An experimental investigation on rheological properties and heat transfer performance of MWCNT-water nanofluid flow inside vertical tubes

Akhavan-Behabadi, M.A.; Shahidi, Mohamad; Aligoodarz, Mohammad Reza; Fakoor-Pakdaman, M.

doi:10.1016/j.applthermaleng.2016.06.076

Cited by 30 publications

(8 citation statements)

References 26 publications

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“…There are many debates on the rheological properties of the nanoflu- www.nature.com/scientificreports/ ids containing carbon nanotubes (CNTs). While some researchers reported that CNT-based nanofluids show non-Newtonian behavior 46 , there are other researchers who observed that the CNT-based nanofluid with the solid concentrations less than 0.5 vol% show Newtonian behavior [47][48][49] , and increasing the solid concentration leads to changing the rheological behavior from Newtonian to non-Newtonian 50 . Thus, in the present study, the rheological properties of the studied nanofluid have been investigated over a different range of shear rates (100-800 1/s), temperatures, and solid concentration to realize that whether the studied nanofluid is a Newtonian or a non-Newtonian fluid.…”

Section: Rheological Behaviormentioning

confidence: 99%

Effects of ultrasonication time on stability, dynamic viscosity, and pumping power management of MWCNT-water nanofluid: an experimental study

Asadi

Alarifi

2020

Sci Rep

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It is known that ultrasonication has a certain effect on thermophysical properties and heat transfer of nanofluids. The present study is the continuation of the authors’ previous research on the effects of ultrasonication on the thermophysical properties of Multi-Walled Carbon Nanotubes (MWCNTs)-water nanofluid. Investigating the effects of ultrasonication time on samples’ stability, rheological properties, and pumping power of a water-based nanofluid containing MWCNTs nanoparticle is the main objective of the present study. The two-step method has been employed to prepared the samples. Moreover, a probe-type ultrasonic device has been used, and different ultrasonication times have been applied. The samples’ stability is investigated in different periods. The results revealed that prolonging the ultrasonication time to 60 min leads to improving the samples’ stability while prolonging ultrasonication time to higher than 60 min resulted in deteriorating the stability. As for dynamic viscosity, it is observed that increasing ultrasonication time to 60 min leads to decreasing the dynamic viscosity of the samples. As for pumping power, it is observed that the maximum increase in fanning friction factor ratio is less than 3%, which shows that adding MWCNTs to water does not impose a considerable penalty in the required energy for pumping power.

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Section: Rheological Behaviormentioning

confidence: 99%

Effects of ultrasonication time on stability, dynamic viscosity, and pumping power management of MWCNT-water nanofluid: an experimental study

Asadi

Alarifi

2020

Sci Rep

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“…Nanofluid viscosity studies show they present a significant higher viscosity, as comparing to their base fluid even at low MWCNT concentrations [28]. This increase is even greater for carbon nanotubes, which present differentiated behavior even at low concentrations causing viscosity increase with the reduction of the shear rate (γ).…”

Section: Viscositymentioning

confidence: 99%

“…In some studies, the thermal conductivity presents a linear increase, proportional to the MWCNT concentration, where the increase in thermal conductivity was not influenced by the temperature of the fluid [26]. In other works such as [10,21,27,28], nonlinear increases in thermal conductivity were found as a function of temperature, indicating that k nf /k bf is larger as the temperature increases.…”

Section: Introductionmentioning

confidence: 97%

MWCNT and COOH–MWCNT aqueous nanofluids: thermophysical and rheological characterization

Freitas

Silveira

Jabardo

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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The nanofluids characterization is of fundamental importance to predict their applicability in a real heat transfer situation. In addition to the transport properties, the nanofluid stability is an important factor to be studied, due to the long pumping, heating, cooling and resting cycles the fluids are usually subjected to. Carbon nanotubes have great potential to be used in nanofluids, due to their high thermal conductivity and low density. However, for aqueous medium, stability requires the use of stabilization methods. This work carried out the study of the transport properties and stability of nanofluids with multiwalled carbon nanotubes (MWCNT), using three stabilization methods: Triton X-100 (TrX-MWCNT) and Arabic gum (AG-MWCNT) as surfactants and functionalized carbon nanotubes with COOH group (COOH-MWCNT). These three nanofluids were compared to investigate the best configuration for heat transfer processes. The thermal conductivity was studied using the hot wire method; rheology was studied through three curves in rotational rheometer of concentric cylinders; specific heat was studied by the differential scanning calorimetry method; density was measured by the Coriolis Effect method; nanoparticles size and zeta potential were measured by the dynamic light scattering method. The COOH-MWCNT nanofluids present the highest thermal conductivity increase reaching 15% at 60 °C and 12% at 30 °C with 1wt% while the A.G-MWCNT and TrX-MWCNT reach 11% and 7.5%, respectively, at 30 °C. A.G-MWCNT nanofluids showed greater stability after long sonication times, while COOH-MWCNT presents best dispersion at 0.125 and 0.25 wt%, from 40 to 160 min of sonication. The specific heat increases with temperature and decreases with MWCNT concentration; however, it presents a peculiar increase in the concentration of 0.25 wt%, increasing about 0.5% and 4.5% for A.G-MWCNT and COOH-MWCNT, respectively at 60 °C. COOH-MWCNT nanofluids showed a thixotropic behavior for 0.5 and 1.0 wt% and large viscosity increase reaching 3.75 and 5.5 times the base fluid viscosity at 5 °C and 60 °C, respectively, with 1 wt%. The nanofluids A.G-MWCNT and COOH-MWCNT present good stability, as well as an increase in transport properties, optimized at a concentration close to 0.25 wt% and the COOH-MWCNT nanofluids can be stabilized simply by changing the water pH.

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“…M. A. A. Behabadi et al 3 conducted experiments using multi-walled carbon nanotubes (MWCNT). They were mixed with water with weight concentrations of 0.05, 0.1 and 0.2.…”

Section: Literature Surveymentioning

confidence: 99%

Heat-transfer enhancement of nanofluids in a car radiator

Ganesan¹,

Kannan²

2018

Mater. Tehnol.

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In recent times, enhancing the efficiency of automobiles has become very important. As part of this effort, increasing the efficiency of the heat transfer in the radiator of an automobile is also crucial. The present approach involves an addition of nanoparticles to the cooling liquid. Most of the current results were obtained using a few types of nanoparticles. Only a limited amount of work involved hybrid nanofluids including several types of nanoparticles. Multi-walled carbon nanotubes (MWCNT) were used along with aluminium-oxide nanoparticles to form a nanofluid with the base fluid (ethylene glycol (EG) + distilled water (DW)-1:1 ratio) having volume concentrations of (0.03, 0.06, 0.09 and 0.12) %. The characterization of the nanoparticles was carried out. The experiments were carried out at inlet temperatures of 40-75°C, with increments of 5°C. The volume flow rate was varied from 0.6 m 3 /h to 0.96 m 3 /h, with increments of 0.12 m 3 /h. An increase in the heat transfer of 35 % was achieved.

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An experimental investigation on rheological properties and heat transfer performance of MWCNT-water nanofluid flow inside vertical tubes

Cited by 30 publications

References 26 publications

Effects of ultrasonication time on stability, dynamic viscosity, and pumping power management of MWCNT-water nanofluid: an experimental study

Effects of ultrasonication time on stability, dynamic viscosity, and pumping power management of MWCNT-water nanofluid: an experimental study

MWCNT and COOH–MWCNT aqueous nanofluids: thermophysical and rheological characterization

Heat-transfer enhancement of nanofluids in a car radiator

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