Special Issue "Advances in Nanofluids"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Biology and Medicines".

Deadline for manuscript submissions: 15 August 2020.

Special Issue Editor

Prof. Dr. Manuel M. Piñeiro
Website
Guest Editor
Department of Applied Physics, University of Vigo, Vigo 36310, Spain
Interests: Characharacterization of nanofluids; molecular simulation; fluid phase theories and modelling; interfacial properties, confined fluids

Special Issue Information

Dear Colleagues,

The study of suspensions of nanoscale-sized particles in a base fluid, termed nanofluids, has become an extremely dynamic research field. The initial works published on this topic soon revealed intriguing heat transfer properties that were not adequately described by the existing classical colloid theories. The inferred implications of this unusual heat transfer profile for practical applications related to cooling and refrigeration boosted research on nanofluids, which soon evidenced a complexity that is still far from being rationalized. The increasing number of contributions in the literature have raised questions about the behavior shown by other transport properties, leading to interesting findings about the complex non-Newtonian viscoelastic properties of nanofluids, that also play a prominent role in their potential applications.

The number of possibilities explored to produce tailored nanofluids with tunable chemical, thermophysical, and transport properties are increasing, and the former studies considering metal or metal oxydes as dispersed particles were followed by the proposal of many alternative materials, including ceramic materials, carbides, and a plethora of carbon allotropes, from carbon nanotubes to graphite or graphene. The possibility to produce chemically modified surface nanostructures and hybrid nanomaterials with different layers and/or shapes has opened perspectives towards many other applications outside the initial heat transfer domain.

Nevertheless, most studies in this field are mainly experimental, and a theoretical framework comprehensively supporting the available laboratory evidence is still poorly developed. The complexity of the needed multiscale approach is a major obstacle, and this underlines the fact that nanofluids still represent a major challenge for the physico-chemical and engineering communities.

Prof. Dr. Manuel M Piñeiro
Guest Editor

Manuscript Submission Information

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Keywords

  • nanofluids
  • thermophysical properties
  • rheology
  • optical properties
  • chemical design
  • stability
  • industrial applications
  • biomedical applications

Published Papers (5 papers)

