Liquid Cooling Network Systems for Energy Conservation in Data Centers

2011 ◽  
Author(s):  
Mayumi Ouchi ◽  
Yoshiyuki Abe ◽  
Masato Fukagaya ◽  
Haruhiko Ohta ◽  
Yasuhisa Shinmoto ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Data Center ◽  
Single Phase ◽  
Cooling System ◽  
Heat Pipes ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Two Phase ◽  
Cooling Systems ◽  
Cooling Methods

Energy consumption in data center has been drastically increasing in recent years. In data center, server racks are cooled down by air conditioning for the whole room in a roundabout way. This air cooling method is inefficient in cooling and it causes hotspot problem that IT equipments are not cooled down enough, but the room is overcooled. On the other hand, countermeasure against the heat of the IT equipments is also one of the big issues. We therefore proposed new liquid cooling systems which IT equipments themselves are cooled down and exhaust heat is not radiated into the server room. For our liquid cooling systems, three kinds of cooling methods have been developed simultaneously. Two of them are direct cooling methods that the cooling jacket is directly attached to heat source, or CPU in this case. Single-phase heat exchanger or two-phase heat exchanger is used as cooling jackets. The other is indirect cooling methods that the heat generated from CPU is transported to the outside of the chassis through flat heat pipes, and condensation sections of the heat pipes are cooled down by liquid. Verification tests have been conducted by use of real server racks equipped with these cooling techniques while pushing ahead with five R&D subjects which constitute our liquid cooling system, which single-phase heat exchanger, two-phase heat exchanger, high performance flat heat pipes, nanofluids technology, and plug-in connector. As a result, the energy saving effect of 50∼60% comparing with conventional air cooling system was provided in direct cooling technique with single-phase heat exchanger.

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.

Relative Cooling With Liquid for Gas Turbines: Part I — A Solution for Exceeding 2000 K at Turbine Inlet

2001 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Thermal Efficiency ◽  
Gas Turbines ◽  
Cooling System ◽  
Turbine Blades ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Turbine Inlet ◽  
Cooling Methods ◽  
Current Operating

Abstract The thermal efficiency of gas turbines is critically dependent on the temperature of burnt gases at turbine inlet, the higher this temperature the higher the efficiency. Stochiometric combustion would provide maximum efficiency, but in the absence of an internal cooling system, turbine blades cannot tolerate gas temperatures that exceed 1300 K. Therefore, for this temperature, the thermal efficiency of turbine engine is 40% less than theoretical maximum. Conventional air-cooling techniques of turbine blades allow inlet temperatures of about 1500 K on current operating engines yielding thermal efficiency gains of about 6%. New designs, that incorporate advanced air-cooling methods allows inlet temperatures of 1750–1800 K, with a thermal efficiency gain of about 6% relative to current operating engines. This temperature is near the limit allowed by air-cooling systems. Turbine blades can be cooled with air taken from the compressor or with liquid. Cooling systems with air are easier to design but have a relatively low heat transfer capacity and reduce the efficiency of the engine. Some cooling systems with liquid rely on thermal gradients to promote re-circulation from the tip to the root of turbine blades. In this case, the flow and cooling of liquid are restricted. For best results, cooling systems with liquid should use a pump to re-circulate the coolant. In the past, designers tried to place this pump on the engine stator and therefore were unable to avoid high coolant losses because it is impossible to reliably seal the stator-rotor interface. Therefore it was assumed that cooling systems with liquid could not incorporate pumps. This is an unwarranted assumption as shown studying the system in a moving frame of reference that is linked to the rotor. Here is the crucial fact overlooked by previous designers. The relative motion of engine stator with respect to the rotor is sufficient to motivate a cooling pump. Both the pump and heat exchange system that is required to provide rapid cooling of liquid with cold ambient air, could be located within the rotor. Therefore, the entire cooling system can be encapsulated within the rotor and the sealing problem is circumvented. Compared to recent designs that use advanced air-cooling methods, such a liquid cooling system would increase the thermal efficiency by 8%–11% because the temperatures at turbine inlet can reach stoichiometric levels and most of the heat extracted from turbine during cooling is recuperated. The appreciated high reliability of the system will permit a large applicability in aerospace propulsion.

