Nanoparticle Volume Concentration Research Articles

Unsteady three-dimensional MHD flow and heat transfer in porous medium suspended with both microorganisms and nanoparticles due to rotating disks

In the present study, the silent characteristics of magnetized mixed convection flow in porous medium suspended with both microorganisms and nanoparticles induced by two expanded or contracted disks are investigated. The Buongiorno’s model, in which the Brownian diffusion and thermophoresis are taken as dominant factors, is introduced to describe behaviors of the nanofluid. Multiple slip boundary conditions are also included into this problem. The nonlinear system is converted into five fully coupled nonlinear ordinary differential equations via suitable scaling transformations. The homotopy-based algorithm BVPh2.0 is employed to give their solutions. Physical interpretation is made through analyzing the graphs of different constraints for profiles of velocity, temperature, nanoparticle volume concentration and density of motile organism. Furthermore, we extend this model to seek the physical behaviors of heat transfer and the wall motile microorganism fluxes. Significant findings are presented, including that the wall expansion ratio and the magnetic parameter impose contrary effects on microorganism profiles, the Prandtl number and the radiation parameter play opposite roles on heat transfer rate, and the Brownian motion and the thermophoresis exhibit totally different influence on microorganism flux rate. It is expected that this study is helpful to understand heat transfer mechanism in multiple physical fields.

Numerical Investigation of wavy channel using several Nanofluids

This study investigates the effect of nano-fluids in enhancing heat transfer. These nano-fluids contain nanoparticles (Ag, CuO, Fe, Al2O3 and Tin) in volume fraction ranging between 2%-5%. Two-dimensional numerical simulation has been conducted on wavy channel using ANSYS Fluent. Two dimensional governing equations such as mass, momentum and energy equations are solved using SIMPLE algorithm and discretized using Finite Volume Method. The results show that there will be enhancement of heat transfer rate as the nanoparticle volume concentration increases and from the present study it is clear that silver-water nanofluid gives better results as compared to other nanoparticles.

Numerical study of graphene-platinum hybrid nanofluid in microchannel for electronics cooling

The objective of this paper is to numerically study the heat transfer and hydrodynamic performance of a graphene-based hybrid nanofluid flowing through a microchannel for electronics cooling applications. Different concentrations of Graphene-Platinum/water hybrid nanofluid were employed as coolants. The thermophysical properties used in this study were considered to be temperature-dependent. The microchannel was modeled as a porous media. The effect of nanoparticle volume concentration on thermal resistance, pressure drop, friction factor and ratio of heat transfer coefficient to pressure drop (Figure of merit) was analyzed and the plots were generated for different Reynolds numbers of the working fluid. The results pointed out that introduction of nanoparticles resulted in the lowering of thermal resistance. However, the pressure drop and friction factor increased. Figure of merit is found to be higher for higher concentrations of hybrid nanofluids compared to base fluid water. On analyzing the results, it was understood that the utilization of Graphene-Platinum/water hybrid nanofluid through microchannels can be highly effective in the laminar region. It also suggests that this graphene based nanofluid has excellent potential as a coolant to remove excess heat from miniature electronic devices.

Thermal and concentration convection in nanofluids for peristaltic flow of magneto couple stress fluid in a nonuniform channel

This article addresses the influence of double-diffusivity convection in nanofluids in relation to peristaltic flow of magneto couple stress fluid in a nonuniform channel. Firstly, mathematical formulations of magneto couple stress fluid in the presence of double-diffusivity convection in nanofluids for 2-dimensional and 2-directional flows are described in detail. The highly nonlinear equations are simplified using approximation of long wavelength and low but finite Reynolds number. Exact solutions of stream function, axial induced magnetic field, axial pressure gradient, nanoparticle volume fraction temperature and concentration are computed. Graphical representations of numerous physical parameters of interest are presented to explain the conduct of flow quantities. It is observed from graphical plots that temperature profile and solutal concentration increases by increasing values of thermophoresis, Brownian motion, Soret and Dufour parameters.

