Nanomaterials

Research

12 pages, 3552 KiB

Open AccessArticle

Experimental Investigation of Rheological Properties and Thermal Conductivity of SiO₂–TiO₂ Composite Nanofluids Prepared by Atomic Layer Deposition

by Zalán István Várady, Thong Le Ba, Bence Parditka, Zoltán Erdélyi, Klara Hernadi, Gábor Karacs, Gyula Gróf and Imre Miklós Szilágyi

Nanomaterials 2022, 12(17), 3014; https://doi.org/10.3390/nano12173014 - 31 Aug 2022

Cited by 3 | Viewed by 1594

Abstract

In the current research, surface-modified SiO₂ nanoparticles were used upon immersion in an applied base fluid (ethylene glycol:water = 1:1). The atomic layer deposition method (ALD) was introduced to obtain a thin layer of TiO₂ to cover the surface of SiO [...] Read more.

In the current research, surface-modified SiO₂ nanoparticles were used upon immersion in an applied base fluid (ethylene glycol:water = 1:1). The atomic layer deposition method (ALD) was introduced to obtain a thin layer of TiO₂ to cover the surface of SiO₂ particles. After the ALD modification, the TiO₂ content was monitored by energy dispersive X-ray spectroscopy (EDS). Transmission electron microscopy (TEM) and FT-IR spectroscopy were applied for the particle characterization. The nanofluids contained 0.5, 1.0, and 1.5 volume% solid particles and zeta potential measurements were examined in terms of colloid stability. A rotation viscosimeter and thermal conductivity analyzer were used to study the nanofluids’ rheological properties and thermal conductivity. These two parameters were investigated in the temperature range of 20 °C and 60 °C. Based on the results, the thin TiO₂ coating significant impacted these parameters. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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19 pages, 5096 KiB

Open AccessArticle

Biosynthesis of Silver Nanoparticles and Their Applications in Harvesting Sunlight for Solar Thermal Generation

by Rebwar Faiq Talabani, Samir Mustafa Hamad, Azeez Abdullah Barzinjy and Usame Demir

Nanomaterials 2021, 11(9), 2421; https://doi.org/10.3390/nano11092421 - 17 Sep 2021

Cited by 43 | Viewed by 7277

Abstract

Silver (Ag) nanoparticles (NPs) have been synthesized through an easy, inexpensive, and ecofriendly method. Petroselinum crispum, parsley, leaf extract was utilized as a reducing, capping, and stabilizing agent, without using any hazardous chemical materials, for producing Ag NPs. The biosynthesized Ag NPs [...] Read more.

Silver (Ag) nanoparticles (NPs) have been synthesized through an easy, inexpensive, and ecofriendly method. Petroselinum crispum, parsley, leaf extract was utilized as a reducing, capping, and stabilizing agent, without using any hazardous chemical materials, for producing Ag NPs. The biosynthesized Ag NPs were characterized using different characterization techniques, namely UV-Vis, FT-IR spectroscopy, X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), dynamic light scattering (DLS), zeta potential, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), transmission electron microscope (TEM), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) analysis to investigate the optical, thermal, structural, morphological, and chemical properties of the plant extract and the biosynthesized Ag NPs. After that, the biosynthesized Ag NPs were utilized in harvesting sunlight for solar thermal generation. Surface plasmon resonance (SPR) for the green synthesized Ag NPs with the dark color were adjusted at nearly 450 nm. Once the Ag NPs are excited at the SPR, a large amount of heat is released, which causes a change in the local refractive index surrounding the Ag NPs. The released heat from the Ag NPs under the solar irradiation at the precise wavelength of plasmon resonance significantly increased the temperature of the aqueous medium. Different percentages of Ag NPs were dispersed in water and then exposed to the sunlight to monitor the temperature of the suspension. It was found that the temperature of the aqueous medium reached its highest point when 0.3 wt. % of Ag NPs was utilized. This investigation is rare and unique, and it shows that utilizing a small amount of the biosynthesized Ag NPs can increase the temperature of the aqueous medium remarkably. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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30 pages, 6697 KiB

Open AccessArticle

Thermal-Hydraulic Analysis of Parabolic Trough Collectors Using Straight Conical Strip Inserts with Nanofluids

by Nabeel Abed, Imran Afgan, Hector Iacovides, Andrea Cioncolini, Ilyas Khurshid and Adel Nasser

Nanomaterials 2021, 11(4), 853; https://doi.org/10.3390/nano11040853 - 26 Mar 2021

Cited by 34 | Viewed by 4057

Abstract

In this study, we numerically investigated the effect of swirl inserts with and without nanofluids over a range of Reynolds numbers for parabolic trough collectors with non-uniform heating. Three approaches were utilized to enhance the thermal-hydraulic performance—the variation of geometrical properties of a [...] Read more.

