Effect Of Nanoparticle Concentration Research Articles

Astray State-Laminar Forced Convective Heat Transfer of Al2O3 – H2O Nanofluid through 3D-Rectangular Cross- Sectional Duct

A Steady state-laminar forced convective heat transfer has been simulated by Computational Fluid Dynamics (CFD) with a Single Phase Model (SPM), Multi Phase model & Diameter effects and also determined the effects of nanoparticles concentration and nanofluid flow rate through 3D rectangular duct under certain boundary condition (constant heat flux). The nanofluid contains Alumina nanoparticles of size 60nm diameter used for MPM which is mixed with base fluid (water) with volume fraction of 0% ≤ ȼ ≤ 5% and Reynolds number (Re) ranges from 250 ≤ Re ≤ 1000. ANSYS 18.0 has been used for simulation. Three cases of analysis have been carried out in which the thermal conductivity (k) and dynamic viscosity (µ) of nanofluids are determined using two sets of theoretical models and one set of experimental k & µ data from literature respectively. The nanoparticles which stay more dispersed in the base fluid due to increase in Reynolds number which improves HTC and also decreases the friction factor accordingly. Particular attention has been paid to the variation of heat transfer characteristics when the modeling approach is switched from SPM to MPM. It is revealed that higher heat transfer rates are observed in MPM. The results shows that the friction factor decreases and Nusselt number (Nu) increases when there is an increase in the flow rate and also increase in the volume concentration of the nanofluid, while the pressure drop increases only slightly. The increase in HTC is one of the most important aims for industry and researchers.

Effect of colloidal nanoparticle concentration on sizing analysis with an electrospray scanning mobility particle sizer

Precise measurement of the size and size distribution of colloidal nanoparticles are an important component of evaluating nanoparticle safety. However, size measurements become increasingly difficult to perform as particle size decreases. The sizes and size distributions of nanoparticles can be determined using a variety of techniques. In this study, we used an electrospray scanning mobility particle sizer (ES-SMPS) to investigate the effect of nanoparticle concentration on the size and size distribution measurements of 20 nm and 50 nm silica nanoparticles. To calculate the size of the water droplets in the electrospray, the droplet size distribution in sucrose solutions was determined at various sucrose concentrations. The average water droplet diameter was ~ 697.5 nm, regardless of sucrose concentration. Based on these results, we estimated the appropriate nanoparticle concentration ranges for the ES-SMPS size determination of 20-nm and 50-nm silica nanoparticles. Reliable measurements of the 20- and 50-nm silica nanoparticles could be performed at concentrations of < 0.01 wt% and < 0.1 wt%, respectively.

Effect of nanoparticles concentration on the evaporation characteristics of biodiesel

Abstract In order to study the evaporation process and mechanism of Jatropha methyl ester-diesel blends which was added nanoparticles, the evaporation characteristics of different concentrations of NPs (0.05%, 0.5%, 2%) in Jatropha methyl ester-diesel blends (BD20) were studied by suspension droplet technology. The evaporation characteristics of these fuels at 873 K and 973 K were analyzed and compared. The evaporation process of different concentrations of NPs (0.05%, 0.5%, 2%) presented a stable performance without intense micro-explosion, and the evaporation stage was divided into two parts. The normalized square diameter of droplet fluctuated slightly during evaporation, and the equilibrium evaporation stage followed the law of D2. The results showed that: at high temperature, low concentration of NPs promoted the absorption of heat in the droplet, thus reducing the evaporation life of the droplet, while high concentration of NPs restrained droplet evaporation, thus increasing the evaporation life of the droplet.

