Framework Convention on Climate Change

Nanofluids are potential heat transfer fluids with enhanced thermophysical properties and heat transfer performance can be applied in many devices for better performances (i.e. energy, heat transfer and other performances). In this paper, a comprehensive literature on the applications and challenges of nanofluids have been compiled and reviewed. Latest up to date literatures on the applications and challenges in terms of PhD and Master thesis, journal articles, conference proceedings, reports and web materials have been reviewed and reported. Recent researches have indicated that substitution of conventional coolants by nanofluids appears promising. Specific application of nanofluids in engine cooling, solar water heating, cooling of electronics, cooling of transformer oil, improving diesel generator efficiency, cooling of heat exchanging devices, improving heat transfer efficiency of chillers, domestic refrigerator-freezers, cooling in machining, in nuclear reactor and defense and space have been reviewed and presented. Authors also critically analyzed some of the applications and identified research gaps for further research. Moreover, challenges and future directions of applications of nanofluids have been reviewed and presented in this paper. Based on results available in the literatures, it has been found nanofluids have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional fluids. This can be considered as one of the key parameters for enhanced performances for many of the applications of nanofluids. Because of its superior thermal performances, latest up to date literatures on this property have been summarized and presented in this paper as well. However, few barriers and challenges that have been identified in this review must be addressed carefully before it can be fully implemented in the industrial applications.

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A review on applications and challenges of nanofluids

A review of the applications of nanofluids in solar energy

A critical synthesis of thermophysical characteristics of nanofluids

Recent developments in phase change materials for energy storage applications: A review

1-D two-phase flow analysis for interlocking double layer counter flow mini-channel heat sink

Enhancement of flow boiling heat transfer by laser-induced periodic surface structures using femtosecond laser

Summary
Electrical energy can be generated by the bubble motion inside the magnetic nanofluid under the influence of an external magnetic field. The relative movement of the magnetic particles dispersed in the magnetic fluid is induced through the movement of the bubbles rising by buoyancy force. This disturbs the external magnetic field associated with the generator coil, and electrical energy can be generated. The bubble movement in this complex physical environment was studied through 2D numerical analysis. Commercial magnetic fluids EFH1 and EFH3, manufactured by Ferrotec, were selected as the working fluid for the investigation. A level set method was used to analyze the 2-phase flow of bubbles motion in the magnetic fluid.

The effect of magnetic particle concentration on the behavior of bubbles and the change of bubble flow patterns through interaction between bubbles were observed by analysis. In addition, the influence of the magnetic force caused by the external magnetic field on the behavior of the bubble was also investigated. The following results can be obtained through the analysis of this study. The high concentration of magnetic particles increases the viscosity and attenuates the rising velocity and the lateral oscillation of the bubbles. The interaction of the 2 bubbles depends on the initial relative distance. Merging occurs only between 2 bubbles within a certain initial distance, which maximizes disturbance of the surrounding magnetic fluid. The magnetic force exerted by the permanent magnets externally applied is relatively small in comparison with gravity. Therefore, the effect on the rise behavior of the bubble is not significant. In consideration of the overall external force and flow conditions, the pattern of the bubble flow that maximizes the efficiency in the present electric energy generation concept was found.

Jaeseon Lee

Papers

1-D two-phase flow analysis for interlocking double layer counter flow mini-channel heat sink

Enhancement of flow boiling heat transfer by laser-induced periodic surface structures using femtosecond laser

Numerical study on bubble behavior in magnetic nanofluid used for waste heat recovery power generation concept

Comparative study on adsorbent characteristics for adsorption thermal energy storage system

Eulerian multiphase analysis for heat transfer enhancement by CO2 sublimation in slot jet impingement