In this study, we numerically investigated the effect of swirl inserts with and without nanofluids over a range of Reynolds numbers for parabolic trough collectors with non-uniform heating. Three approaches were utilized to enhance the thermal-hydraulic performance—the variation of geometrical properties of a single canonical insert to find the optimized shape; the use of nanofluids and analysis of the effect of both the aforementioned approaches; the use of swirl generators and nanofluids together. Results revealed that using the straight conical strips alone enhanced the Nusselt number by 47.13%. However, the use of nanofluids along with the swirl generators increased the Nusselt number by 57.48%. These improvements reduced the thermal losses by 22.3% for swirl generators with nanofluids, as opposed to a reduction of only 15.7% with nanofluids alone. The investigation of different swirl generator designs showed various levels of improvements in terms of the overall thermal efficiency and thermal exergy efficiency. The larger swirl generator (H30mm-θ30°-N4) with 6% SiO₂ nanofluids was found to be the optimum configuration, which improved the overall collector efficiency and thermal exergy by 14.62% and 14.47%, respectively. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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20 pages, 6527 KiB

Open AccessArticle

Heat Transfer Enhancement of Small-Diameter Two-Phase Closed Thermosyphon Using Cellulose Nanofiber and Hydrophilic Surface Modification

by Dongnyeok Choi, Gyosik Jun, Woonbong Hwang and Kwon-Yeong Lee

Nanomaterials 2021, 11(3), 647; https://doi.org/10.3390/nano11030647 - 6 Mar 2021

Cited by 6 | Viewed by 1966

Abstract

In this study, we observed the Geyser phenomenon that occurs in a small-diameter two-phase closed thermosyphon (confinement number of 0.245). This phenomenon interferes with the natural circulation of the internal working fluid and increases the thermal resistance of the system. This study attempts [...] Read more.

In this study, we observed the Geyser phenomenon that occurs in a small-diameter two-phase closed thermosyphon (confinement number of 0.245). This phenomenon interferes with the natural circulation of the internal working fluid and increases the thermal resistance of the system. This study attempts to improve the thermal performance of the system using cellulose nanofiber as the working fluid and hydrophilic surface modification at the inner surface of the evaporator section. As a result, the total thermal resistance showed average reduction rates of 47.51%, 36.69%, and 22.56% at filling ratios of 0.25, 0.5, and 0.75, respectively. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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19 pages, 5501 KiB

Open AccessArticle

Comparative Study of Carbon Nanosphere and Carbon Nanopowder on Viscosity and Thermal Conductivity of Nanofluids

by Thong Le Ba, Marcell Bohus, István Endre Lukács, Somchai Wongwises, Gyula Gróf, Klara Hernadi and Imre Miklós Szilágyi

Nanomaterials 2021, 11(3), 608; https://doi.org/10.3390/nano11030608 - 28 Feb 2021

Cited by 15 | Viewed by 2978

Abstract

A comparative research on stability, viscosity (µ), and thermal conductivity (k) of carbon nanosphere (CNS) and carbon nanopowder (CNP) nanofluids was performed. CNS was synthesized by the hydrothermal method, while CNP was provided by the manufacturer. Stable nanofluids at high concentrations 0.5, 1.0, [...] Read more.

A comparative research on stability, viscosity (µ), and thermal conductivity (k) of carbon nanosphere (CNS) and carbon nanopowder (CNP) nanofluids was performed. CNS was synthesized by the hydrothermal method, while CNP was provided by the manufacturer. Stable nanofluids at high concentrations 0.5, 1.0, and 1.5 vol% were prepared successfully. The properties of CNS and CNP nanoparticles were analyzed with Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), specific surface area (S_BET), X-ray powder diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA), and energy dispersive X-ray analysis (EDX). The CNP nanofluids have the highest k enhancement of 10.61% for 1.5 vol% concentration compared to the base fluid, while the CNS does not make the thermal conductivity of nanofluids (k_nf) significantly higher. The studied nanofluids were Newtonian. The relative µ of CNS and CNP nanofluids was 1.04 and 1.07 at 0.5 vol% concentration and 30 °C. These results can be explained by the different sizes and crystallinity of the used nanoparticles. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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28 pages, 8785 KiB

