Abstract
A coupled numerical model for nanorod-based suspension flow is constructed, and the convective heat transfer and resistance characteristics of the nanofluid duct flow are investigated. The numerical results are verified by experimental results and theoretical models. Most of nanorods are located randomly in the bulk fluid, while particles near the wall aligned with the flow direction. Friction factor of nanofluids with nanorods increases with higher particle volume concentration or aspect ratio, but the increment reduces when the Reynolds number gets larger. The relative Nusselt number is obtained to characterize the intensity of convective heat transfer. The results show that the Nusselt number of nanofluids increases when the particle volume concentration or aspect ratio becomes larger. Compared to increasing the aspect ratio of nanorods, increasing the particle volume concentration would be more effective on enhancing the convective heat transfer intensity in industrial applications although it will cause a slight increase of resistance.
Highlights
Nanofluids, which are fluids with nanosized particles suspended, are considered to be next-generation mediums for advanced heat transfer or cooling technology [1]
Many researchers have reviewed lots of measured experimental data and demonstrated that particle shape plays an important role on convective heat transfer characteristic of nanofluids [10, 11], few models can be found in literatures proposed for nanofluid flow containing nonspherical nanoparticles
Murshed et al [14] measured enhanced thermal conductivity of water-based nanofluid containing TiO2 nanorods with the aspect ratio of 4; they showed that the results Journal of Nanotechnology give 12% higher than that predicted by classical Hamilton– Crosser model. en, two models derived considering interfacial layer existence between particle and base fluid for the effective thermal conductivities of nanofluids with spherical and cylindrical nanoparticles [15]
Summary
Nanofluids, which are fluids with nanosized particles suspended, are considered to be next-generation mediums for advanced heat transfer or cooling technology [1]. Factors that can influence thermophysical properties have been discussed in many literatures, such as nanoparticle size and shape, material of particle and base fluid, particle loading, temperature, and so on, but quantitative understanding is still a lack on the topic [1, 3] Another hot topic is the flow resistance characteristic of nanofluids [6, 7]. En, two models derived considering interfacial layer existence between particle and base fluid for the effective thermal conductivities of nanofluids with spherical and cylindrical nanoparticles [15]. By comparing the defined performance evaluation criterion (PEC), nanofluids containing rod-like nanoparticles with large aspect ratio and a suitable particle volume concentration are more effective for convective heat transfer process at higher Reynolds number. E orientation and movement of nanorod are considered, and key factors that can influence the friction factor and Nusselt number of the fluid flow are discussed in sequence
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