Effects of surface modification and surfactants on stability and thermophysical properties of TiO2/water nanofluids

Zhang, Hao; Qing, Shan; Gui, Qihao; Zhang, Xiao-Hui; Zhang, Aimin

doi:10.1016/j.molliq.2021.118098

Cited by 26 publications

(11 citation statements)

References 44 publications

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“…The maximum effective thermal conductivity of ZnO nanofluid with SDS/CTAB surfactant is 1.38 at 55 °C and 2.292 vol% in this paper. Correspondingly, the maximum relative thermal conductivity of ZnO nanofluid prepared by J. Jeong et al 22 was 1.22, and the highest relative thermal conductivity of TiO 2 /water nanofluid obtained by Zhang et al 41 was about 1.085. Thus, the proposed ZnO nanofluids with mixed cationic and anionic surfactant SDS/CTAB showed good relative thermal conductivity.…”

Section: Resultsmentioning

confidence: 87%

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Zhang,

Yang,

Shi

et al. 2024

ECS J. Solid State Sci. Technol.

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Metal oxide nanofluid is a new type of heat transfer medium with good thermal performance, which can be used to improve the heat collection and photothermal conversion performance of the collector. The development of new nanofluids with excellent stability, thermophysical and photothermal properties is very important for solar thermal utilization. In this paper, the ZnO nanofluids with SDS/CTAB mixed surfactants were prepared by two-step method. Their stability, thermophysical, optical and photothermal properties were studied based on experimental data. Then, the optimum concentration and preparation conditions of the proposed ZnO nanofluid adding SDS/CTAB with good photothermal performance were obtained. The results showed that the ZnO nanofluid adding SDS/CTAB mixed surfactants has good dispersion stability and thermal physical properties with thermal conductivity up to 0.772 W/(m·K). Moreover, it has the lowest transmittance of 0.10% and the highest extinction coefficient of 7.25 cm-1. Moreover, the addition of SDS/CTAB mixed surfactants makes ZnO nanofluids show better photothermal conversion efficiency, up to 87%. Therefore, ZnO nanofluids with SDS/CTAB added have great potential as working fluids for DASC.

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Section: Resultsmentioning

confidence: 87%

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Zhang,

Yang,

Shi

et al. 2024

ECS J. Solid State Sci. Technol.

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“…Figure 10 shows the enhancing effect of SDS, CTAB, and TX‐100 on nanofluid overall heat transfer coefficients. Surfactants enhance the stability of nanofluids 47–49 …”

Section: Resultsmentioning

confidence: 99%

“…Surfactants enhance the stability of nanofluids. [47][48][49] The results indicate that different surfactants enhance the overall heat conduction of nanofluids. In addition, different surfactants had varying effects.…”

Section: Effect Of Surfactantsmentioning

confidence: 90%

Nanofluids effect on the overall transfer coefficients change mechanism analysis

Zhu,

Fan

2023

Energy Science & Engineering

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The understanding of the enhanced thermal conductivity mechanism in nanofluids remains elusive, underscoring the necessity for investigating their influence on heat conduction. A comparative analysis was carried out on the overall heat transfer coefficients of SiO2, TiO2, MgO, ZrO2, CeO2, Al2O3, and Fe3O4, yielding 346.5, 442.9, 569.2, 465.6, 663.2, 562.4, and 706.2 W/m2 K, respectively. Our investigation further extended to the differential impacts of various nanofluids on heat transfer conduction coefficients, with Fe3O4 nanofluids demonstrating the greatest, and SiO2 the least, heat transfer coefficients. Importantly, these nanofluids play a cooperative role in enhancing heat transfer coefficients. Previous studies have largely concentrated on the effects of individual and mixed nanofluids on overall heat transfer coefficients, neglecting the combined effects of different nanofluids. Moreover, the mechanisms underlying these effects remain vague, with insufficient corresponding characterizations. Our study seeks to address these limitations. We also studied the impact of nanofluid concentration, pH, and temperature on heat conduction. Our results suggest that the overall heat transfer coefficient escalates with increasing nanofluid concentration and temperature. For example, the overall heat transfer coefficients for SiO2 nanofluids surged from 346.5 W/m2 K at 25°C to 369.4 W/m2 K at 35°C, 411.4 W/m2 K at 45°C, and 427.6 W/m2 K at 55°C. A rise in pH also led to an increase in overall heat transfer coefficients up to a certain point, after which they started decreasing. The zeta potentials of the aforementioned nanofluids were −12.1, −24.8, −28.6, −23.2, −35.9, −31.3, and −40.4 mV, respectively, and these potentials dwindled with an increase in pH. The influence of nanofluids on overall heat transfer may have implications for the enhanced oil recovery effect.

