Liquid Nanofluids Research Articles

Ionic-Liquid-Based Nanofluids and Their Heat-Transfer Applications: A Comprehensive Review.

Due to the improved thermophysical characteristics of ionic liquids (ILs), such as their strong ionic conductivity, negligible vapor pressure, and thermal stability at high temperatures, they are being looked at viable contender for future heat transfer fluids. Additionally, the dispersing nanoparticles can further improve the thermophysical characteristics and thermal performance of ionic liquids, which is one of the emerging research interests to increase the heat transfer rates of the thermal devices. The latest investigations about the utilization of ionic liquid nanofluids as a heat transfer fluid is summarized in this work. These summaries are broken down into three types: (a) the thermophysical parameters including thermal conductivity, viscosity, density, and specific heat of ionic liquids (base fluids), (b) the thermophysical properties like thermal conductivity, viscosity, density, and viscosity of ionic liquids based nanofluids (IL nanofluids), and (iii) utilization of IL nanofluids as a heat transfer fluid in the thermal devices. The techniques for measuring the thermophysical characteristics and the synthesis of IL nanofluids are also covered. The suggestions for potential future research directions for IL nanofluids are summarized.

Dynamic Monitoring and Enhanced Oil Recovery Evaluation of the Water Flooding Process of Liquid Nanofluids in Tight Reservoirs

The CT scanning technology can observe fluid saturation distribution in the rock at different times during water flooding in tight reservoirs. However, this technology has not been used to study the water flooding characteristics in changing the wettability of liquid nanofluids. First, this study evaluated the basic properties of a nonionic liquid nanofluid, including the contact angle (CA), interfacial tension (IFT), and aqueous stability tests. Then, the water flooding process in tight rocks is dynamically monitored by the CT scanning technology. The water flooding characteristics of liquid nanofluids changing reservoir wettability are analyzed by measuring the rock’s water phase saturation distribution at different times. Finally, the spontaneous imbibition experiment evaluated the enhanced oil recovery of liquid nanofluids. The results show that the particle size of the liquid nanofluid is at the nanometer level (7.5 nm) and can change the wettability of oil-wet to water-wet. Liquid nanofluid has low interfacial tension and can exist stably in brine with a high salinity (20,000–50,000 ppm). In water flooding, the front profile of water phase saturation changes obviously, and it is driven forward with a similar “piston” type. Compared with the brine water, the water invasion front gradually becomes uniform, which is strong evidence that a liquid nanofluid can change the wettability of rocks. Besides, the invasion depth of the fracturing fluid with liquid nanofluids is deeper than that of brine water and displaces more oil. Finally, the spontaneous imbibition test shows that the recovery factor of high-concentration (1 wt %) liquid nanofluids increases by 28.9% compared with that of brine water. This paper provides theoretical support for applying liquid nanofluids in tight reservoirs.

Tuneable-by-design copper oxide nanoparticles in ionic liquid nanofluids.

In this study, copper oxide nanoparticles (CuO-NPs) were synthesised in an ionic liquid, [C2MIm][CnHnCO2], and the respective copper(II) carboxylate precursors. Heating the solution to 120 °C caused a colour change from blue to red, indicating a change in copper salt coordination and nanoparticle formation. Crystallography and UV-Vis spectroscopy were used to monitor the transition upon temperature changes. The particle formation was characterised using TEM and SWAXS analyses. The results showed that different anion chain lengths led to different particle sizes. When using copper(II) acetate precursors, the transformation resulted in CuO(I,II) clusters (<1 nm), depending on the imidazolium-based cation used. However, using a copper(II) octanoate precursor, small CuO-NPs in the range of 10-25 nm were formed, while larger CuO-NPs were obtained using a copper(II) butanoate precursor in the range of 10-61 nm.

Effect of Nanoparticle Addition on Evaporation of Jet Fuel Liquid Films and Nanoparticle Deposition Patterns during Evaporation.