Experimental analysis of the efficacy of vegetable oil-based nanolubricants for improving journal-bearing performance

The present experimental study explores the performance of Hydrodynamic journal bearings operating with vegetable oil-based nanolubricants. For this study, titanium oxide nanoparticles have been added to canola oil by varying the volume fraction from 0% to 0.04%. An assessment of performance characteristics has been done by using a journal-bearing test rig under different operating conditions. The outcome of the experimental results aimed at the addition of nanoparticles to base lubricants to improve the performance was observed to be favorable. However, under high operating conditions, the influence of nanoparticles is observed to be less useful. The fluid film pressure of nanolubricants increased up to a specific volume concentration of titanium oxide nanoparticles (i.e. 0.02%) beyond which no further enhancement was observed. At a load of 3000 N, the fluid film pressure increased up to 10%, when a bearing is lubricated using canola oil with a 0.02% volume fraction of nanoparticles. The heat transfer rate was found to be higher for nanolubricants in comparison to a base oil and the fluid film temperature was reduced by up to 15% at a volume fraction of 0.04%. Furthermore, rheological studies reveal that the prepared nanolubricants exhibited Newtonian behavior under the given conditions. The percentage increment of viscosity varied from 2.1% to 15.4% and 2.43% to 13.89% for a volume fraction ranging from 0.01% to 0.04% at a temperature of 40 °C and 100 °C, respectively. The dynamic light scattering results confirmed that the particles were well distributed in a base lubricant without much aggregation.

Stabilization of Martensite on Nanoprecipitates and Kinetics of Explosive Martensite Transition

Based on the theory of diffuse martensitic transitions (DMT), the physical mechanism of the influence of dispersed precipitate nanoparticles on the appearance of such features of the deformation behavior of alloys with the shape memory effect (SME) as the stabilization of martensite at temperatures significantly higher than the As and Af temperatures characteristic of an alloy in the absence of nanoparticles c-oherent with the matrix is analyzed. The reason for the stabilization of martensite is the internal elastic stress fields associated with the particles, which serve as sites for the heterogeneous nucleation of martensite. It has been shown theoretically that, with an increase in the volume concentration of nanoparticles, the recovery of shape memory deformation occupies an increasingly narrow temperature range and occurs at an ever higher temperature. After reaching a certain critical value of the particle concentration, the return of the deformation of SM loses its stability and becomes explosive.

Experimental study and exergy analysis of three-fluid tubular heat exchanger with nanofluids

The present study investigates the exergetic performance of a three-fluid heat exchanger employing Al2O3-water nanofluids. Numerical and experimental approaches were applied to investigate the effects of varying flow rates, flow arrangements and nanoparticle volume concentrations on overall performance of the exchanger under study. Reynolds number in the range 2500-10,000 and volume concentration of nanoparticles in the range 0%-3% have been considered to study their effects for four flow arrangements. Numerical results revealed that increasing flow rate and addition of nanoparticles resulted in a reduction of exergy loss of the system. Significant deviation between experimental and numerical results was observed. At a maximum Re = 10,000, a drop in exergy loss by 23.7% for parallel, 11.56% for parallel-counter, 10.6% for counter-parallel, and 25.8% for counter flow arrangements by varying ϕ from 0% to 3%. Furthermore, minimum exergy loss for all the flow arrangements was found at φ = 3% and Re = 4500.

Experimental study and exergy analysis of three-fluid tubular heat exchanger with nanofluids

The present study investigates the exergetic performance of a three-fluid heat exchanger employing Al2O3-water nanofluids. Numerical and experimental approaches were applied to investigate the effects of varying flow rates, flow arrangements and nanoparticle volume concentrations on overall performance of the exchanger under study. Reynolds number in the range 2500-10,000 and volume concentration of nanoparticles in the range 0%-3% have been considered to study their effects for four flow arrangements. Numerical results revealed that increasing flow rate and addition of nanoparticles resulted in a reduction of exergy loss of the system. Significant deviation between experimental and numerical results was observed. At a maximum Re = 10,000, a drop in exergy loss by 23.7% for parallel, 11.56% for parallel-counter, 10.6% for counter-parallel, and 25.8% for counter flow arrangements by varying ϕ from 0% to 3%. Furthermore, minimum exergy loss for all the flow arrangements was found at φ = 3% and Re = 4500.

Energy and exergy analyses of flat plate solar collectors with nanofluids containing different size and shape of nanoparticles

The effect of nanoparticle size, shape, and volume concentration upon the flat plate solar collector (FPSC) performance is investigated. The enhancement in efficiency due to volume concentration SiO2/H2O nanofluid was significant whereas the enhancement due to size and shape was marginal. In addition, the paper discusses the effect of the concentration, size and shape of nanoparticles upon the pressure drop, pumping power, exergy destruction and entropy generation. The exergy efficiency is found to increase upon increasing the nanoparticle size and volume concentration. However, the effect due to shape variation on the exergy efficiency is minimal.

