Exergy Analysis of Data Centres-Effect of the Rack Location and Airflow Direction on the Thermal Performance

2016 ◽  
Vol 846 ◽  
pp. 36-41
Author(s):  
Babak Fakhim ◽  
Masud Behnia ◽  
Steven W. Armfield
Keyword(s):  
Temperature Distribution ◽  
Numerical Analysis ◽  
Thermal Performance ◽  
Exergy Analysis ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Temperature Profiles ◽  
Data Centre ◽  
The Impact ◽  
Data Centres

In this paper, a numerical analysis of flow and temperature distribution of a small raised-floor data centre is conducted in order to evaluate the thermal performance of the data centre. The flow patterns and temperature profiles established leads to a detailed exergy analysis of the data centre, which results in better understanding of irreversibilities in room airspace. The impact of the rack location in the data centre room and the airflow direction through perforated tiles on the thermal performance of the data centre is investigated using first-law and second-law of thermodynamics.

Thermal Management of Data Centres – Effect of CRAC Location and Flow Rate on the Performance of Data Centres

2014 ◽  
Vol 553 ◽  
pp. 130-137
Author(s):  
Babak Fakhim ◽  
Faraz Rind Baloch ◽  
Srinarayana Nagarathinam ◽  
Masud Behnia ◽  
Steven W. Armfield
Keyword(s):  
Numerical Analysis ◽  
Thermal Management ◽  
Flow Rate ◽  
Thermal Performance ◽  
Air Conditioning ◽  
Performance Metrics ◽  
Electrical Energy ◽  
Data Centre ◽  
Data Centres

IT Equipment and Systems, Housed in Data Centres, Consume a Considerable Amount Ofenergy. most of the Electrical Energy Consumed by the Data Centre IT Equipment is Released in Theform of Heat. Cooling Issues will have a Significant Impact on the Thermal Manageability and Energyefficiency of the Cooling Infrastructure. in this Paper, a Numerical Analysis of Flow and Temperaturedistribution of a Raised-Floor Data Centre is Conducted in Order to Evaluate the Thermal Performance Ofthe Data Centre. the Effect of the Computer Room Air Conditioning (CRAC) Location and Flow Rate Onthe Data Centre Performance in Investigated Using Thermodynamic-Based Performance Metrics.

Experimental Evaluation of the Thermal Behavior of a Vertical Solar Tank Using Energy and Exergy Analysis

2005 ◽  
Author(s):  
Ali A. Dehghan ◽  
Mohammad H. Hosni ◽  
S. Hoda Shiryazdi
Keyword(s):  
Temperature Distribution ◽  
Flow Rate ◽  
Storage Tank ◽  
Thermal Stratification ◽  
Exergy Analysis ◽  
Hot Water ◽  
Second Law ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Hot Water Supply

The thermal performance of a Thermosyphon Domestic Solar Water Heater (DSWH) with a vertical storage tank is investigated experimentally. The system is installed on a roof - top of a four person family house and its thermal characteristics is evaluated by means of carefully measuring the temperature distribution of water inside the storage tank, solar collector flow rate and its inlet and outlet temperatures as well as load/consumption outlet and inlet temperatures and the corresponding water flow rate under a realistic operating conditions. The measurements are conducted every hour starting from morning until late night on a daily basis and continued for about 120 days during August until November 2004. It is seen that thermal stratification is well established inside the tank from 11 AM until 10 PM especially during August to September enabling the tank to provide the necessary amount of hot water at an acceptable temperature. However, thermal stratification is observed to start degrading from mid-night until morning when there is no hot water supply from the collector and due to the diffusion of heat from the top hot water layers to the bottom cold region and conduction through tank’s wall. The thermal behavior of the storage tank is also assessed based on both energy and exergy analysis and its first and second law efficiencies are calculated. It is observed that the storage tank under study has an average first law efficiency of 47.8% and is able to supply the required amount of hot water at a proper temperature. The average second law efficiency of the storage tank is observed to be 28.7% and, although is less than its first low efficiency, but is high enough to ensure that the quality of the hot water supply is well preserved. The proper level of second law efficiency is due to the preservation of the thermal stratification inside the storage tank, leading to supply of hot water at highest possible temperature and hence highest possible energy potential. Experiments are also done for no-load conditions when the storage tank only interacts with the collector, without hot water withdrawal from the tank. It is seen that for no-load condition, thermal stratification continuously develops from morning until around 16 PM after which no noticeable changes in the temperature distribution inside the tank is observed.

scholarly journals Thermal performance evaluation of a high-density data centre for cooling system under fault conditions

