Impact of Cold Aisle Containment on Thermal Performance of Data Center

2013 ◽  
Author(s):  
Bharathkrishnan Muralidharan ◽  
Saurabh K. Shrivastava ◽  
Mahmoud Ibrahim ◽  
Sami A. Alkharabsheh ◽  
Bahgat G. Sammakia
Keyword(s):  
Data Center ◽  
Heat Load ◽  
Energy Savings ◽  
Air Conditioner ◽  
Cold Air ◽  
Hot Air ◽  
Air Temperatures ◽  
Set Up ◽  
Cold Aisle Containment

The use of air containment systems has been a growing trend in the data center industry and is an important energy saving strategy for data center optimization. Cold Aisle Containment (CAC) is one of the most effective passive cooling solutions for high density heat load applications. Cold Aisle Containment provides a physical separation between the cold air and the hot exhaust air by enclosing the cold aisle, preventing hot air recirculation and cold air bypass. This separation provides uniform inlet air temperatures to the servers, which can further contribute to overall data center efficiency. This paper includes the thermal test data for a data center lab with and without a CAC set up. The paper quantifies the thermal impact of implementing a CAC system over an open Hot Aisle/Cold Aisle (HA/CA) arrangement for three different cabinet heat load conditions at two different CRAC (Computer Room Air Conditioner) return air set point conditions. It studies the advantages of CAC over standard HA/CA arrangement. A case study has been presented showing a cooling energy savings of 22% with the use of a CAC system over a standard HA/CA arrangement.

Energy Savings Through Hot and Cold Aisle Containment Configurations for Air Cooled Servers in Data Centers

2011 ◽  
Author(s):  
Roger Schmidt ◽  
Aparna Vallury ◽  
Madhusudan Iyengar
Keyword(s):  
Energy Efficiency ◽  
Data Center ◽  
Air Conditioning ◽  
Data Centers ◽  
Energy Savings ◽  
Green Technologies ◽  
Advantages And Disadvantages ◽  
Hot Air ◽  
Type Data ◽  
Cold Aisle Containment

The increased focus on green technologies and energy efficiency coupled with the insatiable desire of IT equipment customers for more performance has driven manufacturers to deploy energy efficient technologies in the data centers. This paper describes a technique to achieve significant energy savings by preventing the cold and hot air streams within the data center from mixing. More specifically, techniques will be described that will separate the cool supply air to the server racks and exhaust hot air that returns to the air conditioning units. This separation can be achieved by three types of containment systems — cold aisle containment, hot aisle containment, and server rack exhaust chimneys. The advantages and disadvantages of each technique will be outlined. To show the potential for energy efficiency improvements a case study in deploying a cold aisle containment solution for a 8944 ft2 data center will be presented. This study will show that 59% of the energy required for the computer room air conditioning (CRAC) units used in a traditional open type data center could be saved.

A Numerical Study for Contained Cold Aisle Data Center Using CRAC and Server Calibrated Fan Curves

2013 ◽  
Author(s):  
Sami A. Alkharabsheh ◽  
Bahgat G. Sammakia ◽  
Saurabh Shrivastava ◽  
Roger Schmidt
Keyword(s):  
Temperature Distribution ◽  
Data Center ◽  
Numerical Study ◽  
Air Conditioner ◽  
Cold Air ◽  
Failure Scenario ◽  
The Individual ◽  
Cold Aisle Containment ◽  
Pressure Changes ◽  
The Impact

In the present work, we demonstrate the effect of Cold Aisle Containment Systems (CACS) on the airflow and temperature distribution inside a representative data center. Computational Fluid Dynamics (CFD) is used to conduct this analysis. This study includes calibrated fan curves in the Computer Room Air Conditioner (CRAC) and the servers in order to capture the impact of pressure changes on the flow field. The system characteristics curve for the open (uncontained) system and contained system including the leakage effect is established. Since the IT-equipment has a crucial effect on the performance of contained systems, the individual and combined effect of fully enclosing the cold aisle and IT-equipment are investigated. Partially contained systems including doors only and ceilings only configurations are also considered in this study. Steady state and dynamic scenarios are simulated to characterize different containment systems. It is found that the pressure inside the fully contained system is determined by the IT-equipment as well as the geometrical obstructions of fully containing the cold aisle. Increasing the pressure due to enclosing the cold aisle is reduced by introducing IT-equipment, load banks in this case, which leads to a reduction of the total static pressure and an increase of the flow rate. It is also found that the fully contained system presents the best configurations in achieving low and uniform temperature distribution; however, partially contained systems can be a good solution if a certain cold air provision is maintained during operation. The dynamic analysis shows a significant increase in the safe time at full CRAC failure scenario compared with uncontained system due to utilizing the trapped cold air inside the plenum by the load banks fans.

