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Author: Amith Mathew Publisher: ISBN: Category : Languages : en Pages : 31
Book Description
Data centers are used by organizations for storing, processing and distribution of data. These data centers are run through-out the year due to which their thermal management is a growing concern. A popular way of eliminating such thermal cooling issues is Liquid cooling. Conventionally Liquid cooling involves the supply of constant liquid flow (water or refrigerant) through the IT rack irrespective of the IT load, which in a Multi-chip module causes hotspots and temperature gradients across the module due to non-uniform heating. A dynamic cold-plate and a regulatory flow control device (FCD) is incorporated in this experimental set-up to assist targeted delivery of coolant to the servers based on their IT load. A single high-power thermal test vehicle is used in each of the IT rack (simulating a processor). Dynamic cold plate is placed on the thermal vehicle accompanied by pressure, temperature, and flow sensors. The Flow control device is placed in the downstream of the manifold for regulation of the flow based on temperature of the coolant leaving from each server. The flow of each of the IT racks are monitored and varied based on the pressure of the system and the IT load on the server. This reduces the pumping power consumed by systemically varying the flow towards servers which withstand high IT load instead of constantly dispensing coolant to all the racks. Also due to the varying flow rates, the servers sustaining higher loads are provided with higher flowrates, hence increasing the reliability of the servers.
Author: Amith Mathew Publisher: ISBN: Category : Languages : en Pages : 31
Book Description
Data centers are used by organizations for storing, processing and distribution of data. These data centers are run through-out the year due to which their thermal management is a growing concern. A popular way of eliminating such thermal cooling issues is Liquid cooling. Conventionally Liquid cooling involves the supply of constant liquid flow (water or refrigerant) through the IT rack irrespective of the IT load, which in a Multi-chip module causes hotspots and temperature gradients across the module due to non-uniform heating. A dynamic cold-plate and a regulatory flow control device (FCD) is incorporated in this experimental set-up to assist targeted delivery of coolant to the servers based on their IT load. A single high-power thermal test vehicle is used in each of the IT rack (simulating a processor). Dynamic cold plate is placed on the thermal vehicle accompanied by pressure, temperature, and flow sensors. The Flow control device is placed in the downstream of the manifold for regulation of the flow based on temperature of the coolant leaving from each server. The flow of each of the IT racks are monitored and varied based on the pressure of the system and the IT load on the server. This reduces the pumping power consumed by systemically varying the flow towards servers which withstand high IT load instead of constantly dispensing coolant to all the racks. Also due to the varying flow rates, the servers sustaining higher loads are provided with higher flowrates, hence increasing the reliability of the servers.
Author: Manasa Sahini Publisher: ISBN: Category : Data libraries Languages : en Pages : 111
Book Description
Data centers house a variety of compute, storage, network IT hardware where equipment reliability is of utmost importance. Heat generated by the IT equipment can substantially reduce its service life if Tj,max, maximum temperature that the microelectronic device tolerates to guarantee reliable operation, is exceeded. Hence, data center rooms are bound to maintain continuous conditioning of the cooling medium. This approach often results in over-provisioned cooling systems. In 2014, U.S. Data center electricity consumption is about 1.8% of the total electrical energy in the country. Hence, data center power and cooling have become significant issues facing the IT industry. The first part of the study focuses on air cooling of electronic equipment at room level. Data centers are predominantly cooled by perimeter computer air handling units that supply cold air to the raised floor plenum and the cold air helps in removing the heat generated by IT equipment. This method tends to be inadequate especially when the average power density per rack rises above 4 kW. As a solution to mitigate this problem, different rack and row based cooling solutions have been proposed and used. The primary focus of these cooling methods is to bring cooling closer to the heat source which is the IT rack thereby improving the heat dissipation process along with controlled air flow management in the data center room. Mostly known close-coupled cooling solutions include rear-door heat exchanger, in-row coolers, and over-head cooling. In this study, a new end-of-aisle close-coupled cooling solution for small data center cooling room has been proposed. As oppose to the existing designs, this design is distinctive in eliminating the risk of placing the liquid on top of IT racks along with achieving cooling energy efficiency. Three different configurations of the proposed designs are studied for its thermal performance using computational modeling. The second part of the study focuses on liquid cooling at rack level. Liquid cooling addresses the critical issues related to typical air cooling in servers because of its better heat transfer characteristics. Water-cooling at the device level can be an efficient solution since water has higher thermal capacitance when compared to traditional heat carrying medium i.e., air. The emerging practice in the data center industry is to maximize the use of economizer usage by reducing/eliminating the usage of chiller while taking advantage of outside ambient conditions to cool the data centers. Liquid cooled racks are generally designed with different configuration of pumping systems. Empirical study is conducted on a state-of-art liquid cooled electronic rack for high coolant