Development of Advanced Cooling Network Systems for Data Centers

2010 ◽  
Author(s):  
Yoshiyuki Abe ◽  
Mayumi Ouchi ◽  
Masato Fukagaya ◽  
Takashi Kitagawa ◽  
Haruhiko Ohta ◽  
...  
Keyword(s):  
High Performance ◽  
Data Centers ◽  
Cooling System ◽  
Heat Pipes ◽  
Energy Utilization ◽  
Liquid Cooling ◽  
Network Systems ◽  
Two Phase ◽  
Cooling Systems ◽  
Development Organization

Energy utilization in data centers, especially cooling systems for server racks, needs extensive improvement. The present authors proposed advanced cooling network systems for data centers, and R & D activities have been conducted under the so-called Green IT Project sponsored by NEDO (New Energy and Industrial Technology Development Organization). In the present concept, CPUs in servers are cooled down by either direct liquid cooling system or heat pipes with liquid cooling systems in the condensation region. The liquid cooling systems are integrated in each server rack and among server racks. A series of studies on both single phase and two phase narrow channel heat exchangers, high performance heat pipes with self-rewetting fluids and nanofluids for heat transfer enhancement are ongoing. In addition, a prototype server rack with the cooling network systems is also under development toward commercial products. This paper reports the updated status of the present R & D.

The Effectiveness of Data Center Overhead Cooling in Steady and Transient Scenarios: Comparison of Downward Flow to a Cold Aisle Versus Upward Flow From a Hot Aisle

2015 ◽  
Author(s):  
Luis Silva-Llanca ◽  
Marcelo del Valle ◽  
Alfonso Ortega
Keyword(s):  
Energy Efficiency ◽  
Heat Exchanger ◽  
Cooling System ◽  
Control Flow ◽  
Air Cooling ◽  
Upward Flow ◽  
Cooling Systems ◽  
Cooling Effectiveness ◽  
Downward Flow ◽  
Pressure Drops

The most common approach to air cooling of data centers involves the pressurization of the plenum beneath the raised floor and delivery of air flow to racks via perforated floor tiles. This cooling approach is thermodynamically inefficient due in large part to the pressure losses through the tiles. Furthermore, it is difficult to control flow at the aisle and rack level since the flow source is centralized rather than distributed. Distributed cooling systems are more closely coupled to the heat generating racks. In overhead cooling systems, one can distribute flow to distinct aisles by placing the air mover and water cooled heat exchanger directly above an aisle. Two arrangements are possible: (i.) placing the air mover and heat exchanger above the cold aisle and forcing downward flow of cooled air into the cold aisle (Overhead Downward Flow (ODF)), or (ii.) placing the air mover and heat exchanger above the hot aisle and forcing heated air upwards from the hot aisle through the water cooled heat exchanger (Overhead Upward Flow (OUF)). This study focuses on the steady and transient behavior of overhead cooling systems in both ODF and OUF configurations and compares their cooling effectiveness and energy efficiency. The flow and heat transfer inside the servers and heat exchangers are modeled using physics based approaches that result in differential equation based mathematical descriptions. These models are programmed in the MATLAB™ language and embedded within a CFD computational environment (using the commercial code FLUENT™) that computes the steady or instantaneous airflow distribution. The complete computational model is able to simulate the complete flow and thermal field in the airside, the instantaneous temperatures within and pressure drops through the servers, and the instantaneous temperatures within and pressure drops through the overhead cooling system. Instantaneous overall energy consumption (1st Law) and exergy destruction (2nd Law) were used to quantify overall energy efficiency and to identify inefficiencies within the two systems. The server cooling effectiveness, based on an effectiveness-NTU model for the servers, was used to assess the cooling effectiveness of the two overhead cooling approaches.

scholarly journals Analysis of Solar District Cooling systems: the Effect of Heat Rejection

2020 ◽  
Vol 197 ◽  
pp. 08018
Author(s):  
Giovanni Brumana ◽  
Giuseppe Franchini ◽  
Elisa Ghirardi ◽  
Antonio Perdichizzi
Keyword(s):  
Heat Exchanger ◽  
Cooling System ◽  
Optimization Procedure ◽  
Abu Dhabi ◽  
Air Cooling ◽  
Gulf Region ◽  
Cooling Systems ◽  
Heat Rejection ◽  
Absorption Chillers ◽  
Water Pipeline

The paper presents the performance assessment of a solar district cooling system with special attention to the heat rejection process. The investigation includes energetic, economic and environmental aspects. The district cooling network is driven by two-stage Li-Br absorption chillers coupled with parabolic trough solar collectors. The whole system, including solar field, storage tanks and chilled water pipeline, has been modelled in Trnsys. The focus is on the heat rejection systems, and their impact on the performance of the cooling plant. Four different types of heat rejection systems are considered: Air Cooling (AC), Evaporative Cooling Tower (ECT), Groundwater Heat Exchanger (GHE) and Geothermal Boreholes (GB). The paper presents two case studies in the Gulf region: the warm climate is compared for two condition of humidity, dry (Riyadh) and humid (Abu Dhabi). Furthermore, the work presents a multivariable optimization procedure based on GenOpt software interacting with Trnsys model under the constraint of a 70% annual solar fraction. The best option resulted to be the one based on absorption chillers coupled with Groundwater Heat Exchanger in both locations. The annual power consumption is reduced by 83% in Abu Dhabi and 82% in Riyadh compared to conventional cooling systems.