Energy and exergy analyses of flat plate solar collectors with nanofluids containing different size and shape of nanoparticles

The effect of nanoparticle size, shape, and volume concentration upon the flat plate solar collector (FPSC) performance is investigated. The enhancement in efficiency due to volume concentration SiO2/H2O nanofluid was significant whereas the enhancement due to size and shape was marginal. In addition, the paper discusses the effect of the concentration, size and shape of nanoparticles upon the pressure drop, pumping power, exergy destruction and entropy generation. The exergy efficiency is found to increase upon increasing the nanoparticle size and volume concentration. However, the effect due to shape variation on the exergy efficiency is minimal.

A review on latest development in heat transfer through porous media in combination with nanofluids and wavy walls

Heat flow through porous media and different phenomenon in these media are studied widely in recent years due to their extraordinary applications in different fields of engineering, bio-engineering and energy systems etc. In this report, recent advances in the numerical investigation of completely or partial filled porous media alone or in combination with wavy walls and nanofluids/nanoparticles have been reviewed. The main emphasis of this is to review the theoretical and numerical aspects of the effect of position of porous insert, nanoparticle volume concentration and the amplitude of the waves associated with wavy channels on the Nusselt number, pressure drop, entropy generation and efficiency of heat transfer. The conditions which define the boundary for the use of LTE (Local thermal equilibrium) and LTNE (Local thermal nonequilibrium) equations for evaluation of the porous media have also been reviewed. The LTE equations were found to be appropriate for the systems in which the temperature different between the solid and fluid phase is very small whereas, if the temperature difference between the two is large, then only LTNE can be employed. The porous media along with wavy walls and nanofluid combinations was found to exhibit better results in terms of Nusselt number and heat transfer efficiency but to obtain bets results, minimum amplitude in case of wavy walls and volume concentration of nanoparticle concentration should be optimized.

The Role of Nanoparticles and Different Tube Diameter on Thermal Performance in Shell and Helically Coiled Tube Heat Exchangers with Single Phase and Sub-cooled Boiling Flow

In the present research, effects of nanoparticles and changing of tube diameter have been scrutinized on heat transfer parameters in the shell and helically coiled tube heat exchanger. A CFD analysis and also a modeling of the mentioned heat exchager have carried out by writing a code in MATLAB software for two regimes involving forced convection heat trasnfer in single phase fluid flow and sub-cooled boiling. In the case under analysis, considered nanoparticles in this research was Nickel nanoparticles with 0.1 and 1% volumetric concentration. Based on the results, both going up of volume concentration of nanoparticles and increasing of tube diameter are cause to make better heat transfer parameters. In truth, heat transfer coefficient and Nusselt number have been enhanced by 0.1 and 1 % volumetric concentration of Nickel nanoparticles.

Heat transfer and fluid flow analysis using nanofluids in diamond-shaped cavities with novel obstacles

This work computationally explores the two-phase flow of nanofluids and their thermal energy transport coefficients in 3D diamond-shaped cavities with square-shaped barriers having reducing dimensions. Materials with two emissivity values, and 0.9, have been considered to investigate the effect of the radiation thermal energy transport coefficient while the hot side is maintained at 400 or 500 K. Two values of the Rayleigh number, Ra = 106 and 108, are used for the study. Cu nanoparticles (NPs) with an average size of 25 nm have been used at a concentration of 0.01–0.05% in the base fluid. The temperature gradients and thermal energy transport coefficient characteristics are enhanced by raising the volume concentration of nanoparticles, but the streamlines do not alter substantially. By increasing Ra, the thermal energy transport coefficient rate is further augmented. It is also found that increasing the Ra and volume concentration of NPs results in enhanced heat transfer inside a cavity, while a change in the emissivity coefficient has no significant impact on the thermal and flow characteristics of the nanofluid. For each case, there is an optimum NP volume fraction for each model that leads to the highest Nusselt number.

