From Chip to Cooling Tower Data Center Modeling: Influence of Chip Temperature Control Philosophy

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Ed J. Walsh ◽  
Thomas J. Breen ◽  
Jeff Punch ◽  
Amip J. Shah ◽  
Cullen E. Bash
Keyword(s):  
Heat Sink ◽  
Data Center ◽  
Energy Performance ◽  
Coefficient Of Performance ◽  
Control Algorithms ◽  
Cooling Power ◽  
Operational Strategies ◽  
The Impact ◽  
Heat Sink Temperature

The chiller cooled data center environment consists of many interlinked elements that are usually treated as individual components. This chain of components and their influences on each other must be considered in determining the benefits of any data center design and operational strategies seeking to improve efficiency, such as temperature controlled fan algorithms. Using the models previously developed by the authors, this paper extends the analysis to include the electronics within the rack through considering the processor heat sink temperature. This has allowed determination of the influence of various cooling strategies on the data center coefficient of performance. The strategy of increasing inlet aisle temperature is examined in some detail and found not to be a robust methodology for improving the overall energy performance of the data center, while tight temperature controls at the chip level consistently provide better performance, yielding more computing per watt of cooling power. These findings are of strong practical relevance for the design of fan control algorithms at the rack level and general operational strategies in data centers. Finally, the impact of heat sink thermal resistance is considered, and the potential data center efficiency gains from improved heat sink designs are discussed.

An Exergy-Based Figure-of-Merit for Electronic Packages

2005 ◽  
Vol 128 (4) ◽  
pp. 360-369 ◽  
Author(s):  
Amip J. Shah ◽  
Van P. Carey ◽  
Cullen E. Bash ◽  
Chandrakant D. Patel
Keyword(s):  
Heat Sink ◽  
Data Center ◽  
Figure Of Merit ◽  
Performance Metrics ◽  
Exergy Loss ◽  
Junction Temperature ◽  
Cooling Power ◽  
Computational Performance ◽  
Thermodynamic Performance ◽  
The Impact

Chip power consumption and heat dissipation have become important design issues because of increased energy costs and thermal management limitations. As a global compute utility evolves, seamless connectivity from the chip to the data center will become increasingly important. The optimization of such an infrastructure will require performance metrics that can adequately capture the thermodynamic and compute behavior at multiple physical length scales. In this paper, an exergy-based figure-of-merit (FoM), defined as the ratio of computing performance (in MIPS) to the thermodynamic performance (in exergy loss), is proposed for the evaluation of computational performance. The paper presents the framework to apply this metric at the chip level. Formulations for the exergy loss in simple air-cooled heat sink packages are developed, and application of the proposed approach is illustrated through two examples. The first comparatively assesses the loss in performance resulting from different cooling solutions, while the second examines the impact of non-uniformity in junction power in terms of the FoM. Modeling results on a 16mm×24mm chip indicate that uniform power and temperature profiles lead to minimal package irreversibility (and therefore the best thermodynamic performance). As the nonuniformity of power is increased, the performance rapidly degrades, particularly at higher power levels. Additionally, the competing needs of minimization of junction temperature and minimization of cooling power were highlighted using the exergy-based approach. It was shown that for a given power dissipation and a specific cooling architecture (such as an air-cooled heat sink solution), an optimal thermal resistance value exists beyond which the costs of increased cooling may outweigh any potential benefits in performance. Thus, the proposed FoM provides insight into thermofluidic inefficiencies that would be difficult to gain from a traditional first-law analysis. At a minimum, the framework presented in this paper enables quantitative evaluation of package performance for different nonuniform power inputs and different choices of cooling parameters. At best, since the FoM is scalable, the proposed metric has the potential to enable a chip-to-data-center strategy for optimal resource allocation.

scholarly journals Optimization of a Mixed Refrigerant Based H2 Liquefaction Pre-Cooling Process and Estimate of Liquefaction Performance with Varying Ambient Temperature

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6090
Author(s):  
Steven Jackson ◽  
Eivind Brodal
Keyword(s):  
Energy Consumption ◽  
Ambient Temperature ◽  
Heat Sink ◽  
Design Parameters ◽  
Ambient Conditions ◽  
Cooling Process ◽  
Transportation Capacity ◽  
Liquefaction Process ◽  
The Impact ◽  
Heat Sink Temperature

