Magnetite Ferrofluid Research Articles

Effects of Newtonian heating and thermal radiation on micropolar ferrofluid flow past a stretching surface: Spectral quasi‐linearization method

AbstractThis study article addressesthe flow and heat transfer characteristics of a magnetite Fe3O4 micropolar ferrofluid flow past a stretching sheet. For practical interest, thermal radiation, Newtonian heating, and a heat source or sink are considered in this investigation. A useful Tiwari‐Das nanofluid model is considered to analyze the microstructure and inertial characteristics of the water‐based nanofluids containing iron oxide. The dimensionless nonlinear ordinary differential equations are solved by employing suitable similarity variables. The resulting nonlinear system is solved by the spectral quasi‐linearization method. The effects of different nondimensional parameters on various profiles are shown graphically and explored in detail. It is found that the micropolar ferrofluid exhibits a higher energy distribution than that of a classical micropolar fluid. Compared to the classical micropolar liquid, local skin‐friction is more significant for the micropolar magnetite ferrofluid. In the presence of Newtonian heating, the thermal behavior of the micropolar nanofluid is remarkably better than that of the classical micropolar fluid.

Study of non-isothermal incompressible flow and heat flux of nano-ferrofluid with induced magnetic induction

Presently we have studied the nonlinear magnetohydrodynamic convective boundary-layer flow of water- based nano-ferrofluid adjacent to a non-isothermal stretching sheet. Three different ferrofluid suspensions are considered, namely water containing magnetite (Fe3O4), (Mn − Zn)and cobalt ferrite (CoFe2O4) ferriteferro-particles. Magnetic field is sufficiently strong to induce induction effects. Applying similarity transformations, the boundary region equations for mass, momentum, magnetic induction and energy are reduced to coupled, multi-degree, nonlinear differential equations. The non-dimensional boundary value problem is then solved computationally under specified wall and free stream conditions, with Maple quadrature and shooting techniques. Non-isothermal as well as constant heat flux cases are examined. The key parameters emerging in the model are the reciprocal of magnetic Prandtl number, Prandtl number, the reciprocal of magnetic body force parameter, heat source/sink parameter, nano-particle volume fraction and power-law index. The influence of these parameters on flow fields like velocity, temperature, and gradient of magnetic stream function for different ferro-particle cases, is presented graphically. Detailed elucidation of the results is also included. Validation is conducted with a finite element method (FEM). Significantly greater temperatures are observed for magnetite ferro-particles as compared with cobalt or Manganese-Zinc ferroparticles. Stream function (Magnetic) is found to be suppressed with increasing power-law index. With increasing magnetic force number there is a substantial elevation in induced magnetic field. Increasing reciprocal of magnetic Prandtl number i.e. decreasing magnetic Prandtl number leads to a depression in velocity i.e. flow deceleration, for the Fe3O4 − H2O magnetite ferrofluid. The study proposed here is of concern to the processing of nano-ferro-materials.

Heat transfer enhancement of a fin-and-tube compact heat exchanger by employing magnetite ferrofluid flow and an external magnetic field

Compact heat exchangers as modern industrial devices are designed to improve heat recovery and saving energy processes in restricted spaces. In the current study, effect of a uniform external magnetic field with Fe3O4/water nanofluid for heat transfer enhancement of a fin-and-tube compact heat exchanger is numerically investigated. The obtained results are verified by the available experimental data to demonstrate accuracy of the present simulation. The results indicated that the local and average heat transfer coefficients increase around the tubes in the presence of an external magnetic field due to the vortex formation behind the tubes as well as the flow pattern alteration in the heat exchanger, no mention that the pressure drop increment is subtle through this variation. Also, it is figured out that employing an external magnetic field at low Reynolds numbers (approximately ReD<30) is much more appropriate since the heat exchanger effectiveness increases exponentially. A maximum heat transfer enhancement of 8.7% was obtained by employing 2%Vol. magnetite nanoparticles in deionized water as a coolant. This value surges up to 52.4% by applying an external magnetic field in the compact heat exchanger. Based on these results, employing an external magnetic field for heat transfer enhancement of compact heat exchangers and heat sinks designed for restricted spaces and low Reynolds numbers can be more efficient in comparison with other available methods since no pumping power for mass flow rate augmentation is required in the present approach.