inlet, commonly known as warm-water cooling in order to evaluate the cooling performance of distributed vs. centralized coolant pumping systems. Experimental set up is instrumented such that detailed analysis is employed to study component temperatures as well as cooling performance of the rack at elevated inlet conditions. The third part of the study focuses on the impact of high server inlet temperatures to static power at server level. In order to maximize the use of economizers, the IT hardware will be exposed to higher inlet temperatures which would lead to higher operating temperatures of the processors. The operating temperature of the CPU has direct influence on the static power due to subthreshold leakage which is known to reduce the performance of the processor. The current work serves as a firsthand investigation to study trade-off between IT performance and energy efficiency for elevated inlet temperature in air vs. liquid cooled servers. Air cooled IT along with the liquid cooled counter-parts are instrumented and extensively tested to simulate the high ambient conditions at the test bed data center.
Author: Jun Dai Publisher: Springer Science & Business Media ISBN: 1461456029 Category : Technology & Engineering Languages : en Pages : 196
Book Description
This book describes the use of free air cooling to improve the efficiency of, and cooling of, equipment for use in telecom infrastructures. Discussed at length is the cooling of communication installation rooms such as data centers or base stations, and this is intended as a valuable tool for the people designing and manufacturing key parts of communication networks. This book provides an introduction to current cooling methods used for energy reduction, and also compares present cooling methods in use in the field. The qualification methods and standard reliability assessments are reviewed, and their inability to assess the risks of free air cooling is discussed. The method of identifying the risks associated with free air cooling on equipment performance and reliability is introduced. A novel method of assessment for free air cooling is also proposed that utilizes prognostics and health management (PHM). This book also: Describes how the implementation of free air cooling can save energy for cooling within the telecommunications infrastructure. Analyzes the potential risks and failures of mechanisms possible in the implementation of free air cooling, which benefits manufacturers and equipment designers. Presents prognostics-based assessments to identify and mitigate the risks of telecommunications equipment under free air cooling conditions, which can provide the early warning of equipment failures at operation stage without disturbing the data centers' service. Optimum Cooling for Data Centers is an ideal book for researchers and engineers interested in designing and manufacturing equipment for use in telecom infrastructures.
Author: Uschas Chowdhury Publisher: ISBN: Category : Electronic data processing departments Languages : en Pages : 120
Book Description
The objective of this study is to improve and optimize the cooling efficiency of liquid and air cooling from server to room level while applying best practices in the industry. The effect of increased air and coolant temperature has been explored through a literature survey and studies are conducted from device level to room level for air and liquid cooling. Three major aspects are considered. A closed-form air cooling solution is proposed for high-powered racks in a modular data center equipped with in-row coolers. Direct-to-chip liquid cooling technology is extensively studied at the server level for raised air and coolant inlet temperature for determining thermal performance and reliability of IT equipment. A cost analysis for liquid cooling has been conducted with a TCO model for the performance improvement and holistic evaluation of a data center with air and liquid cooling.The first part consists of a room-level numerical study conducted with high powered racks in a modular data center with regular low-powered racks. Typical modular data centers are cooled by perimeter or outdoor cooling units. A comparative analysis is performed for a typical small-sized non-raised facility to investigate the efficacy and limitations of in-row coolers in thermal management of IT equipment with variation in rack heat load and containment. Several other aspects like a parametric study of variable opening areas of duct between racks and in-row coolers, the variation of operating flow rate, and failure scenarios are also studied to find proper flow distribution, uniformity of outlet temperature, and predict better performance, energy savings and reliability. The results are presented for general guidance for flexible and quick installation and safe operation of in-row coolers to improve thermal efficiency. The Second Part consists of a server-level numerical and experimental study with raised inlet air and coolant temperature for a hybrid cooled server. A detailed numerical study of an enterprise 1U hybrid cooled server is performed to predict the effect of raised inlet air temperature on the component temperatures following the limits of ASHARE air cooling classes. Then, an experimental study is performed in an environmental chamber with high inlet air temperatures. Results for both studies are compared. Previously warm water cooling or increased coolant inlet temperature has been experimentally tested on the respective server. Thus, the effect of both air and liquid coolant temperature has been presented and scaled up to a data center level with help of industry-standard tools for 1D flow network analysis to address the cooling efficiency improvement. The third part consists of a cost analysis of a data center with air and liquid cooling using an established TCO model. The ASHRAE cooling classes for air and liquid cooling are used based on the experimental findings. Also, the effect of cooling efficiency improvements at component and server level and increased inlet conditions are used to compare with a baseline model with air cooling.
