Heat transfer characteristics of nanofluids: a review

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.

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A review on nanofluids: preparation, stability mechanisms, and applications

Suspended nanoparticles in conventional fluids, called nanofluids, have been the subject of intensive study worldwide since pioneering researchers recently discovered the anomalous thermal behavior of these fluids. The enhanced thermal conductivity of these fluids with small-particle concentration was surprising and could not be explained by existing theories. Micrometer-sized particle-fluid suspensions exhibit no such dramatic enhancement. This difference has led to studies of other modes of heat transfer and efforts to develop a comprehensive theory. This article presents an exhaustive review of these studies and suggests a direction for future developments. The review and suggestions could be useful because the literature in this area is spread over a wide range of disciplines, including heat transfer, material science, physics, chemical engineering and synthetic chemistry.

https://www.tandfonline.com/doi/pdf/10.1080/01457630600904593

Heat Transfer in Nanofluids—A Review

This study provides a detailed literature review and an assessment of results of the research and development work forming the current status of nanofluid technology for heat transfer applications. Nanofluid technology is a relatively new field, and as such, the supporting studies are not extensive. Specifically, experimental results were reviewed in this study regarding the enhancement of the thermal conductivity and convective heat transfer of nanofluids relative to conventional heat transfer fluids, and assessments were made as to the state-of-the-art of verified parametric trends and magnitudes. Pertinent parameters of particle volume concentration, particle material, particle size, particle shape, base fluid material, temperature, additive, and acidity were considered individually, and experimental results from multiple research groups were used together when assessing results. To this end, published research results from many studies were recast using a common parameter to facilitate comparisons of data among research groups and to identify thermal property and heat transfer trends. The current state of knowledge is presented as well as areas where the data are presently inconclusive or conflicting. Heat transfer enhancement for available nanofluids is shown to be in the 15-40% range, with a few situations resulting in orders of magnitude enhancement.

Review and Comparison of Nanofluid Thermal Conductivity and Heat Transfer Enhancements

A review of nanofluid stability properties and characterization in stationary conditions

A novel one-step chemical method for preparation of copper nanofluids.

Interface characteristics in diffusion bonding of Fe3Al with Cr18-Ni8 stainless steel.

Fe-16Al alloy and Cr18-Ni8 austenitic stainless steel were diffusion bonded in a vacuum of 10-4Pa. Microstructure characteristics at the bonded Fe-16Al/Cr18-Ni8 interface were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD) technologies. The results indicated that FeAl, Fe3Al, Ni3Al and α-Fe (Al) solid solutions were produced at the bonded Fe-16Al/Cr18-Ni8 interface after diffusion bonding. These phases may accelerate the diffusion and even the formation of the bonded Fe-16Al/Cr18-Ni8 interface. The growth of the interface obeyed the parabolic law and its thickness (X) was expressed by X2=7.0×10-4exp(-82900/RT)(t-t0) withtemperature (T) and time (t).

Microstructure and diffusion kinetics at the bondedFe-16Al/Cr18-Ni8interface

The microstructure near a diffusion interface was studied by means of scanning electron microscopy and electron probe microscopy, and the results indicated that the interface transition zone of Fe3Al/Q235 dissimilar materials was composed of a diffusion interface, a mixed transition region, and A/B transition regions at the sides of the interface. Microstructures of the interface and base materials were interlaced to form the microstructure of layer characteristic. With increased heating temperature and holding time, the width of the Fe3Al/Q235 interface transition zone increased and the microstructure gradually became coarse. The microhardness in the diffusion transition zone was decreased and there was a peak value at the diffusion interface. The distribution of Al, Fe, and Cr in the interface transition zone was increased or decreased monotonically with some local concentration fluctuation. There was nearly no change in the concentration of C element near the interface.

Yan-sheng Yin

Papers

A novel one-step chemical method for preparation of copper nanofluids.

Interface characteristics in diffusion bonding of Fe3Al with Cr18-Ni8 stainless steel.

Microstructure and diffusion kinetics at the bondedFe-16Al/Cr18-Ni8interface

Division and microstructure feature in the interface transition zone of Fe3Al/Q235 diffusion bonding