Jet fuel-based nanofluid fuel has been proposed for improving the energy density and utilization efficiency of jet fuel that is widely applied in aircraft powered by aviation turbine engines. To recognize the evaporation behavior of the formed liquid film as a jet fuel-based nanofluid sprayed onto the engine wall or blades, this paper presents the evaporation and deposition characteristics of the jet fuel-based nanofluid liquid film adhering on the hydrophilic substrate. The changes in contact line, contact angle, volume, and deposition pattern during liquid film evaporation under different substrate temperatures, different nanoparticle concentrations, and different kinds of nanoparticle additions were investigated. The effect of nano-Al addition on the evaporation kinetics and deposition pattern of the nano-Al/jet fuel (nAl/JF) nanofluid fuel liquid film was explored. Repeated pinning and de-pinning of contact lines during evaporation occurred, resulting in the formation of concentric multi-ring deposition patterns. The addition of nano-Al increased the evaporation rate and shortened the evaporation lifetime, demonstrating a promotion effect on jet fuel liquid film evaporation. The existence of an energy barrier shows that the movement of three-phase contact lines on the hydrophilic solid surface presented not a continuous sliding behavior but a "stick-slip" behavior, and there were multiple jumps in contact lines and contact angles. Finally, a comparison was made with the deposition pattern of jet fuel liquid films with different graphite and Fe nanoparticle additions during evaporation. The mechanism of deposition phenomena was deeply revealed by the analysis of capillary flow and Marangoni recirculation.

Performance Comparison of a Microchannel Heat Sink Using Different Nano-Liquid Metal Fluid Coolant: A Numerical Study

Abstract This article presents performance comparison between different liquid metal-based nanofluids termed as nano-liquid metal fluids in a microchannel heat sink to achieve ultimate cooling solutions without sacrificing the compact structure and heavy computing speed. The hydraulic and thermal performance of nanofluids having five different liquid metals (Ga, GaIn, EGaIn, GaSn, and EGaInSn) as base fluid and four different nanoparticles (carbon nanotube (CNT), Al2O3, Cu, and diamond) as solute are evaluated comparing with water-based nanofluids. Three-dimensional flow inside miniaturized channels are predicted using single-phase and two-phase numerical simulations. Numerical models are validated against data obtained from experimental studies from the literature. Three different grids are developed, and several element sizes were compared to obtain the grid independence. Upon evaluation, the study can point out that liquid metal-based nanofluids can generate much superior heat transport characteristics with more than 3.41 times higher heat transfer coefficient compared to conventional water-based nanofluids. GaIn–CNT combination exhibits the best thermal solution possible with a heat transfer coefficient increment of 2.68%, 17.19%, 22.16%, and 2.62% over CNT particle-based EGaIn, EGaInSn, Ga, GaSn liquid metal, respectively, for Re = 750. Considering hydraulic performance, performance evaluation criterion (PEC) has been introduced and Ga-based nanofluids are found to be most effective in this perspective. The effect on overall cooling effectiveness has also been carried out with a detailed particle concentration study. This study paves the pathway of using these extraordinary coolants in mini/microchannel heat sinks.

MHD dissipative Casson nanofluid liquid film flow due to an unsteady stretching sheet with radiation influence and slip velocity phenomenon

Abstract The problem of non-Newtonian Casson thin film flow of an electrically conducting fluid on a horizontal elastic sheet was studied using suitable dimensionless transformations on equations representing the problem. The thin film flow and heat mechanism coupled with mass transfer characteristics are basically governed by the slip velocity, magnetic field, and the dissipation phenomenon. The present numerical analysis by the shooting method was carried out to study the detailed, fully developed heat and mass transfer techniques in the laminar thin film layer by solving the competent controlling equations with eight dominant parameters for the thin liquid film. Additionally, the predicted drag force via skin-friction coefficient and Nusselt and Sherwood numbers were correlated. In view of the present study, a smaller magnetic parameter or a smaller slip velocity parameter exerts very good influence on the development of the liquid film thickness for the non-Newtonian Casson model. Furthermore, a boost in the parameter of unsteadiness causes an increase in both velocity distribution and concentration distribution in thin film layer while an increase in the same parameter causes a reduction in the film thickness. Likewise, the present results are observed to be in an excellent agreement with those offered previously by other authors. Finally, some of the physical parameters in this study, which can serve as improvement factors for heat mass transfer and thermophysical characteristics, make nanofluids premium candidates for important future engineering applications.

