CuO Nanoparticles In Water Research Articles

Numerically hydrothermal fully developed forced convective hybrid nanofluid flow through annular sector duct

In this paper, fully developed forced convective flow properties of hybrid nanofluid through annular sector duct are discussed. The studies of hybrid nanofluid, i.e. the combination of a nanofluid (nanoparticles plus water) with another nanoparticles’ volume fraction, are considered. Hybrid nanofluids become most important due to enhancement in the heat transfer rate. Copper oxide (CuO)–water is taken as the nanofluid. The volume fraction of CuO nanoparticles in water is kept fixed at 4%, whereas the volume fractions of Cu nanoparticles are taken in the range of 0–4% in this study. Under the assumption of hydrodynamically and thermally fully developed flow, the deviation in the velocity components along the axial direction vanishes in the case of momentum equations; however, the deviation in the temperature becomes constant in the case of energy equation. After dimensionless analysis, the finite volume method is applied to find the numerical solutions for velocity, temperature, heat transfer rate and fanning friction factor. During physical analysis, it has been concluded that the percentage enhancement in heat transfer rate is comparably more than fanning friction factor when we increase the volume fraction of Cu nanoparticles in the CuO–water nanofluid. Furthermore, the same observation has been noticed in the case of heat transfer rate when the platelet shape factor of the nanoparticles has been used instead of brick and cylinder shape factors. Increase in fRe is 8.01% when we increase the Cu nanoparticles’ volume fraction from 1% to 4%, whereas the increments in Nu are 15.09%, 18.56% and 20.81% for the brick-, cylinder- and platelet-shaped nanoparticles, respectively, for all values of the ratio of radii, [Formula: see text], and apex angle, [Formula: see text], in both thermal cases.

Exponential space-based heat source on Sakiadis flow of a dusty nanofluid using KKL model useful in solar radiation

The emission of solar energy is one of the greatest challenges due to its global impact nowadays. Further, the improved heat transport properties of the nanofluids have also important aspects in industries as well as engineering equipment and any others. Therefore, the present analysis motivates the enhancement in the heat transport enrichment of Sakiadis nanofluid by imposing Koo–Kleinstreuer–Li (KKL) model conductivity along with dusty CuO nanoparticles in water. Dust particles in conjunction with the magnetic effect and the radiative heat explore its greater role in the enhancement of the heat transport phenomena. Suitable transformation is proposed for the governing equations to get its non-dimensional form with significant parameters to characterize the flow properties. Moreover, numerical treatment using Runge–Kutta shooting is a good approach to handle the complex nonlinear system equipped with nanofluid phase and dusty phase liquids. Several factors impacting the flow phenomena have been examined graphically. In careful observation, it reveals that the augmented thermal radiation along with the heat source encourages the nanofluid phase temperature but the reverse impact is rendered in the dust phase.

Flow and Heat Transfer in a Trapezoidal Cross-Sectional Microchannel Heat Sink Using Nanofluid

In this study, the effects of microchannel number, volume concentration, Reynolds number, and nanofluid type on heat transfer and flow characteristics in the heat sink consisting of trapezoidal microchannels are investigated numerically. Governing equations are solved by assuming three-dimensional, incompressible, steady and laminar flow. The channel material is chosen as copper, and a constant heat flux boundary condition is defined on the upper wall of heat sink. For two different nanofluids, CuO-water and Al2O3-water, investigated parameters are the number of trapezoidal channels (n=3-5) in the heat sink, Reynolds number (Re=200-1500), and volume concentration (=0-4%). Results show that using nanoparticles in base fluid causes to increase both heat transfer coefficient and pressure drop. Heat transfer coefficient increases with increasing number of trapezoidal cross-sectional channel in the heat sink, nanofluid volume concentration and Reynolds number. Pressure drop enhances with enhancing Reynolds number and microchannel number in the heat sink. The nanofluid type and volume concentration do not importantly affect the friction factor. According to the performance index, it is seen that adding CuO nanoparticles in water is convenient, but Al2O3 nanoparticles in water is not appropriate. It is observed that volume concentration for CuO-water nanofluid affects the thermal performance, but volume concentration for Al2O3-water nanofluid does not affect.

