Investigating the effects of pH, surfactant and ionic strength on the stability of alumina/water nanofluids using DLVO theory

Zareei, Maliheh; Yoozbashizadeh, H.; Hosseini, Hamid Reza Madaah

doi:10.1007/s10973-018-7620-1

Cited by 68 publications

(27 citation statements)

References 48 publications

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“…The magnitude of the net positive charge on the polymeric backbones depends on the degree of doping 50 . Consequently, the high positive surface charge (zeta potential) induced the strong repulsive forces which kept the PANI nanotubes suspended inside base fluid (EG) 9 . Moreover, the utilization of ultra‐sonication also played a vital role in the stable dispersion of colloidal suspensions (NFs) by disintegrating the entangled (Figure 3A‐C) PANI nanotubes 37 …”

Section: Resultsmentioning

confidence: 99%

“…The NFs stability has been tailored adopting various methods, such as suspension charge balance (pH adjustment), steric hindrance (surfactants adsorption) and surface functionalities (covalent functionalization of NPs) 9 . The pH adjustment approach has limitation, as at any value below 7, NFs may cause extensive corrosive damages to the HT surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…The limited work on the PANI‐based NFs has shown that the research is still on its way as the colloidal stability, pressure losses and PP aspects were not explored much. These aspects play a vital role in long‐term operation of HTFs and are the decisive factors required in the process design 9,33,34 …”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…As moving away from this point the stability of nanofluid increases. The point of zero charge was at pH 10 and the stability of nanofluid was maximum at pH 4 …”

Section: Challenges With Nanofluidsmentioning

confidence: 99%

Performance enhancement of photovoltaic modules by nanofluid cooling: A comprehensive review

2020

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Summary Only 15‐20% of solar radiation incident on the photovoltaic (PV) cells is utilized which further reduces due to the rise in the temperature of the PV module and it also degrades the lifespan of the PV module. Therefore, numerous attempts were made to reduce this rising temperature of the PV module and different cooling techniques were employed. Nanofluid cooling is one of the potential cooling techniques for lowering the temperature of the PV module and augmenting the heat transfer by increasing the thermal conductivity of the nanofluid relative to the base fluid (BF). The experimental and numerical studies related to the cooling of PV cells with nanofluids have been reviewed. It was found that the heat transfer from the back of the PV module is enhanced with the augmentation in the concentration of nanoparticle in BF; however, some studies also demonstrate that the enhancement in the heat transfer also depends upon other factors such as the geometry at the rear of the PV module, nanoparticle material, nanoparticle size, BF, ambient conditions, etc. This review article also demonstrates the various issues with nanofluids such as instability, technological difficulties, high system costs, and the impossibility of finding a viable operational design which creates a barrier in the commercialization of the nanofluid cooling technique for PV modules.

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“…Jorge et al [209] investigated the MWCNT/water nanofluid at pH values of 2 and 5.5 and reported that the mentioned nanofluids were stable because of the deposition of amines on the MWCNT surface. Zareei et al [210] evaluated the stability of Al2O3/water nanofluid at various pH values and showed that the Al2O3/water nanofluid had the highest stability at pH=4 while pH=10 showed less stability. Each type of nanoparticle became stably dispersed at its optimized pH value that leads to optimum thermal properties.…”

Section: Stability Of Nanofluidsmentioning

confidence: 99%

Thermal conductivity, viscosity and heat transfer process in nanofluids: A critical review

Noorzadeh

Moghanlou

Vajdi

et al. 2020

jcc

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Investigating the effects of pH, surfactant and ionic strength on the stability of alumina/water nanofluids using DLVO theory

Cited by 68 publications

References 48 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

Performance enhancement of photovoltaic modules by nanofluid cooling: A comprehensive review

Thermal conductivity, viscosity and heat transfer process in nanofluids: A critical review

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