scholarly journals Comprehensive Experimental and Computational Analysis of a Fully Contained Hybrid Server Cabinet

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Kourosh Nemati ◽  
Husam A. Alissa ◽  
Bruce T. Murray ◽  
Bahgat G. Sammakia ◽  
Russell Tipton ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Data Centers ◽  
Heat Dissipation ◽  
Cooling System ◽  
Thermal Characterization ◽  
Temperature Limit ◽  
Research Area ◽  
Air Cooling ◽  
Steady State Mode ◽  
Compact Models

The rapid growth in the number of data centers combined with the high-density heat dissipation of computer and telecommunications equipment has made energy efficient thermal management of data centers a key research area. Localized hybrid air–water cooling is one approach to more effectively control the cooling when there is wide variation in the amount of dissipation in neighboring racks while the traditional air cooling approach requires overprovisioning. In a closed, hybrid air–water cooled server cabinet, the generated heat is removed by a self-contained system that does not interact with the room level air cooling system. Here, a hybrid-cooled enclosed cabinet and all its internal components were characterized experimentally in steady-state mode (e.g., experimentally determined heat-exchanger effectiveness and IT characterization). Also, a comprehensive numerical model of the cabinet was developed and validated using the experimental data. The computational model employs full numerical modeling of the cabinet geometry and compact models to represent the servers and the air/water heat exchanger. The compact models were developed based on experimental flow and thermal characterization of the internal components. The cabinet level model has been used to simulate a number of operating scenarios relevant to data center applications such as the effect of air leakage within the cabinet. The effect of the air side and the water side failure of the cooling system on the IT performance were investigated experimentally. A comparison was made of the amount of time required to exceed the operating temperature limit for the two scenarios.

New Thermal Management Systems for Data Centers

2012 ◽  
Vol 4 (3) ◽  
Author(s):  
Mayumi Ouchi ◽  
Yoshiyuki Abe ◽  
Masato Fukagaya ◽  
Takashi Kitagawa ◽  
Haruhiko Ohta ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Single Phase ◽  
Data Centers ◽  
Cooling System ◽  
Heat Pipes ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Two Phase ◽  
Cooling Jacket ◽  
Cooling Methods

Energy consumption in data centers has seen a drastic increase in recent years. In data centers, server racks are cooled down in an indirect way by air-conditioning systems installed to cool the entire server room. This air cooling method is inefficient as information technology (IT) equipment is insufficiently cooled down, whereas the room is overcooled. The development of countermeasures for heat generated by IT equipment is one of the urgent tasks to be accomplished. We, therefore, proposed new liquid cooling systems in which IT equipment is cooled down directly and exhaust heat is not radiated into the server room. Three cooling methods have been developed simultaneously. Two of them involve direct cooling; a cooling jacket is directly attached to the heat source (or CPU in this case) and a single-phase heat exchanger or a two-phase heat exchanger is used as the cooling jacket. The other method involves indirect cooling; heat generated by CPU is transported to the outside of the chassis through flat heat pipes and the condensation sections of the heat pipes are cooled down by coolant with liquid manifold. Verification tests have been conducted by using commercial server racks to which these cooling methods are applied while investigating five R&D components that constitute our liquid cooling systems: the single-phase heat exchanger, the two-phase heat exchanger, high performance flat heat pipes, nanofluid technology, and the plug-in connector. As a result, a 44–53% reduction in energy consumption of cooling facilities with the single-phase cooling system and a 42–50% reduction with the flat heat pipe cooling system were realized compared with conventional air cooling system.

Experimentally Validated Numerical Model of a Fully-Enclosed Hybrid Cooled Server Cabinet

2015 ◽  
Author(s):  
Kourosh Nemati ◽  
Husam A. Alissa ◽  
Bruce T. Murray ◽  
Bahgat Sammakia ◽  
Mark Seymour
Keyword(s):  
Data Centers ◽  
Heat Dissipation ◽  
Cooling System ◽  
Air Flow ◽  
Sensitivity Study ◽  
Average Error ◽  
Air Cooling ◽  
Cfd Validation ◽  
Air Cooling System ◽  
Good Agreement