Investigating thermo-physical properties and thermal performance of Al2O3 and CuO nanoparticles in Water and Ethylene Glycol based fluids

The thermophysical properties and thermal performance of water- and ethylene-glycol-based nanofluids containing and CuO nanoparticles were examined. Nanofluids were prepared at four concentrations (1- 4 vol%) using an electric mixer and magnetic stirrer, and the thermophysical properties were measured. Surfactants were used to improve stability. The transient hot-wire method (KD2-Pro device), Dynamic Light Scattering (DLS), and Ostwald viscometer (ASTM D445-06) were used to measure the resulting thermal conductivity coefficient, nanoparticle diameter, and nanofluid viscosity, respectively. The experiments were carried out in the 20 to 50 °C temperature range. Adding 1 wt% sodium dodecyl sulfate (SDS) to the CuO–water and the same amount of sodium dodecylbenzene sulfonate (SDBS) to the –water nanofluid were found to stabilize them for 20 and 22 days, respectively. Increasing the nanoparticle volume fraction, raising the temperature, and reducing nanoparticle diameter were found to increase the thermal conductivity coefficient. The density also increases with the nanoparticle volume fraction in the base fluid increasing. Moreover, at the same volume fraction, the CuO–water nanofluid had a higher density than –water. Better base fluid thermal properties amplify the effect on the nanofluid's thermal conductivity coefficient. The actual thermal conductivity coefficient was determined by comparing model predictions of the coefficient.

The Effect of Turbulence Model and Nanofluid on Fluid Flow and Heat Transfer in a Narrow Rectangular Duct

The effect of turbulence model and nanofluid on the heat transfer and fluid flow in a horizontal narrow rectangular duct is numerically studied under constant wall heat flux boundary condition. Numerical study is carried out using ANSYS Fluent 17.0 software. Examined parameters are the type of turbulence model, the type of nanofluid, the volume fraction of nanofluid, and the Reynolds number. Three different k-e and four different k-w turbulence models are employed. Aluminum oxide Al2O3-water and copper oxide CuO-water are used as nanofluids. Volume fractions of nanoparticles used are 0%, 0.1%, 0.5%, 1%, 2% and 4%. Reynolds number changes from 3×103 to 50×103. Results showed that k-ω standard turbulence model with low Reynolds number correction gives better result. It is seen that both the type and volume fraction of nanofluid affect heat transfer and pressure drop. Using Al2O3 and CuO nanoparticles in water increases thermal performance. It is found that the performance of CuO-water nanofluid is better than that of Al2O3-water nanofluid. It is seen that using turbulent fully developed correlations derived for circular ducts may end up with incorrect results for the flow in a two dimensional rectangular duct.

Size and Shape-Dependent Solubility of CuO Nanostructures.

In our theoretical study, the enhanced solubility of CuO nanoparticles in water saturated by air is predicted based on a simple thermodynamic model. CuO is considered in the form of nanoparticles with various shapes. The interfacial energy of a solid CuO/dilute aqueous solution interface was assessed by applying the average CuO surface energy and contact angle of a sessile drop of water. The equilibrium CuO solubility was calculated using Gibbs energy minimization technique. For the smallest spherical nanoparticles considered in this work (r = 2 nm), the solubility is significantly higher than the solubility of bulk material. In the case of cylindrical nanoparticles, the solubility increase is even more considerable. The CuO spherical nanoparticles solubility was also calculated using the Ostwald–Freundlich equation which is known to overestimate the solubility as discussed in this contribution.

Experimental study on pool boiling and Critical Heat Flux enhancement of metal oxides based nanofluid

Critical Heat Flux or CHF is a phenomenon in pool boiling, which limits the thermal flux during the nucleate heating phase. Presented research paper is an investigation of the CHF of Al2O3, Fe2O3 and CuO nanoparticles in water as base fluids. Critical Heat Flux of water and nanofluids were measured at 100 °C and 0.10325 MPa using 29 × 22 W DC power supply and NiCr 32AWG wire as the primary heater. Concentration of nanoparticles in the respective base fluids was varied from 0.01 vol% to 0.1 vol% in the step of 0.1%. Nanofluids were used as the working fluid and sent to circular bath. A significant enhancement in CHF was found of nanofluid over base fluid is found in the study. As the concentration of nanoparticles in water increases, the CHF also increases up to their optimum concentration and then starts to drop and almost becomes constant at 0.1%. The enhancement is due to enhanced surface wettability, increased heat transfer coefficient and nanoparticle deposition on heating element. The decrease in CHF over higher concentration is due to probable agglomeration due to prevalent surface charges of nanoparticles.

