Mohamoud Jama 1 and Tejvir Singh 1 and Seifelislam Mahmoud Gamaleldin 1 and Muammer Koc 1 and Ayman Samara 2 and Rima J. Isaifan 2 and Muataz A. Atieh 2 1, College of Science and Engineering, Hamad ...Bin Khalifa University (HBKU), Qatar Foundation, P.O. Box 5825, Doha, Qatar, qf.org.qa 2, Qatar Environment and Energy Research Institute (QEERI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, P.O. Box 5825, Doha, Qatar, qf.org.qa Received Aug 10, 2017; Accepted Aug 17, 2017 This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 M. Jama, T. Singh, S. M. Gamaleldin, M. Koc, A. Samara, R. J. Isaifan, M. A. Atieh, "Critical review on nanofluids: preparation, characterization, and applications," Journal of Nanomaterials, vol. 2016,DOI: 10.1155/2016/6717624, 2016.
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.
NUMERICAL COMPARISON OF VISCOSITY MODELS ON MIXED CONVECTION IN DOUBLE LID-DRIVEN CAVITY UTILIZED CuO-WATER NANOFLUID by Nader POURMAHMOUD, Ashkan GHAFOURI Link to the corrected article ...10.2298/TSCI130309048P.
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Nanofluids are complex fluids, mainly proposed to improve the efficiency of thermal systems. However, their poor stability, caused by the agglomeration and sedimentation of ...nanoparticles over time, has limited their practical application. A common technique to increase the stability of nanofluids is to add surfactants, which produce electrostatic or steric repulsion between nanoparticles, thus avoiding their agglomeration. This work evaluated the effects of surfactants and their concentration on the zeta potential and hydrodynamic diameter at different pH values as an indicator of nanofluids stability. Commercial alumina nanoparticles (0.1 wt.%) were dispersed in deionized water using two surfactants (cetyltrimethylammonium bromide, CTAB and sodium dodecylbenzenesulfonate, SDBS) at different concentrations, and the pH values were varied (2–12) by adding hydrochloric acid and sodium hydroxide. The results show the importance of the critical micelle concentration value in the nanofluids stabilization by electrostatic repulsion between nanoparticles and indicate that SDBS at a concentration of 0.064 wt.% (critical micelle concentration) offers the best dispersion conditions according with their zeta potential values, allowing high stability regardless of the pH value of the suspension.
Nanofluid flows are characterized by intricate and multi-level physics, which has led to substantial study from both fundamental and practical viewpoints. This collection examines the progress made ...in modeling and experimental methods used to study nanofluids. It specifically focuses on how these nanofluids might be used to tackle thermal challenges in renewable energy systems. The phenomenon of improving heat transfer via the use of nanofluids is well recognized; however, further research is necessary to comprehensively comprehend the interplay between nanoparticles and base fluids, as well as their influence on heat convection. Furthermore, the extensive use of nanofluids in solar thermal, geothermal, heat storage, and heat recovery systems has not been thoroughly investigated. The current difficulty is in creating precise and economical computational methods to forecast the heat transfer characteristics of nanofluids. This requires thorough experimental investigations at the system level. This edition highlights the significant contribution of nanofluid heat transfer in promoting carbon-free thermal technology and supporting the shift from fossil fuels to renewable energy sources, in line with the worldwide effort to decarbonize the energy sector.
•The unsteady flow and heat transfer past a stretching/shrinking sheet in a hybrid nanofluid is studied.•The governing equations of the problem are transformed to the similarity equations.•The ...problem is solved numerically using the boundary value problem solver (bvp4c) in Matlab software.•It is found that dual solutions exist for a certain range of the unsteadiness parameter.•A temporal stability analysis is performed to determine the stability of the dual solutions.
The unsteady flow and heat transfer past a stretching/shrinking sheet in a hybrid nanofluid is studied. The governing equations of the problem are transformed to the similarity equations by using similarity transformation technique. The problem is solved numerically using the boundary value problem solver (bvp4c) in Matlab software. The plots of the skin friction coefficient and the local Nusselt number as well as the velocity and temperature profiles for selected parameters are presented. It is found that dual solutions exist for a certain range of the unsteadiness parameter. A temporal stability analysis is performed to determine the stability of the dual solutions in a long run, and it is reveals that only one of them is stable while the other is unstable.
•Short lookback of the applications of mono-nanofluids in solar energy systems is presented.•Fabrication methods and characteristics of hybrid nanofluids are discussed briefly.•Useful correlations ...for hybrid-nanofluids are listed in this study.•Brief summary of applications of hybrid-nanofluids in solar energy systems is presented.•Issues that hinder the commercial use of hybrid nanofluids have been discussed in detail.•Economic and ecologic benefits of nanofluid based solar systems are discussed.•Recommendations are given to direct the future research.
Solar energy is the ultimate perceived solution of incessantly proliferating energy crisis. Diverse range of solar energy conversion systems has been employed to convert solar energy into desired useful form. Performance of solar energy systems is subject to the type of the working fluid that they use for solar energy conversion and transportation. Application of hybrid nanofluids in solar energy systems as working fluid has turned out to be very gainful in terms of performance, owing to distinct thermal transportation characteristics of hybrid nanofluids. Current article has briefly reviewed the studies discoursing the performance of hybrid nanofluid based solar energy systems. Moreover, the performance of solar energy systems based on mono nanofluids has also been overviewed. Considering the importance, fabrication methods and characteristics of hybrid nanofluids as well as their implications on performance parameters of solar systems have been discussed. Reviewed studies have reported remarkable enhancement in power output and efficiency of these systems. However, there are several issues associated with hybrid nanofluids that have abstained the commercialization of binary nanofluid based systems. These issues include instability, increased friction factor, rheological issues, and increased pumping power. Subsequently, economic and ecologic gains of using binary nanofluids in solar energy systems are presented.
Nanofluids are attracting many researchers for their superior thermo-physical properties with no or low penalty in pressure drop. The review is made by considering different parameters which govern ...the nanofluids characteristics, heat transfer performance and its application. Maximum effort is taken to account the contributions of different researchers available in open literature on different aspects of nanofluids such as thermal conductivity, viscosity, experimental, numerical studies on heat transfer performances and applications of nanofluids. The intention of this review is to provide an overview of the most recent studies on nanofluid in the literatures. It will be very useful for the scientific community working on nanofluid to update their knowhow about the nanofluid.
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