and 2U servers manufactured by IBM. It is shown that in general the high-velocity jet has a mild effect on the airflow taken by the servers, and the airflow reduction is limited to servers at the bottom of the rack. Racks in a symmetrical configuration are more susceptible to the airflow starvation. In the most critical conditions, an airflow reduction of 15% is calculated for the server located at the bottom of the rack. Using the result obtained from the computational analysis, a simple model is developed to predict the reduction of the cooling air under the most critical situation for the server placed at the bottom of the rack.

Download Full-text

Improvements of Airflow Distribution in a Container Data Center

Energy Procedia ◽

10.1016/j.egypro.2015.07.153 ◽

2015 ◽

Vol 75 ◽

pp. 1819-1824 ◽

Cited By ~ 20

Author(s):

I-Nuo Wang ◽

Yeng-Yung Tsui ◽

Chi-Chuan Wang

Keyword(s):

Data Center ◽

Airflow Distribution

Download Full-text

Airflow and Cooling in a Data Center

Journal of Heat Transfer ◽

10.1115/1.4000703 ◽

2010 ◽

Vol 132 (7) ◽

Cited By ~ 111

Author(s):

Suhas V. Patankar

Keyword(s):

Fluid Dynamics ◽

Data Center ◽

Cfd Simulations ◽

Flow Rates ◽

Factors Affecting ◽

Hot Air ◽

Airflow Distribution ◽

Computational Fluid Dynamics Cfd ◽

Cooling Air ◽

Insight Into

This paper deals with the distribution of airflow and the resulting cooling in a data center. First, the cooling challenge is described and the concept of a raised-floor data center is introduced. In this arrangement, cooling air is supplied through perforated tiles. The flow rates of the cooling air must meet the cooling requirements of the computer servers placed next to the tiles. These airflow rates are governed primarily by the pressure distribution under the raised floor. Thus, the key to modifying the flow rates is to influence the flow field in the under-floor plenum. Computational fluid dynamics (CFD) is used to provide insight into various factors affecting the airflow distribution and the corresponding cooling. A number of ways of controlling the airflow distribution are explored. Then attention is turned to the above-floor space, where the focus is on preventing the hot air from entering the inlets of computer serves. Different strategies for doing this are considered. The paper includes a number of comparisons of measurements with the results of CFD simulations.

Download Full-text

Comparison Between Numerical and Experimental Results of Airflow Distribution in Diffuser Based Data Center

Journal of Electronic Packaging ◽

10.1115/1.4005912 ◽

2012 ◽

Vol 134 (1) ◽

Cited By ~ 6

Author(s):

Qifei Jian ◽

Qiaoli Wang ◽

Haoting Wang ◽

Zheng Zuo

Keyword(s):

Data Center ◽

Distribution Systems ◽

Volume Flow Rate ◽

Mathematic Model ◽

Experimental Results ◽

Air Distribution ◽

Test Results ◽

Airflow Distribution ◽

Computational Fluid Dynamics Cfd

This paper studies the flow and temperature patterns in an overhead diffuser based data center. In-situ measurements of the data center were carried out to validate a mathematic model for predicting the effect of different air distribution systems. With the measured data of temperatures and airflow velocities, the mathematic model is constructed using a commercial Computational Fluid Dynamics (CFD) software and experimental data to present a comparison between test results and numerical simulations. The area of the data center is 311 square meters and the heat load of the equipment is 320~360 watt per square meter. In-situ temperatures and humidity of the data center were measured with an Automatic Temperature and Humidity measuring instrument, whose error is ±0.5 °C. The discrepancy of the temperature and velocity between the numerical and experimental results were within ±2.3 °C and ±1.8 m/s, respectively. In addition, analysis shows that changing the volume flow rate of the cold air delivered to some diffusers can optimize the temperature field and thereby save the energy.

Download Full-text

A review on airflow distribution and management in data center

Energy and Buildings ◽

10.1016/j.enbuild.2018.08.050 ◽

2018 ◽

Vol 179 ◽

pp. 264-277 ◽

Cited By ~ 18

Author(s):

Hongjie Lu ◽

Zhongbin Zhang ◽

Liu Yang

Keyword(s):

Data Center ◽

Airflow Distribution

Download Full-text

Techniques for Controlling Airflow Distribution in Raised-Floor Data Centers

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

10.1115/ipack2003-35282 ◽

2003 ◽

Cited By ~ 26

Author(s):

Kailash C. Karki ◽

Suhas V. Patankar ◽

Amir Radmehr

Keyword(s):

