Experimental Analysis for Optimization of Thermal Performance of a Server in Single Phase Immersion Cooling
Experimental Analysis for Optimization of Thermal Performance of a Server in Single Phase Immersion Cooling

Author: Pravin Ashok Shinde

Publisher:

Published: 2019

Total Pages: 57

ISBN-13:

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Liquid immersion cooling of servers in synthetic dielectric fluids is an emerging technology which offers significant cooling energy saving and increased power densities for data centers. A noteworthy advantage of using immersion cooling is high heat dissipation capacity which is roughly 1200 times greater than air. Other advantages of dielectric fluid immersion cooling include high rack density, better server performance, even temperature profile, reduction in noise. The enhanced thermal properties of oil lead to the considerable saving of both upfront and operating cost over traditional methods. In this study, a server is completely submerged in a synthetic dielectric fluid. Experiments were conducted to observe the effects of varying the volumetric flow rate and oil inlet temperature on thermal performance and power consumption of the server. Various parameters like total server power consumption, the temperature of all heat generating components like Central Processing Unit (CPU), Dual in Line Memory Module (DIMM), input/output hub (IOH) chip, Platform Controller Hub (PCH), Network Interface Controller (NIC) will be measured at steady state. Since this is an air-cooled server, the results obtained from the experiments will help in proposing better heat removal strategies like heat sink optimization, better ducting and server architecture. Assessment will also be made on the effect of thermal shadowing caused by the two CPUs on the nearby componentslike DIMMs and PCH.

Computational Analysis for Thermal Optimization of Servers for Single-phase Immersion Cooling
Computational Analysis for Thermal Optimization of Servers for Single-phase Immersion Cooling

Author: Dhruvkumar Vimalkumar Gandhi

Publisher:

Published: 2020

Total Pages: 79

ISBN-13:

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Complete immersion of servers in synthetic dielectric fluids is rapidly becoming a popular technique to minimize the energy consumed by data centers for cooling purposes. In general, immersion cooling offers noteworthy advantages over conventional air-cooling methods as synthetic dielectric fluids have high heat dissipation capacities which are roughly about 1200 times greater than air. Other advantages of dielectric fluid immersion cooling include even temperature profile on chips, reduction in noise and addressing reliability and operational enhancements like whisker formation and electrochemical migration. Nevertheless, lack of data published and availability of long-term reliability data on immersion cooling is insufficient which makes most of data centers operators reluctant to implement this technique. The first part of this paper will compare thermal performance of single-phase oil immersion cooled HP ProLiant DL160G6 server against air cooled server using computational fluid dynamics on 6 SigmaET®. Focus of the study are major components of the server like Central Processing Unit (CPU), Dual in Line Memory Module (DIMM), Input/output Hub (IOH) chip, Input controller Hub (ICH) and Baseboard Management Controller (BMC). The second part of this paper focuses on thermal performance optimization of oil immersion cooled servers by varying oil and its inlet temperature and volumetric flow rate.

Experimental Analysis of a Single-phase Direct Liquid Cooled Server Performance at Extremely Low Temperatures for Extended Time Periods
Experimental Analysis of a Single-phase Direct Liquid Cooled Server Performance at Extremely Low Temperatures for Extended Time Periods

Author: Gautam Gupta (M.S.)

Publisher:

Published: 2019

Total Pages: 28

ISBN-13:

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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.

Measurement of the Thermal Performance of a Single-phase Immersion Cooled Server at Elevated Temperatures for Prolonged Time
Measurement of the Thermal Performance of a Single-phase Immersion Cooled Server at Elevated Temperatures for Prolonged Time

Author: Pratik Vithoba Bansode

Publisher:

Published: 2019

Total Pages: 35

ISBN-13:

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Fully immersion of servers in electrically non-conductive (dielectric) fluid has recently become a promising technique for minimizing cooling energy consumption in data centers. The improved thermal properties of these dielectric fluids facilitate considerable savings in both upfront and operating cost over traditional air-cooling. This technology provides an opportunity for accommodating increased power densities. It also minimizes and addresses the common operational issues of air cooling methods like overheating and temperature swing in the system, fan failures, dust, air quality, and corrosion. This paper presents various data about the performance of a fully single-phase dielectric fluid immersed server over wide temperature ranges (environment temperature) from 25°C to 55°C for prolonged periods in an environmental chamber. This work explores the effects of high temperature on the performance of a server and other components like pump, along with potential issues associated with extreme climatic conditions. The experimental data serves as a means to determine failure criteria for the server and pump by subjecting the system to accelerated thermal aging conditions i.e. around 55°C, consequently simulating the most extreme environmental conditions that the server may encounter. Connector seals are inspected for expected degradation upon temperature cycling typically at such extreme conditions. Throttling limit for the server and pump power draw for different temperatures are examined to assess pump performance. Determining the relations between component behavior and operating temperature provides an accurate measure of lifetime of a server. The scope of this paper can be expanded by reviewing the effects of low temperatures (from -20°C to room temperature) on server and component performance. Changes to various performance parameters like power draw of pump and server, lowest operating temperature and an understanding of issues like condensation can be examined to quantify upper and lower limits for pump and server performance.