Numerical Investigation of Liquid Nanofluids Based Photovoltaic/Thermal (Pv/T) System with Square Tube Absorber Configuration

Numerical Investigation of Liquid Nanofluids Based Photovoltaic/Thermal (Pv/T) System with Square Tube Absorber Configuration

Linear Instability of Electromagnetic Viscoelastic Nanofluid: Analytical and Numerical Study

In this study, the effect of the induced electromagnetic fields on the linear instability of a viscoelastic nanofluid liquid layer is discussed. Two physical cases are considered for the channel flow. The first one is considered for the free–free boundaries and the second for the rigid–rigid boundaries. The instability is investigated analytically due to the normal mode analysis and numerically according to the relation between the energy density function and time. The Routh–Hurwitz criteria are applied. The dispersion relation is obtained as a sixth-degree equation of the growth rate. Also, the stationary, as well as oscillatory states of the thermal Rayleigh number, are obtained. The numerical solution is compared with the exact solution for a special choice of the parameters and the results show higher match between the results. The main important result of the study concludes that the Brownian motion of the nanoparticles destabilizes the nanofluid layer. This means that the pure fluid layer is more stable than the nanofluid layer. Also, the results confirm that the flow between the rigid–rigid boundaries is more stable than the free–free boundaries. Finally, due to the Lorentz force, the induced magnetic field destabilizes the motion due to the temperature rise.

Comparative numerical study of single and two-phase models of nanofluid liquid film evaporation in a vertical channel

The main purpose of this study is to survey numerically comparison of two-phase and single-phase models of heat and mass transfer of Al2O3-water nanofluid liquid film flowing downward a vertical channel. A finite difference method is developed to produce the computational predictions for heat and mass transfer during the evaporation of the liquid film approached by the single-phase and two-phase models. The model solves the coupled governing equations in both nanofluid and gas phases together with the boundary and interfacial conditions. The systems of equations obtained by using an implicit finite difference method are solved by Tridiagonal Matrix Algorithm. The results show that the two-phase model is more realistic since it takes into account the thermophoresis and Brownian effects.

Ultra-trace cadmium determination in eucalyptus and rosemary tea samples using a novel method: deep eutectic solvent based magnetic nanofluid liquid phase microextraction-slotted quartz tube-flame atomic absorption spectrometry

A deep eutectic solvent-based magnetic nanofluid liquid phase microextraction method was developed for the preconcentration of cadmium prior to its determination using the slotted quartz tube flame atomic absorption spectrophotometry system.

Role of base fluid on enhancement absorption properties of Fe3O4/ionic liquid nanofluids for direct absorption solar collector

Different types of ionic liquid-based nanofluids have been studied by the researchers since the last two decades. Most of the studies have focused on the effect of nanoparticles on the enhancement optical properties (absorption, transmittance, scattering, and extinction coefficient) of the corresponding ionic liquid-based nanofluids. However, optical properties of ionic liquid-based fluid have considerable contribution to absorbance in nanofluids. Therefore, it is necessary to study absorption properties of the different ionic liquid-based fluid of corresponding nanofluids to utilize ionic liquid-based nanofluids in solar thermal applications. The effect of the anion and cation radius in the ionic liquid on the enhancement absorption properties of the corresponding nanofluids is investigated. Through the measurement results, we find that as the cation radius or anion radius increases, the transmittances of the corresponding nanofluids decrease sharply, which is beneficial to enhance absorption properties of Fe3O4/ionic liquid nanofluids. At the same time, we also find that the large viscosity increase the stability of ionic liquid nanofluids, which can affect the absorption properties. Understanding the effect of ILs base fluid on enhancement absorption properties of the corresponding nanofluids will pave the road for improving the efficiency for direct absorption solar collectors.