A novel heat sink design for simultaneous heat transfer enhancement and pressure drop reduction utilizing porous fins and magnetite ferrofluid

PurposeWith development of the modern electronic and mechanical devices, cooling requirement has become a serious challenge. Innovative heat transfer enhancement methods are generally accompanied by undesirable increase of pressure drop and consequently a pumping power penalty. The current study aims to present a novel and easy method to manufacture a mini heat sink using porous fins and magnetite nanofluid (Fe3O4/water) as the coolant for simultaneous heat transfer enhancement and pressure drop reduction.Design/methodology/approachA three-dimensional numerical study is carried out to evaluate the thermal and hydrodynamic performance of the mini heat sink at different volume fractions, porosities and Reynolds numbers, using finite volume method. The solver specifications for discretization of the domain involve the SIMPLE, second-order upwind and second order for pressure, momentum and energy, respectively.FindingsResults show that porous fins have a favorable effect on both heat transfer and pressure drop compared to solid fins. Creation of a virtual velocity slip on the channel-fin interfaces similar to the micro scale conditions and the flow permeation into the porous fins are the main mechanisms of pressure drop reduction. On the other hand, the heat transfer enhancement is attributed to the increase of the solid-fluid contact area and the improvement of the flow mixing because of the flow permeation into the porous fins. An optimal porosity for maximum convective heat transfer enhancement is obtained as a function of Reynolds number. However, taking both pressure drop and heat transfer effects into account, the overall heat sink performance is shown to be improved at high of Reynolds numbers, volume fractions and fin porosities.Research limitations/implicationsThermal radiation and gravity effects are ignored, and thermal equilibrium is assumed between solid and fluid phases.Originality/valueA maximum of 32 per cent increase of convective heat transfer is achieved along with a maximum of 33 per cent reduction in the pressure drop using porous fins and ferrofluid in heat sink.

Crystal Structure Evolution of Magnetite Ferrofluids: Effect of Heating Treatment

This work aimed at investigating the crystal evolution, crystallite phase, morphology, and particle size of the magnetite ferrofluids as the effects of heating temperature. The iron sand was used to prepare magnetite ferrofluids by employing a simple chemical method. The high-resolution transmission microscopy characterization presented that the particle size and morphology were expanded from small to bigger size in nanometric size with aggregation. The electron and X-ray diffractions patterns exhibited that the magnetite particles in the fluids evolved from Fe3O4 (cubic structure) structure to α-Fe2O3 (rhombohedral structure) as the effect of heating treatment. At a temperature of 500 °C, the magnetite particles had a mixed crystallite phases consisting of α-Fe2O3 and Fe3O4 structures. Interestingly, at the temperature of 600 °C or higher, the magnetite particles in the fluids changed to the pure α-Fe2O3 structure. Such evolution phenomenon gives significant information in designing new sophisticated application of the magnetite ferrofluids, especially for the temperature sensor.

Microstructure and inertial characteristic of a magnetite Ferro fluid over a stretched sheet embedded in a porous medium with viscous dissipation using the spectral quasi-linearisation method

The innovative micropolar nanofluid is introduced in this piece of work to examine the microstructure and inertial characteristics of the substructure particles. To be more precise, the flow and heat transport of micropolar Ferro fluid over a stretched sheet embedded in a porous medium with viscous dissipation is considered. The mathematical model is formulated with the help of Tiwari–Das nanofluid model. There after a convergent spectral quasi-linearisation method is applied to work out the resulting nonlinear system of equations. The impacts of pertinent parameter on velocity, micro-rotation velocity are exposed graphically and analysed thoroughly. Finally, the numerical outcomes are compared with previously published results under special cases and found a decent agreement. Main remarks are: the outcomes demonstrate that micro-rotation velocity decreases initially and after that increases with the increment in micro-rotation parameter, and for higher values of Eckert number there is an increase in temperature.

