Тип публикации: статья из журнала
Год издания: 2014
Идентификатор DOI: 10.1016/j.ijheatmasstransfer.2014.05.045
Ключевые слова: Nanofluid, Forced convection, Heat transfer, Circular tube, Thermophoresis, Numerical simulation, Alumina, Computer simulation, Heat convection, Heat flux, Heat transfer coefficients, Nanoparticles, Nusselt number, Rate constants, Tubes (components), Volume fraction, Average heat transfers, Circular tubes, Convective heat transfer, Nanofluids, Nanoparticle volume fractions, Thermophoretic effect, Two-component model, Viscosity reduction, Nanofluidics
Аннотация: Laminar convective heat transfer of water-alumina nanofluid in a circular tube with uniform heat flux is investigated numerically on the basis of two-component model, which takes into account nanoparticle transport by diffusion and thermophoresis. A new expression for thermophoretic mobility is suggested on the basis of existing experimental results and theoretical concepts. It is shown that thermophoresis leads to a significant reduction of nanoparticle volume fraction in the boundary layer near the wall. The corresponding viscosity reduction causes the velocity increase near the wall and flattening of velocity profile near the tube axis to keep the mass flow rate constant. The decrease of wall shear stress leads to the decrease of the required pressure drop. The calculations for two-component model provide higher values of the local and average heat transfer coefficients in comparison with the one-component model. The difference does not exceed 10% and decreases with increasing the thermal Peclet number. The calculations for one-component model show the independence of local and average Nusselt numbers on the nanoparticle volume fraction. The results for two-component model predict the increase of Nusselt number when the thermophoretic effect becomes stronger. The effectiveness of water-alumina nanofluid is analyzed by plotting the average heat transfer coefficient against the required pumping power. It is shown that the nanofluid shows better performance than the base fluid in the range of low pumping power and, correspondingly, low inlet velocity. (C) 2014 Elsevier Ltd. All rights reserved.
Журнал: INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
Выпуск журнала: Vol. 77
Номера страниц: 956-969
ISSN журнала: 00179310
Место издания: OXFORD
Издатель: PERGAMON-ELSEVIER SCIENCE LTD
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