Mathematical Model ◽

Data Center ◽

Heat Load ◽

Data Centers ◽

Open Area ◽

Flow Rates ◽

Airflow Distribution ◽

Wide Range ◽

Optimum Utilization ◽

Load Pattern

In raised-floor data centers, the airflow rates through the perforated tiles must meet the cooling requirements of the computer servers placed next to the tiles. The data centers house a wide range of equipment, and the heat load pattern on the floor can be quite arbitrary and changes as the data center evolves. To achieve optimum utilization of the floor space and the flexibility for rearrangement and retrofitting, the designers and managers of data centers must be able to modify the airflow rates through the perforated tiles. The airflow rates through the perforated tiles are governed primarily by the pressure distribution under the raised floor. Thus, the key to modifying the flow rates is to influence the flow field in the plenum. This paper discusses a number of techniques that can be used for controlling airflow distribution. These techniques involve changing the plenum height and open area of perforated tiles, and installing thin (solid and perforated) partitions in the plenum. A number of case studies, using a mathematical model, are presented to demonstrate the effectiveness of these techniques.

Download Full-text

Local Cooling Control of Data Centers With Adaptive Vent Tiles

ASME 2009 InterPACK Conference, Volume 2 ◽

10.1115/interpack2009-89035 ◽

2009 ◽

Cited By ~ 7

Author(s):

Monem H. Beitelmal ◽

Zhikui Wang ◽

Carlos Felix ◽

Cullen Bash ◽

Christopher Hoover ◽

...

Keyword(s):

Data Center ◽

Data Centers ◽

Dynamic Models ◽

Algorithm Design ◽

Local Cooling ◽

Fine Grained ◽

Airflow Distribution ◽

Equipment Configuration ◽

Tile Flow ◽

Configuration Changes

Local airflow distribution in data center environments has historically been accomplished through ventilation tiles distributed over a raised floor air distribution plenum. The tiles are initially configured upon the commissioning of the facility and, as IT equipment configuration changes with time, the tiles are adjusted accordingly. However, tile adjustment is a manual process that is error-prone and often non-intuitive. Tile flow rates are a strong function of under floor plenum pressure distribution which is subject to change as tile layouts are reconfigured. Thermal models are often developed to assist with layout changes, but these models can be time-consuming to generate and require skilled users to achieve accurate results. This paper presents an adaptive vent tile (AVT) for use in raised floor data centers that can adapt to the needs of nearby IT equipment. We present a multi-input-multi-output (MIMO) AVT controller that automatically and dynamically adjusts a multiplicity of AVT openings in coordination such that thermal management requirements are met with minimum use of airflow. We describe the development of dynamic models and algorithm design of the MIMO controller. The controller was evaluated with a set of AVT units in a production data center environment. Results show that the controller can optimize local airflow distribution, provide fine-grained rack intake temperature control and respond to disturbances in a manner that is not achievable through static distribution of tiles.

Download Full-text

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.

Download Full-text

A Study of Air Flow through Perforated Tile for Air Conditioning System in Data Center

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.249-250.126 ◽

2012 ◽

Vol 249-250 ◽

pp. 126-131 ◽

Cited By ~ 2

Author(s):

Jetsadaporn Priyadumkol ◽

Chawalit Kittichaikarn

Keyword(s):

Data Center ◽

Air Conditioning ◽

Heat Dissipation ◽

Cooling System ◽

Air Flow ◽

Heat Index ◽

Energy Usage ◽

Air Conditioning System ◽

Airflow Distribution ◽

Air Flow Velocity

The power trend of using server systems in data center is continuously increasing. Cooling system consumed 38% of total energy usage which is a significant contribution in the energy consumption. As a result, the efficient energy usage in data center is concerned.Normally a raised-floor is widely used in data center cooling system which delivers cool air through perforated tiles to a front of server racks. However it is usually found that this cool air cannot effectively remove a heat dissipation at the top of server racks. Therefore, the environmental condition in data center must be designed strictly to avoid disruption that caused by overheat.This paper gives some guidelines to help in the better design. Commercial Computational Fluid Dynamics (CFD) program was used to analyze the air flow from raised-floor air conditioning system. A tetrahedral of 1.8 million meshes with k- turbulence model were used to obtain the air flow velocity and temperature distributions in the room. The model was validated by comparing simulation results with actual measurements. As a result, dimensionless parameters in the form of supply heat index(SHI), for understanding the optimization of relative airflow distribution to the heat load of server rack was found. It shows that these parameters provide an effective tool to the improvement of energy efficiency in raised floor data center.

Download Full-text