Unexpected sharp peak in thermal conductivity of carbon nanotubes water-based nanofluids

Maré, Thierry; Halelfadl, Salma; Vaerenbergh, Stefan Van; Estellé, Patrice

doi:10.1016/j.icheatmasstransfer.2015.05.013

Cited by 33 publications

(12 citation statements)

References 30 publications

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“…Beyond 0.0011%, a reduction in thermal conductivity was also noted up to certain limit of concentration. Thus it was concluded a rigorous concentration optimization is mandatory such that the concentration of NPs remain to lower limit to avoid severe viscosity enhancements 61 . In addition the good match of phonon frequency on both sides of the interfaces in NFs may cause reduced thermal contact resistance leading to the enhanced thermal conductivity.…”

Section: Resultsmentioning

confidence: 99%

Thermal conductivity, rheology and stability analysis of 2D tungsten disulphide‐doped polyaniline‐based nanofluids: An experimental investigation

et al. 2020

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Summary In this study, polyaniline (PANI) nanocomposite‐based nanofluids (NFs) in ethylene glycol were obtained with a two‐step method by varying volume concentrations from 0.005% to 0.02%. Tungsten disulphide (WS2) nanoparticles were doped in PANI having different weight percentage (1%, 2% and 5%) via oxidative in situ polymerization employing ammonium persulphate oxidant in an acidic environment. The nanocomposites were comprehensively characterised using various techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy and high‐resolution transmission electron microscopy. The formulated NFs were extensively investigated with zeta‐sizer, particle size analyzer, thermal property analyzer and rheometer in a temperature range of 25°C to 70°C. The zeta potential results (up to 54.5 mV) were evident of extraordinary stability of NFs at all targeted temperatures along with polydispersity index <30% and mean particle/agglomerate size in the range of 335.8 to 489 nm. Additionally, a remarkable thermal conductivity improvement (~20.7%) was achieved with intrinsic PANI‐based NFs at an operating temperature of 50°C. Subsequently, it varied substantially with WS2 doping within PANI matrix and reached to 117.9%. Furthermore, the rheological measurements have revealed the viscoelastic nature of NFs along with a remarkable reduction in apparent viscosity (up to 8.4%). The temperature sweep viscosity indicated the transition of relative viscosity from high to low at a critical temperature of about 55°C. The NF10 (WS2 + PANI 5, at 0.005 vol%) was found to be the best candidate with 63.8% thermal conductivity enhancement and 6.4% viscosity reduction as compared with the base fluid at an operating temperature of 50°C. Thus, WS2 doping within PANI has proved to be crucial in the proliferation of thermal conductivity and mitigation of viscosity.

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Section: Resultsmentioning

confidence: 99%

Thermal conductivity, rheology and stability analysis of 2D tungsten disulphide‐doped polyaniline‐based nanofluids: An experimental investigation

et al. 2020

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“…Although most of the research work dealt with the effect of NPs concentration on fluid viscosity, there is lack of investigations in the other related effect factors such as the type of base fluid, application temperature limit, the size and shape of NPs [100]. Practically, in better use of NFs in thermal applications, there is a trade-off between the augmentation in thermal conductivity and increase in viscosity, taking into account the type of NPs, concentration/volume fraction, fluid temperature, shape, and size of NPs [101].…”

Section: Viscosity Incrementmentioning

confidence: 99%

Single and Hybrid Nanofluids to Enhance Performance of Flat Plate Solar Collectors: Application and Obstacles

Al-Yasiri

Szabó

Arıcı

2020

Period. Polytech. Mech. Eng.

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Solar energy represents the best alternative for traditional energy sources used in many thermal energy systems. Among solar thermal systems, Flat Plate Solar Collectors (FPSCs) are the most utilized type implemented in low and medium-level thermal domestic applications. Recently, the usage of nanofluids (NFs) to enhance FPSCs is one of the newest technologies that has drawn the attention of researchers to improve the overall thermal efficiency of solar systems. This paper briefly reviews the recent studies carried on thermal performance enhancement of FPSCs by implementing NFs (single and hybrid NFs) considering the main influential parameters such as particle concentration, particle size, and collector area. Finally, the main obstacles reported by the researchers such as the instability, viscosity, concentration limit, corrosion effect and others are identified, which is believed to be useful for interested newcomers in this research area. Based on the studies investigated in this paper, NFs, even under low concentrations, can remarkably improve the energetic and exergetic efficiency of FPSCs.

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“…These results disclose that the preferable morphology of nanofluid is decided by molecular distribution of nanoparticles associated with the molecular interactions, aspect ratio of the nanoparticles and number of contacts. P. Estelle et al [24], for the first time measured the thermal conductivity and viscosity of CNT water-based nanofluids comprising surfactant lignin. In their study, they used lignin (a by-product of wood having many molecular structure of OH branched groups) as surfactant to stabilize the MWCNT's (1.5 µm in mean length, 9.2 nm in mean diameter and thermal conductivity 3000 W/m-k) in distilled water.…”

Section: Literature Reviewmentioning

confidence: 99%

Thermal Conductivity of CNT - Wated Nanofluids: a Review

Akhilesh¹,

Santarao²,

Babu³

2018

Mechanics and Mechanical Engineering

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In heat transportation applications, water is most commonly used fluid. The efficiency of equipment used in these applications depends on thermal characteristics of water used. The thermal characteristics of water could be upgraded by suspending high thermal conducting solid nanoparticles. In this paper an attempt has been made to know how the use of surfactants and functionalization of carbon nanotube walls can affect the thermal characteristics and stability of nanofluid. A thorough analysis of collected literature revealed that carbon nanotubes have much higher thermal conductivity than any other nanoparticles and hence improve the thermal properties of water when suspended in them. Further it is concluded that suspension of carbon nanotubes in water requires use of surfactant or functionalization of carbon nanotube walls with proper group. By setting optimum pH and better dispersion, better thermal conductivity is possible. Experimental studies in the literature survey reveal that chemical stabilization techniques and physical stabilization techniques together decide the stability of the nanofluid.

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Unexpected sharp peak in thermal conductivity of carbon nanotubes water-based nanofluids

Cited by 33 publications

References 30 publications

Thermal conductivity, rheology and stability analysis of 2D tungsten disulphide‐doped polyaniline‐based nanofluids: An experimental investigation

Thermal conductivity, rheology and stability analysis of 2D tungsten disulphide‐doped polyaniline‐based nanofluids: An experimental investigation

Single and Hybrid Nanofluids to Enhance Performance of Flat Plate Solar Collectors: Application and Obstacles

Thermal Conductivity of CNT - Wated Nanofluids: a Review

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