Special Issue "Heat Transfer and Fluids Properties of Nanofluids"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Synthesis, Interfaces and Nanostructures".

Deadline for manuscript submissions: 31 January 2022.

Special Issue Editor

Prof. Dr. S M Sohel Murshed
E-Mail Website1 Website2
Guest Editor
University of Lisbon (IST), Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal
Interests: nanofluids; thermophysical properties of fluids; advanced cooling technologies; droplet-based microfluidics; energy technologies; fluids flow and phase-change heat transfer; thermal managements
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Special Issue Information

Dear Colleagues,

Nanofluids have recently emerged as a hot research field, as evidenced by the worldwide research and publication explosion on them. Despite being a popular topic, though, the real progress of this field is rather slow, and its real-world application is impeded due to various complicated challenges, including its anomalous thermophysical properties, stability, sustainable usefulness, and compatibility in many conventional systems or devices. Although extensive research efforts have been focused on thermophysical properties of nanofluids and most of the research has demonstrated significant enhancement in thermophysical properties, there remains a large volume of scattered and inconsistent data leading to not yet reaching unanimous conclusions on the enhancement and its underlying mechanisms. Additionally, a large number of research efforts have been made to develop models for the prediction of the thermophysical properties, particularly thermal conductivity of nanofluids. Again, no widely accepted theoretical models are available for nanofluids. The viscosity of nanofluids is also a key property, particularly important for their applications under a flowing condition. On top of all these, a major challenge with nanofluids is to obtain sustainable stability and persistent properties over a long duration. All these issues are very crucial for nanofluid development and applications, and research in these areas has been growing in recent years.

The aim of this Special Issue is to publish a wide range of topics related to nanofluids with special emphasis on thermophysical and heat transfer properties and features, challenges, and applications in all spectra in order make this Special Issue a useful resource for the people involved in this field as well as for the progress of this field.

Articles to be considered for this Special Issue include original full papers, communications, and critical reviews in any area/topic of the keywords and beyond.


Prof. Dr. S M Sohel Murshed
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nanofluids
  • Hybrid nanofluids
  • Ionanofluids
  • Nanosalts
  • NanoPCM
  • Nanoparticles
  • Thermophysical properties
  • Convective heat transfer performance
  • Boiling heat transfer features
  • Nanofluids in MEMs
  • Nanofluid applications

Published Papers (7 papers)