The effect of the thermal vibration of graphene nanosheets on viscosity of nanofluid liquid argon containing graphene nanosheets

The impact of the thermal vibration of graphene nanosheets on viscosity and diffusion coefficient of nanofluid liquid argon containing graphene nanosheets are investigated by means the molecular dynamics simulation (MDS) combined with Green-Kubo formalism and the Einstein's formula respectively, and the hybrid BNC Tersoff potential is used to describe the interactions inter-atomic in graphene nanosheet. The numerical calculations of viscosity and diffusion coefficient are executed in the temperature range of 84–92 K and for graphene nanosheets volume fractions which are 3.93 vol%, 5.01 vol%, 6.88 vol% and 9.74 vol%. Firstly, the molecular dynamics code, the Green-Kubo framework and Einstein's formula are confirmed by comparing the viscosity and diffusion coefficient of argon liquid, with those calculated by preceding numerical simulations (MDS) and experimental studies. The results have indicated that the shear viscosity increases and the diffusion coefficient decreases when the graphene nanosheets volume fraction increases. Furthermore, the thermal vibration of graphene nanosheet has been considered among the responsible mechanisms to be the origin of enhanced shear viscosity.

EVAPORATION CHARACTERISTICS OF A CONFINED NANOFLUID BRIDGE BETWEEN TWO HEATED PARALLEL PLATES

This paper focusses on understanding the thermophysics and contact line dynamics of evaporating liquid bridges of pure water and nanofluids (0.1% and 0.5% v/v of CuO nanoparticles of average particle size < 50 nm), confined between two heated parallel glass substrates, maintained at a fixed distance, under near constant temperature boundary conditions (60°C and 80°C, respectively). Externally controlled, thin film indium-tin oxide (ITO) coated heaters were fabricated on the glass substrate to maintain the thermal boundary condition. High-resolution images of the liquid bridges were obtained during the evaporation process and later digitally analyzed to find the temporal evolution of relevant geometrical parameters. Subsequently, different thermal resistances involved were estimated, leading to the overall heat transfer coefficient. The order of magnitude of the interfacial resistance was found negligible as compared to the internal thermal resistance of the liquid bridge. Nanofluids evidently showed enhanced diffusional conductivity, and hence increased overall heat transfer coefficient, with a unique contact line motion, involving stick-slip behavior. Strong pinning effect at the contact line was observed during nanofluid evaporation, as a result of deposition of the particles, due to which the life span of nanofluid liquid bridge was much shorter than that of pure water. The rate of evaporation was dependent on the nanoparticle loading.

Preparation and photo-thermal conversion performance of modified graphene/ionic liquid nanofluids with excellent dispersion stability

Dispersion stability has been long considered as a critical issue for applying nanofluids in various fields, especially for the applications at elevated temperatures. Herein a novel route is explored to improve the dispersion stability of graphene (GE)/ionic liquid (IL) nanofluids for use as working fluids in medium- and high-temperature direct absorption solar collectors (DASCs), which involves modifying GE according to the molecular structure of the IL. Specifically, GE was modified using the reagents and process for synthesizing [HMIM]BF4, followed by dispersing the modified GE (MGE) into [HMIM]BF4. It is verified that the molecular chains similar to [HMIM]BF4 have been grafted on the nanosheets of GE, and the MGE/[HMIM]BF4 nanofluids exhibit much better dispersion stability than the one containing the unmodified GE, even at elevated temperatures. Moreover, the temperature profiles of the nanofluids containing MGE and GE were obtained both from the experimental measurement and the theoretical prediction using a one-dimensional transient heat transfer model. It is shown that the experimental data are in good agreement with the numerical ones for the MGE nanofluids, while a large deviation between them is found for the one containing the unmodified GE. And the MGE nanofluid shows enhanced receiver efficiency as compared to the GE one due to its much improved dispersion stability. Further, the transient model was used to predict the performance of the MGE nanofluid based DASCs under high solar concentrations. And by integrating the MGE concentration and the receiver height into a parameter, namely optical thickness, the optimization of the MGE nanofluid based DASC was carried out varying solar concentration, MGE concentration, nanofluid height and exposure time. It is revealed that the photo-thermal conversion performance of nanofluids greatly depends on its dispersion stability at elevated temperatures, and the MGE/[HMIM]BF4 nanofluids possess excellent dispersion stability and show great potentials for use as the working fluids in DASCs. This work sheds light on effective routes for improving dispersion stability of nanofluids as well as numerical investigations on nanofluid based DASCs.