Because of the rapid growth in the number of data centers combined with the high density heat dissipation in the IT and telecommunications equipment, energy efficient thermal management of data centers has become a key research focus in the electronics packaging community. Traditional legacy data centers still rely largely on chilled air flow delivered to the IT equipment racks through perforated tiles from the raised floor plenum. When there is large variation in the amount of heat dissipated by the racks in a given aisle, the standard air cooling approach requires over-provisioning. Localized hybrid air-water cooling is one approach to more effectively control the cooling when there is wide variation in the amount of dissipation in neighboring racks. In a closed hybrid air-water cooled server cabinet, the generated heat is removed by a self-contained system that does not interact with the room level air cooling system. In this study, a comprehensive procedure for CFD validation in a close coupled hybrid cooled enclosed cabinet is described. The commercial enclosure has been characterized experimentally in an earlier study, where the effectiveness values were applied as boundary conditions to the compact heat exchanger model. Here, the previously obtained experimental data are used to validate the results from computational modeling. Two cases with different air flow rates are compared. Very good agreement is achieved, with the maximum overall average error less than 4%. Due to relatively high pressure inside the cabinet, it is possible that air leakage from the cabinet may be responsible for the discrepancy between the model and experimental results. A sensitivity study was applied to the validated model to investigate the effect leakage had on the cabinet’s performance.

Steady State and Transient Experimentally Validated Analysis of Hybrid Data Centers

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Tianyi Gao ◽  
Bahgat Sammakia ◽  
Emad Samadiani ◽  
Roger Schmidt
Keyword(s):  
Steady State ◽  
Heat Exchanger ◽  
Thermal Management ◽  
Information Technologies ◽  
Data Centers ◽  
Cooling System ◽  
Hybrid Approach ◽  
Air Cooling ◽  
Air Conditioner ◽  
Density Data

Data centers consume a considerable amount of energy which is estimated to be about 2% of the total electrical energy consumed in the U.S. in the year 2010, and this number continues to increase every year. Thermal management is becoming increasingly important in the effort to improve the energy efficiency and reliability of data centers. The goal is to keep the information technologies (IT) equipment temperature within the allowable range in high power density data centers while reducing the energy used for cooling. In this regard, liquid and hybrid air/water cooling systems are alternatives to traditional air cooling. In particular, these options offer advantages for localized cooling higher power racks which may not be manageable using the room level air cooling system without requiring significantly more energy. In this paper, a hybrid cooling system in data centers is investigated. In addition to traditional raised floor, cold aisle-hot aisle configuration, a liquid–air heat exchanger attached to the back of racks is considered. First of all, the paper presents a review of literature of the study of this heat exchanger strategy in the thermal management of a data center. The discussion focus on rear door heat exchanger (RDHx) performance, both the steady state and transient impact are analyzed. The studies show that under some circumstances, this hybrid approach could be a viable alternative to meet the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) recommended inlet air temperatures, while at the same time reducing the overall energy consumption in high density data centers. The hybrid design approach can also significantly improve the dynamic performance during rack power increases or computer room air conditioner (CRAC) unit failure. And then, additional parametric steady state and dynamic analyses, are presented in detail for the different scenarios.

Numerical Study to Analyze the Effects of Hot/Cold Aisle Configurations on Heat Transfer Phenomenon in a Data Center

2013 ◽  
Author(s):  
Kamran Nazir ◽  
Naveed Durrani ◽  
Imran Akhtar ◽  
M. Saif Ullah Khalid
Keyword(s):  
Heat Transfer ◽  
Data Center ◽  
Data Centers ◽  
Cooling System ◽  
Numerical Study ◽  
High Energy ◽  
Research Area ◽  
Transfer Phenomenon ◽  
Heat Transfer Phenomenon ◽  
Active Research