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Research

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Article
Molecular Dynamics Simulation on Behaviors of Water Nanodroplets Impinging on Moving Surfaces
Nanomaterials 2022, 12(2), 247; https://doi.org/10.3390/nano12020247 - 13 Jan 2022
Viewed by 90
Abstract
Droplets impinging on solid surfaces is a common phenomenon. However, the motion of surfaces remarkably influences the dynamical behaviors of droplets, and related research is scarce. Dynamical behaviors of water nanodroplets impinging on translation and vibrating solid copper surfaces were investigated via molecular [...] Read more.
Droplets impinging on solid surfaces is a common phenomenon. However, the motion of surfaces remarkably influences the dynamical behaviors of droplets, and related research is scarce. Dynamical behaviors of water nanodroplets impinging on translation and vibrating solid copper surfaces were investigated via molecular dynamics (MD) simulation. The dynamical characteristics of water nanodroplets with various Weber numbers were studied at five translation velocities, four vibration amplitudes, and five vibration periods of the surface. The results show that when water nanodroplets impinge on translation surfaces, water molecules not only move along the surfaces but also rotate around the centroid of the water nanodroplet at the relative sliding stage. Water nanodroplets spread twice in the direction perpendicular to the relative sliding under a higher surface translation velocity. Additionally, a formula for water nanodroplets velocity in the translation direction was developed. Water nanodroplets with a larger Weber number experience a heavier friction force. For cases wherein water nanodroplets impinge on vibration surfaces, the increase in amplitudes impedes the spread of water nanodroplets, while the vibration periods promote it. Moreover, the short-period vibration makes water nanodroplets bounce off the surface. Full article
(This article belongs to the Special Issue Heat Transfer and Fluids Properties of Nanofluids)
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Article
Enhanced Heat Transfer for NePCM-Melting-Based Thermal Energy of Finned Heat Pipe
Nanomaterials 2022, 12(1), 129; https://doi.org/10.3390/nano12010129 - 31 Dec 2021
Viewed by 192
Abstract
Using phase change materials (PCMs) in energy storage systems provides various advantages such as energy storage at a nearly constant temperature and higher energy density. In this study, we aimed to conduct a numerical simulation for augmenting a PCM’s melting performance within multiple [...] Read more.
Using phase change materials (PCMs) in energy storage systems provides various advantages such as energy storage at a nearly constant temperature and higher energy density. In this study, we aimed to conduct a numerical simulation for augmenting a PCM’s melting performance within multiple tubes, including branched fins. The suspension contained Al2O3/n-octadecane paraffin, and four cases were considered based on a number of heated fins. A numerical algorithm based on the finite element method (FEM) was applied to solve the dimensionless governing system. The average liquid fraction was computed over the considered flow area. The key parameters are the time parameter (100 t600 s) and the nanoparticles’ volume fraction (0%φ8%). The major outcomes revealed that the flow structures, the irreversibility of the system, and the melting process can be controlled by increasing/decreasing number of the heated fins. Additionally, case four, in which eight heated fins were considered, produced the largest average liquid fraction values. Full article
(This article belongs to the Special Issue Heat Transfer and Fluids Properties of Nanofluids)
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Article
Modelling Thermal Conduction in Polydispersed and Sintered Nanoparticle Aggregates
Nanomaterials 2022, 12(1), 25; https://doi.org/10.3390/nano12010025 - 22 Dec 2021
Viewed by 316
Abstract
Nanoparticle aggregation has been found to be crucial for the thermal properties of nanofluids and their performance as heating or cooling agents. Most relevant studies in the literature consider particles of uniform size with point contact only. A number of forces and mechanisms [...] Read more.
Nanoparticle aggregation has been found to be crucial for the thermal properties of nanofluids and their performance as heating or cooling agents. Most relevant studies in the literature consider particles of uniform size with point contact only. A number of forces and mechanisms are expected to lead to deviation from this ideal description. In fact, size uniformity is difficult to achieve in practice; also, overlapping of particles within aggregates may occur. In the present study, the effects of polydispersity and sintering on the effective thermal conductivity of particle aggregates are investigated. A simulation method has been developed that is capable of producing aggregates made up of polydispersed particles with tailored morphological properties. Modelling of the sintering process is implemented in a fashion that is dictated by mass conservation and the desired degree of overlapping. A noticeable decrease in the thermal conductivity is observed for elevated polydispersity levels compared to that of aggregates of monodisperse particles with the same morphological properties. Sintered nanoaggregates offer wider conduction paths through the coalescence of neighbouring particles. It was found that there exists a certain sintering degree of monomers that offers the largest improvement in heat performance. Full article
(This article belongs to the Special Issue Heat Transfer and Fluids Properties of Nanofluids)
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Article
Appearance of a Solitary Wave Particle Concentration in Nanofluids under a Light Field
