Abstract
Due to the significantly enhanced thermal properties of nanofluids, a considerably large amount of research has been performed to further develop this heat transfer medium. Not only has research been carried out in homogeneous suspensions of nanoparticles but research into the effectiveness of hybrid nanofluids has also been conducted. It has been observed
experimentally that the critical heat flux (CHF) can also be enhanced by having low volume concentrations of nanoparticles in suspension. An up to 700% for hybrid opposed to up to 300% for having non-hybrid nanoparticles have been reported. This review covers the models used to predict the enhancements of thermal conductivity and convective heat transfer coefficient.
Moreover, the main focus is given to the CHF enhancement with the possible mechanisms and explanations proposed for such an enhancement. Nanoparticles’ deposition onto the heating surface together with the contact angle reduction and capillary wicking are thought to be the underlying causes for CHF enhancement. The Zuber correlation and Kandllikar’s model have
been found to be able to describe some experimental CHE enhancement data reasonably well. Onto the stability issue, among the three commonly used methods: chemical stabilisation, polymer stabilisation and sonication, it is thought that the chemical approach is favored as it is less affected by the operating and environmental conditions. Towards potential industrial
applications, quantitative understanding of the enhancement mechanisms and maintaining long period of stability together with real time characterisation techniques of nanoparticles in fluids are thought to still remain as the main obstacles lying ahead to be addressed, and indeed, these are still the real challenges.
experimentally that the critical heat flux (CHF) can also be enhanced by having low volume concentrations of nanoparticles in suspension. An up to 700% for hybrid opposed to up to 300% for having non-hybrid nanoparticles have been reported. This review covers the models used to predict the enhancements of thermal conductivity and convective heat transfer coefficient.
Moreover, the main focus is given to the CHF enhancement with the possible mechanisms and explanations proposed for such an enhancement. Nanoparticles’ deposition onto the heating surface together with the contact angle reduction and capillary wicking are thought to be the underlying causes for CHF enhancement. The Zuber correlation and Kandllikar’s model have
been found to be able to describe some experimental CHE enhancement data reasonably well. Onto the stability issue, among the three commonly used methods: chemical stabilisation, polymer stabilisation and sonication, it is thought that the chemical approach is favored as it is less affected by the operating and environmental conditions. Towards potential industrial
applications, quantitative understanding of the enhancement mechanisms and maintaining long period of stability together with real time characterisation techniques of nanoparticles in fluids are thought to still remain as the main obstacles lying ahead to be addressed, and indeed, these are still the real challenges.
Original language | English |
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Article number | 7310207 |
Pages (from-to) | 35-56 |
Number of pages | 22 |
Journal | International Journal of Nanoscience and Nanoengineering |
Volume | 4 |
Issue number | 3 |
Publication status | Published - 10 Aug 2018 |