2019 ◽  
Vol 111 ◽  
pp. 01043
Author(s):  
Jinkyun Cho ◽  
Beungyong Park ◽  
Yongdae Jeong ◽  
Sangmoon Lee
Keyword(s):  
Thermal Performance ◽  
Cooling System ◽  
High Density ◽  
Cooling Systems ◽  
System Availability ◽  
Density Data ◽  
Data Centre ◽  
Operational Characteristics ◽  
Time Required ◽  
Data Centres

In this study, an actual 20 MW data centre project was analysed to evaluate the thermal performance of an IT server room during a cooling system outage under six fault conditions. In addition, a method of organizing and systematically managing operational stability and energy efficiency verification was identified for data centre construction in accordance with the commissioning process. It is essential to understand the operational characteristics of data centres and design optimal cooling systems to ensure the reliability of high-density data centres. In particular, it is necessary to consider these physical results and to perform an integrated review of the time required for emergency cooling equipment to operate as well as the back-up system availability time.

Numerical Simulations and Experimental Characterization of Heat Transfer From a Periodic Impingement of Droplets

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Mario F. Trujillo ◽  
Jorge Alvarado ◽  
Eelco Gehring ◽  
Guillermo S. Soriano
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Numerical Simulations ◽  
Droplet Impact ◽  
Numerical Comparison ◽  
Temperature Profiles ◽  
Conductive Heat ◽  
Radial Temperature ◽  
The Impact

In this combined experimental and simulation investigation, a stream of HFE-7100 droplets striking a prewetted surface under constant heat flux was studied. An implicit free surface capturing technique based on the Volume-of-Fluid (VOF) approach was employed to simulate this process numerically. Experimentally, an infrared thermography technique was used to measure the temperature distribution of the surface consisting of a 100 nm ITO layer on a ZnSe substrate. The heat flux was varied to investigate the heat transfer behavior of periodic droplet impingement at the solid–liquid interface. In both experiments and simulations, the morphology of the impact zone was characterized by a quasi-stationary liquid impact crater. Comparison of the radial temperature profiles on the impinging surface between the experiments and numerical simulations yielded reasonable agreement. Due to the strong radial flow emanating from successive droplet impacts, the temperature distribution inside the crater region was found to be significantly reduced from its saturated value. In effect, the heat transfer mode in this region was governed by single phase convective and conductive heat transfer, and was mostly affected by the HFE-7100 mass flow rates or the number of droplets. At higher heat fluxes, the minimum temperature, and its gradient with respect to the radial coordinate, increased considerably. Numerical comparison between average and instantaneous temperature profiles within the droplet impact region showed the effect of thermal mixing produced by the liquid crowns formed during successive droplet impact events.

scholarly journals Exergy Analysis of Integrated Gas-Steam Cycle

1994 ◽  
Author(s):  
Onkar Singh ◽  
R. Yadav
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Second Law Of Thermodynamics ◽  
Heat Recovery Boiler ◽  
Second Law ◽  
Operating Parameters ◽  
Insight Into ◽  
Steam Cycle

The thermodynamic analysis of integrated gas/steam cycle has been carried out on the basis of second law of thermodynamics. The exergy analysis provides a viable understanding of the influence of various parameters on the distribution of losses in the constituent components of the cycle. The paper also provides the insight into the influence of changing operating parameters on the performance of the waste heat recovery boiler, which in turn questions the viability of the integrated gas/steam cycle.

Discussion of Energy Consumption Analysis Method on Energy System

2011 ◽  
Vol 130-134 ◽  
pp. 1578-1581
Author(s):  
Cai Juan Zhang ◽  
Li Gang Wang ◽  
Ling Nan Wu ◽  
Tong Liu ◽  
Qiang Lu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Economic Analysis ◽  
Energy Saving ◽  
Exergy Analysis ◽  
Energy Analysis ◽  
Rapid Development ◽  
Second Law Of Thermodynamics ◽  
Energy Utilization ◽  
Second Law ◽  
Analysis Method

With the social rapid development, the earth's limited primary energy such as coal, oil, natural gas etc will be exhausted; energy problem has caused worldwide widespread attention. Therefore, under the development of renewable energy, without exception, each country is actively trying to explore the new theory and using energy-saving and technology to improve energy utilization ratio and reduce the energy consumption and the harm on environment. Scientific analysis of energy saving is an important link of digging energy saving potential, effective energy analysis method plays a pivotal role in implementing saving energy. This paper summarized several energy analysis methods on the basis of the first and second law of thermodynamics, introduced the most widely used enthalpy analysis method, entropy analysis, exergy analysis and exergy economic analysis which are based on the second law of thermodynamics, introduced emphatically the specific consumption analysis theory development with exergy analysis and exergy economic analysis.

