Mineral Oil As an Alternative Cooling Method

2021 ◽  
Author(s):  
Bahareh Estejab ◽  
John Tobin
Keyword(s):  
Data Centers ◽  
Convective Heat Transfer Coefficient ◽  
Mineral Oil ◽  
Working Fluid ◽  
Noise Levels ◽  
Conductive Liquid ◽  
Cooling Fluid ◽  
Cooling Method ◽  
C 50 ◽  
Lower Noise

Abstract In an effort to increase the performance ceiling and reduce the size of modern personal computers especially gaming computers and consequently data centers and supercomputers, mineral oil is proposed as the working fluid to cool the system. Mineral oil operates as an avenue for transmission rather than a liquid heatsink for heat storage, which differentiates this project from traditional mineral oil systems. Using non-conductive liquid as cooling fluid brings many advantages due to its higher convective heat transfer coefficient, which leads to more compact computers, higher speed of data transition, more efficient processors, lower noise levels, and less upkeep costs with respect to data centers. Modeling and simulations are done in NX to gauge temperature expectations; which is the most important limitation when designing and testing a computer before construction. The temperature range was found to be 34°C–50°C in the motherboard and 45°C–67°C in the graphic card. Based on the modeling results, a prototype of the proposed computer is built and tested. Ultimately, this project is trying to open up an avenue through which processor design can be reconsidered.

Design Considerations Relating to Non-Thermal Aspects of Oil Immersion Cooling

2016 ◽  
Author(s):  
Jimil M. Shah ◽  
Syed Haider I. Rizvi ◽  
Indu Sravani Kota ◽  
Sahithi Reddy Nagilla ◽  
Dhaval Thakkar ◽  
...  
Keyword(s):  
Data Center ◽  
Data Centers ◽  
Energy Savings ◽  
Cost Savings ◽  
Mineral Oil ◽  
Critical Element ◽  
Air Cooling ◽  
Cooling Fluid ◽  
Trade Offs ◽  
Oil Immersion

Full submersion of servers in dielectric oils offers an opportunity for significant cooling energy savings and increased power densities for data centers. The enhanced thermal properties of oil can lead to considerable savings in both the upfront and operating costs over traditional air cooling methods. Despite recent findings showing the improved cooling efficiency and cost savings of oil as a cooling fluid, this technique is still not widely adopted. Many uncertainties and concerns persist regarding the non-thermal aspects of an oil immersion cooled data center. This paper presents useful information regarding a variety of factors related to the operation of an oil cooled data center. Pertinent material property considerations such as the chemistry, flammability, material compatibility, human health effects, and sustainability of mineral oil are discussed. A general introduction as to the chemical composition and production of mineral oil is provided. A discussion of the trade-offs in thermal performance and cost of the mineral oil is presented. The dielectric nature of oils is critical to their success as a cooling fluid for electronic applications. Factors such as temperature, voltage, and age that affect this property are reviewed. Flammability of oils is a valid concern when immersing costly IT equipment and the pertinent concerns of this aspect are reviewed. The evaporation loss of oil is also mentioned as refueling and safety are important parameters in the establishment of any facility. Leeching of materials, especially plastics, is a reoccurring concern expressed regarding mineral oil immersed IT equipment. Mineral oils are by-products of petroleum refining processes and as such may bring forth sustainability concerns associated with their use and disposal. The long term stability and performance of key physical and material parameters of oils used in applications such as high voltage power are typically monitored. The similarity and implications of the longevity of oils, when used for data center applications, will be examined. Other issues related to the design, operation, and serviceability of submerged IT equipment and racks will also be addressed. Switching to an oil immersion cooled data center typically brings about several designs and operational changes compared to a typical air-cooled approach. A critical element of oil cooling often cited by opponents of the technology is the issue of serviceability of IT equipment. This paper will discuss some of the additional features a data center may need in place to help alleviate these concerns, as well as, best practices based on experience and observations by the authors. This paper also includes Cup Burner Experiment as per ISO 14520/NFPA 2001 standard to determine the minimum design concentration of fire extinguishing agent for the class B hazard of heavy mineral oil and the class C hazard of electronic equipment as a part of the safety concerns for oil cooled data centers. The visual observations of the servers after immersion in oil for 8 months are also explained for a better view of the system related issues. The discussion presented here is based primarily on literature gathered on the subject and quantifiable data gathered by the authors.