Open AccessArticle

Optimization of Thermophysical and Rheological Properties of Mxene Ionanofluids for Hybrid Solar Photovoltaic/Thermal Systems

by Balaji Bakthavatchalam, Khairul Habib, R. Saidur, Navid Aslfattahi, Syed Mohd Yahya, A. Rashedi and Taslima Khanam

Nanomaterials 2021, 11(2), 320; https://doi.org/10.3390/nano11020320 - 27 Jan 2021

Cited by 40 | Viewed by 3541

Abstract

Since technology progresses, the need to optimize the thermal system’s heat transfer efficiency is continuously confronted by researchers. A primary constraint in the production of heat transfer fluids needed for ultra-high performance was its intrinsic poor heat transfer properties. MXene, a novel 2D [...] Read more.

Since technology progresses, the need to optimize the thermal system’s heat transfer efficiency is continuously confronted by researchers. A primary constraint in the production of heat transfer fluids needed for ultra-high performance was its intrinsic poor heat transfer properties. MXene, a novel 2D nanoparticle possessing fascinating properties has emerged recently as a potential heat dissipative solute in nanofluids. In this research, 2D MXenes (Ti₃C₂) are synthesized via chemical etching and blended with a binary solution containing Diethylene Glycol (DEG) and ionic liquid (IL) to formulate stable nanofluids at concentrations of 0.1, 0.2, 0.3 and 0.4 wt%. Furthermore, the effect of different temperatures on the studied liquid’s thermophysical characteristics such as thermal conductivity, density, viscosity, specific heat capacity, thermal stability and the rheological property was experimentally conducted. A computational analysis was performed to evaluate the impact of ionic liquid-based 2D MXene nanofluid (Ti₃C₂/DEG+IL) in hybrid photovoltaic/thermal (PV/T) systems. A 3D numerical model is developed to evaluate the thermal efficiency, electrical efficiency, heat transfer coefficient, pumping power and temperature distribution. The simulations proved that the studied working fluid in the PV/T system results in an enhancement of thermal efficiency, electrical efficiency and heat transfer coefficient by 78.5%, 18.7% and 6%, respectively. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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12 pages, 5196 KiB

Open AccessArticle

In Situ Synthesis of Alumina Nanoparticles in a Binary Carbonate Salt Eutectic for Enhancing Heat Capacity

by Yousof Nayfeh, Syed Muhammad Mujtaba Rizvi, Baha El Far and Donghyun Shin

Nanomaterials 2020, 10(11), 2131; https://doi.org/10.3390/nano10112131 - 27 Oct 2020

Cited by 8 | Viewed by 2912

Abstract

A binary carbonate salt eutectic (Li₂CO₃-K₂CO₃)-based nanofluid was in situ synthesized by mixing with a precursor material, aluminum nitrate nonahydrate (Al(NO₃)₃·9H₂O). Thermal decomposition of the precursor was successfully carried [...] Read more.

A binary carbonate salt eutectic (Li₂CO₃-K₂CO₃)-based nanofluid was in situ synthesized by mixing with a precursor material, aluminum nitrate nonahydrate (Al(NO₃)₃·9H₂O). Thermal decomposition of the precursor was successfully carried out to synthesize alumina (Al₂O₃) nanoparticles at 1 wt.% concentration. A thermogravimetric analysis (TGA) confirmed a complete thermal decomposition of aluminum nitrate nonahydrate to alumina nanoparticles. A transmission electron microscope (TEM) was employed to confirm the size and shape of the in situ formed nanoparticles; the result showed that they are spherical in shape and the average size was 28.7 nm with a standard deviation of 11.7 nm. Electron dispersive X-ray spectroscopy (EDS) confirmed the observed nanoparticles are alumina nanoparticles. A scanning electron microscope (SEM) was employed to study microstructural changes in the salt. A differential scanning calorimeter (DSC) was employed to study the heat capacity of the in situ synthesized nanofluid. The result showed that the heat capacity was enhanced by 21% at 550 °C in comparison with pure carbonate salt eutectic. About 10–11 °C decrease of the onset melting point of the binary carbonate salt eutectic was observed for the in situ synthesized nanofluids. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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26 pages, 5767 KiB

Open AccessArticle

Improved Thermophysical Properties and Energy Efficiency of Aqueous Ionic Liquid/MXene Nanofluid in a Hybrid PV/T Solar System

by Likhan Das, Khairul Habib, R. Saidur, Navid Aslfattahi, Syed Mohd Yahya and Fazlay Rubbi

Nanomaterials 2020, 10(7), 1372; https://doi.org/10.3390/nano10071372 - 14 Jul 2020

Cited by 81 | Viewed by 6411

Abstract

In recent years, solar energy technologies have developed an emerging edge. The incessant research to develop a power source alternative to fossil fuel because of its scarcity and detrimental effects on the environment is the main driving force. In addition, nanofluids have gained [...] Read more.

