Comparative study of high ambient inlet temperature effects on the performance of air vs. liquid cooled IT equipment

Sahini, Manasa; Chowdhury, Uschas; Siddarth, Ashwin; Pradip, Tanmay; Agonafer, Dereje; Zeigham, Roy; Metcalf, Jeff; Branton, Steve

doi:10.1109/itherm.2017.7992534

Cited by 12 publications

(4 citation statements)

References 3 publications

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“…Such heat sink contact temperature reductions are of practical interest, since they can benefit the lifespan and the performance of electronic chips. For instance, Sahini, et al [46] found that increasing the coolant inlet temperature from 25°C to 50°C of an Enterprise-class server increased the processor electric power consumption by 4%. According to equation (12), the total thermal resistance of the microchannel is equal to the temperature difference shown in Figure 6, divided by the bottom wall heat flux 𝑞̇.…”

Section: The Effect Of Fin Design On Thermal Characteristicsmentioning

confidence: 99%

Numerical analysis on the thermal performance of microchannel heat sinks with Al2O3 nanofluid and various fins

Ali

Angelino

Rona

2021

Applied Thermal Engineering

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Section: The Effect Of Fin Design On Thermal Characteristicsmentioning

confidence: 99%

Numerical analysis on the thermal performance of microchannel heat sinks with Al2O3 nanofluid and various fins

Ali

Angelino

Rona

2021

Applied Thermal Engineering

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“…Both are directly related to the CPU load ratio. Sahini [31] found by experiments that the server inlet air temperature also has a significant impact on the server rack power and server fan speed. Based on Sahini's experimental results, we derived the performance curves of the server power and server fan air flow rate, which are inputs for the prototype models in EnergyPlus.…”

Section: Supply and Return Approach Temperaturesmentioning

confidence: 99%

“…For calculating the real IT load under each specific setting, the efficiency factors of the CPU power and the IT equipment fan power were considered. We referred to two sets of empirical fitted curves to describe the efficiency factors, i.e., CPU power ratio and ITE fan air flow ratio under different ITE inlet temperatures and load ratios [31]. They correspond to Curve 1 and Curve 2 in Figure 3, respectively.…”

Section: Server Airflow and Power Sensitivitymentioning

confidence: 99%

Prototype energy models for data centers

Sun

Luo

et al. 2021

Energy and Buildings

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Data centers in the United States consume about two percent of the nation's electricity. Because heat gains from IT equipment drive cooling demand, data centers offer unique opportunities for energy savings. However, no prototype energy model for data centers is available in the suite of existing U.S. Department of Energy's Commercial Prototype Building Models. This study presented the development of two new data center prototype models and their implementation in OpenStudio and EnergyPlus. The small-size data center model represents a computer room in a building served by computer room air conditioners (CRACs); while the large-sized model represents stand-alone data centers served by computer room air handlers (CRAHs) with a central chiller plant. For each data center model, two levels of IT equipment (ITE) load density were considered, to cover the wide range of IT power density of data centers: 40 and 100 W/ft 2 (430 and 1,076 W/m 2) for the computer room, and 100 and 500 W/ft 2 (1,076 and 5,382 W/m 2) for the standalone data center. All other assumptions, such as building envelope, lighting, HVAC efficiencies and schedules, were based on the minimal requirements of ASHRAE Standard 90.1 at various vintages. We introduced a novel concept of supply and return air approach temperatures to capture the essential effects of non-uniform airflow and temperature distribution in data centers. The approach temperatures were pre-computed by computational fluid dynamics (CFD) simulations for various configurations of ITE loads and airflow containment management in data centers. A new feature was developed in EnergyPlus to implement the approach temperature method. A case study was conducted to demonstrate the use of the data center models. The two data center models cover all U.S. climate zones and can be used to evaluate energy saving measures for data centers, as well as to support development of data center energy efficiency codes and standards.

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“…Druzhinin et al [12,13] found that increasing the inlet water temperature to the RSC Tornado server from 19 to 65 decreases the computational performance of the server from 2.72 to 2.44 GFLOPS/W while increasing the server power consumption from 365 to 398W, respectively. Sahini et al [14] investigated the effect of high inlet coolant temperature on the CPU temperatures and static power losses at the Enterprise-class server and found that increasing the inlet water temperature from 25 to 50 increases the CPU average temperatures by 21 and the power consumption of the server by about 4%. Ramakrishnan et al [15] investigated the effect of the coolant flow rate on the thermal resistance of a CoolIT System's DCLC cold plate.…”

Section: Introductionmentioning

confidence: 99%

Rack Level Study of Hybrid Liquid/Air Cooled Servers: The Impact of Flow Distribution and Pumping Configuration on Central Processing Units Temperature

Kadhim

Kapur

Summers

et al. 2019

Heat Transfer Engineering

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The flow distribution and central processing unit (CPU) temperatures inside a rack of thirty 1U (single rack unit) Sun Fire V20z servers retrofitted with direct to chip liquid cooling and two coolant pumping configuration scenarios (central and distributed) are investigated using the EPANET open source network flow software. The results revealed that the servers in the top of the rack and close to the cooling distribution unit can receive up 30% higher flow rate than the servers in the bottom of the rack, depending on the pumping scenario. This results in a variation in the CPU temperatures depending on the position in the rack. Optimisation analysis is carried out and shows that increasing the flow distribution manifold's dimensions can reduce the flow variation through the servers and increase the total coolant flow rate in the rack by roughly 10%. In addition, activating the small pumps in the direct to chip liquid cooling loops inside the servers (distributed pumping) resulted in an increase of 2 in the CPU temperatures at the high computational workload.

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Comparative study of high ambient inlet temperature effects on the performance of air vs. liquid cooled IT equipment

Cited by 12 publications

References 3 publications

Numerical analysis on the thermal performance of microchannel heat sinks with Al2O3 nanofluid and various fins

Numerical analysis on the thermal performance of microchannel heat sinks with Al2O3 nanofluid and various fins

Prototype energy models for data centers

Rack Level Study of Hybrid Liquid/Air Cooled Servers: The Impact of Flow Distribution and Pumping Configuration on Central Processing Units Temperature

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