Second Law Efficiency of an Intercooled-Reheated-Regenerative-Brayton Cycle With Variable Temperature Heat Reservoirs

2012 ◽  
Author(s):  
Vishal Anand ◽  
Krishna Nelanti ◽  
Kamlesh G. Gujar
Keyword(s):  
Gas Turbine ◽  
Variable Temperature ◽  
Pressure Ratio ◽  
Working Fluid ◽  
Thermodynamic Efficiency ◽  
Second Law ◽  
Brayton Cycle ◽  
Cooling Fluid ◽  
Turbine Engine ◽  
Temperature Heat

The gas turbine engine works on the principle of the Brayton Cycle. One of the ways to improve the efficiency of the gas turbine is to make changes in the Brayton Cycle. In the present study, Brayton Cycle with intercooling, reheating and regeneration with variable temperature heat reservoirs is considered. Instead of the usual thermodynamic efficiency, the Second law efficiency, defined on the basis of lost work, has been taken as a parameter to study the deviation of the irreversible Brayton Cycle from the ideal cycle. The Second law efficiency of the Brayton Cycle has been found as a function of reheat and intercooling pressure ratios, total pressure ratio, intercooler, regenerator and reheater effectiveness, hot and cold side heat exchanger effectiveness, turbine and compressor efficiency and heating capacities of the heating fluid, the cooling fluid and the working fluid (air). The variation of the Second law efficiency with all these parameters has been presented. From the results, it can be seen that the Second law efficiency first increases and then decreases with increase in intercooling pressure ratio and increases with increase in reheating pressure ratio. The results show that the Second law efficiency is a very good indicator of the amount of irreversibility of the cycle.

scholarly journals Applications of nanotechnology with hybrid Photovoltaic/Thermal systems

2020 ◽  
pp. 1-15
Author(s):  
Mohammed Alktranee
Keyword(s):  
Thermophysical Properties ◽  
Base Fluid ◽  
Volume Fraction ◽  
Working Fluid ◽  
Spectral Filter ◽  
Thermal Systems ◽  
Cooling Fluid ◽  
Numerical Studies ◽  
The Impact ◽  
T System

This paper appears potential of use nanofluids as a working fluid with the photovoltaic/thermal (PV/T) systems as an alternative of the conventional liquids in improves the efficiency of the hybrid PV/T system. The review highlights the impact of some parameters (base fluid, volume fraction, the concentration of nanoparticles, surfactants, shape, and size of nanoparticles) on nanofluids' thermophysical properties and their effect on the PV/T system's efficiencies. Hence, it discusses the PV/T behavior, which uses different nanofluids based on previous experimental, analytical, and numerical studies. The review concluded that using nanofluid as a cooling fluid or spectral filter contributes by enhancing the performance and increasing the PV/T system's efficiency. Thus, each type of nanofluids has certain features that contribute to removing the PV cells' excess heat by cooling it, contributing to its work's stability, and increasing its productivity. Nanofluids thermophysical properties play an intrinsic role by enhancing nanofluids' performance, thus positively reflecting on the PV/T system's performance. Despite the variation in the values of thermal and electrical efficiency, Most of the studies that used nanofluids have achieved encouraging results that appeared by improving the performance of PV/T systems.

Investigations on Transient Natural Convection in Boron Nitride-Mineral Oil Nanofluid Systems

2012 ◽  
Author(s):  
Shijo Thomas ◽  
C. B. Sobhan ◽  
Jaime Taha-Tijerina ◽  
T. N. Narayanan ◽  
P. M. Ajayan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Boron Nitride ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Mineral Oil