Hydrogen used as an energy carrier can provide an important route to the decarbonization of energy supplies, but realizing this opportunity will require both significantly increased production and transportation capacity. One route to increased transportation capacity is the shipping of liquid hydrogen, but this requires an energy-intensive liquefaction step. Recent study work has shown that the energy required in this process can be reduced through the implementation of new and improved process designs, but since all low-temperature processes are affected by the available heat-sink temperature, local ambient conditions will also have an impact. The objective of this work is to identify how the energy consumption associated with hydrogen liquefaction varies with heat-sink temperature through the optimization of design parameters for a next-generation mixed refrigerant based hydrogen liquefaction process. The results show that energy consumption increases by around 20% across the cooling temperature range 5 to 50 °C. Considering just the range 20 to 30 °C, there is a 5% increase, illustrating the significant impact ambient temperature can have on energy consumption. The implications of this work are that the modelling of different liquified hydrogen based energy supply chains should take the impact of ambient temperature into account.

Efficiency Enhancement Using Cold Storage for Solar Powered Absorption Cooling of Data Centers

2008 ◽  
Author(s):  
Russell Muren ◽  
Van P. Carey
Keyword(s):  
Cold Storage ◽  
Data Center ◽  
Data Centers ◽  
Peak Load ◽  
Coefficient Of Performance ◽  
Cycle Performance ◽  
Absorption Refrigeration ◽  
Absorption Cooling ◽  
Solar Powered ◽  
The Impact

Use of solar powered absorption refrigeration to augment data center afternoon cooling has three advantages: (1) it replaces non-renewable electrically powered cooling with cooling provided by renewable power, (2) it reduces operating costs by reducing consumption of costly peak load electrical power, and (3) use of a carbon free energy source reduces the carbon footprint of the data center. In the investigation summarized here, a computational model of a lithium bromide (LiBr) and water absorption system performance was used to explore the advantages of using nighttime cooling and cold storage to enhance the performance of solar powered absorption refrigeration for peak cooling in data centers. In this study, the model accounts for thermodynamic property effects on the absorption cycle performance and finite heat exchanger effectiveness. The model is used to explore the impact of parametric changes on system coefficient of performance (COP) and system payback. The results indicate that COP enhancements above 15% can be achieved with simple cold storage strategies. The results indicate that that when optimally designed, this type of system achieves energy efficiency, offering environmental and economic advantages that make it an attractive initial step in incorporating solar powered absorption cooling into green data center designs. Strategies for maximizing the positive contributions of cold storage suggested by the results are discussed.

scholarly journals Energy Efficiency Analysis in Buildings using Dynamic Simulations

2017 ◽  
Vol 2 (5) ◽  
pp. 1
Author(s):  
Elena Eftimie
Keyword(s):  
Energy Efficiency ◽  
Energy Performance ◽  
Design Stage ◽  
Dynamic Simulations ◽  
Heating Systems ◽  
Use Phase ◽  
Comfort Parameters ◽  
The Impact

This paper proposes an analysis of factors that have a significant impact on energy efficiency in buildings. Thus, as a first objective proposes an analysis of the impact of rehabilitation and modernization of buildings in view of their energy performance improvement. A second followed objective consisted of the study of some production and use thermal energy systems in order to increase the thermal comfort. Based on a case study, this paper provides the opportunity for comparative analyses both among different insulation materials for buildings and among different heating systems. Determination of energy consumption for space heating and of the building comfort parameters was achieved using dynamic simulations by means of TRNSYS program; it was envisaged that the assessment of energy efficiency in buildings, the design stage or before their rehabilitation, is more economical than finding solutions in the use phase of buildings.

scholarly journals A novel model and design of a MEMS Stirling cooler for local refrigeration

2021 ◽  
Vol 313 ◽  
pp. 10001
Author(s):  
Sylvie Bégot ◽  
Muluken GETIE ◽  
Alpha Diallo ◽  
François Lanzetta ◽  
Magali Barthès ◽  
...  
Keyword(s):  
Microelectromechanical Systems ◽  
Coefficient Of Performance ◽  
Squeeze Film ◽  
Design Parameters ◽  
Cooling Power ◽  
Macro Scale ◽  
Stirling Engines ◽  
Parametric Studies ◽  
Scale Design ◽  
The Impact