Due to high energy demands of data centers and the energy crisis throughout the world, efficient heat transfer in a data center is an active research area. Until now major emphasis lies upon study of air flow rate and temperature profiles for different rack configurations and tile layouts. In current work, we consider different hot aisle (HA) and cold aisle (CA) configurations to study heat transfer phenomenon inside a data center. In raised floor data centers when rows of racks are parallel to each other, in a conventional cooling system, there are equal number of hot and cold aisles for odd number of rows of racks. For even number of rows of racks, whatever configuration of hot/cold aisles is adopted, number of cold aisles is either one greater or one less than number of hot aisles i.e. two cases are possible case A: n(CA) = n(HA) + 1 and case B: n(CA) = n(HA) − 1 where n(CA), n(HA) denotes number of cold and hot aisles respectively. We perform numerical simulations for two (case1) and four (case 2) racks data center. The assumption of constant pressure below plenum reduces the problem domain to above plenum area only. In order to see which configuration provides higher heat transfer across servers, we measure heat transfer across servers on the basis of temperature differences across racks, and in order to validate them, we find mass flow rates on rack outlet. On the basis of results obtained, we conclude that for even numbered rows of rack data center, using more cold aisles than hot aisles provide higher heat transfer across servers. These results provide guidance on the design and layout of a data center.

scholarly journals Improving the performance of the air-cooling unit in the cooling system of a radar

2021 ◽  
Vol 2057 (1) ◽  
pp. 012004
Author(s):  
Yu A Borisov ◽  
V V Volkov-Muzilev ◽  
D A Kalashnikov ◽  
H S Khalife
Keyword(s):  
Heat Exchanger ◽  
Gas Flow ◽  
Cooling System ◽  
Experimental Studies ◽  
Air Cooling ◽  
Axial Fan ◽  
Gas Dynamic ◽  
Cooling Unit ◽  
Calculation Results ◽  
Axial Fans

Abstract The article discusses the issues of reducing the size of the cooling unit of the antenna of a radar station by improving the gas-dynamic processes occurring in the air-cooling unit. The results of the experimental studies of the gas flow in a plate-fin heat exchanger, being blown by one axial fan are presented. The feasibility of changing the number of axial fans for organizing a more uniform flow around the heat-exchange surfaces has been determined by calculation and theoretical methods. The calculation results are confirmed by experimental studies of the air flow in the segment of the heat exchanger, which is provided by a smaller fan.

scholarly journals Outdoor Air-Cooling System for a Computer Room and Its Corresponding Energy-Saving Effect

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5719
Author(s):  
JiHyun Hwang ◽  
Taewon Lee
Keyword(s):  
Power Consumption ◽  
Energy Saving ◽  
Data Centers ◽  
Cooling System ◽  
Stable Operation ◽  
Air Cooling ◽  
Outdoor Air ◽  
Air Conditioners ◽  
Air Cooling System ◽  
Saving Effect

The recent expansion of the internet network and rapid advancements in information and communication technology are expected to lead to a significant increase in power consumption and the number of data centers. However, these data centers consume a considerable amount of electric power all year round, regardless of working days or holidays; thus, energy saving at these facilities has become essential. A disproportionate level of power consumption is concentrated in computer rooms because air conditioners in these rooms are required to operate throughout the year to maintain a constant indoor environment for stable operation of computer equipment with high-heat release densities. Considerable energy-saving potential is expected in such computer rooms, which consume high levels of energy, if an outdoor air-cooling system and air conditioners are installed. These systems can reduce the indoor space temperature by introducing a relatively low outdoor air temperature. Therefore, we studied the energy-saving effect of introducing an outdoor air-cooling system in a computer room with a disorganized arrangement of servers and an inadequate air conditioning system in a research complex in Korea. The findings of this study confirmed that annual energy savings of up to approximately 40% can be achieved.

Understanding the True Total Cost of Ownership of Water Cooling for Data Centers

2015 ◽  
Author(s):  
Dustin W. Demetriou ◽  
Vinod Kamath ◽  
Howard Mahaney
Keyword(s):  
Data Center ◽  
Data Centers ◽  
Heat Dissipation ◽  
Cost Effective ◽  
Electric Utility ◽  
Air Cooling ◽  
Water Cooling ◽  
Total Cost Of Ownership ◽  
Total Cost ◽  
Cost Of Ownership

The generation-to-generation IT performance and density demands continue to drive innovation in data center cooling technologies. For many applications, the ability to efficiently deliver cooling via traditional chilled air cooling approaches has become inadequate. Water cooling has been used in data centers for more than 50 years to improve heat dissipation, boost performance and increase efficiency. While water cooling can undoubtedly have a higher initial capital cost, water cooling can be very cost effective when looking at the true lifecycle cost of a water cooled data center. This study aims at addressing how one should evaluate the true total cost of ownership for water cooled data centers by considering the combined capital and operational cost for both the IT systems and the data center facility. It compares several metrics, including return-on-investment for three cooling technologies: traditional air cooling, rack-level cooling using rear door heat exchangers and direct water cooling via cold plates. The results highlight several important variables, namely, IT power, data center location, site electric utility cost, and construction costs and how each of these influence the total cost of ownership of water cooling. The study further looks at implementing water cooling as part of a new data center construction project versus a retrofit or upgrade into an existing data center facility.