A combined numerical and experimental study on graphene/ionic liquid nanofluid based direct absorption solar collector

Novel heat transfer fluids with very low vapor pressure and high thermal stability are highly desirable for both high temperature direct solar collectors and concentrated solar collector. Herein a combined analytical and experimental study has been conducted on high temperature direct solar thermal collectors using graphene/ionic liquid nanofluids as the absorbers. A one-dimensional transient heat transfer model has been used to predict the receiver temperature and efficiency with varying parameters such as solar and graphene concentration and receiver height. The results show that the experimental temperature is in good agreement with numerical results under the same conditions. Based on the model, it is shown that the receiver efficiency increases with the solar concentration and receiver height, but decreases with the graphene concentration. The receiver efficiency could be maintained 0.7 under the conditions of 0.0005wt% of graphene in 5cm receiver under 20×1000Wm−2 at 600K. This work provided an important perspective to the graphene/ionic liquid nanofluids for use as a kind of novel heat transfer fluid in direct solar thermal collectors under concentrated solar incident radiation.

Enhance heat transfer in the channel with V-shaped wavy lower plate using liquid nanofluids

The heat transfer and flow characteristics in corrugated with V-shape lower plate using nanofluids are numerically studied. The computations are performed on uniform heat flux over a range of Reynolds number (Re) 8000–20,000. The governing equations are numerically solved in the domain by a finite volume method (FVM) using the k–ε standard turbulent model. Studies are carried out for different types of nanoparticles Al2O3,CuO, SiO2 and ZnO with different volume fractions in the range of 0–4%. Three different types of base fluid (water, glycerin, ethylene glycol) are also examined. Results indicated that the average Nusselt number for nanofluids is greater than that of the base liquid. The SiO2 nanofluid yields the best heat transfer enhancement among all other type of nanofluids. Heat transfer enhancement increase with increases the volumetric concentration, but it is accompanied by increasing pressure drop values. Moreover, the average Nusselt number increases with an increase in Reynolds number and volume concentration. The SiO2–glycerin nanofluid has the highest Nusselt number compared with other base fluids. The present study shows that these V-shaped wavy channels have advantages by using nanofluids and thus serve as promising candidates for incorporation into efficient heat transfer devices.

Property-Structure Relationship of Titania Ionic Liquid Nanofluids

A series of the TiO2-ionic liquid nanofluids through surface modification by varying its molecular structure were synthesized. First, the different quaternary ammonium salts with silanol groups were grafted on TiO2 nanoparticles through hydroxyl groups. Then, the anion C9H19-C6H4-(OCH2CH2)20(CH2)3SO3- replaced the chloride in an ion-exchange process. Three kinds of synthesized TiO2-ionic liquid nanofluids showed liquid-like behaviors without solvent, and their structures and properties were characterized by Transmission electron microscopy (TEM), Fourier transform infrared spectrum (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and rheology meter. The property-structure relationship was obtained and further analyzed.

Potential of Nanoparticle-Enhanced Ionic Liquids (NEILs) as Advanced Heat-Transfer Fluids

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPotential of Nanoparticle-Enhanced Ionic Liquids (NEILs) as Advanced Heat-Transfer FluidsNicholas J. Bridges, Ann E. Visser, and Elise B. Fox*View Author Information Savannah River National Laboratory, Aiken, South Carolina 29808, United StatesTelephone: 803-507-8560. E-mail: [email protected]Cite this: Energy Fuels 2011, 25, 10, 4862–4864Publication Date (Web):September 26, 2011Publication History Received8 August 2011Revised26 September 2011Published online4 October 2011Published inissue 20 October 2011https://doi.org/10.1021/ef2012084Copyright © 2011 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views1212Altmetric-Citations98LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (680 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Fluids,Heat capacity,Salts,Solvents,Thermal stability Get e-Alerts