A simple homogeneous numerical solution for nanofluid natural convection in an enclosure with disconnected and conducting solid blocks

Following a series of discrepancies in the literature regarding the effects of nanoparticle concentration on the heat transfer rate, this paper proposes a simple homogeneous modeling for natural convection of nanofluids. The proposed modeling allows a custom choice of correlations for the nanofluid’s thermophysical properties, which proved to be very convenient in validations carried out for the case of natural convection inside a clear enclosure. The general heat transfer decreasing behavior for high concentrations of nanoparticles, previously observed in experimental and two-phase numerical works, was successfully represented. A very interesting and pioneer case study of laminar natural convection of nanofluids in a laterally heated enclosure with conductive solid blocks uniformly distributed within the enclosure was numerically investigated with the proposed modeling. To compute the nanofluids characteristics, Corcione’s correlations for thermal conductivity and dynamic viscosity for effective properties and generic correlations for density, specific heat and thermal expansion coefficient were employed. Therefore, it was possible to isolate the nanoparticle’s influence on the heat transfer rate, evaluated by the average Nusselt number. By isolating the nanoparticle’s parameters, the effects of diameter and material have been interpreted from the homogeneous solution. A parametric investigation was conducted by varying the number of blocks inside the enclosure and the effective Rayleigh number. A numerical correlation for the average Nusselt number was derived for a wide range of effective Rayleigh number and number of blocks. The model developed herein is suitable to other applications in which the total heat transfer rate needs to be computed.

Mixed Mucoadhesive Amphiphilic Polymeric Nanoparticles Cross a Model of Nasal Septum Epithelium in Vitro.

Intranasal administration of nano-drug-delivery systems emerged as an appealing strategy to surpass the blood-brain barrier and thus increase drug bioavailability in the central nervous system. However, a systematic study of the effect of the structural properties of the nanoparticles on the nose-to-brain transport is missing. In this work, we synthesized and characterized mixed amphiphilic polymeric nanoparticles combining two mucoadhesive graft copolymers, namely, chitosan- g-poly(methyl methacrylate) and poly(vinyl alcohol)- g-poly(methyl methacrylate), for the first time. Chitosan enables the physical stabilization of the nanoparticles by ionotropic cross-linking with tripolyphosphate and confers mucoadhesiveness, while poly(vinyl alcohol) is also mucoadhesive and, owing to its nonionic nature, it improves nanoparticle compatibility in nasal epithelial cells by reducing the surface charge of the nanoparticles. After a thorough characterization of the mixed nanoparticles by dynamic light scattering and nanoparticle tracking analysis, we investigated the cell uptake by fluorescence light and confocal microscopy and imaging flow cytometry. Mixed nanoparticles were readily internalized at 37 °C, while the uptake was inhibited almost completely at 4 °C, indicating the involvement of energy-dependent mechanisms. Finally, we assessed the nanoparticle permeability across liquid-liquid and air-liquid monolayers of a nasal septum epithelial cell line and studied the effect of nanoparticle concentration and temperature on the apparent permeability. Overall, our findings demonstrate that these novel amphiphilic nanoparticles cross this in vitro model of intranasal epithelium mainly by a passive (paracellular) pathway involving the opening of epithelial tight junctions.

Synthesis and characterization of a novel hydride polymer P-DSBT/ZnO nano-composite for optoelectronic applications

This paper presents the effect of nanoparticle concentration on the performance of hybrid polymer (P-DSBT)/Zinc Oxide (ZnO) thin layers. For studying the morphology, the structure and the optical behavior of the different synthesized nanocomposites, FTIR transmission spectra, scanning electron microscopy (SEM), Transmission electron microscopy, and X-ray diffractometry (XRD) were used to characterize ZnO nanostructures, atomic force microscopy, UV–Vis absorption, photoluminescence spectroscopies and contact angle measurement were used to characterize (P-DSBT)/Zinc Oxide (ZnO) nanocomposites. It has been shown that the RMS (Root Mean Square) roughness of the hybrid layers increases as a function of the percentages of ZnO in the matrix. A clear participation of nanoparticles in the nanocomposites absorption has been demonstrated in UV–Vis spectra with maintaining the absorption features of the polymer. A photoluminescence study at room temperature was been also carried out under optical excitation set as λ = 375 nm. It was confirmed that when increasing the ZnO concentration in the polymer, a shift towards red was observed and the contact angle of the composite layers decreases progressively comparing with the pure polymer. Interestingly, this confirms that polymer and polymer–ZnO hybrid nanocomposites are well adherent to the contaminated free solid surface.

