Experimental analysis of natural convection in vertical annuli filled with AlN and TiO2/mineral oil-based nanofluids

Peña, Natalia L. Cadena-de la; Rivera-Solorio, Carlos I.; Payán-Rodríguez, Luis A.; García-Cuéllar, Alejandro J.; Lopez-Salinas, Jose Luis

doi:10.1016/j.ijthermalsci.2016.08.010

Cited by 56 publications

(13 citation statements)

References 21 publications

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“…Cadena-dela et al [84] studied the thermal properties of mineral oil-based nanofluids containing dispersed aluminum nitride nanoparticles (nano-AlN) and nano-TiO 2 . Their results indicated that the thermal transfer coefficient of mineral insulating oil can be improved and the internal heat of the transformer can be easily dissipated through the addition of nanoparticles.…”

Section: Effect Of Nanoparticles On the Thermal Stability Of Mineral mentioning

confidence: 99%

Review of Research Progress on the Electrical Properties and Modification of Mineral Insulating Oils Used in Power Transformers

et al. 2018

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Abstract:In November 2017, the first ±1100 kV high-voltage direct-current power transformer in the world, which was made by Siemens in Nurnberg, passed its type test. Meanwhile, in early 2017, a ±1000 kV ultra-high voltage (UHV) substation was officially put into operation in Tianjin, China. These examples illustrate that the era of UHV power transmission is coming. With the rapid increase in power transmission voltage, the performance requirements for the insulation of power transformers are getting higher and higher. The traditional mineral oils used inside power transformers as insulating and cooling agents are thus facing a serious challenge to meet these requirements. In this review, the basic properties of traditional mineral insulating oil are first introduced. Then, the variation of electrical properties such as breakdown strength, permittivity, and conductivity during transformer operation and aging is summarized. Next, the modification of mineral insulating oil is investigated with a focus on the influence of nanoparticles on the electrical properties of nano-modified insulating oil. Recent studies on the performance of mineral oil at molecular and atomic levels by molecular dynamics simulations are then described. Finally, future research hotspots and notable research topics are discussed.

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Section: Effect Of Nanoparticles On the Thermal Stability Of Mineral mentioning

confidence: 99%

Review of Research Progress on the Electrical Properties and Modification of Mineral Insulating Oils Used in Power Transformers

et al. 2018

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“…They concluded that with the increase of particle concentration, Nusselt number deteriorates and particle concentration has a much more distinct effect at low Rayleigh number. Contrary to these works, Natalia et al 25 recently reported enhancement of Nusselt number, when using mineral oil‐based nanofluids inside vertical annuli with low nanoparticle concentration of 0.01wt% and further observed reduction at higher nanoparticle concentration.…”

Section: Introductionmentioning

confidence: 80%

Numerical studies on heat and fluid flow of nanofluid in a partially heated vertical annulus

Khan¹,

Siddiqui²

2020

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A numerical investigation on natural convective heat transfer of nanofluid (Al 2 O 3 +water) inside a partially heated vertical annulus of high aspect ratio (352) has been carried out. The computational fluid dynamics solver Ansys Fluent is used for simulation and results are presented for various volume fraction of nanoparticles (0-0.04) at different heat flux values (3-12 kW/m 2 ). Two well-known correlations for evaluating thermal conductivity and viscosity have been used. Thus different combinations of the available correlations have been set to form four models (I, II, III, and IV). Therefore, a detailed analysis has been executed to identify effects of thermophysical properties on heat transfer and fluid flow of nanofluids using different models. The results show enhancement in heat transfer coefficient with volume fraction of nanoparticles. Highest enhancement achieved is found to be 14.17% based on model III, while the minimum is around 7.27% based on model II. Dispersion of nanoparticles in base fluid declines the Nusselt number and Reynolds number with different rates depending on various models. A generalized correlation is proposed for Nusselt number of nanofluids in the annulus in terms of volume fraction of nanoparticles, Rayleigh number, Reynolds number, and Prandtl number. K E Y W O R D S modeling, nanofluids, natural convection, thermophysical properties, vertical annulus Coolant Fuel Pellet Cladding F I G U R E 1 Typical structure of nuclear reactor core [Color figure can be viewed at wileyonlinelibrary.com]

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“…Cadena-de la Peña et al [ 151 ] examined the thermo-convection of MO-based AIN and TiO 2 (0.01–0.50 wt.%) NF contained in a vertical annular cylinder. The result revealed that for both NF, Nu was enhanced when φ = 0.10 wt.% and it deteriorated at higher φ .…”

Section: Convective Heat Transfer Performance Of Nanofluidsmentioning

confidence: 99%

Experimental Research and Development on the Natural Convection of Suspensions of Nanoparticles—A Comprehensive Review

et al. 2020

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Suspensions of nanoparticles, widely known as nanofluids, are considered as advanced heat transfer media for thermal management and conversion systems. Research on their convective thermal transport is of paramount importance for their applications in such systems such as heat exchangers and solar collectors. This paper presents experimental research on the natural convection heat transfer performances of nanofluids in different geometries from thermal management and conversion perspectives. Experimental results and available experiment-derived correlations for the natural thermal convection of nanofluids are critically analyzed. Other features such as nanofluid preparation, stability evaluation and thermophysical properties of nanofluids that are important for this thermal transfer feature are also briefly reviewed and discussed. Additionally, techniques (active and passive) employed for enhancing the thermo-convection of nanofluids in different geometries are highlighted and discussed. Hybrid nanofluids are featured in this work as the newest class of nanofluids, with particular focuses on the thermophysical properties and natural convection heat transfer performance in enclosures. It is demonstrated that there has been a lack of accurate stability evaluation given the inconsistencies of available results on these properties and features of nanofluids. Although nanofluids exhibit enhanced thermophysical properties such as viscosity and thermal conductivity, convective heat transfer coefficients were observed to deteriorate in some cases when nanofluids were used, especially for nanoparticle concentrations of more than 0.1 vol.%. However, there are inconsistencies in the literature results, and the underlying mechanisms are also not yet well-understood despite their great importance for practical applications.

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Experimental analysis of natural convection in vertical annuli filled with AlN and TiO2/mineral oil-based nanofluids

Cited by 56 publications

References 21 publications

Review of Research Progress on the Electrical Properties and Modification of Mineral Insulating Oils Used in Power Transformers

Review of Research Progress on the Electrical Properties and Modification of Mineral Insulating Oils Used in Power Transformers

Numerical studies on heat and fluid flow of nanofluid in a partially heated vertical annulus

Experimental Research and Development on the Natural Convection of Suspensions of Nanoparticles—A Comprehensive Review

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