Nanofluids are suspensions or colloids produced by dispersing nanoparticles in base fluids like water, oil or organic fluids, so as to improve their thermo-physical properties. Investigations reported in recent times have shown that the addition of nanoparticles significantly influence the thermophysical properties, such as the thermal conductivity, viscosity, specific heat and density of base fluids. The convective heat transfer coefficient also has shown anomalous variations, compared to those encountered in the base fluids. By careful selection of the parameters such as the concentration and the particle size, it has been possible to produce nanofluids with various properties engineered depending on the requirement. A mineral oil–boron nitride nanofluid system, where an increased thermal conductivity and a reduced electrical conductivity has been observed, is investigated in the present work to evaluate its heat transfer performance under natural convection. The modified mineral oil is produced by chemically dispersing boron nitride nanoparticles utilizing a one step method to obtain a stable suspension. The mineral oil based nanofluid is investigated under transient free convection heat transfer, by observing the temperature-time response of a lumped parameter system. The experimental study is used to estimate the time-dependent convective heat transfer coefficient. Comparisons are made with the base fluid, so that the enhancement in the heat transfer coefficient under natural convection situation can be estimated.

scholarly journals Dustproof cooling of the electrical box

2018 ◽  
Vol 180 ◽  
pp. 02072
Author(s):  
Patrik Nemec ◽  
Katarína Kaduchová ◽  
Milan Malcho
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Phase Change ◽  
Thermal Performance ◽  
Working Fluid ◽  
Cooling Method ◽  
Box Space

In present are electrical boxes cooled by air through the intake hole on the bottom electrical box to the box space with electrotechnical elements and exhaust through the hole at the top to the surrounding by natural convection. This cooling method is effective but operate with the risk of contamination electrotechnical elements by dust sucking from surrounding air. The goal of this work is solution of the dustproof cooling of the electrical box by natural convection. The work deal with design of the device with the heat transfer by the phase change of the working fluid and experimental measuring its thermal performance at the cooling electrotechnical elements loaded by heat 1 200 W in the dustproof electrical box.

Impact of Tile Design on Thermal Performance of Open and Enclosed Aisles

2017 ◽  
Author(s):  
Sadegh Khalili ◽  
Mohammad I. Tradat ◽  
Kourosh Nemati ◽  
Mark Seymour ◽  
Bahgat Sammakia
Keyword(s):  
Data Centers ◽  
Area Ratio ◽  
Inlet Temperature ◽  
Open Area ◽  
Cfd Simulations ◽  
Physical Separation ◽  
Hot Air ◽  
Airflow Distribution ◽  
The Impact ◽  
Lower Noise

In raised floor data centers, tiles with high open area ratio or complex understructure are used to fulfill the demand of today’s high-density computing. Using more open tiles reduces pressure drop across the raised floor with the potential advantages of increased airflow and lower noise. However, it introduces the disadvantage of increased non-uniformity of airflow distribution. In addition, there are various tile designs available on the market with different opening shapes or understructures. Furthermore, a physical separation of cold and hot aisles (containment) has been introduced to minimize the mixing of cold and hot air. In this study, three types of floor tiles with different open area, opening geometry, and understructure are considered. Experimentally validated detail models of tiles were implemented in CFD simulations to address the impact of tile design on the cooling of IT equipment in both open and enclosed aisle configurations. Also, impacts of under-cabinet leakage on the IT equipment inlet temperature in the provisioned and under-provisioned scenarios are studied. Finally, a predictive equation for the critical under-provisioning point that can lead to a no-flow condition in IT equipment with weaker airflow systems is presented.

Experimental Investigation of the CHF Condition During Flow Boiling of Water in Microtubes

2007 ◽  
Author(s):  
Anand P. Roday ◽  
Michael K. Jensen
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Mass Flux ◽  
Flow Boiling ◽  
Heat Transfer Process ◽  
Working Fluid ◽  
Two Phase ◽  
Flow Boiling Heat Transfer ◽  
C 50 ◽  
Different Diameters

The critical heat flux (CHF) condition sets an upper limit on the flow-boiling heat transfer process. With the growing demand for the use of two-phase flow in micro and nano-sized devices, there is a strong need to understand the CHF phenomenon in channels of such small dimensions. This study experimentally investigates the critical heat flux condition during flow boiling in a single stainless steel microtube of two different diameters—0.427mm, and 0.286 mm. Degassed water is the working fluid. The effects of various parameters—diameter, mass flux (350–1500 kg/m2s), inlet subcooling (2°C–50°C), and length-to-diameter ratio (75–200) on the CHF condition are studied for the exit condition being nearly atmospheric pressure. The CHF increases with an increase in mass flux. The effect of the inlet subcooling on the CHF condition is more complex. With a decreasing inlet subcooling, the CHF decreases until saturated liquid is reached; thereafter, the CHF increases with quality.