MHD natural convection of Cu–Al2O3 water hybrid nanofluids in a cavity equally divided into two parts by a vertical flexible partition membrane

The aim of the present study is to investigate the effects of a hybrid nanofluid in a square cavity that is divided into two equal parts by a vertical flexible partition in the presence of a magnetic field. A numerical method called the Galerkin finite element method is utilized to solve the governing equations. The effects of different parameters, namely the Rayleigh number (106 ≤ Ra ≤ 108) and the Hartmann number (0.0 ≤ Ha ≤ 200) as well as the effects of nanoparticles concentration (0.0 ≤ φ ≤ 0.02) and magnetic field orientation (0 ≤ γ ≤ π), on the flow and heat transfer fields for the cases of pure fluid, nanofluid and hybrid nanofluid are investigated. The results indicate that the streamline patterns change remarkably and the convective heat transfer augments with increasing values of the Rayleigh number. Additionally, the maximum stress imposed on the flexible partition resulting from the interaction of the partition and pure fluid is more than those caused by the nanofluid and the hybrid nanofluid. Furthermore, the increase in the magnetic field strength decreases the fluid velocity in the cavity, which declines the fluid thermal mixing and heat transfer effects.

An experimental investigation of nanoemulsion enhanced oil recovery: Use of unconsolidated porous systems

Utilization of nanoparticles in oil and gas industry has attracted considerable attention of engineers and researchers. In this article, the feasibility of nanoemulsion flooding is investigated as a method for Enhanced Oil Recovery (EOR) through coreflooding experiments, using a packed bed and real reservoir fluids. Nine different mixtures of the solvent, surfactant, and nanoparticles in the form of a nanoemulsion phase are generated and used to recover the oil in the context of an EOR process. Various tests are conducted to determine the properties of porous medium and fluids. To study the production performance of this EOR technique, pressure drop across the packed bed are measured, along with the volumetric measurements of the produced fluids. A baseline injection scheme using seawater is also performed. All the nanoemulsion fluids are synthesized using the same base seawater. The Taguchi experimental design approach is employed in this research to design the experiments. The effects of nanoparticles concentration, along with those of surfactant and solvent components of the injection fluid on the oil recovery at the laboratory scale are investigated using the Analysis of Variance (ANOVA) method. Comparing the performance of waterflooding (WF) and nanoemulsion flooding, enhancement in the Recovery Factor (RF) by using emulsions is between 40–107%. Both the pressure and pressure fluctuations are surprisingly higher in the case of WF in comparison to the emulsion flooding. It is also found that under optimal concentration conditions (0.01 g of nanoparticles, 0.015 mL of surfactant, and 1 mL of solvent per one liter of brine), a recovery factor of up to 60% is achieved.

Effects of Cu–Ag hybrid nanoparticles on the momentum and thermal boundary layer flow over the wedge

In this work, the effects of hybrid nanoparticles on the momentum and thermal boundary layers as well as flow characteristics and thermal performance of the hybrid nanofluid are investigated over the wedge. The fluid in the enclosure is water containing hybrid nanoparticles Cu–Ag. The physical model of homogenous hybrid nanofluid is derived using the elementary equations of thermo-hydrodynamic and co-relation's model of a mixture that supports the effective physical features. The results are calculated to measure the effects of nanoparticle concentration on thermal and momentum boundary layers and displayed in graphs for discussions. In addition, the effects of nanoparticles concentration and different compositions of hybrid nanoparticles on temperature and velocity profiles, physical properties, skin friction, and convective heat transfer coefficient are deliberated through graphs and tables. To check its heat transfer performance, a comparison of hybrid nanofluid is made between the base fluid and single material nanofluids. It is found that the efficiency of hybrid nanofluids as a heat transfer fluid is much more than conventional fluids or single nanoparticles-based nanofluids. These results in terms of boundary layers phenomena, heat transfer performance, and temperature and velocity profiles under hybrid nanomaterial could help chemical engineers to design the critical equipment in a process industry such as heat exchangers and pumps and others.