Liquid-Coupled Indirect-Transfer Exchanger Application to the Diesel Engine

1979 ◽  
Vol 101 (4) ◽  
pp. 516-523 ◽  
Author(s):  
James C. Eastwood
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cooling System ◽  
Relative Effectiveness ◽  
Ambient Air ◽  
Air Cooling ◽  
Performance Curves ◽  
Air Cooling System ◽  
Cooling Function ◽  
Low Charge

The efficiency of turbocharged diesel engines can be increased by cooling the charge air. This paper presents a design approach for liquid-coupled indirect-transfer heat exchanger systems to perform the air-cooling function. The two advantages most commonly cited for this approach to charge-air cooling are (1) the heat exchangers involved are easily packaged so that their shapes can be controlled by judicious design, and (2) simple gas ducting allows for compact machinery arrangements and relatively low charge-air pressure drop. An analytical approach to the design of liquid-coupled indirect-transfer heat exchanger systems is presented. Performance curves are constructed on the basis of this analysis. Four important design conditions are evident from the observation of these performance curves including (1) the relative capacity rate combination of the three fluids (ambient air, coupling liquid, and engine charge-air) which yields the highest overall effectiveness, (2) an optimum coupling-liquid flow rate, (3) the relative effectiveness distribution for each of the two component heat exchangers (hot and cold components), and (4) a broad design range for the optimum area distribution between the hot and cold exchangers. These performance curves serve as a guide for the design of a liquid-coupled charge-air cooling system.

Experimental Study of Heat Pipe Exchanger for High Power LED Cooling System

2011 ◽  
Vol 295-297 ◽  
pp. 1985-1988
Author(s):  
Yu Jun Gou ◽  
Zhong Liang Liu ◽  
Xiao Hui Zhong
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
High Power ◽  
Heat Dissipation ◽  
High Efficiency ◽  
Cooling System ◽  
Two Phase ◽  
High Power Led ◽  
New Type ◽  
Two Phase Heat Transfer

A new cooling concept for high power LED by combining the heat release of high power LED with two-phase heat transfer heat pipes was proposed, and in this study a new type of heat pipe with specific fins structure was developed. Through experimental results, we found the new heat pipe heat exchanger has the features of high efficiency of heat dissipation and compact construction which meets the demand of heat dissipation for high power LED. We also found the heat dissipation performance of the HP heat exchanger changed with the work angle.

Thermal Performance of Domestic Replacement A19 LED Lighting Products

2016 ◽  
Author(s):  
Thomas Storey ◽  
Robin Rackerby ◽  
Heather Dillon ◽  
Lydia Gingerich
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Heat Dissipation ◽  
Cooling System ◽  
Light Emitting Diode ◽  
Research Process ◽  
Light Emitting ◽  
Led Lighting ◽  
Proper Design ◽  
The Cost

In an effort to create a Light Emitting Diode (LED) lighting system that is as efficient as possible, the heat dissipation system must be accurately measured for proper design and operation. Because LED lighting technology is new, little optimization has been performed on typical cooling system required for most A19 replacement products. This paper describes the research process for evaluating the thermal performance of over 15 LED lighting products and compares their performance to traditional lighting sources, namely incandescent and compact fluorescent (CFL). This process uses radiation and convection to model typical cooling mechanisms for domestic A19 type replacement LED products. The A19 products selected for this investigation had input wattages ranging between 7 to 60 Watts, with outputs ranging from 450 to 1100 lumens. The average LED tested dissipated 43% (± 5%) of the total heat generated in the lighting product through the heat exchanger. The best thermal performance was observed in an LED product that dissipated approximately 58% of the total product heat through the heat exchanger. Results indicate that significant improvements to the current LED heat exchanger designs are possible, which will help lower the cost of future LED products, improve performance, and reduce the environmental footprint of the products.

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