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

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.

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

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.

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

Energies ◽  
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.

Fast and Accurate Evaluation of Cooling in Data Centers

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Harshad Bhagwat ◽  
Umesh Singh ◽  
Anirudh Deodhar ◽  
Amarendra Singh ◽  
Anand Sivasubramaniam
Keyword(s):  
Data Center ◽  
Data Centers ◽  
Cfd Simulation ◽  
Computation Time ◽  
Production Data ◽  
Real Time Control ◽  
Cfd Simulations ◽  
Accurate Evaluation ◽  
Time Control ◽  
Data Center Cooling

Cooling is a major component in the enormous energy consumption in data centers. Accurate evaluation of cooling inside a data center forms the backbone of all the attempts for improving cooling efficiency. Models based on computational fluid dynamics (CFD) are typically used for accurate evaluation, but have a drawback of high computation time. This paper presents a novel thermal predictor to evaluate data center cooling in seconds. The key idea is to extract information from a single instance of CFD simulation using metrics called as influence indices to build the fast thermal predictor. Then, this predictor can evaluate the cooling for altered operation of data center with comparable accuracy in seconds without the need for repetitive CFD simulations. This paper demonstrates the accuracy of the thermal predictor by comparing with CFD simulations for a sample, but realistic data center. The fast thermal predictor then successfully passed more challenging tests in a real production data center and proved its practical utility. The results of the thermal predictor compared with measurements carried out in the production data center are also presented. This fast thermal predictor is an important milestone in the development of a method for model-based real time control of data center cooling.

Inviscid and Viscous Numerical Models Compared to Experimental Data in a Small Data Center Test Cell

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Ethan Cruz ◽  
Yogendra Joshi
Keyword(s):  
Experimental Data ◽  
Data Center ◽  
Data Centers ◽  
Numerical Models ◽  
Computational Effort ◽  
Grid Size ◽  
Test Cell ◽  
Small Data ◽  
Air Cooling ◽  
Measured Temperature

Both localized power densities and overall power consumption within the data center continue to rise, following the same upward trend as the information technology (IT) equipment stored within the data center. Air cooling this increasing power has proved a significant challenge at both the IT equipment and data center level. In order to combat this challenge, computational fluid dynamics and heat transfer (CFD/HT) models have been employed as the dominant technique for the design and optimization of both new and existing data centers. This study is a continuation of earlier comparisons of CFD/HT models to experimentally measured temperature and flow fields in a small data center test cell. It compares an inviscid model, a laminar flow model, and three turbulence models to six sets of experimentally collected data. The six sets of data are from two different IT equipment rack power dissipations using three different layouts of perforated tiles. Insight into the location of the deviation between the different CFD/HT models and experimental data are discussed, along with the computational effort involved in running the models. A new grid analysis was performed on the different CFD/HT models in order to try to minimize computational effort. The inviscid model was able to run with a smaller grid size than the viscous models and even for the same size grid was found to run 30% faster than the fastest viscous model. Due to both the reduced grid size and computational effort (due to the simpler equation set), the inviscid model ran over thirty times faster than the next fastest model. The fact that the inviscid model ran the fastest is not surprising, however what was not expected is that the inviscid model was also found to have the smallest deviations from the experimental data for all six of the cases. This is most likely due to the arrangement of the data center test cell with the relatively few high velocity air jets and large open space around the IT equipment. More tightly packed data centers with higher air velocities and turbulent mixing conditions will certainly produce different results than those found in this study.

Simulation Model of the Dynamic Behavior of a Tire Running Over an Obstacle

1988 ◽  
Vol 16 (2) ◽  
pp. 62-77 ◽  
Author(s):  
P. Bandel ◽  
C. Monguzzi
Keyword(s):  
Simulation Model ◽  
Dynamic Behavior ◽  
Black Box ◽  
Box Model ◽  
Vehicle Suspension ◽  
Empirical Relationships ◽  
Static Tests ◽  
High Speeds ◽  
Dynamic Forces ◽  
Vehicle Suspension System

Abstract A “black box” model is described for simulating the dynamic forces transmitted to the vehicle hub by a tire running over an obstacle at high speeds. The tire is reduced to a damped one-degree-of-freedom oscillating system. The five parameters required can be obtained from a test at a given speed. The model input is composed of a series of empirical relationships between the obstacle dimensions and the displacement of the oscillating system. These relationships can be derived from a small number of static tests or by means of static models of the tire itself. The model can constitute the first part of a broader model for description of the tire and vehicle suspension system, as well as indicating the influence of tire parameters on dynamic behavior at low and medium frequencies (0–150 Hz).