Magnetization of Ferrofluid and its Influence on Improving Oil Recovery

Large amount of crude oil remains in the reservoir due to the poor sweep and displacement efficiency after displacing fluid injection. To remediate this effect, a thicker displacing fluid is used to reduce viscous fingering for a more stable flood front. A ferrofluid is a suitable candidate due to the tunable viscosity profile when subjected to a magnetic field [1]. In this work, the ability of cobalt substituted magnetite ferrofluid to improve incremental recovery after waterflooding has been investigated via sand pack flooding. Prior to sand pack flooding, structural and magnetic properties of cobalt substituted magnetite nanoparticles were characterized via XRD, FESEM and VSM. Viscosity tests with field strength variation from 0 to 66.88 mT have shown a significant dependency of the ferrofluid’s viscosity on the applied field strength. 6-fold increment of viscosity was recorded when magnetic field strength changes from 19.5 to 66.88 mT. During sand pack flooding, 7.20% of incremental oil was obtained with the ferrofluid injection, even without the presence of a magnetic field. When subjected to a magnetic field, 12.93% and 15.83% of the incremental oil was obtained at 19.5 and 66.88 mT, respectively. It is proven that increase of ferrofluid viscosity with magnetic field strength results in higher incremental recovery. Improved sweep and displacement efficiency has been achieved by injecting the ferrofluid into the oil reservoir.

Effect of magnetic field on the hydrodynamic and heat transfer of magnetite ferrofluid flow in a porous fin heat sink

Abstract The present study numerically investigates the effects of a uniform external magnetic field and porous fins on convective heat transfer and pressure drop of magnetite ( F e 3 O 4 /water) nanofluid in a heat sink. Effects of volume fraction, porosity, Reynolds number, and magnetic field strength on the performance of the heat sink are studied. Results indicate that heat transfer increases at high volume fractions, fin porosities and magnetic field intensities and decreases with the Reynolds number. A 13% enhancement of heat transfer is obtained for the heat sink with solid fins by using ferrofluid compared to the pure water flow. This value grows up to 35% by using porous fins and imposing magnetic field to the heat sink. Moreover, using porous fins is shown to decrease the pressure drop while the magnetic field effect is not considerable. Therefore, it is concluded that the proposed methods result in a remarkable heat transfer enhancement while decreasing the pressure drop.

Dimethylsulfoxide as a media for one-stage synthesis of the Fe3O4-Based ferrofluids with a controllable size distribution

Abstract The ultrafine (d = 4 nm) magnetite ferrofluid with a narrow nanoparticle size distribution has been synthesized in one stage at room temperature from a solution of iron(II) and (III) chlorides in dimethylsulfoxide (DMSO) with the propylene epoxide admixture. This is the first example of obtaining a stable concentrated ultrafine magnetite/DMSO ferrofluid at room temperature. X-ray diffraction, transmission electron microscopy, ferromagnetic resonance, Mossbauer spectroscopy, and magnetostatic study have been used to elucidate the role of DMSO and the H2O/DMSO ratio in the formation of a stable colloid with a desired nanoparticle size. The initial stages of the magnetite nanoparticles formation have been investigated by the ferromagnetic resonance technique.

