Details

Autor(en) / Beteiligte

• Xiong, Qingang
• Bozorg, Mehdi Vahabzadeh
• Doranehgard, Mohammad Hossein
• Hong, Kun
• Lorenzini, Giulio

Titel

A CFD investigation of the effect of non-Newtonian behavior of Cu–water nanofluids on their heat transfer and flow friction characteristics

Ist Teil von

• Journal of thermal analysis and calorimetry, 2020-02, Vol.139 (4), p.2601-2621

Ort / Verlag

Cham: Springer International Publishing

Erscheinungsjahr

2020

Link zum Volltext

Quelle

SpringerLink (Online service)

Beschreibungen/Notizen

• In the present study, a finite volume method is used to investigate heat transfer and flow friction behavior of non-Newtonian nanofluids. To study a practical application of the mentioned concept, a simple model of a parabolic trough solar receiver is simulated. The main objective of the present study is to investigate the effect of non-Newtonian behavior of the working fluid on the performance of a parabolic trough solar collector. The heat transfer fluid is assumed to be a non-Newtonian nanofluid, and the flow regime is considered to be laminar. The effect of Cu nanoparticle addition on heat transfer coefficient and flow friction of Newtonian, shear-thinning and shear-thickening nanofluids are studied. To comprehensively investigate the effect of buoyancy-driven secondary flows on the average Nusselt number and friction factor of the absorber tube, simulations are carried out for different Grashof numbers ( Gr  = 10 5 , 10 6 , 10 7 ), Reynolds numbers ( Re  = 200, 500, 1000), Cu nanoparticle volume fractions ( φ  = 0, 0.01, 0.03) and non-Newtonian power-law indexes ( n  = 0.25, 0.75, 1, 1.25, 1.75). It is concluded that when shear-thickening nanofluids are utilized as the working fluid, nanoparticle addition makes no sensible changes in the average Nusselt number. Besides, for all values of non-Newtonian power-law index, variations in volume fraction values do not have any significant effect on the friction factor. Furthermore, it is shown that when the working fluid is shear-thinning, nanoparticle addition triggers to considerable increment in Nusselt number. At high Grashof and Reynolds numbers, the ratios of Nusselt number and friction factor of shear-thinning nanofluids ( n  = 0.25) to those of shear-thickening nanofluids are up to 3.57 and 0.08, respectively.