scholarly journals Reducing Indoor Noise Levels Using People’s Perception on Greenery

2013 ◽  
Vol 11 ◽  
pp. 19-27
Author(s):  
Christina E. Mediastika ◽  
Floriberta Binarti
Keyword(s):  
Prior Knowledge ◽  
Indoor Environment ◽  
Noise Levels ◽  
People’S Perception ◽  
Open Plan ◽  
Insignificant Difference ◽  
Lower Noise

Abstract Employees working in cubicles of open-plan offices in Indonesia were studied in regard to their perception on the ability of indoor greenery to reduce noise levels. Sansevieria trifasciata and Scindapsus sp were used. Each was placed in the cubicle and noise levels were measured without plants, with Sansevieria, and with Scindapsus in place. The meters showed very insignificant difference. However, responses to surveys indicated a perception of lower noise in the presence of greenery. This seemed to be supported by prior knowledge and preconception and may be useful in creating a “quieter” indoor environment.

Classroom Noise and Teachers' Voice Production

2015 ◽  
Vol 58 (5) ◽  
pp. 1397-1406 ◽  
Author(s):  
Leena M. Rantala ◽  
Suvi Hakala ◽  
Sofia Holmqvist ◽  
Eeva Sala
Keyword(s):  
Fundamental Frequency ◽  
Ambient Noise ◽  
Noise Levels ◽  
Working Environments ◽  
Objective Metrics ◽  
Before And After ◽  
Working Day ◽  
Sound Spectrum ◽  
Voice Use ◽  
Lower Noise

Purpose The aim of this study was to research the associations between noise (ambient and activity noise) and objective metrics of teachers' voices in real working environments (i.e., classrooms). Method Thirty-two female and 8 male teachers from 14 elementary schools were randomly selected for the study. Ambient noise was measured during breaks in unoccupied classrooms and, likewise, the noise caused by pupils' activity during lessons. Voice samples were recorded before and after a working day. Voice variables measured were sound pressure level (voice SPL), fundamental frequency, jitter, shimmer, and the tilt of the sound spectrum slope (alpha ratio). Results The ambient noise correlated most often with the fundamental frequency of men and voice SPL, whereas activity noise correlated with the alpha ratio and perturbation values. Teachers working in louder ambient noise spoke more loudly before work than those working in lower noise levels. Voice variables generally changed less during work among teachers working in loud activity noise than among those working in lower noise levels. Conclusions Ambient and activity noises affect teachers' voice use. Under loud ambient noise teachers seem to speak habitually loudly, and under loud activity noise teachers' ability to react to loading deteriorates.

scholarly journals CONVECTIVE HEAT TRANSFER AND POWER SAVING APPLICATION OF SI BASED NANOPARTICLES IN A CIRCULAR PIPE

2020 ◽  
Vol 50 (4) ◽  
pp. 321-327
Author(s):  
Md Insiat Islam Rabby ◽  
Farzad Hossain ◽  
S.A.M. Shafwat Amin ◽  
Tazeen Afrin Mumu ◽  
MD Ashraf Hossain Bhuiyan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Base Fluid ◽  
Volume Fraction ◽  
Numerical Study ◽  
Convective Heat Transfer Coefficient ◽  
Circular Pipe ◽  
Working Fluid ◽  
Pumping Power

A numerical study of laminar forced convection heat transfer for the fully developed region inside a circular pipe filled with Si based nanoparticle is presented for investigating the parameters of heat transfer. Four Si based nanoparticles Si, SiC, SiO2, Si3N4 with 1-5% volume fraction have been mixed with water to prepare nanofluids which is used for working fluid to flow over a circular pipe with 5mm diameter and 700mm length. Heat transfer characteristics and pumping power have been calculated at fully developed region with constant heat flux condition on pipe wall to identify the heat transfer enhancement ratio and pumping power reduction ratio among base fluid water and each nanofluids. It is worth mentioning that utilizing SiC nanoparticle shows not only the highest increment of Nusselt number and convective heat transfer coefficient but also the highest decrement of pumping power requirement and FOM in comparison to the base fluid.

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