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Jacopo Buongiorno

Bio: Jacopo Buongiorno is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: Boiling & Nanofluid. The author has an hindex of 40, co-authored 170 publications receiving 12125 citations. Previous affiliations of Jacopo Buongiorno include Electric Power Research Institute & Tokyo Electric Power Company.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors considered seven slip mechanisms that can produce a relative velocity between the nanoparticles and the base fluid and concluded that only Brownian diffusion and thermophoresis are important slip mechanisms in nanofluids.
Abstract: Nanofluids are engineered colloids made of a base fluid and nanoparticles (1-100 nm) Nanofluids have higher thermal conductivity' and single-phase heat transfer coefficients than their base fluids In particular the heat transfer coefficient increases appear to go beyond the mere thermal-conductivity effect, and cannot be predicted by traditional pure-fluid correlations such as Dittus-Boelter's In the nanofluid literature this behavior is generally attributed to thermal dispersion and intensified turbulence, brought about by nanoparticle motion To test the validity of this assumption, we have considered seven slip mechanisms that can produce a relative velocity between the nanoparticles and the base fluid These are inertia, Brownian diffusion, thermophoresis, diffusioplwresis, Magnus effect, fluid drainage, and gravity We concluded that, of these seven, only Brownian diffusion and thermophoresis are important slip mechanisms in nanofluids Based on this finding, we developed a two-component four-equation nonhomogeneous equilibrium model for mass, momentum, and heat transport in nanofluids A nondimensional analysis of the equations suggests that energy transfer by nanoparticle dispersion is negligible, and thus cannot explain the abnormal heat transfer coefficient increases Furthermore, a comparison of the nanoparticle and turbulent eddy time and length scales clearly indicates that the nanoparticles move homogeneously with the fluid in the presence of turbulent eddies so an effect on turbulence intensity is also doubtful Thus, we propose an alternative explanation for the abnormal heat transfer coefficient increases: the nanofluid properties may vary significantly within the boundary layer because of the effect of the temperature gradient and thermophoresis For a heated fluid, these effects can result in a significant decrease of viscosity within the boundary layer, thus leading to heat transfer enhancement A correlation structure that captures these effects is proposed

5,329 citations

Journal ArticleDOI
TL;DR: The International Nanofluid Property Benchmark Exercise (INPBE) as mentioned in this paper was held in 1998, where the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or "nanofluids" was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady state methods, and optical methods.
Abstract: This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about the sample average with only few outliers. The thermal conductivity of the nanofluids was found to increase with particle concentration and aspect ratio, as expected from classical theory. There are (small) systematic differences in the absolute values of the nanofluid thermal conductivity among the various experimental approaches; however, such differences tend to disappear when the data are normalized to the measured thermal conductivity of the basefluid. The effective medium theory developed for dispersed particles by Maxwell in 1881 and recently generalized by Nan et al. [J. Appl. Phys. 81, 6692 (1997)], was found to be in good agreement with the experimental data, suggesting that no anomalous enhancement of thermal conductivity was achieved in the nanofluids tested in this exercise.

942 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the pool boiling characteristics of dilute dispersions of alumina, zirconia and silica nanoparticles in water and found that a significant enhancement in critical heat flux (CHF) can be achieved at modest nanoparticle concentrations (< 0.1% by volume).

806 citations

Journal ArticleDOI
TL;DR: In this paper, heat transfer and viscous pressure loss were investigated for alumina-water and zirconia-water nanofluids in a flow loop with a vertical heated tube.

472 citations

Journal ArticleDOI
TL;DR: The turbulent convective heat transfer behavior of alumina (Al 2 O 3 ) and zirconia (ZrO 2 ) nanoparticle dispersions in water is investigated experimentally in a flow loop with a horizontal tube test section at various flow rates (9000
Abstract: The turbulent convective heat transfer behavior of alumina (Al 2 O 3 ) and zirconia (ZrO 2 ) nanoparticle dispersions in water is investigated experimentally in a flow loop with a horizontal tube test section at various flow rates (9000

455 citations


Cited by
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01 Jan 2015
TL;DR: The work of the IPCC Working Group III 5th Assessment report as mentioned in this paper is a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change, which has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.
Abstract: The talk with present the key results of the IPCC Working Group III 5th assessment report. Concluding four years of intense scientific collaboration by hundreds of authors from around the world, the report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.

3,224 citations

Book ChapterDOI
01 Jan 1982
TL;DR: In this article, the authors discuss leading problems linked to energy that the world is now confronting and propose some ideas concerning possible solutions, and conclude that it is necessary to pursue actively the development of coal, natural gas, and nuclear power.
Abstract: This chapter discusses leading problems linked to energy that the world is now confronting and to propose some ideas concerning possible solutions. Oil deserves special attention among all energy sources. Since the beginning of 1981, it has merely been continuing and enhancing the downward movement in consumption and prices caused by excessive rises, especially for light crudes such as those from Africa, and the slowing down of worldwide economic growth. Densely-populated oil-producing countries need to produce to live, to pay for their food and their equipment. If the economic growth of the industrialized countries were to be 4%, even if investment in the rational use of energy were pushed to the limit and the development of nonpetroleum energy sources were also pursued actively, it would be extremely difficult to prevent a sharp rise in prices. It is evident that it is absolutely necessary to pursue actively the development of coal, natural gas, and nuclear power if a physical shortage of energy is not to block economic growth.

2,283 citations

01 Jan 2007

1,932 citations

Journal ArticleDOI
TL;DR: In this article, a similarity solution is presented which depends on the Prandtl number Pr, Lewis number Le, Brownian motion number Nb and thermophoresis number Nt.

1,565 citations

Journal ArticleDOI
TL;DR: In this article, the authors summarized the recent progress on the study of nanofluids, such as the preparation methods, the evaluation methods for the stability of nanometrics, and the ways to enhance the stability for nanofl fluids, and presented the broad range of current and future applications in various fields including energy and mechanical and biomedical fields.
Abstract: Nanofluids, the fluid suspensions of nanomaterials, have shown many interesting properties, and the distinctive features offer unprecedented potential for many applications. This paper summarizes the recent progress on the study of nanofluids, such as the preparation methods, the evaluation methods for the stability of nanofluids, and the ways to enhance the stability for nanofluids, the stability mechanisms of nanofluids, and presents the broad range of current and future applications in various fields including energy and mechanical and biomedical fields. At last, the paper identifies the opportunities for future research.

1,320 citations