Thermal Conductivity of Water Based Magnetite Ferrofluids at Different Temperature for Heat Transfer Applications

Magnetic magnetite, Fe3O4 nanoparticles produced by Massart’s procedure were used to prepare water based magnetite, Fe3O4 ferrofluids without addition of any stabilizing agent or surfactant. The thermal properties and suspension stabilization of the ferrofluids were investigated by varying the magnetite, Fe3O4 nanoparticles concentration in the ferrofluids prepared. The thermal conductivity of water based ferrofluids prepared using five different volume fraction of magnetite, Fe3O4 suspension (0.1, 0.05, 0.02, 0.01 and 0.005) were measured at five different temperature, 25°C, 30°C, 40°C, 50°C and 60°C in order to evaluate its potential application as heat transfer fluid. The results shows that the thermal conductivity of the ferrofluids are higher than the base fluid, and the thermal conductivity of the ferrofluids increased as the magnetite concentration in the ferrofluids decreased however reached its optimum for ferrofluids prepared using 0.01 volume fraction of magnetite suspension over 0.99 volume fraction of water. Accordingly, the thermal conductivity of the ferrofluids significantly increased as the temperature increased where 49.4% enhancement with respect to water were observed at temperature 60°C.

Thermal performance analysis of tunable magnetite nanofluids for an energy system

This study is based on the effect of external magnetic field on heat transfer performance and pumping power of Fe3O4/DI-water nanofluid is experimentally investigated under both laminar and turbulent flow regimes. The magnetite ferrofluids with 0.25% and 0.50% of weight fractions are prepared by a chemical precipitating method using ammonium hydroxide reagent for maximising the stabilisation. The experiments were conducted at various mass flow rates with two different external magnets arrangements and input powers. The result shows that the enhancement in local heat coefficient was more pronounced by introducing more magnets on the tube of the test section, especially in the turbulent flow regime. The heat transfer coefficient improves with an increase in Reynolds number as well. In addition, the effect of the magnetic field was not significant on the increment of pressure loss. Therefore, the highest performance index and lowest exergy loss were found for external magnets configurations at 0.25wt% of nanofluids. The rise in heat transfer is assumed to be an accumulation of nanoparticles near the ring magnets, which may lead to a local thermal conductivity improvement. This aggregation formation enhancing the momentum and energy transfer in the fluid flow.

Studying the Temperature Effect on the Magnetic Behavior of Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Water Based Ferrofluid

In this study, Iron Oxide (Fe3O4) nanoparticles water based ferrofluid, was synthesized by co-precipitation method. XRD was used to study the structural characterization of the sample and to measure the size of the crystallites (using Scherrer equation). TEM was utilized to examine the shape, the size distribution and the morphology of the nanoparticles. VSM was carried out to measure the magnetic properties (like Mr, Ms and Hc) of the Fe3O4 (magnetite) nanoparticle and magnetite ferrofluid at 80 and 300 K. The results indicate that the average size of the magnetite roughly spherical shape nanoparticles is 13nm. The VSM results show that the magnetite ferrofluid contains single domain magnetic nanoparticles with superparamagnetic behavior. In addition, the magnetic measurements demonstrate that with decreasing the temperature of the ferrofluid, its magnetic softness decreases while its anisotropy increases.

Study Of CuZnFerrite and Ferrofluid In The Flow Injection Synthesis

Ferrofluid is a nanoscale materials that are easy to make but of easily made these materials have physical properties that are relatively easy to change. Originally made of magnetite ferrofluid and are now able to be made in such a wide variety, and various kinds of physical properties caused. Ferrofluid will be made with basic ingredients CuZnFerrite.One process to do step wise such as Flow Injection Synthesis-FIS, to result material previously. This material is relatively toxic, but weakly. Of the various variants turns out there are two ingredients that have almost the same compound but the physical properties are extremely different. Such materials Bath088P and Bath09P.Bath088P of magnetic properties of ferromagnetic character and character Anti-ferromagnetic Bath09P.This situation is favorable for the division of tasks and responsibilities Bath088 can be directed into a ferrofluid, both cannot stable mixing, if mixing used strong magnetic to separately.