Exergetic Efficiencies and the Exergy Content of Terrestrial Solar Radiation

2004 ◽  
Vol 126 (1) ◽  
pp. 673-676 ◽  
Author(s):  
Sean E. Wright ◽  
Marc A. Rosen
Keyword(s):  
Solar Radiation ◽  
Exergy Analysis ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Radiative Fluxes ◽  
Solar Engineering ◽  
Practical Performance ◽  
Maximum Work ◽  
Energy Conversion Devices ◽  
Better Than

In the field of solar engineering the practical performance of solar energy conversion devices is generally evaluated strictly on an energy (first law) basis. However, the second law of thermodynamics determines the maximum work potential or exergy content of radiative fluxes independent of any conceptual device. The work in this paper quantifies the effect of directional and spectral distribution of terrestrial solar radiation (SR) on its exergy content. This is particularly important as the thermodynamic character of terrestrial SR is very different from that of blackbody radiation (BR). Exergetic (second law) efficiencies compare the work output of a device to the exergy content of the radiative source flux rather than its energy flux. As a result, exergetic efficiencies reveal that the performance of devices in practice is always better than what is indicated by the corresponding energy efficiency. The results presented in this paper introduce the benefits of using exergy analysis for solar cell design, performance evaluation and optimization.

Numerical Analysis of Temperature Distribution in Generator Stator Bar with Different Insulation Thermal Performance

2014 ◽  
Vol 529 ◽  
pp. 655-659
Author(s):  
Li Zhang ◽  
Yi Ming Lei
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Numerical Analysis ◽  
Thermal Performance ◽  
Good For ◽  
Generator Stator

Accurate descripting the temperature distribution of stator bars for the genaraors with big capacity is necessary. The stator bar of one 600MW generator was simulated for getting the temperature distribution. Several methods of dealing with the insulations were compared. How the heat conduction performance of insulations is good for the heat transfer of stator bars was discussed.

Exergy Analysis of Transcritical Regenerative Organic Rankine Cycle Using Isobutane

2013 ◽  
Vol 442 ◽  
pp. 183-186
Author(s):  
Kyoung Hoon Kim
Keyword(s):  
Exergy Analysis ◽  
Organic Rankine Cycle ◽  
Internal Heat ◽  
Second Law Of Thermodynamics ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Second Law ◽  
Source Temperature ◽  
Internal Heat Exchanger ◽  
Maximum Value

Exergy analysis is performed for transcritical Organic Rankine Cycle (ORC) with internal heat exchanger based on the second law of thermodynamics. Effects of source temperature as well as turbine inlet pressure (TIP) are investigated on the exergy destructions (or anergies) of the system as well as exergy efficiency. Results show that irreversibility of the system decreases with increasing TIP or decreasing source temperature. Exergy efficiency decreases with increasing source temperature; however has a maximum value with respect to TIP.

scholarly journals ‘The optimization of a jet turbojet engine by PSO and searching algorithms’

2019 ◽  
Author(s):  
Sorush Niknamian
Keyword(s):  
Sea Level ◽  
Exergy Analysis ◽  
Pressure Ratio ◽  
Second Law Of Thermodynamics ◽  
Computer Code ◽  
Exergy Efficiency ◽  
Second Law ◽  
Combustion Chambers ◽  
Software Environment ◽  
Turbojet Engine

The turbojet engine operates on the ideal Brayton cycle (gas turbine) and consists of six main parts: diffusers, compressors, combustion chambers, turbines, afterburners and nozzles. Using computer code writing in MATLAB software environment, exergy analysis on all selected turbojet engine components, exergy analysis on J85-GE-21 turbojet engine for selective height of 10008000 meters above sea level at speeds of 200 m/s and temperatures of 10, 20 and 40 ° C have been provided and then, according to the system functions, the system is optimized based on the PSO method. For the purpose of optimization, variables of Mach number, efficiency of the compressor, turbine, nozzle and compressor pressure ratio are considered in the range of 0.6 to 1.4, 0.8 to 0.95, 0.8 to 0.95 and 7 to 10, respectively. The highest exergy efficiency of different parts of the engine at sea level with an inlet air velocity of 200 m/s corresponds to a diffuser with 73.1%. Then, the nozzle and combustion chamber are respectively 68.6% and 51.5%. The lowest exergy efficiency is related to compressor with 4%. After that, the afterburner is ranked second with 11.6%. Also, the values of entropy produced and the efficiency of the second law before optimization were 1176.99 and 479 w/k respectively and the same values after optimization were 1129 and 51.4 w/k respectively which is identified. After the optimization process, the amount of entropy produced is reduced and the efficiency of the second law of thermodynamics has increased.

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