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Research

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Open AccessArticle
Graphene IoNanofluids, Thermal and Structural Characterization
Nanomaterials 2019, 9(11), 1549; https://doi.org/10.3390/nano9111549 - 31 Oct 2019
Cited by 1
Abstract
Graphene is considered a promising substance in applications related to the capture and reduction of the environmental impact of fluorinated gases. However, further research is still required to explore all related possibilities. In this work, the potential use in this context of nanofluids [...] Read more.
Graphene is considered a promising substance in applications related to the capture and reduction of the environmental impact of fluorinated gases. However, further research is still required to explore all related possibilities. In this work, the potential use in this context of nanofluids (NFs), obtained by dispersing graphene nanosheets in fluorinated ionic liquids (FILs) is investigated. As a starting step, a thermal and structural characterization for this type of IoNanofluids (IoNFs) is presented. The highly nanostructured nature of FILs has been recently demonstrated. The presence of fluorinated moieties is responsible for enhancing the accommodation of solutes such as small gases. The strong tendency to self-assemble forming continuous and supramolecular structures, and the versatility to rearrange in several conformational features allows the stabilization of nano colloidal systems. It is essential to perform a comprehensive study of their structural features to understand the behavior of this type of heterogeneous systems. Therefore, we present screening on the phase and structural behavior of these novel IoNFs to discover and develop optimized systems where FILs turn out to be advantageous. Thermogravimetric analysis (TGA) was employed to evaluate IoNFs mass losses with temperature, and their solid–fluid phase transitions were located using a differential scanning calorimeter (DSC). Their rheological properties were also determined through oscillatory experiments, obtaining the viscous and loss moduli. In addition, the structural percolation transition was also identified. Full article
(This article belongs to the Special Issue Advances in Nanofluids)
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Open AccessArticle
Experimental Investigation of Thermal and Pressure Performance in Computer Cooling Systems Using Different Types of Nanofluids
Nanomaterials 2019, 9(9), 1231; https://doi.org/10.3390/nano9091231 - 29 Aug 2019
Cited by 1
Abstract
A modern computer generates a great amount of heat while working. In order to secure appropriate working conditions by extracting the heat, a specific mechanism should be used. This research paper presents the effect of nanofluids on the microchannel heat sink performance of [...] Read more.
A modern computer generates a great amount of heat while working. In order to secure appropriate working conditions by extracting the heat, a specific mechanism should be used. This research paper presents the effect of nanofluids on the microchannel heat sink performance of computer cooling systems experimentally. CeO2, Al2O3 and ZrO2 nanoparticles suspended in 20% ethylene glycol and 80% distilled water are used as working fluids in the experiment. The concentration of the nanoparticles ranges from 0.5% to 2%, mass flow rate ranges from 0.028 kg/s to 0.084 kg/s, and the ambient temperature ranges from 25 °C to 40 °C. Regarding the thermal component, parameters such as thermophysical properties of the nanofluids and base fluids, central processing unit (CPU) temperature, heat transfer coefficient, pressure drop, and pumping power have been experimentally investigated. The results show that CeO2-EG/DW, at a concentration of 2% and a mass flow rate of 0.084 kg/s, has with 8% a lower temperature than the other nanofluids and with 29% a higher heat transfer coefficient compared with the base fluid. The Al2O3-EG/DW shows the lowest pressure drop and pumping power, while the CeO2-EG/DW and ZrO2-EG/DW show the highest. However, a slight increase of pumping power and pressure drop can be accepted, considering the high improvement that the nanofluid brings in computer cooling performance compared to the base fluid. Full article
(This article belongs to the Special Issue Advances in Nanofluids)
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Open AccessArticle
Significantly Enhanced Electrical Performances of Eco-Friendly Dielectric Liquids for Harsh Conditions with Fullerene
Nanomaterials 2019, 9(7), 989; https://doi.org/10.3390/nano9070989 - 09 Jul 2019
Cited by 3
Abstract
The eco-friendly vegetable liquid is increasingly used because of the growing demand for environmentally friendly dielectric liquid. A vegetable liquid/fullerene nanofluid was fabricated via ultrasonic processing with good dispersion of the fullerene nanoparticles. It was observed that a small amount of fullerene (~100 [...] Read more.
The eco-friendly vegetable liquid is increasingly used because of the growing demand for environmentally friendly dielectric liquid. A vegetable liquid/fullerene nanofluid was fabricated via ultrasonic processing with good dispersion of the fullerene nanoparticles. It was observed that a small amount of fullerene (~100 mg/L) can significantly improve the electrical properties of vegetable insulating liquid (dissipation factor decreased by 20.1%, volume resistivity increased by 23.3%, and Alternating Current (AC) dielectric breakdown strength increased by 8.6%). Meanwhile, the trace amount of fullerene is also able to improve the electrical performances (i.e., dissipation factor and electrical resistivity) of the vegetable nanofluid under harsh conditions of long-term thermal aging compared with the blank contrast. The reduced acid values (25%) and dissolved decomposition gases (58.2% for hydrogen) in the aged vegetable nanofluid indicate the inhibition of molecule decomposition of vegetable liquid with fullerene. The improved electrical performances and thermal resistance of the vegetable nanofluid contribute to the electron affinity of fullerene proved by calculation of electron density distribution on the surface. The thermogravimetric analysis of the nanofluid under different atmospheres interprets that the oxygen absorbed inevitably in the fullerene contributes to the performance deterioration of the nanofluids during the initial aging. This work provides a potential method towards eco-friendly dielectric liquid with great electrical performances for harsh environments. Full article
(This article belongs to the Special Issue Advances in Nanofluids)
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Open AccessArticle
A Promising Nano-Insulating-Oil for Industrial Application: Electrical Properties and Modification Mechanism
Nanomaterials 2019, 9(5), 788; https://doi.org/10.3390/nano9050788 - 23 May 2019
Cited by 2
Abstract
Despite being discovered more than 20 years ago, nanofluids still cannot be used in the power industry. The fundamental reason is that nano-insulating oil has poor stability, and its electrical performance decreases under negative impulse voltage. We found that C60 nanoparticles can [...] Read more.
Despite being discovered more than 20 years ago, nanofluids still cannot be used in the power industry. The fundamental reason is that nano-insulating oil has poor stability, and its electrical performance decreases under negative impulse voltage. We found that C60 nanoparticles can maintain long-term stability in insulating oil without surface modification. C60 has strong electronegativity and photon absorption ability, which can comprehensively improve the electrical performance of insulating oil. This finding has great significance for the industrial application of nano-insulating oil. In this study, six concentrations of nano-C60 modified insulating oil (CMIO) were prepared, and their breakdown strength and dielectric properties were tested. The thermally stimulated current (TSC) curves of fresh oil (FO) and CMIO were experimentally determined. The test results indicate that C60 nanoparticles can simultaneously improve the positive and negative lightning impulse and power frequency breakdown voltage of insulating oil, while hardly increasing dielectric loss. At 150 mg/L, the positive and negative lightning impulse breakdown voltages of CMIO increased by 7.51% and 8.33%, respectively, compared with those of FO. The AC average breakdown voltage reached its peak (18.0% higher compared with FO) at a CMIO concentration of 200 mg/L. Based on the test results and the special properties of C60, we believe that changes in the trap parameters, the strong electron capture ability of C60, and the absorption capacity of C60 for photons enhanced the breakdown performance of insulating oil by C60 nanoparticles. Full article
(This article belongs to the Special Issue Advances in Nanofluids)
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Review

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Open AccessReview
On the Role of Nanofluids in Thermal-hydraulic Performance of Heat Exchangers—A Review
Nanomaterials 2020, 10(4), 734; https://doi.org/10.3390/nano10040734 - 11 Apr 2020
Abstract
Heat exchangers are key components in many of the devices seen in our everyday life. They are employed in many applications such as land vehicles, power plants, marine gas turbines, oil refineries, air-conditioning, and domestic water heating. Their operating mechanism depends on providing [...] Read more.
Heat exchangers are key components in many of the devices seen in our everyday life. They are employed in many applications such as land vehicles, power plants, marine gas turbines, oil refineries, air-conditioning, and domestic water heating. Their operating mechanism depends on providing a flow of thermal energy between two or more mediums of different temperatures. The thermo-economics considerations of such devices have set the need for developing this equipment further, which is very challenging when taking into account the complexity of the operational conditions and expansion limitation of the technology. For such reasons, this work provides a systematic review of the state-of-the-art heat exchanger technology and the progress towards using nanofluids for enhancing their thermal-hydraulic performance. Firstly, the general operational theory of heat exchangers is presented. Then, an in-depth focus on different types of heat exchangers, plate-frame and plate-fin heat exchangers, is presented. Moreover, an introduction to nanofluids developments, thermophysical properties, and their influence on the thermal-hydraulic performance of heat exchangers are also discussed. Thus, the primary purpose of this work is not only to describe the previously published literature, but also to emphasize the important role of nanofluids and how this category of advanced fluids can significantly increase the thermal efficiency of heat exchangers for possible future applications. Full article
(This article belongs to the Special Issue Advances in Nanofluids)
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