Synergetic effects of nanoparticle concentration and electrification on the breakup performance of nanofluid fuel

In the case of nanofluids, the nanoparticle concentration has a significant effect on individual physical properties such as density, surface tension, and viscosity. However, there have been few studies on the comprehensive, interactive effects of nanoparticle concentration and electrification. This study demonstrates the synergetic effects of nanoparticle concentration and electrification on the breakup performance of nanofluid fuel (Al/n-decane). The secondary breakup behaviours associated with the interactive actions of gravity, surface tension, viscous forces, and electric-field force were investigated. When the Al-nanoparticle concentration of the n-decane increased, there was a linear increase in the density, and a trinomial increase in the viscosity; however, there was a piecewise influence on the surface tension. The addition of the Al nanoparticles simultaneously influenced the electrification of the nanofluid fuel, and synergistically contributed to the deformation of the Taylor cones and the secondary breakup of the jets. The effective surface tension was calculated and analysed; the results demonstrated that the Weber number decreased when the Al-nanoparticle concentration was elevated. This resulted in enlarged Taylor cone angles and minimized the average diameter of the breakup droplets. More importantly, at a critical Al-nanoparticle concentration (7.9 mg/ml), the effective surface tension was minimized; consequently, the average diameter of the breakup droplets was minimized (72 μm).

Numerical investigation of non-Newtonian water-CMC/CuO nanofluid flow in an offset strip-fin microchannel heat sink: Thermal performance and thermodynamic considerations

This paper aims to investigate the hydrothermal and entropy generation characteristics of a non-Newtonian nanofluid containing CuO nanoparticles in an offset strip-fin microchannel heat sink (MCHS). The base fluid is solution of 0.5 wt% Carboxymethyl Cellulose (CMC) in water. This study investigates the effects of nanoparticles concentration, Reynolds number and geometric size of strip-fin on the performance of MCHS from the viewpoint of both the first and the second thermodynamic law. The results reveal that enhancing the Reynolds number improves the performance of MCHS by boosting the convective heat transfer coefficient of the working fluid which favourably reduces the CPU surface temperature and thermal entropy generation rate and importantly leads to the temperature uniformity of the CPU surface. However, increase in Reynolds number adversely affects both the pumping power and the frictional entropy generation in the system. Therefore, the optimal strip-fin size is investigated to find the optimum performance of the offset strip-fins MCHS from the viewpoint of both the first and the second thermodynamic law. The optimal results show that the highest ratio of heat transfer enhancement to pressure drop increment, using the nanofluid instead of base fluid, is 2.29. In addition in the optimal case, the minimum total entropy generation rate of the nanofluid is 2.7% less than the base fluid.

Improve the thermal conductivity of 10w40-engine oil at various temperature by addition of Al2O3/Fe2O3 nanoparticles

Oils are used as coolants and lubricants in different industrial systems with the aim of reducing friction between parts and their abrasion. The objective of the present study was to investigate the effect of addition of Al2O3-Fe2O3 Nano powder hybrid on the thermal properties of 10w40 engine oil. In this study, the effect of nanoparticle concentration at different mass fractions (0, 0.25, 0.5, 1, 2, and 4) was examined. Experiments were conducted within a temperature range of 25–65 °C. The nano-lubricant was prepared using the two-stage method. An ultrasonic probe was used for 45 min to uniformly distribute the nanoparticles in the base fluid. The thermal conductivity coefficient of the hybrid nanofluid was measured using the KD2-Pro thermal analyzer, the results of which indicated that even the smallest mass concentration improved the thermal properties of the nano-lubricant. Accordingly, the largest improvement occurred at a mass fraction of 4%, i.e. 33% of the base oil. In order to calculate the thermal conductivity of the nano-lubricant using the temperature and mass fractions of the particles, the curve fitting method was applied to the experimental data to find a highly accurate experimental relation in SigmaPlot V12.