In this paper, we present a new model design and parametric studies of a miniature Stirling cooler machine for on-site refrigeration. The MEMS (Microelectromechanical systems) technology is investigated to design this machine. The concept could be used to provide cooling at chip scale and mitigate hot spots in electronic devices. Whereas numerous works deal with Stirling engines at a macroscopic scale, only a few works concern miniaturized Stirling engines. Therefore, a model analysis giving insights of the impact of the technological choices and downsizing of the machine is needed. A base design model is presented. The model results lead to a cooling power of 10 mW and a Coefficient Of Performance of 1.45. A parametric study is conducted for operational and design parameters. Compared to macro-scale design, the same trend is observed for the influence of the thermal performance regenerator. Different trends from macroscopic engines were observed for hysteresis losses importance, and the choice of the working gas. The raise in power due to the raise in frequency expected for micro-scale devices is counterbalanced by the degradation of the COP due to the increase in thermofluidic losses. Squeeze film damping and finite speed losses can be neglected at this scale.

scholarly journals Modeling of a PCM TES Tank Used as an Alternative Heat Sink for a Water Chiller. Analysis of Performance and Energy Savings

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3652 ◽  
Author(s):  
Real-Fernández ◽  
Navarro-Esbrí ◽  
Mota-Babiloni ◽  
Barragán-Cervera ◽  
Domenech ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Energy Performance ◽  
Coefficient Of Performance ◽  
Maximum Deviation ◽  
Outlet Temperature ◽  
Vapor Compression ◽  
Transient Model

Phase change materials (PCMs) can be used in refrigeration systems to redistribute the thermal load. The main advantages of the overall system are a more stable energy performance, energy savings, and the use of the off-peak electric tariff. This paper proposes, models, tests, and analyzes an experimental water vapor compression chiller connected to a PCM thermal energy storage (TES) tank that acts as an alternative heat sink. First, the transient model of the chiller-PCM system is proposed and validated through experimental data directly measured from a test bench where the PCM TES tank is connected to a vapor compression-based chiller. A maximum deviation of 1.2 °C has been obtained between the numerical and experimental values of the PCM tank water outlet temperature. Then, the validated chiller-PCM system model is used to quantify (using the coefficient of performance, COP) and to analyze its energy performance and its dependence on the ambient temperature. Moreover, electrical energy saving curves are calculated for different ambient temperature profiles, reaching values between 5% and 15% taking the experimental system without PCM as a baseline. Finally, the COP of the chiller-PCM system is calculated for different temperatures and use scenarios, and it is compared with the COP of a conventional aerothermal chiller to determine the switch ambient temperature values for which the former provides energy savings over the latter.

Solid-State Refrigeration Based on the Electrocaloric Effect for Electronics Cooling

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Y. Sungtaek Ju
Keyword(s):  
Solid State ◽  
Experimental Studies ◽  
Heat Diffusion ◽  
Coefficient Of Performance ◽  
Irreversible Processes ◽  
Design Parameters ◽  
Cooling Power ◽  
Electrode Arrays ◽  
Actual Performance ◽  
The Impact

Subambient temperature operations of advanced semiconductor devices offer many benefits, including improved reliability, reduced leakage currents, and enhanced signal to noise ratios. We discuss a new design concept for compact solid-state refrigerators based on the electrocaloric (EC) effect. The EC refrigerators are attractive because they may approach the Carnot efficiency more closely than Peltier coolers, which involve intrinsically irreversible processes. To address parasitic losses and other practical considerations that limit the actual performance of EC coolers, we incorporate laterally interdigitated electrode arrays with high effective thermal conductivity and switchable thermal interfaces with high switching ratios and high off-state thermal resistance. Numerical simulations are used to quantify the impact of various design parameters and the expected performance of the module, focusing in particular on the heat diffusion time and RC thermal time constant. Based on the material properties reported in the literature, we project that cooling power densities >10 W/cm2 may be achieved across ΔT of the order of 10 K at coefficient of performance (COP)>10. The present work motivates further experimental studies to develop advanced electrocaloric materials and fabricate/test cooling modules to assess the feasibility of their practical application.

Impact of roof shading on building energy performance in warm & humid climatic places of India

2020 ◽  
pp. 50-64
Author(s):  
Kuladeep Kumar Sadevi ◽  
Avlokita Agrawal
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Energy Performance ◽  
General Assumption ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Passive Cooling ◽  
Base Case ◽  
U Value ◽  
The Impact

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

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