Magnetic dynamics of ferrofluids: mathematical models and experimental investigations

Magnetite ferrofluids with unique magnetic behaviors are attractive for biomedical applications such as magnetic fluid hyperthermia and magnetic particle imaging. A precise nanoparticle-specific characterization by theoretical models and experiments to predict dynamics of ferrofluids and optimize their behaviors for emerging biomedical applications is necessary. In this paper, combining experiments and modeling, we have uncovered interesting magnetic dynamics of nanoparticles that are dependent on magnetic field strength, polymer coating of nanoparticles, viscosity of ferrofluid, and dipolar interactions. It is concluded that either by changing the magnitude of magnetic field or the concentrations of nanoparticles, we are able to convert the dominating relaxation process of magnetic nanoparticles from Néel to Brownian, and vice versa. Polymer coatings on nanoparticles and viscosity of ferrofluids are demonstrated to have varying degrees of influence on effective relaxation times of nanoparticles with different sizes and under different field strengths. Our theoretical models are used to predict the magnetic response of ferrofluid consisting of 35 nm magnetite nanoparticles under alternating magnetic fields, and it turns out that our theoretical data fits well with the experimental data.

Environmental effect on the impact of ferrofluid on Caulerpa Racemosa Oil methyl ester from marine macroalgae

ABSTRACTThis paper investigated the role of emission characteristics of a diesel engine when ferrofluid blended with Caulerpa Racemosa oil methyl ester (CROME) is used as a fuel. The major problem areas for compression ignition (CI) engines are emissions. Nanofluid using magnetite was synthesized by reacting Iron II (FeCl2) and Iron III (FeCl3) in aqueous ammonia (H5NO) solution to form magnetite ferrofluid (Fe3O4). The fuel that was used in the CI engine was prepared comprising 98.7% [CROME], 1% [Fe3O4], and 0.3% [(CH3)3NOH] by volume. The results show that the CI engine works well and the power outputs are steady running with the biodiesel blends at different loads. The acquired information was studied and it was found that there was a decrease in hydrocarbon (HC), carbon monoxide (CO), nitrogen oxide (NOx), sulfur dioxide (SO2), and smoke.

Effect of Magnetite Ferrofluid on the Performance and Emissions Characteristics of Diesel Engine Using Methyl Esters of Mustard Oil

This present work is intended to find out the additional information on using methyl esters of mustard oil as a substitute for diesel. Higher NOX emissions and lower brake thermal efficiency are the main drawbacks of methyl esters of mustard oil when fueled in diesel engine. In this work, magnetite ferrofluid is added to methyl esters of mustard oil to view its influence on performance and emission characteristics. The possible reason for choosing magnetite ferrofluid is that unlike another additive it can be removed from exhaust gas. Magnetite also releases abundant heat when exposed to higher combustion temperature which in turn reduces the ignition delay and NOX emissions of mustard oil. Experimental tests were carried out in constant speed diesel engine fueled by diesel, methyl esters of mustard oil and methyl esters of mustard oil by adding magnetite ferrofluid. It has been experimentally found that by adding magnetite ferrofluid (1 % by volume) to methyl esters of mustard oil, 5.122 % increase in brake thermal efficiency and 4.72 % reduction in fuel consumption were observed. Further, 5.8, 2.66 and 7.74 % reductions in HC, CO and NOx emissions were also observed. From this work, it is concluded that methyl esters of mustard oil subjected to addition of magnetite ferrofluid have a positive impact on reducing various drawbacks associated with it.

Dynamic and wear study of an extremely bidisperse magnetorheological fluid

In this work the friction and wear properties of five magnetorheological fluids (MRFs) with varying compositions are investigated. Considering that many of the proposed applications for these fluids involve lubricated contact between mobile metal–metal or polymer–metal parts, the relationship between MR response and wear behavior appears to be of fundamental importance. One of the fluids (MR#1) contains only the iron microparticles and base oil; the second and third ones (MR#2 and MR#3) contain an anti-wear additive as well. The fourth one (MR#4) is a well known commercial MRF. Finally, MR#5 is stabilized by dispersing the iron particles in a magnetite ferrofluid. The MR response of the latter fluid is better (higher yield stress and post-yield viscosity) than that of the others. More importantly, it remains (and even improves) after the wear test: the pressure applied in the four-ball apparatus produces a compaction of the magnetite layer around the iron microparticles. Additionally, the friction coefficient is larger, which seems paradoxical in principle, but can be explained by considering the stability of MR#5 in comparison to the other four MRs, which appear to undergo partial phase separation during the test. In fact, electron and optical microscope observations confirm a milder wear effect of MR#5, with almost complete absence of scars from the steel test spheres and homogeneous and shallow grooves on them. Comparatively, MR#2, MR#3 and, particularly, MR#1 produce a much more significant wear.