Numerical and Experimental Characterization of the Transient Effectiveness of a Water to Air Heat Exchanger for Data Center Cooling Systems

2015 ◽  
Author(s):  
Tianyi Gao ◽  
Marcelo del Valle ◽  
Alfonso Ortega ◽  
Bahgat G. Sammakia
Keyword(s):  
Heat Exchanger ◽  
Mass Flow ◽  
Data Center ◽  
Heat Exchangers ◽  
Cooling System ◽  
Cross Flow ◽  
Inlet Temperature ◽  
Experimental Measurements ◽  
Cooling Systems ◽  
Flow Heat

The cross flow heat exchanger is at the heart of most cooling systems for data centers. Air/Water or air/refrigerant heat exchangers are the principal component in Central Room Air Conditioning (CRAC) units that condition data room air that is delivered through an underfloor plenum. Liquid/air heat exchangers are also increasingly deployed in close-coupled cooling systems such as rear door heat exchangers, in-row coolers, and overhead coolers. In all cases, the performance of liquid/air heat exchangers in both steady state and transient scenarios are of principal concern. Transient scenarios occur either by the accidental failure of the cooling system or by intentional dynamic control of the cooling system. In either scenario, transient boundary conditions involve time-dependent air or liquid inlet temperatures and mass flow rates that may be coupled in any number of potential combinations. Understanding and characterizing the performance of the heat exchanger in these transient scenarios is of paramount importance for designing better thermal solutions and improving the operational efficiency of existing cooling systems. In this paper, the transient performance of water to air cross flow heat exchangers is studied using numerical modeling and experimental measurements. Experimental measurements in 12 in. × 12 in. heat exchanger cores were performed, in which the liquid (water) mass flow rate or inlet temperature are varied in time following controlled functional forms (step jump, ramp). The experimental data were used to validate a transient numerical model developed with traditional assumptions of space averaging of heat transfer coefficients, and volume averaging of thermal capacitances. The complete numerical model was combined with the transient effectiveness methodology in which the traditional heat exchanger effectiveness approach is extended into a transient domain, and is then used to model the heat exchanger transient response. Different transient scenarios were parametrically studied to develop an understanding of the impact of critical variables such as, the fluid inlet temperature variation and the fluid mass flow rate variation, and a more comprehensive understanding of the characteristics of the transient effectiveness. Agreement between the novel transient effectiveness modeling approach and the experimental measurements enable use of the models as verified predictive design tools. Several studies are designed based on the practical problems related to data center thermal environments and the results are analyzed.

Experimental Study of Effect Factors on Performance of Heat Dissipation of HP Heat Exchanger for LED Cooling System

2012 ◽  
Vol 490-495 ◽  
pp. 2530-2533
Author(s):  
Yun Jun Gou ◽  
Zhong Liang Liu ◽  
Chun Min Wang ◽  
Xiao Hui Zhong
Keyword(s):  
Heat Exchanger ◽  
High Power ◽  
Heat Dissipation ◽  
Environmental Temperature ◽  
Cooling System ◽  
Heat Pipes ◽  
Two Phase ◽  
High Power Led ◽  
Street Lamp ◽  
Two Phase Heat Transfer

A new cooling concept for high power LED street lamp by combining the heat release of high power LED with two-phase heat transfer heat pipes was proposed, and in this paper we study the effect of heat pipe numbers, fins structure and ambient temperature on the performance of heat dissipation of HP heat exchanger. Through experimental results, we found the heat pipes number plays a more importent role on the performance of heat dissipation than the fins material and the final surface temperature will increase with the environmental temperature.

scholarly journals MODELING MATEMATIS DAN SIMULASI DROPLET UNTUK PENDINGINAN ALAT-ALAT TEKNOLOGI INFORMASI DAN KOMPUTER DENGAN METODE LATTICE-BOLTZMANN

2021 ◽  
Vol 3 (3) ◽  
pp. 389-393
Author(s):  
Wiji Nurastuti ◽  
Kumara Ari Yuana
Keyword(s):  
Single Phase ◽  
Cooling System ◽  
High Heat ◽  
High Heat Flux ◽  
Liquid Cooling ◽  
Computational Stability ◽  
Two Phase ◽  
Fluid Convection ◽  
Spurious Currents ◽  
Multi Phase