Nanomaterials 2021, 11(5), 1291; https://doi.org/10.3390/nano11051291 - 14 May 2021
Cited by 1 | Viewed by 647
Abstract
In this study, the nonlinear dynamics of nanoparticle concentration in a colloidal suspension (nanofluid) were theoretically studied under the action of a light field with constant intensity by considering concentration convection. The heat and nanoparticle transfer processes that occur in this case are [...] Read more.
In this study, the nonlinear dynamics of nanoparticle concentration in a colloidal suspension (nanofluid) were theoretically studied under the action of a light field with constant intensity by considering concentration convection. The heat and nanoparticle transfer processes that occur in this case are associated with the phenomenon of thermal diffusion, which is considered to be positive in our work. Two exact analytical solutions of a nonlinear Burgers-Huxley-type equation were derived and investigated, one of which was presented in the form of a solitary concentration wave. These solutions were derived considering the dependence of the coefficients of thermal conductivity, viscosity, and absorption of radiation on the nanoparticle concentration in the nanofluid. Furthermore, an expression was obtained for the solitary wave velocity, which depends on the absorption coefficient and intensity of the light wave. Numerical estimates of the concentration wave velocity for a specific nanofluid—water/silver—are given. The results of this study can be useful in the creation of next-generation solar collectors. Full article
(This article belongs to the Special Issue Heat Transfer and Fluids Properties of Nanofluids)
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Article
Numerical Study of Natural Convection Heat Transfer in a Porous Annulus Filled with a Cu-Nanofluid
Nanomaterials 2021, 11(4), 990; https://doi.org/10.3390/nano11040990 - 12 Apr 2021
Cited by 1 | Viewed by 619
Abstract
Natural convection heat transfer in a porous annulus filled with a Cu nanofluid has been investigated numerically. The Darcy–Brinkman and the energy transport equations are employed to describe the nanofluid motion and the heat transfer in the porous medium. Numerical results including the [...] Read more.
Natural convection heat transfer in a porous annulus filled with a Cu nanofluid has been investigated numerically. The Darcy–Brinkman and the energy transport equations are employed to describe the nanofluid motion and the heat transfer in the porous medium. Numerical results including the isotherms, streamlines, and heat transfer rate are obtained under the following parameters: Brownian motion, Rayleigh number (103–105), Darcy number (10−4–10−2), nanoparticle volume fraction (0.01–0.09), nanoparticle diameter (10–90 nm), porosity (0.1–0.9), and radius ratio (1.1–10). Results show that Brownian motion should be considered. The nanoparticle volume fraction has a positive effect on the heat transfer rate, especially with high Rayleigh number and Darcy number, while the nanoparticle diameter has an inverse influence. The heat transfer rate is enhanced with the increase of porosity. The radius ratio has a significant influence on the isotherms, streamlines, and heat transfer rate, and the rate is greatly enhanced with the increase of radius ratio. Full article
(This article belongs to the Special Issue Heat Transfer and Fluids Properties of Nanofluids)
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Article
Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3
Nanomaterials 2021, 11(1), 136; https://doi.org/10.3390/nano11010136 - 08 Jan 2021
Cited by 21 | Viewed by 991
Abstract
The superiority of nanofluid over conventional working fluid has been well researched and proven. Newest on the horizon is the hybrid nanofluid currently being examined due to its improved thermal properties. This paper examined the viscosity and electrical conductivity of deionized water (DIW)-based [...] Read more.
The superiority of nanofluid over conventional working fluid has been well researched and proven. Newest on the horizon is the hybrid nanofluid currently being examined due to its improved thermal properties. This paper examined the viscosity and electrical conductivity of deionized water (DIW)-based multiwalled carbon nanotube (MWCNT)-Fe2O3 (20:80) nanofluids at temperatures and volume concentrations ranging from 15 °C to 55 °C and 0.1–1.5%, respectively. The morphology of the suspended hybrid nanofluids was characterized using a transmission electron microscope, and the stability was monitored using visual inspection, UV–visible, and viscosity-checking techniques. With the aid of a viscometer and electrical conductivity meter, the viscosity and electrical conductivity of the hybrid nanofluids were determined, respectively. The MWCNT-Fe2O3/DIW nanofluids were found to be stable and well suspended. Both the electrical conductivity and viscosity of the hybrid nanofluids were augmented with respect to increasing volume concentration. In contrast, the temperature rise was noticed to diminish the viscosity of the nanofluids, but it enhanced electrical conductivity. Maximum increments of 35.7% and 1676.4% were obtained for the viscosity and electrical conductivity of the hybrid nanofluids, respectively, when compared with the base fluid. The obtained results were observed to agree with previous studies in the literature. After fitting the obtained experimental data, high accuracy was achieved with the formulated correlations for estimating the electrical conductivity and viscosity. The examined hybrid nanofluid was noticed to possess a lesser viscosity in comparison with the mono-particle nanofluid of Fe2O3/water, which was good for engineering applications as the pumping power would be reduced. Full article
(This article belongs to the Special Issue Heat Transfer and Fluids Properties of Nanofluids)
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Review