Experimental investigation on viscosity of AlN and SiC nanofluids

The quest for effective and efficient heat exchange systems has been a subject of recent research. Nanofluids are high performance ultra-modern heat transfer fluids with superior properties compared to those of regular heat transfer fluids. Therefore, studies on the viscosity of nanofluids are essential owing to its effect on the pumping requirements of thermal systems. This article investigates the influence of concentration and temperature on the dynamic viscosity of AlN and SiC nanofluids. Nanofluids with a volume concentration of 0.5–5% were prepared by dispersing AlN nanoparticles in ethylene glycol (EG), SiC in ethylene glycol, and SiC in distilled water (DW) using the two-step method. The experimental investigation on the viscosity of these nanofluids was performed at the temperature range of 28–60 °C using an Ostwald viscometer. It was observed that the measured nanofluids exhibited an increase in the viscosity with an increase in the volume concentration of nanoparticles. Specifically, for SiC/DW nanofluids at 0.5 and 5% volume concentration, the viscosity ratio was 1.023 and 1.435 times that of the base fluid. Moreover, the viscosity of nanofluids is reduced by increasing the temperature relative to that of their base fluids. The experimental values were compared with existing theoretical model, and their predictions are below the experimental results; therefore, correlation was derived on the basis of the experimental data. The margin of deviation of these models in predicting the viscosity of the studied nanofluids varied between −15 and 23% for AlN/EG; −7 and 21% for SiC/EG, and −11 and 4% for SiC/DW nanofluid.

Two‐phase study of nanofluids mixed convection and entropy generation in an I‐shaped porous cavity with triangular hot block and different aspect ratios

The nanofluids mixed convection in a porous I‐shaped cavity using Buongiorno's method of nanofluids simulation is reported in this paper. The nanofluids have been assumed as a mixture of water and TiO2 nanoparticles up to 4% of volume concentration. Having accurate prediction of thermal properties of nanofluids is crucial for a numerical solution. Thus, a new predictive correlation for effective thermal conductivity is developed using the multivariable regression method with a high accuracy compared to the experimental data. Six different problems, including two different porous media and three different aspect ratios of the cavity, are solved implementing the finite volume method. As the first time, an internal triangular hot block in a cavity has been studied. The results showed that the entropy generation reduces with any increase in the aspect ratio of the cavity and the nanoparticle volume concentration. Any increase in the nanoparticle volume concentration also leads to enhance the average Nusselt number, in all considered aspect ratios.

Effectiveness of Hall current and ion slip on hydromagnetic biologically inspired flow of Cu − Fe 3 O 4/H 2 O hybrid nanomaterial

Heat transfer augmentation is a significant concern in numerous engineering and industrial cooling/heating appliances nowadays. The usage of hybrid nanoliquids has been drawing attention of scientists in order to reduce the limitations of nanofluids and merge the chemical and physical characteristics of nanoparticles in an effective manner. Keeping such effectiveness in mind, present article aims to investigate the peristaltic flow of hybrid nanofluid with heat transfer and irreversibility analysis. Hybrid nanofluid is formed by mixing copper (Cu) and iron oxide (Fe 3 O 4) nanoparticles in water (H 2 O). The Cu − Fe 3 O 4 hybrid nanofluid with nanoparticles volume concentration 2% is used in this study. Impacts of Hall current, ion-slip, mixed convection and viscous dissipation are taken into consideration. Mathematical modeling for entropy generation is formulated via second law of thermodynamics. Governing equations of given problem are first converted into ordinary differential equations by employing lubrication approach. Obtained dimensionless equations are then tackled analytically with the aid of regular perturbation technique. Results reveal that temperature of hybrid nanofluid decreases by improving concentration of nanoparticles. Heat transfer rate at wall increases by improving Hartman number. Entropy generation reduces by improving Hall and ion-slip parameters. Bejan number increases by increasing Hartman number. Velocity of hybrid nanofluid increases by enhancing Grashof number. Pressure gradient of hybrid nanofluid increases by increasing Hall parameter. Pressure rise per wavelength decreases by enhancing ion-slip parameter. A comparison of temperature for base fluid, nanofluid and hybrid nanofluid is also furnished in tabular form. Additionally, comparison of numerical and analytical outcomes of velocity is also provided graphically. It is anticipated that the present study provides a theoretical data for the selection and design of hybrid nanofluid based heat exchanger.

INVESTIGATION OF DIELECTRIC PROPERTIES OF COMPOSITE NANOFLUID WITH SURFACTANT

Mineral oil in transformer is replaced by the ester oil due to its biodegradability and good thermal & dielectric properties. Ester oil plays a vital role in enhancing the design of high voltage apparatus, as it has better electric and thermal properties. In this paper, the impact of dielectric properties on the mixture of 20% ester oil and 80% mineral oil, due to the effect of TiO2 nanoparticles was studied. The optimum volume concentration of TiO2 nanoparticles was found based on the Corona Inception Voltage (CIV) and Break Down Voltage (BDV) and also the optimum concentration of nanoparticles having CTAB surfactant and having oleic acid surfactant was analyzed. The solubility of TiO2 in composite fluid depends upon the percentage weight of nanoparticles and surfactant. It is concluded that Titania (TiO2) nanoparticles dispersed composite oil having CTAB surfactant has greater CIV and BDV when compared to the oleic acid surfactant. It is also found that Negative Direct Current (NDC) voltages have higher breakdown voltage than Positive Direct Current (PDC) voltages and AC voltages. The statistical analysis depending upon the CIV and BDV of the composite oil, nanofluid and nanofluid with surfactants were made.