A Study of the Effect of Nanoparticle Concentration on the Characteristics of Nanofluid Sprays

A Study of the Effect of Nanoparticle Concentration on the Characteristics of Nanofluid Sprays

Hollow particles templated from Pickering emulsion with high thermal stability and solvent resistance: Young investigator perspective

HypothesisHollow particles have been used in a variety of applications and many methods have been developed. Hollow particles templated from Pickering emulsions due to nanoparticle adsorption at the oil-water interface usually suffer from the collapsed morphologies and low thermal and solvent stability and enhancement of the shell can significantly improve the hollow particle performance. ExperimentsThis paper reports hollow particles templated from Pickering emulsion droplets in combination with UV photopolymerization. The Pickering emulsions were stabilized by functional silica nanoparticles at the O/W interface and the oil phase contains photosensitive reactants, initiator, catalyst and volatile solvents. The effects of nanoparticles concentration, O/W volume ratio, pH, dispersion speed and time on the stabilization of Pickering emulsion were firstly carried out and the properties of hollow particles formed by traditional interfacial crosslinking and UV photopolymerization were systematically investigated. FindingsCompared with previous interfacial crosslinking method, the UV photopolymerization method gives much more robust shells and we show in the paper that the hollow particles have much higher solvent resistance and thermal stability. The enhancement of thermal stability and solvent resistance of the hollow particle could extend its applications to more harsh fields such as self-healing coatings used in deep sea conditions.

Experimental investigation of the effect of TiO2 nanofluid and KCl salt on polymeric water-based drilling fluid properties

In petroleum industries, nanofluids have the potential to improve the characteristics of the fluids used in drilling wells or Enhanced Oil Recovery (EOR) processes. In this study, a water based mud containing polymer was considered as the base fluid. Different concentrations of TiO2 nanoparticle (0, 0.5 and 0.75 wt%) and different concentrations of KCl salt (0, 0.5, 1.5, and 3 wt%) were added to the base fluid and exposed to different temperatures (30, 50, 70 and 90 °C) with 19 different shear rates for investigating the effects of nanoparticle concentration, salt concentration, temperature and shear rate on viscosity of the base mud. Presence of TiO2 particles enhanced not only the rheological behavior but also electrical and thermal conductivity of fluid up to 25% and 43%, respectively. Furthermore, the stability of the fluid containing salt and nanoparticle was investigated in these temperatures owing to the fact that the temperature could cause degradation of the fluid. For the purpose of investigating this phenomenon, the after cooling experiment was conducted. In addition, the data gathered in this investigation were examined by using three famous rheological models (Power law, Herschel-Bulkley and Herschel-Bulkley-Papanastasiou models) and the rheological parameters of each model were determined.

Natural convection of Al2O3/H2O nanofluid in a cavity with a heat-generating element. Heatline visualization

Cooling of electronic devices is a very important topic. The present paper deals with numerical simulation of natural convection cooling of heat-conducting and heat-generating source using an alumina-water nanofluid under the effect of cold vertical walls. Governing equations formulated in dimensionless stream function, vorticity and temperature variables have been solved by the finite difference method. The effects of nanoparticles concentration, heat source location, internal heat generation flux and heat source material on fluid flow and heat transfer have been studied. It has been found that an addition of nanoparticles can intensify the cooling process when the heat is located near the vertical cold wall.

On the assessment of modeling combined convection heat transfer in nanofluids using dissipative particle dynamics

The effect of nanoparticles on mixed convection heat transfer mechanisms in a vertical lid-driven cavity using dissipative particle dynamics method is addressed. The effect of nanoparticle concentration on the random heat flux and the total heat flux is assessed via simulating the opposing buoyancy mechanism in a lid-driven cavity filled with Al2O3-water nanofluids. The study covered a wide range of nanoparticles volume fraction (1% ≤ φ ≤ 5%), and three Richardson numbers were considered, Ri = 0.1, 1, and 10. The results were verified via comparing the temperatures and the streamlines contours with the ones obtained using finite-volume method over the same range of Richardson number and nanoparticles concentration. The effect of the compressibility of the system for natural convection dominated flows has been noted in the results as a deviation from the finite-volume results. The results reveal that the enhancement in the convection heat transfer is directly connected to the nanoparticles concentration, though the effect of the convection mechanism is more dominant. Also, it is found that the role of Brownian motion in the vicinity of hot and cold walls are negligible, where the ratio of random heat flux to the total heat flux is below 5%. For low nanoparticle concentration the enhancement of the total heat transfer is disperse, however for high nanoparticle concentration it is more localized to certain region depending on the Richardson number.

