Recent advances in modeling and simulation of nanofluid flows-Part I: Fundamentals and theory

Selection of suitable heat transfer fluid for heat dissipation is an important consideration in the design of heat exchanging systems. Nanofluid, a colloidal mixture made of a base fluid and a nanoparticle, is a new generation of heat transfer fluids becoming a high potential fluid in heat transfer applications due to enhanced thermal conductivity. Research studies about nanofluids are on the rise owing to the mounting interest and demand for nanofluids as heat transfer fluids in a wide variety of applications. Recently, nanofluid technology has a new dimension of impregnating two or more nanoparticles in base fluids, namely hybrid or composite nanofluids. This paper reviews the preparation of metal and metal oxides nanofluids and hybrid nanofluids and the various techniques used to study the physical and chemical characteristics of nanofluids. Thermo-physical and heat transfer properties of nanofluids including the improved thermal conductivity, viscosity and specific heat models for nanofluids are presented. Finally, various application areas of nanofluids, such as transportation, electronic cooling, energy storage, mechanical applications etc. are discussed.

A review on preparation, characterization, properties and applications of nanofluids

Enhanced heat transfer and friction factor of MWCNT–Fe3O4/water hybrid nanofluids

Nanofluids, i.e., well-dispersed (metallic) nanoparticles at low- volume fractions in liquids, may enhance the mixture’s thermal conductivity, knf, over the base-fluid values. Thus, they are potentially useful for advanced cooling of micro-systems. Focusing mainly on dilute suspensions of well-dispersed spherical nanoparticles in water or ethylene glycol, recent experimental observations, associated measurement techniques, and new theories as well as useful correlations have been reviewed. It is evident that key questions still linger concerning the best nanoparticle-and-liquid pairing and conditioning, reliable measurements of achievable knf values, and easy-to-use, physically sound computer models which fully describe the particle dynamics and heat transfer of nanofluids. At present, experimental data and measurement methods are lacking consistency. In fact, debates on whether the anomalous enhancement is real or not endure, as well as discussions on what are repeatable correlations between knf and temperature, nanoparticle size/shape, and aggregation state. Clearly, benchmark experiments are needed, using the same nanofluids subject to different measurement methods. Such outcomes would validate new, minimally intrusive techniques and verify the reproducibility of experimental results. Dynamic knf models, assuming non-interacting metallic nano-spheres, postulate an enhancement above the classical Maxwell theory and thereby provide potentially additional physical insight. Clearly, it will be necessary to consider not only one possible mechanism but combine several mechanisms and compare predictive results to new benchmark experimental data sets.

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Experimental and theoretical studies of nanofluid thermal conductivity enhancement: a review

A review of entropy generation in nanofluid flow

Laminar convective heat transfer and viscous pressure loss of alumina–water and zirconia–water nanofluids

Laminar convective heat transfer and viscous pressure loss were investigated for alumina-water nanofluid in a flow loop with a vertical heated tube. The experimental results are in good agreement with traditional model predictions for laminar flow, if the loading- and temperature-dependent thermophysical properties are utilized. No abnormal heat transfer enhancement was observed. The heat transfer coefficients in the entrance region and in the fully-developed region are estimated to increase by 17% and 27%, respectively, for alumina nanofluid at 6 vol%. Measured pressure loss of the nanofluid is within 20% of theory. It is concluded that the nanofluid laminar convective heat transfer and viscous pressure loss behavior can be predicted by existing models as long as the correct mixture properties are used. This finding is consistent with our previous observation for alumina nanofluid tested in the fully-developed turbulent flow regime.Copyright © 2008 by ASME

Ulzie Rea

Papers

Laminar convective heat transfer and viscous pressure loss of alumina–water and zirconia–water nanofluids

Experimental Study of Laminar Convective Heat Transfer and Viscous Pressure Loss of Alumina-Water Nanofluid