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Review
Carbon-Based Nanofluids and Their Advances towards Heat Transfer Applications—A Review
Nanomaterials 2021, 11(6), 1628; https://doi.org/10.3390/nano11061628 - 21 Jun 2021
Cited by 5 | Viewed by 1232
Abstract
Nanofluids have opened the doors towards the enhancement of many of today’s existing thermal applications performance. This is because these advanced working fluids exhibit exceptional thermophysical properties, and thus making them excellent candidates for replacing conventional working fluids. On the other hand, nanomaterials [...] Read more.
Nanofluids have opened the doors towards the enhancement of many of today’s existing thermal applications performance. This is because these advanced working fluids exhibit exceptional thermophysical properties, and thus making them excellent candidates for replacing conventional working fluids. On the other hand, nanomaterials of carbon-base were proven throughout the literature to have the highest thermal conductivity among all other types of nanoscaled materials. Therefore, when these materials are homogeneously dispersed in a base fluid, the resulting suspension will theoretically attain orders of magnitude higher effective thermal conductivity than its counterpart. Despite this fact, there are still some challenges that are associated with these types of fluids. The main obstacle is the dispersion stability of the nanomaterials, which can lead the attractive properties of the nanofluid to degrade with time, up to the point where they lose their effectiveness. For such reason, this work has been devoted towards providing a systematic review on nanofluids of carbon-base, precisely; carbon nanotubes, graphene, and nanodiamonds, and their employment in thermal systems commonly used in the energy sectors. Firstly, this work reviews the synthesis approaches of the carbon-based feedstock. Then, it explains the different nanofluids fabrication methods. The dispersion stability is also discussed in terms of measuring techniques, enhancement methods, and its effect on the suspension thermophysical properties. The study summarizes the development in the correlations used to predict the thermophysical properties of the dispersion. Furthermore, it assesses the influence of these advanced working fluids on parabolic trough solar collectors, nuclear reactor systems, and air conditioning and refrigeration systems. Lastly, the current gap in scientific knowledge is provided to set up future research directions. Full article
(This article belongs to the Special Issue Heat Transfer and Fluids Properties of Nanofluids)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Nanoparticle Aggregation in Aqueous Solutions and their Application
Authors: Hammad Younes; Haiping Hong; G. P. Peterson
Affiliation: 1Department of Electrical Engineering South Dakota School of Mines and Technology Rapid City, South Dakota 57701, USA 2Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta, Georgia 30332, USA
Abstract: A better understanding of the bonding and aggregation process that occurs between carbon nanomaterials and metal oxide particles in aqueous solutions is important in the development of nanofluids for applications in the areas of sensor development, highly conductive thermal nanofluids, high capacity electro-magnetic shielding, nanotube alignment, polymer composites, Li-ion batteries, and many other areas. The current work investigated this process and presents a detailed description of the aggregation process between the carbon nanomaterials and metal oxide particles (metals) in various aqueous solutions. The results indicate that the charge attraction between the particles results in a strong, homogeneous bonding process that occurs within the aqueous solution and for the first time demonstrates and describes the nanoscale aggregation process. The relative importance of the many parameters that impact that aggregation process are identified and discussed. Guidelines for controlling this process are presented and discussed, along with methodologies whereby the manufacturing process can be optimized to improve the manufacturing processes commonly utilized. The results have significant commercial value in the fabrication of application specific nanofluids.

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