Pool boiling heat transfer on the microheater surface with and without nanoparticles by pulse heating

We study the pool boiling heat transfer on the microheater surface with and without nanoparticles by pulse heating. Nanofluids are the mixture of de-ionized water and Al 2O 3 particles with 0.1%, 0.2%, 0.5% and 1.0% weight concentrations. The microheater is a platinum surface by 50 × 20 μm. Three types of bubble dynamics were identified. The first type of bubble dynamics is for the boiling in pure water, referring to a sharp microheater temperature increase once a new pulse cycle begins, followed by a continuous temperature increase during the pulse duration stage. Large bubble is observed on the microheater surface and it does not disappear during the pulse off stage. The second type of bubble dynamics is for the nanofluids with 0.1% and 0.2% weight concentrations. The microheater surface temperature has a sharp increase at the start of a new pulse cycle, followed by a slight decrease during the pulse duration stage. Miniature bubble has oscillation movement along the microheater length direction, and it disappears during the pulse off stage. The third type of bubble dynamics occurs at the nanofluid weight concentration of 0.5% and 1.0%. The bubble behavior is similar to that in pure water, but the microheater temperatures are much lower than that in pure water. A structural disjoining pressure causes the smaller contact area between the dry vapor and the heater surface, decreasing the surface tension effect and resulting in the easy departure of miniature bubbles for the 0.1% and 0.2% nanofluid weight concentrations. For the 0.5% weight concentration of nanofluids, coalescence of nanoparticles to form larger particles is responsible for the large bubble formation on the heater surface. The microlayer evaporation heat transfer and the heat transfer mechanisms during the bubble departure process account for the higher heat transfer coefficients for the 0.1% and 0.2% nanofluid weight concentrations. The shortened dry area between the bubble and the heater surface, and the additional thin nanofluid liquid film evaporation heat transfer, account for the higher heat transfer coefficient for the 0.5% nanofluid weight concentration, compared with the pure water runs.

Gold-ionic liquid nanofluids with preferably tribological properties and thermal conductivity

Gold/1-butyl-3-methylimidazolium hexafluorophosphate (Au/[Bmim][PF6]) nanofluids containing different stabilizing agents were fabricated by a facile one-step chemical reduction method, of which the nanofluids stabilized by cetyltrimethylammonium bromide (CTABr) exhibited ultrahighly thermodynamic stability. The transmission electron microscopy, UV-visible absorption, Fourier transform infrared, and X-ray photoelectron characterizations were conducted to reveal the stable mechanism. Then, the tribological properties of these ionic liquid (IL)-based gold nanofluids were first investigated in more detail. In comparison with pure [Bmim][PF6] and the nanofluids possessing poor stability, the nanofluids with high stability exhibited much better friction-reduction and anti-wear properties. For instance, the friction coefficient and wear volume lubricated by the nanofluid with rather low volumetric concentration (1.02 × 10-3%) stabilized by CTABr under 800 N are 13.8 and 45.4% lower than that of pure [Bmim][PF6], confirming that soft Au nanoparticles (Au NPs) also can be excellent additives for high performance lubricants especially under high loads. Moreover, the thermal conductivity (TC) of the stable nanofluids with three volumetric fraction (2.55 × 10-4, 5.1 × 10-4, and 1.02 × 10-3%) was also measured by a transient hot wire method as a function of temperature (33 to 81°C). The results indicate that the TC of the nanofluid (1.02 × 10-3%) is 13.1% higher than that of [Bmim][PF6] at 81°C but no obvious variation at 33°C. The conspicuously temperature-dependent and greatly enhanced TC of Au/[Bmim][PF6] nanofluids stabilized by CTABr could be attributed to micro-convection caused by the Brownian motion of Au NPs. Our results should open new avenues to utilize Au NPs and ILs in tribology and the high-temperature heat transfer field.