Energy Conservation Measures of a Primary Data Center on an Academic Campus

2013 ◽  
Author(s):  
Kyosung Choo ◽  
Renan Manozzo Galante ◽  
Michael Ohadi
Keyword(s):  
Energy Conservation ◽  
Data Center ◽  
Power Saving ◽  
Primary Data ◽  
University Of Maryland ◽  
Conservation Measures ◽  
Air Temperatures ◽  
Cold Aisle Containment ◽  
The University ◽  
Energy Conservation Measures

Energy Conservation Measures (ECMs) of the primary data center at the University of Maryland are developed. Measurement and simulation are performed to validate the developed ECMs. Three ECMs — 1) Increase in the return temperature at Computer Room Air Conditionings (CRACs) 2) Cold aisle containment 3) Elimination of unnecessary CRACs — are suggested to reduce energy consumption by optimizing the thermo-fluid flow in the data center. Power savings of 12.7 kW – 17.4 kW and 14.1 kW are obtained by increasing the return air temperatures at the CRACs and performing the cold aisle containment, respectively. In addition, a power saving of 11.2 kW is obtained by turning off CRACs 3 and 8 which have an adverse effect on the data center cooling.

Raised Floor Hybrid Cooled Data Center: Effect on Rack Inlet Air Temperatures When In Row Cooling Units are Installed Between the Racks

2015 ◽  
Author(s):  
Tianyi Gao ◽  
James Geer ◽  
Russell Tipton ◽  
Bruce Murray ◽  
Bahgat G. Sammakia ◽  
...  
Keyword(s):  
Flow Rate ◽  
Data Center ◽  
Heat Load ◽  
Data Centers ◽  
Cooling System ◽  
Air Flow ◽  
Inlet Temperature ◽  
Air Flow Rate ◽  
Air Temperatures ◽  
Cooling Unit

The heat dissipated by high performance IT equipment such as servers and switches in data centers is increasing rapidly, which makes the thermal management even more challenging. IT equipment is typically designed to operate at a rack inlet air temperature ranging between 10 °C and 35 °C. The newest published environmental standards for operating IT equipment proposed by ASHARE specify a long term recommended dry bulb IT air inlet temperature range as 18°C to 27°C. In terms of the short term specification, the largest allowable inlet temperature range to operate at is between 5°C and 45°C. Failure in maintaining these specifications will lead to significantly detrimental impacts to the performance and reliability of these electronic devices. Thus, understanding the cooling system is of paramount importance for the design and operation of data centers. In this paper, a hybrid cooling system is numerically modeled and investigated. The numerical modeling is conducted using a commercial computational fluid dynamics (CFD) code. The hybrid cooling strategy is specified by mounting the in row cooling units between the server racks to assist the raised floor air cooling. The effect of several input variables, including rack heat load and heat density, rack air flow rate, in row cooling unit operating cooling fluid flow rate and temperature, in row coil effectiveness, centralized cooling unit supply air flow rate, non-uniformity in rack heat load, and raised floor height are studied parametrically. Their detailed effects on the rack inlet air temperatures and the in row cooler performance are presented. The modeling results and corresponding analyses are used to develop general installation and operation guidance for the in row cooler strategy of a data center.

Analytical Modeling of Energy Consumption and Thermal Performance of Data Center Cooling Systems: From the Chip to the Environment

2007 ◽  
Author(s):  
Madhusudan Iyengar ◽  
Roger R. Schmidt
Keyword(s):  
Energy Consumption ◽  
Data Center ◽  
Energy Use ◽  
It Industry ◽  
Cooling Systems ◽  
Air Temperatures ◽  
Data Center Cooling ◽  
Total Data ◽  
Heat Transfer Phenomenon

The increasingly ubiquitous nature of computer and internet usage in our society, has driven advances in semiconductor technology, server packaging, and cluster level optimizations, in the IT industry. Not surprisingly this has an impact on our societal infrastructure with respect to providing the requisite energy to fuel these power hungry machines. Cooling has been found to contribute to about a third of the total data center energy consumption, and is the focus of this study. In this paper we develop and present physics based models to allow the prediction of the energy consumption and heat transfer phenomenon in a data center. These models allow the estimation of the microprocessor junction and server inlet air temperatures for different flow and temperature conditions at various parts of the data center cooling infrastructure. For a case study example considered, the chiller energy use was the biggest fraction of about 41% and also the most inefficient. The room air conditioning was the second largest energy component and also the second most inefficient. A sensitivity analysis of plant and chiller energy efficiency with chiller set point temperature and outdoor air conditions is also presented.