CFD Study Based on Effect of Employing the Single-Walled Carbon Nanotube (SWCNT) and Graphene Quantum Dots (GQD) Nanoparticles and a Particular Fin Configuration on the Thermal Performance in the Shell and Tube Heat Exchanger

In this research, the thermal attributes of shell and finned tube heat exchanger such as thermal efficiency, pressure drop, heat transfer rate and average temperature in the tube side of heat exchanger with using the different volume concentration of nanoparticles (SWCNT and Graphene quantum dot) at the various Reynolds number by applying either fin blades and without fin blades have been conducted numerically. In this heat exchanger the hot fluid or nanofluid flows in the tube section and cold fluid or pure water moves in the shell side. As regarding to results obtained the majority of thermal characteristics like heat transfer rate, pressure drop and effectiveness enhanced with augmentation of Reynolds number and increasing of volume concentration of nanofluids to 1% volumetric of working fluid whereas at the higher volume concentrations of nanoparticles (upper from 1% volumetric) the thermal properties of heat exchanger decreased generally. Also pressure drop intensifies with increment of Reynolds number and volume concentration of nanoparticles that at higher Reynolds number the effects of nanoparticles on the pressure drop were more noticeable. The average temperature of heat exchanger in the end section of inside tubes increased with augmentation of Reynolds number and nanoparticles. Finally, according to the results obtained in this study, most impression on the thermal attributes enhancement was found by employing of finned tubes compared to other factor which this factor increased heat transfer rate of heat exchanger by almost 188% also the effects of nanoparticles at the high levels of volume concentration especially for 5% of SWCNT nanoparticle on the pressure drop obtained about 80% compared to the base fluid.

NUMERICAL STUDY OF VARIATION IN DRAG AND VIRTUAL MASS FORCES FOR A NANOFLUID FLOW THROUGH A MICROCHANNEL USING EULERIAN-EULERIAN TWO-PHASE MODEL

Laminar forced convection of copper oxide (CuO) and titanium oxide (TiO2 ) water-based nanofluid flow through a microchannel has been studied numerically using a Eulerian–Eulerian two-phase model. The governing equations of the liquid phase and solid phase are solved using sixth-order compact finite difference schemes. The effects of Reynolds number and nanoparticle volume concentrations on drag and virtual mass forces are reported. Estimation of thermal conductivity for nanofluid has been discussed here using two-phase results. Results show that significant heat transfer enhancement is observed with an increase in Reynolds number and nanoparticle volume concentrations compared with pure water. The 2 vol % CuO nanofluid has shown 3.44% and 18.65% enhancement in average Nusselt number compared to pure water for Re = 50 and Re = 600, respectively. An increase in particle concentration from 1% to 3% leads to a 4.45% increase in the average Nusselt number at Re = 200 for CuO nanofluid. A significant change of 26.5% is found in the dimensionless drag force with an increase in Reynolds number from 50 to 600. A negligible change in dimensionless drag force is observed with an increase in nanoparticle concentrations for Re ≥ 200. The virtual mass force is less significant than the drag force for nanofluid flows. Present results show a small deviation between the obtained and experimental thermal conductivity of nanofluid. The developed two-phase numerical model is validated with the numerical and experimental results available in the literature.

Investigate the effect of nano cutting fluid and cutting parameters under minimum quantity lubrication (MQL) on surface roughness in turning of DSS-2205

The Paper focused on Effect of Nano cutting fluids under minimum quantity lubrication (MQL) and parameters on surface roughness during turning of Duplex stainless steel-2205. The Nanofluids are prepared via two step processes dispersing the nano particles of Aluminium oxide (Al2O3), Copper oxide (CuO) and Silicon carbide (SiC) with the base fluid of Neat Cut oil with different volume concentration 0.3%, 0.5% and 0.7%. The experimentation were conducted based on face centered composite design(CCF) with varying % of volume concentration of nano particles, speed, feed and depth of cut. ANOVA was used to examine the influence of turning factors on roughness. The ANOVA and R-Squared value reveals the developed models were significant. The results revealed that copper oxide nano fluid are better surface roughness fallowed by silicon carbide and aluminium oxide and feed was the most significant factor followed by DOC, concentration of nano particles and cutting speed.