Author: John Edward Fernandes Publisher: ISBN: Category : Cooling Languages : en Pages : 129
Book Description
Data center energy consumption continues to increase with the proliferation in online services such as social networking, banking, entertainment, cloud computing, etc. Recent estimates show that associated power consumption accounts for around 2% and 1.8% of electricity production in the United States and worldwide respectively. In addition to growth in the industry, power densities continue to rise in IT equipment increasing the criticality of thermal management in data center operation. Cooling systems account for around a third of overall power consumption requiring more energy-efficient solutions across all levels within the facility. Liquid cooling of high power modules using cold plates has been around since the early 1980s. However, till today, designs remain fairly static and fail to adapt to variations in power dissipation at the device. This can be alleviated through the introduction of a "dynamic" cold plate design. Through implementation of sensing and control, the solution can distribute available resources based on local cooling requirements. A high-power multi-chip module (MCM) platform is chosen as reference for the design of such a solution. In-depth computational fluid dynamics (CFD) analysis is conducted to select appropriate heat transfer surfaces and predict thermal performance of the cold plate, when assembled with the MCM. A cost-effective MCM thermal test vehicle is assembled to enable experimental testing of both dynamic and static cold plates. Components of a liquid cooling test bench and control system are selected and permit future evaluation of thermal performance and energy-efficiency of both solutions. The current trend in air cooling of data centers involves higher ambient temperatures to maximize use of free cooling. However, power consumption at the server-level may increase due to elevated fan activity and CPU leakage current. Minimizing power consumption of web servers (1.5U profile) is achieved by studying the effect of ambient temperature on performance and investigating means to improve chassis fan control through accurate selection of CPU target temperature. Multiple servers are instrumented and deployed in a test bed data center and are subjected to different air supply temperatures and fan speeds to achieve the same. Limits of energyefficient operation and available savings will be discussed. Fan efficiency is known to increase with size. Departing from conventional server designs, wherein fans are installed within the chassis, and consolidating air moving devices at the rear of a rack or 'stack' of servers permits increase in size and cooling efficiency. Preliminary studies have shown that replacing server-enclosed 60mm units with a rear-mounted wall of larger fans (80mm or 120mm) enables savings in fan power of the order of 50%. A methodology for row-wise control of such rack-level fans, with the purpose of simulating an actual product, is previewed and savings are reported. In addition, performance under real-life scenarios such as non-uniform loads and fan failure is investigated. Each rack-level setup has distinct advantages. However, selecting between configurations would necessitate a compromise between efficiency, redundancy and cost.