Abstrak : Kebutuhan inovasi skema pendinginan untuk pemeliharaan perangkat elektronik dengan suhu aman dibawah batas yang telah ditentukan oleh batasan material dan kendala realibilitas yang terkait pada miniaturisasi microchip yang agresif pada komponen elektronik. Pergeseran dari ketergantungan pada sistem berpendingin kipas menjadi ke skema pendinginan yang memanfaatkan pendingin cairan dielektrik menggunakan berbagai skema pendinginan fase tunggal. Perekayasa (engineer) sistem pendingin memusatkan perhatian pada skema pendinginan dua fase, untuk memanfaatkan kedua system pendingin. Sifat yang harus dimiliki perekayasa sistem pendingin ini yaitu konveksi fluida dan panas laten untuk memindahkan jumlah kalor yang jauh lebih besar dari pada skema fase tunggal, sambil mempertahankan suhu perangkat yang lebih rendah. Beberapa skema pendingin cairan dua fase telah direkomendasikan untuk menghilangkan fluks kalor tinggi dari perangkat yang digunakan diaplikasi. Momentum droplet memungkinkan cairan menembus penghalang uap yang dibuat oleh gelembung nukleasi dan secara lebih efektif mengisi kembali permukaan, keduanya sangat bermanfaat untuk pendinginan fluks tinggi. Pada model dan simulasi pengembangan droplet menggunakan metode LBM multi fase, parameter penting yang selalu didapatkan adalah arus semu maksimum (maximum spurious currents) yang menetukan stabilitas komputasi. Kata kunci : Modeling Matematis, Simulasi Droplet, Metode Latice-Boltzman   Abstract: The need for innovative cooling schemes for maintaining electronic devices with safe temperatures below predetermined limits by material limitations and reliability constraints associated with aggressive microchip miniaturization of electronic components. Shifting from reliance on fan-cooled systems to cooling schemes that utilize dielectric liquid cooling using a variety of single-phase cooling schemes. The cooling system engineer focuses on two-phase cooling schemes, to take advantage of both cooling systems. Properties that these cooling system engineers must possess are fluid convection and latent heat to transfer a much greater amount of heat than a single-phase scheme, while maintaining a lower device temperature. Several two-phase liquid cooling schemes have been recommended to remove the high heat flux from the apparatus used in the application. The droplet momentum allows the liquid to penetrate the vapor barrier created by the nucleation bubbles and more effectively replenish the surface, both of which are very beneficial for high flux cooling. In droplet development models and simulations using the multi-phase LBM method, an important parameter that is always obtained is the maximum spurious currents which determine the computational stability. Keywords: Mathematical Modeling, Droplet Simulation, Latice-Boltzman Method  

Study on Alternative Cooling Methods Beyond Next Generation Microprocessors

2003 ◽  
Author(s):  
Albert Chan ◽  
Jie Wei
Keyword(s):  
Heat Dissipation ◽  
Low Cost ◽  
Ambient Pressure ◽  
Operating Conditions ◽  
Heat Sinks ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Two Phase ◽  
Field Service ◽  
Cooling Methods

Feasibility study on alternative cooling methods to air-cooling with heat sinks is provided in this paper. The study focuses on cooling of 64-bit microprocessor at 80nm technology node with projected heat dissipation of 200W. An example was presented to illustrate limitation of air-cooling for the 200W microprocessor using an all-Cu heat sink with tall fins. Three alternatives to air-cooling were studied in this work: liquid cooling, two-phase convective flow cooling and refrigeration cooling. Thermodynamic analysis was used to estimate operating conditions and fluid flow rates for each alternative. The information provides a preliminary basis for assessing capabilities and weaknesses among alternatives. Liquid and two-phase cooling simply transfer heat from high to low temperature. In contrast, refrigeration cooling operates as a heat pump, moving heat from low to high temperature. Refrigeration cooling offers capability to cool microprocessor (LSI) chip to temperatures below ambient or freezing. The drawback is more heat must be removed from the system. Liquid cooling operates at close to ambient pressure, while two-phase and refrigeration cooling operate at higher pressures. Challenges to implementation of all three alternatives include availability of low cost, miniature components (pumps or compressors, heat exchanger and condenser), designing for redundancy (or reliability) and ease of installation and field service. In terms of component availability and cost, liquid cooling is preferred choice, followed by two-phase and refrigeration cooling.

Sign in / Sign up

Export Citation Format

Share Document