Data Center Equipment Reliability Concerns—Contamination Issues, Standards Actions, and Case Studies

2013 ◽  
Author(s):  
Chris Muller ◽  
Chuck Arent ◽  
Henry Yu
Keyword(s):  
Case Studies ◽  
Data Center ◽  
Data Centers ◽  
Electronic Equipment ◽  
Circuit Board ◽  
Lead Free ◽  
Reliable Operation ◽  
Contamination Assessment ◽  
Equipment Reliability ◽  
Equipment Failures

Abstract Lead-free manufacturing regulations, reduction in circuit board feature sizes and the miniaturization of components to improve hardware performance have combined to make data center IT equipment more prone to attack by corrosive contaminants. Manufacturers are under pressure to control contamination in the data center environment and maintaining acceptable limits is now critical to the continued reliable operation of datacom and IT equipment. This paper will discuss ongoing reliability issues with electronic equipment in data centers and will present updates on ongoing contamination concerns, standards activities, and case studies from several different locations illustrating the successful application of contamination assessment, control, and monitoring programs to eliminate electronic equipment failures.

scholarly journals MFPP: Morphological Fragmental Perturbation Pyramid for Black-Box Model Explanations

2021 ◽  
Author(s):  
Qing Yang ◽  
Xia Zhu ◽  
Jong-Kae Fwu ◽  
Yun Ye ◽  
Ganmei You ◽  
...  
Keyword(s):  
Black Box ◽  
Box Model

scholarly journals Synchronous Machine Winding Modeling Method Based on Broadband Characteristics

2021 ◽  
Vol 11 (10) ◽  
pp. 4631
Author(s):  
Yu Chen ◽  
Xiaoqing Ji ◽  
Zhongyong Zhao
Keyword(s):  
Equivalent Circuit ◽  
High Frequency ◽  
Equivalent Circuit Model ◽  
Black Box ◽  
Synchronous Machine ◽  
Circuit Model ◽  
Modeling Method ◽  
Experimental Results ◽  
Box Model ◽  
Impedance Curve

The accurate establishment of the equivalent circuit model of the synchronous machine windings’ broadband characteristics is the basis for the study of high-frequency machine problems, such as winding fault diagnosis and electromagnetic interference prediction. Therefore, this paper proposes a modeling method for synchronous machine winding based on broadband characteristics. Firstly, the single-phase high-frequency lumped parameter circuit model of synchronous machine winding is introduced, then the broadband characteristics of the port are analyzed by using the state space model, and then the equivalent circuit parameters are identified by using an optimization algorithm combined with the measured broadband impedance characteristics of port. Finally, experimental verification and comparison experiments are carried out on a 5-kW synchronous machine. The experimental results show that the proposed modeling method identifies the impedance curve of the circuit parameters with a high degree of agreement with the measured impedance curve, which indicates that the modeling method is feasible. In addition, the comparative experimental results show that, compared with the engineering exploratory calculation method, the proposed parameter identification method has stronger adaptability to the measured data and a certain robustness. Compared with the black box model, the parameters of the proposed model have a certain physical meaning, and the agreement with the actual impedance characteristic curve is higher than that of the black box model.

scholarly journals Is This a Geolibrary? A Case of the Idaho Geospatial Data Center

2017 ◽  
Vol 19 (1) ◽  
pp. 4-10 ◽  
Author(s):  
Maria Anna Jankowska ◽  
Piotr Jankowski
Keyword(s):  
Digital Library ◽  
Future Development ◽  
Data Center ◽  
Data Centers ◽  
Public Domain ◽  
The State ◽  
Geospatial Data ◽  
Design And Implementation ◽  
Geographic Data

The article presents the Idaho Geospatial Data Center (IGDC), a digital library of public-domain geographic data for the state of Idaho. The design and implementation of IGDC are introduced as part of the larger context of a geolibrary model. The article presents methodology and tools used to build IGDC with the focus on a geolibrary map browser. The use of IGDC is evaluated from the perspective of accessa and demand for geographic data. Finally, the article offers recommendations for future development of geospatial data centers.

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