Author: Chinmay Sanjay Kshirsagar Publisher: ISBN: Category : Languages : en Pages : 53
Book Description
As the worldwide demand for the data centers grows, so does the size and load placed on data centers which leads to the applied constraints on power and space available to the operator. Cooling power consumption is a major contributor of the total energy consumption of the system. In the process of optimization of cooling energy consumption per performance unit, liquid cooling technology has emerged as one of the most viable solutions. In this rack level study, 2OU (Open U) hybrid cooled web servers are tested for an evaluation of warm water cooling in centralized coolant system. Effects of higher inlet temperatures of the coolant in terms of device temperatures as well as IT and cooling power have been observed as a part of the evaluation. The study discusses the significance of variable pumping in centralized coolant system for its more efficient use. The experimental setup for cooling consists of 1/3rd sized mini rack capable of housing up to eleven liquid cooled web servers and two heat exchangers. The cooling configuration is centralized and has two redundant pumps placed in series with heat exchanger at the rack. CPUs of each server are liquid cooled with using passive micro channel cold plates while rests of the components are air cooled. Synthetic load has been generated on each servers for thermal stress testing and observed performance characteristics such as device temperatures and cooling power consumption of servers. Centralized redundant pumps are separately powered using an external DC power supply unit. The pump speed is varied with variable voltage supply ranging from 11V to 17V across the armature. The experimental testing is carried out at higher inlet temperatures ranging from 25°C to 45°C which falls within the ASHRAE liquid cooled envelope W4.Variable pumping at higher inlet temperatures has been achieved to evaluate to operating temperatures of device components for reliability and reduction in operational cooling power consumption of the servers.
Author: FNU Akash Publisher: ISBN: Category : Languages : en Pages : 31
Book Description
A data center is a cluster of multiple servers that a company uses to store and process large amounts of data. Due to never-ending demands, the processor densities are increasing every day. A higher processor density would result in the servers heating up more than it would normally creating a need for an efficient cooling system. On an average a water-cooled system would consume up to 40% of the total power required by a data center. Studies are being conducted on improving the overall efficiency of the system by either improving the thermal properties of the system or by improving the pumping efficiency. This study explores a way of improving the efficiency by saving pumping power. Practically looking at the situation, not every server is going to be used at all times. The loads would vary depending on the process where one would need the computing power of the whole rack in which case the system would need to be cooled equally but a different process would only engage 2 servers out of the available ones in the rack. In this scenario these two racks would consume more power in turn dissipating more heat compared to the others. This gives us room to vary the flow rate and introduce dynamic cooling to save pumping power. This study concentrates on a control strategy using a flow control device that is used to vary the flow rate individually on different levels based on the temperature of the coolant. The variation of flow rates is directly going to be related to the savings in pumping power. Variations in temperature, pressure and flow rate is observed at different intervals and the setup is built with these parameters in focus. Two strategies are developed to observe the effect of dynamic cooling, pressure based and temperature based. The results of this experiment will prove the efficiency of dynamic cooling.
Author: Gautam Gupta (M.S.) Publisher: ISBN: Category : Languages : en Pages : 28
Book Description
A data center is a centralized facility that we use for housing the computer systems and its related components such as high-end servers, redundant data connection and security controls. The next radical change in the thermal management of data centers is to shift from conventional cooling methods like air-cooling to direct liquid cooling (DLC) to deal with high thermal mass. The past few years have consistently seen wider adoption of direct liquid cooling because of its simplicity and high heat dissipation capacity. Passive single phase engineered fluid immersion cooling has several other benefits like better server performance, even temperature profile and higher rack densities.This report provides an overview of the considerations of using single-phase dielectric fluid to cool a server based on experiments conducted at extreme conditions in an environmental chamber. The server was placed in the environmental chamber ranging from extremely low temperatures at -20°C to 20°C and varying humidity for extended durations. Thermal overstress experiment was performed on a fully immersed server and its cooling system components. This work explores the effects of low temperature on the performance of a server and other components like pump including flow rate drop and starting trouble under extreme climatic conditions. The possibility of connector seals observing reduced performance upon accelerated temperature cycling is addressed. Throttling limit for the CPU along with power draw over a range of different temperatures was recorded. Similar observations were recorded for pump. Dependence of pump performance on operating temperature determines the flow rate and operating temperature relationship. Pumping power consumption is directly related to the operating cost of a data center.This research can be expanded by performing similar experiments at elevated temperatures to establish an operating temperature envelope in order to get the optimum performance of a direct liquid cooled high-density server.
Author: Amith Mathew
Author: Amith Mathew
Author: Manasa Sahini
Author: Jun Dai
Author: Uschas Chowdhury
Author: John Edward Fernandes
Author: Chinmay Sanjay Kshirsagar
Author: Nicolas Lamaison
Author: FNU Akash
Author: 
Author: Gautam Gupta (M.S.)