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“…Therefore, improving the static stability of DES-based nanofluids through adding a dispersant is not a recommended way. Surface modification on the nanoparticle is another desired way with the purpose of increasing the compatibility between nanoparticle and base solvents with the help of some covalent chemical bonding formation reactions, while the whole process will inevitably cause the increase of cost and operative complexity. − Therefore, a promising way to obtain DES-based nanofluids with good static stability in the absence of application of covalently modification on the surface of nanoparticles is in highly demand. Meanwhile, besides working as a promising heat transfer fluid, DES are actually a good solvent for chemical reactions thanks to its excellent solubility and suitable polarity, therefore, we envisioned that it is possible to comprehensive utilize the advantages of DES, in which DES are not only used as a heat transfer fluid but also employed as a solvent system to mediate the formation of nanoparticle in a “one-pot one-step” manner and realize a “self-driving” process and finally fabricate a DES nanofluid with superior stability without the participation of a dispersant.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on a Superstable Nano-TiO₂ Deep Eutectic Solvent Nanofluid for Solar Energy Harvesting

Zhao

et al. 2022

ACS Sustainable Chem. Eng.

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Nanofluids have emerged as an important working fluid for various heat transfer and thermal energy transportation demands thanks to its promising thermal conductivity. While, poor static stability brought by segregation of nanoparticle heavily hinders its wide practical utilization. In this work, a novel “one-pot one-step” strategy was realized to generate a superior stable nanofluid which can stand uneventfully for at least 2 months without observation of any sedimentation with tetrabutyl titanate as a TiO2 precursor in glycerol/chlorine chloride deep eutectic solvents. Mechanism study reveals that the good stability of this nanofluid is mainly attributed to in situ formation protocol for which the inherent aggregation of TiO2 can be theoretically avoided. Meanwhile, thermophysical properties, such as viscosity, thermal conductivity, and rheological behavior, were comprehensively studied, which indicates that the obtained nanofluids exhibit a non-Newtonian shear thinning fluid behavior with a thermal conductivity enhancement ratio up to 9.0%. More importantly, photothermal conversion efficiency of the nanofluid could reach 51.2%, and the efficiency enhancement is 181.9% over the pristine deep eutectic solvents. This work paves a novel avenue for fabricating nanofluids with super static stability and gives a supplementary idea for “one-step” nanofluids preparation process.

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Effects of surface modification and surfactants on stability and thermophysical properties of TiO2/water nanofluids

Cited by 26 publications

References 44 publications

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Nanofluids effect on the overall transfer coefficients change mechanism analysis

Experimental Study on a Superstable Nano-TiO₂ Deep Eutectic Solvent Nanofluid for Solar Energy Harvesting

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Effects of surface modification and surfactants on stability and thermophysical properties of TiO2/water nanofluids

Cited by 26 publications

References 44 publications

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Nanofluids effect on the overall transfer coefficients change mechanism analysis

Experimental Study on a Superstable Nano-TiO2 Deep Eutectic Solvent Nanofluid for Solar Energy Harvesting

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Experimental Study on a Superstable Nano-TiO₂ Deep Eutectic Solvent Nanofluid for Solar Energy Harvesting