Giant magnetoimpedance effect of Co68.15 Fe4.35 Si12.5 B15 amorphous wire in the presence of magnetite ferrofluid

Giant magnetoimpedance effect (GMI) in Co68.15 Fe4.35 Si12.5 B15 amorphous wire was studied in the presence of magnetite ferrofluid and without it. Magnetite nanoparticles for ferrofluid were prepared by the traditional wet chemistry co-precipitation method. GMI was measured in the frequency range of 2 to 6MHz. The maximum value of GMI value of the ferrofluid covered amorphous wire was increased in all frequency intervals in comparison with GMI response of the wire non-covered by ferrofluid. These results open a new way of increasing magnetoimpedance effect value useful for sensor applications.

Nano-Structural Studies on Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Particles Dispersing in a Magnetic Fluid Using X-Ray Diffractometry and Small-Angle Neutron Scattering

Ferrofluid (magnetite/Fe3O4magnetic fluid) is colloidal suspension containing Fe3O4nanoparticles dispersed in a liquid carrier. In this work, Fe3O4particles in the fluid have been prepared by a simple co-precipitation route. The nano-structural behaviors such as phase purity and crystal structure of magnetite particles in ferrofluid were studied by means of X-ray diffractometry (XRD). Meanwhile, the form and structure factors were investigated by small-angle neutron scattering (SANS) spectrometer. The XRD pattern confirmed a single phase of spinel cubic Fe3O4structure. Further XRD data analysis revealed that the magnetite has a lattice parameter of 8.38 Å. The SANS data was fitted by applying a lognormal spherical calculation as a form factor and a mass fractal model as a structure factor. It showed that the magnetite ferrofluid has primary particles of 7.6 nm in diameter with fractal dimension of 1.2, which can be associated with chain-like structure. The chain-like structured Fe3O4ferrofluid based on local natural iron sand in this work opens new opportunities to be applied for novel prospective applications.

Direct observations of field-induced assemblies in magnetite ferrofluids.

Evolution of microstructures in magnetite-based ferrofluids with weak dipolar moments (particle size ≤ 10 nm) is studied with an emphasis on examining the effects of particle concentration (ϕ) and magnetic field strength (H) on the structures. Nanoparticles are dispersed in water at three different concentrations, ϕ = 0.15%, 0.48%, and 0.59% (w/v) [g/ml%] and exposed to uniform magnetic fields in the range of H = 0.05-0.42 T. Cryogenic transmission electron microscopy is employed to provide in-situ observations of the field-induced assemblies in such systems. As the magnetic field increases, the Brownian colloids are observed to form randomly distributed chains aligned in the field direction, followed by head-to-tail chain aggregation and then lateral aggregation of chains termed as zippering. By increasing the field in low concentration samples, the number of chains increases, though their length does not change dramatically. Increasing concentration increases the length of the linear particle assemblies in the presence of a fixed external magnetic field. Thickening of the chains due to zippering is observed at relatively high fields. Through a systematic variation of concentration and magnetic field strength, this study shows that both magnetic field strength and change in concentration can strongly influence formation of microstructures even in weak dipolar systems. Additionally, the results of two commonly used support films on electron microscopy grids, continuous carbon and holey carbon films, are compared. Holey carbon film allows us to create local regions of high concentrations that further assist the development of field-induced assemblies. The experimental observations provide a validation of the zippering effect and can be utilized in the development of models for thermophysical properties such as thermal conductivity.