Rheology of a colloidal suspension of carbon nanotube particles in a water-based drilling fluid

High-pressure and high-temperature rheology of a nanomud suspension is studied. The nanomud is prepared by dispersing a water-based drilling mud suspension with multi-walled carbon nanotubes (MWCNT). Effect of nanoparticle concentration, shear rate, pressure, and temperature are investigated. The pressure and temperature are independently varied from ambient conditions to 170 MPa and 180 °C respectively. The results presented show that the addition of CNT increases the viscosity of the drilling mud. A shear thinning non-Newtonian behavior is observed for the basemud and the nanomud samples at all pressures and temperatures. The basemud showed an increase in viscosity with an increase in pressure. However, with CNT particle addition this trend is observed to have reversed. For the basemud and the nanomud at lower concentrations, the viscosity values are observed to have initially increased with the increase in temperature and to have reduced beyond 100 °C. For a higher particle loading, a consistent decrease in viscosity with temperature is observed. The behavior of higher concentration nanomud samples with respect to pressure and temperature are seen to follow a similar trend to that of water. It is reasoned that an adequate addition of CNT nanoparticles helps retain the mud particles in a more homogenous and stable state, where they are held within the CNT chains. However, with further addition of CNT nanoparticles, the mud particles become agglomerated with the long chains of CNT, eventually separating water from the drilling fluid mixture.

Energy, exergy and economic assessments of shell and tube condenser using hybrid nanofluid as coolant

The energy, exergy and economic assessments of a shell and tube condenser of 580 MW nuclear power plant have been carried out using different water-based hybrid nanofluids such as Al2O3 + MWCNT, Al2O3 + Ag, Al2O3 + Cu and Al2O3 + TiO2 as coolant. The effect of nanoparticle concentration on reductions of coolant requirement, pumping power and operating cost has been investigated. The results reveal that Al2O3 + MWCNT shows the highest reduction of coolant mass flow rate of 3.6%. The effectiveness of shell and tube condenser enhances with the addition of nanoparticles. The reduction of the pressure drop is maximum for Al2O3 + MWCNT hybrid nanofluid (5.8%) and minimum for Al2O3 + Ag (3.7%) at 1% volume concentration. Therefore, Al2O3 + MWCNT requires 11.2% less pumping power followed by Al2O3 + TiO2 (10.9%), Al2O3 + Cu (10.2%) and Al2O3 + Ag (9.6%) as compared to the base fluid. Al2O3 + Ag shows maximum (29.97%) and Al2O3 + MWCNT shows minimum (29.81%) second law efficiency at 1% volume concentration. Al2O3 + MWCNT hybrid nanofluid yields maximum saving of operating cost (11.1%) and Al2O3 + Ag shows minimum (9.62%) at 1% volume concentration. However, Al2O3 + Ag shows payback period about 247 years and Al2O3 + TiO2 about 9.8 years. Hence, the payback period needs to be reduced before practical implementation, which may be possible by reducing the nanoparticle cost and increasing nanofluid stability.

Impacts of moving wall and heat-generating element on heat transfer and entropy generation of Al2O3/H2O nanofluid

Development of various electronic devices demands to create effective cooling complexes. The present paper deals with computational analysis of mixed convection cooling of heat-conducting and heat-generating element located inside an alumina–water nanofluid enclosure with upper moving wall. Usage of upper moving wall, nanofluid and cooling vertical walls allows to create the effective cooling process. Analysis has been performed numerically using the Oberbeck–Boussinesq equations. The effects of nanoparticles concentration, heat source location and upper wall velocity on flow structures, heat exchange and entropy generation have been investigated. It has been ascertained that effective cooling of the heated element occurs for high Reynolds number and central position of the heat-generating element.