Thermal Degradation of Passive Components for Use in Single Phase Immersion Cooling Application
Thermal Degradation of Passive Components for Use in Single Phase Immersion Cooling Application

Author: Keerthivasan Padmanaban

Publisher:

Published: 2020

Total Pages: 59

ISBN-13:

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The growth in the computing and data industry demands high-performance data centers where the thermal management issues are of greater concern. A cooling system paradigm using the immersion cooling technology is a more reliable and effective method. In immersion cooling, servers are directly submerged into a dielectric fluid. A comparative study on the reliability of the passive components cooled by air, mineral oil and EC-100 was carried out. The Accelerated Thermal Cycling test based on ATC JEDEC is applicable only for air cooling. The ASTM standards D 3455 with some suitable modification was adopted to test the material compatibility with Immersion cooling. The experiment is designed to operate at an elevated temperature of 45oC and relative humidity of 35%. For every 72-hour time interval 3 samples each of thick film resistor, an electrolytic capacitor, polymer capacitor and transistors were taken out and the experiment was continued for the remaining samples. The study focuses on analyzing the change in the electrical properties, and the formation of cracks in the microstructural level of the passive components. The electrical properties such as resistance, capacitance etc. are measured using the multimeter and the microstructure study is done using the Scanning Electron Microscope (SEM). This experiment will provide with trend data of the effect of thermal aging on the electrical property of the passive components aged by air, mineral oil and synthetic fluid. This trend data provides with the comparative performance study of the passive components aged by air, mineral oil and synthetic fluid and, provides the advantages and disadvantages of each medium.

Cooling Efficiency Improvement of a Data Center Using Optimized Cabinet Design and Hybrid Cooling with High Inlet Conditions of Single-phase Coolant and Air
Cooling Efficiency Improvement of a Data Center Using Optimized Cabinet Design and Hybrid Cooling with High Inlet Conditions of Single-phase Coolant and Air

Author: Uschas Chowdhury

Publisher:

Published: 2021

Total Pages: 120

ISBN-13:

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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.

Computational Study of Form Factor of 3rd Generation Open Compute Servers Using Different Dielectric Fluids for Single-phase Immersion Cooling
Computational Study of Form Factor of 3rd Generation Open Compute Servers Using Different Dielectric Fluids for Single-phase Immersion Cooling

Author: Pranavi Rachamreddy

Publisher:

Published: 2019

Total Pages: 38

ISBN-13:

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Computer system dependency has been increased in the modern world and that has encouraged the rapid growth of data centers in leading business units like banking, education, transportation, social media and many more. Data center is a facility that incorporates an organisation's IT operations and equipment, as well as where it stores, processes, and manages the data. To fulfill the demands of data storage and data processing, corresponding increase in power density of servers are needed. The data center energy efficiency largely depends on the thermal management of servers. Currently, air cooling is the most widely used thermal management technique in data centers. But air cooling has started to reach its limitations due to high powered microprocessors and packaging. Therefore, industries are looking for single-phase immersion cooling using different dielectric fluids which reduces operational and cooling costs by enhancing the thermal management of servers. Form factor study of 3rd generation open compute server is another area of research in which impact of form factor (geometry of different Open Rack Units) on maximum junction temperature and thermal resistance at the server level is documented. This work is to provide an insight to increase the rack density by reducing form factor of an existing server. This work could open to more heat load per rack. A computational study is conducted in operational range of temperatures and the thermal efficiency has been optimized. A parametric study is conducted by changing the velocities and inlet temperatures of cooling liquid for different heights of the open compute 3rd generation server. The comparative study was carried out for white mineral oil and synthetic fluid (EC100). The results show an enhancement in thermal management for synthetic fluid when compared to mineral oil for the same inlet temperatures. This study clearly indicates that the single-phase immersion cooling is efficient and capable to accommodate high thermal mass.

Computational Fluid Dynamics
Computational Fluid Dynamics

Author: Jiri Blazek

Publisher: Elsevier

Published: 2005-12-20

Total Pages: 491

ISBN-13: 0080529674

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Computational Fluid Dynamics (CFD) is an important design tool in engineering and also a substantial research tool in various physical sciences as well as in biology. The objective of this book is to provide university students with a solid foundation for understanding the numerical methods employed in today’s CFD and to familiarise them with modern CFD codes by hands-on experience. It is also intended for engineers and scientists starting to work in the field of CFD or for those who apply CFD codes. Due to the detailed index, the text can serve as a reference handbook too. Each chapter includes an extensive bibliography, which provides an excellent basis for further studies.

Advanced Flip Chip Packaging
Advanced Flip Chip Packaging

Author: Ho-Ming Tong

Publisher: Springer Science & Business Media

Published: 2013-03-20

Total Pages: 562

ISBN-13: 1441957685

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Advanced Flip Chip Packaging presents past, present and future advances and trends in areas such as substrate technology, material development, and assembly processes. Flip chip packaging is now in widespread use in computing, communications, consumer and automotive electronics, and the demand for flip chip technology is continuing to grow in order to meet the need for products that offer better performance, are smaller, and are environmentally sustainable.