Exergy-Based Optimization Strategies for Multi-Component Data Center Thermal Management: Part II — Application and Validation

2005 ◽  
Author(s):  
Amip J. Shah ◽  
Van P. Carey ◽  
Cullen E. Bash ◽  
Chandrakant D. Patel
Keyword(s):  
Recent Work ◽  
Thermal Management ◽  
Data Center ◽  
Heat Load ◽  
Air Conditioning ◽  
Individual Data ◽  
Flow Measurements ◽  
Experimental Heat ◽  
Center Configuration

Recent work has proposed an exergy-based strategy to achieve optimal system-wide performance via localized control of individual data center thermal management components. This paper presents the results of a case study where the proposed approach is applied to a data center with two rows of computing racks and two Computer Room Air-Conditioning (CRAC) units. The formulated model is used to predict the optimal data center configuration in terms of supply temperatures, flowrates, and rack heat load configurations. Two extreme cases are chosen: one with the maximum experimental heat load in the data center, and one with a minimal experimental heat load. For each case, the optimal settings for each CRAC unit were predicted using the model and using temperature + flow measurements in the data center. The setpoints predicted by the model for optimal CRAC flow and supply temperature were within 25% of the experimentally determined optima.

Refrigeration Heat Exchanger Systems for Server Rack Cooling in Data Centers

2009 ◽  
Author(s):  
Takeshi Tsukamoto ◽  
Jyunji Takayoshi ◽  
Roger R. Schmidt ◽  
Madhusudan K. Iyengar
Keyword(s):  
Heat Exchanger ◽  
Data Center ◽  
Heat Exchangers ◽  
Energy Savings ◽  
Vapor Compression ◽  
Data Center Cooling ◽  
Thermal Data ◽  
Coolant Loop ◽  
Vapor Compression System

In 2005, IBM released a water cooled heat exchanger product that significantly enhanced data center cooling capability while also demonstrating substantial energy savings. In 2008, IBM released an enhanced water less solution to cool the electronic racks via a R410A refrigerant based vapor compression system, which is the focus of this paper. The paper provides a detailed description of device and coolant loop construction, the experimental thermal data collected, as well as a discussion of its’ cooling energy efficiency relative to both typical air cooled facilities and water cooled heat exchangers, respectively. A data center level case study was performed with experimental measurements collected and discussed herein. Significant energy savings were realized even when the heat exchanger devices were implemented on a small part of the data center. Based on the test data and the experimental data center study, the CRAC units based loops have a COP of 1.95, while the refrigerant refrigerant heat exchanger loop has a COP of 5.0.

Maintaining Datacom Rack Inlet Air Temperatures With Water Cooled Heat Exchanger

2005 ◽  
Author(s):  
Roger Schmidt ◽  
Richard C. Chu ◽  
Mike Ellsworth ◽  
Madhu Iyengar ◽  
Don Porter ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Data Center ◽  
Air Flow ◽  
Small Region ◽  
Electronic Equipment ◽  
Hot Air ◽  
Air Temperatures ◽  
Wide Range ◽  
Air Intake ◽  
Proper Operation

The heat dissipated by electronic equipment continues to increase at a alarming rate. This has occurred for products covering a wide range of applications. Manufacturers of this equipment require that the equipment be maintained within an environmental envelope in order to guarantee proper operation. Achievement of these environmental conditions are becoming increasingly difficult given the increases in rack heat loads and the desire for customers of such equipment to cluster racks in a small region for increased performance. And with the increased heat load of the racks and correspondingly increased air flowrate the chilled air flow supplied either through data center raised floor perforated tiles or diffusers for non raised floors is not sufficient to match the air flow required by the datacom racks. In this case some of the hot air exhausting the rear of a rack can return to the front of the rack and be ingested into the air intake thereby reducing the reliability of the electronic equipment. This paper describes a method to reduce the effect of the hot air recirculation with a water cooled heat exchanger attached to the rear door of the rack. This heat exchanger removes a large portion of the heat from the rack as well as significantly lowering the air temperature exhausting the rear of the rack. This paper describes the hardware and presents the test results showing that a large portion of the heat is removed from the rack and the temperature exhausting the rear of the rack is significantly reduced. Finally the effectiveness of the solution is shown in modeling of this water cooled solution in a data center application.