In recent years, solar energy technologies have developed an emerging edge. The incessant research to develop a power source alternative to fossil fuel because of its scarcity and detrimental effects on the environment is the main driving force. In addition, nanofluids have gained immense interest as superior heat transfer fluid in solar technologies for the last decades. In this research, a binary solution of ionic liquid (IL) + water based ionanofluids is formulated successfully with two dimensional MXene (Ti₃C₂) nano additives at three distinct concentrations of 0.05, 0.10, and 0.20 wt % and the optimum concentration is used to check the performance of a hybrid solar PV/T system. The layered structure of MXene and high absorbance of prepared nanofluids have been perceived by SEM and UV–vis respectively. Rheometer and DSC are used to assess the viscosity and heat capacity respectively while transient hot wire technique is engaged for thermal conductivity measurement. A maximum improvement of 47% in thermal conductivity is observed for 0.20 wt % loading of MXene. Furthermore, the viscosity is found to rise insignificantly with addition of Ti₃C₂ by different concentrations. Conversely, viscosity decreases substantially as the temperature increases from 20 °C to 60 °C. However, based on their thermophysical properties, 0.20 wt % is found to be the optimum concentration. A comparative analysis in terms of heat transfer performance with three different nanofluids in PV/T system shows that, IL+ water/MXene ionanofluid exhibits highest thermal, electrical, and overall heat transfer efficiency compared to water/alumina, palm oil/MXene, and water alone. Maximum electrical efficiency and thermal efficiency are recorded as 13.95% and 81.15% respectively using IL + water/MXene, besides that, heat transfer coefficients are also noticed to increase by 12.6% and 2% when compared to water/alumina and palm oil/MXene respectively. In conclusion, it can be demonstrated that MXene dispersed ionanofluid might be great a prospect in the field of heat transfer applications since they can augment the heat transfer rate considerably which improves system efficiency. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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16 pages, 2773 KiB

Open AccessArticle

The Role of the Interactions at the Tungsten Disulphide Surface in the Stability and Enhanced Thermal Properties of Nanofluids with Application in Solar Thermal Energy

by Paloma Martínez-Merino, Antonio Sánchez-Coronilla, Rodrigo Alcántara, Elisa I. Martín, Iván Carrillo-Berdugo, Roberto Gómez-Villarejo and Javier Navas

Nanomaterials 2020, 10(5), 970; https://doi.org/10.3390/nano10050970 - 18 May 2020

Cited by 12 | Viewed by 2712

Abstract

Transition metal dichalcogenides (TMCs) exhibit unique properties that make them of interest for catalysis, sensing or energy storage applications. However, few studies have been performed into nanofluids based on TMCs for heat transfer applications. In this study, nanofluids based on 2D-WS₂ are [...] Read more.

Transition metal dichalcogenides (TMCs) exhibit unique properties that make them of interest for catalysis, sensing or energy storage applications. However, few studies have been performed into nanofluids based on TMCs for heat transfer applications. In this study, nanofluids based on 2D-WS₂ are prepared by liquid phase exfoliation to analyze their potential usage in concentrating solar power plants. Periodic-Density Functional Theory (DFT) calculations were performed to rationalize the success of the exfoliation process. The hydrogen bond interaction between the hydroxyl group from PEG, which acts as a surfactant, and the S atoms of the WS₂ surface stabilizes the nanosheets in the fluid. Electron localization function (ELF) analysis is indicative of the stability of the S–H interaction from WS₂ with the molecules of surfactant due to the tendency to interact through weak intermolecular forces of van der Waals solids. Moreover, improvements in thermal properties were also found. Isobaric specific heat increased by up to 10% and thermal conductivity improved by up to 37.3%. The high stability of the nanofluids and the thermal improvements were associated with the high surface area of WS₂ nanosheets. These results suggest that these nanofluids could be a promising heat transfer fluid in concentrating solar power plants. Full article

(This article belongs to the Special Issue Nanofluids for Thermal Solar Energy)

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