Performance of Temperature Controlled Perimeter and Row-Based Cooling Systems in Open and Containment Environment

2015 ◽  
Author(s):  
Kourosh Nemati ◽  
Husam Alissa ◽  
Bahgat Sammakia
Keyword(s):  
Data Center ◽  
Heat Load ◽  
Flow Behavior ◽  
Air Flow ◽  
High Density ◽  
Computational Time ◽  
Air Cooling ◽  
Cooling Systems ◽  
Continuous Increase ◽  
Cold Aisle Containment

The continuous increase of data center usage is leading the industry to increase the load density per square foot of existing facilities. High density (HD) IT load per rack demands bringing the cooling source closer to the heat load in contrast to room level air cooling. For high density racks, the use of in-row cooling systems is becoming increasingly popular. In-row cooling can be the main source of cooling for a data center or work jointly with perimeter cooling in what is called a hybrid cooled room level system. Also, hot or cold aisle containment can be integrated with perimeter cooling and used throughout the data center to reduce the mixing of hot and cold air. Currently, there has not been much work comparing the performance of in-row cooling in open versus contained environments. The present work builds on a previous study where the interaction of perimeter and row-based cooling was evaluated for a cold-aisle containment (CAC) environment. Previously, the benefit of using row-based cooled in an aisle has not been compared with an aisle in open conditions. Here, we numerically investigate the performance of in-row coolers in both opened and cold-aisle contained environments. Groups of IT equipment that differ in air flow strength are used to provide the heat load. Empirically measured flow curves for common IT equipment are employed to provide simplified models of the IT equipment in the CFD software used. The steady state analysis includes information provided in the manufacturer’s specifications such as heat exchanger performance characteristics. The model was validated using a new data center laboratory with perimeter cooling. A single aisle of the data center is modeled to reduce the computational time, and the results are generalized. The cold aisle contains 16 racks of IT equipment distributed on both sides. In addition, the aisle contains 2 power distribution units. Full details are incorporated in the computational model. A single Liebert® CW114 CRAC unit provides the perimeter cooling in the data center. The model captures the particular air flow behavior in the cold aisle when row-based cooling is utilized. Correlations are derived to predict the ability of air cooling units to maintain set points at different air flow rates. The effect of leakage is also considered.

Ranking and Optimization of CAC and HAC Leakage Using Pressure Controlled Models

2015 ◽  
Author(s):  
Husam A. Alissa ◽  
Kourosh Nemati ◽  
Bahgat Sammakia ◽  
Kanad Ghose ◽  
Mark Seymour ◽  
...  
Keyword(s):  
Data Center ◽  
Management Practices ◽  
Real Life ◽  
Pressure Differential ◽  
Hot Air ◽  
Containment Model ◽  
Cooling Unit ◽  
Unit Model ◽  
Cold Aisle Containment ◽  
Different Characteristics

In cold aisle containment (CAC) the supply of cold air is separated within the contained volume. The hot air exhaust leaves the IT and increases the room’s temperature before returning to the cooling unit. On the other hand, hot aisle containment (HAC) generates a cooler environment in the data center room as a whole by segregating hot air within the containment. Hot air is routed back to the cooling unit return by a drop ceiling or a chimney. Each system has different characteristics and airflow paths. For instance, leakage introduces different effects for CACs and HACs since the hot and cold aisles are switched. This article utilizes data center measurements and containment characterization carried out circa April 2015 in the ES2 Data Center lab at Binghamton University. Details on the containment model include leakages at below racks, above racks, below CAC doors, between doors, and above doors. The model deploys the experimentally obtained flow curves approach for flow-pressure correlation. Data center operators rely on the pressure differential to measure how much the IT is provided. Hence, in this study the level of provisioning was expressed in terms of pressure differentials between the hot and cold aisles. In this manner the model reflected real-life DC thermal management practices. This was done by integrating a pressure differential based controller to the cooling unit model. Leakages in each system are quantified and ranked based on a proposed LIF (Leakage Impact Factor) metric. The LIF describes the transport contribution each leakage location has. This metric can be used by containment designers and data center operators to prioritize their sealing efforts or consider deploying the containment solution differently. Finally, a systematic approach is shown in which containment models can be used to optimize operations at the real-life site.

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