Numerical investigation of MHD nanofluid free convective heat transfer in a porous tilted enclosure

PurposeThe effect of a magnetic field on nanofluid natural convection in a porous annulus is simulated. Control volume-based finite element method (CVFEM) is applied to find the influence of tilted angle and Darcy, Rayleigh and Hartmann numbers on nanofluid hydrothermal behavior. Vorticity stream function formulation is taken into account. Also, Brownian motion effect on nanofluid thermal conductivity is considered. Results reveal that Hartmann number and tilted angle make changes in nanofluid flow style. Nusselt number enhances with augment of Darcy number and buoyancy forces but reduces with rise of tilted angle and Hartmann number.Design/methodology/approachThe influence of adding CuO nanoparticles in water on the velocity and temperature distribution in an inclined half-annulus was studied considering constant heat flux. CVFEM is applied to the simulation procedure.FindingsInfluences of CuO volume fraction, inclination angle and Rayleigh number on hydrothermal manners are presented.Originality/valueResults indicate that inclination angle makes changes in flow style. The temperature gradient enhances with rise of buoyancy forces, whereas it reduces with augment of inclination angle.

ChemInform Abstract: Sequence Selective Michael Addition for Synthesis of Indeno‐Pyridine and Indeno‐Pyran Derivatives in One‐Pot Reaction Using CuO Nanoparticles in Water.

AbstractProduct formation in this efficient, green, three‐component one‐pot reaction is simply controlled by the sequence of addition.

Heat Transfer Enhancement using CuO / Water Nanofluid in a Shell and Helical Coil Heat Exchanger

Forced convective heat transfer studies have been carried out in an agitated shell and helical coil heat exchanger using CuO/water nanofluid. Experiments have been carried out in a shell and helical coil heat exchanger at various concentrations of CuO nanoparticles in water (0.3, 0.6, 1, 1.5 and 2% wt.), stirrer speeds (500, 1000 and 1500rpm) and shell-side fluid (heating medium) temperatures (40, 45 and 50oC). Water has been used as coil-side fluid, and studies have been conducted at different values of Dean number (flow rates). Enhancement in heat transfer due to the use of nanofluid has been reported in terms of heat transfer rate.

Entropy Generation during Turbulent Flow of Zirconia-water and Other Nanofluids in a Square Cross Section Tube with a Constant Heat Flux

The entropy generation based on the second law of thermodynamics is investigated for turbulent forced convection flow of ZrO2-water nanofluid through a square pipe with constant wall heat flux. Effects of different particle concentrations, inlet conditions and particle sizes on entropy generation of ZrO2-water nanofluid are studied. Contributions from frictional and thermal entropy generations are investigated, and the optimal working condition is analyzed. The results show that the optimal volume concentration of nanoparticles to minimize the entropy generation increases when the Reynolds number decreases. It was also found that the thermal entropy generation increases with the increase of nanoparticle size whereas the frictional entropy generation decreases. Finally, the entropy generation of ZrO2-water was compared with that from other nanofluids (including Al2O3, SiO2 and CuO nanoparticles in water). The results showed that the SiO2 provided the highest entropy generation.

Sequence Selective Michael Addition for Synthesis of Indeno-Pyridine and Indeno-Pyran Derivatives in One-Pot Reaction Using CuO Nanoparticles in Water

The alternate synthesis of indeno-pyridine and indeno-pyran derivatives have been described by an unprecedented, green, one-pot reaction of aromatic aldehydes, malononitrile, and indane 1,3-dione. The formation of either indeno-pyridine or indeno-pyran derivatives based on a precise change in the Michael addition of indane 1,3-dione or malononitrile on Knoevenagel product during the progress of reaction has been investigated. The reaction completed up to 30 min of time using CuO nanoparticles in water at an ambient temperature renders the protocol novel and environment friendly. All the synthesized compounds have been confirmed on the basis of their spectroscopic data. The CuO nanoparticles have been prepared by coprecipitation method and characterized by SEM, PXRD spectroscopy, and UV spectroscopy.

ChemInform Abstract: Divergent Reactivities of O‐Haloanilides with CuO Nanoparticles in Water: A Green Synthesis of Benzoxazoles and O‐Hydroxyanilides.

AbstractChloride and fluoride can act as leaving group as well, yet requiring longer reaction time and giving lower yields.

Sulfidation of copper oxide nanoparticles and properties of resulting copper sulfide

Sulfidation of 40 nm CuO nanoparticles in water yields poorly structured CuxSyand crystalline covellite (CuS) with increasing apparent solubility.

Divergent reactivities of o-haloanilides with CuO nanoparticles in water: a green synthesis of benzoxazoles and o-hydroxyanilides

In the present study, three divergent reaction paths emerged when o-haloanilides were subjected to CuO nanoparticles in water. o-Halo (I, Br) phenylbenzamides in the presence of CuO nanoparticles and Cs2CO3 in water at 100 °C provided o-hydroxyphenyl benzamides as the major product. However, a complete change in selectivity was observed in the presence of an organic base/ligand (TMEDA), giving 2-arylbenzoxazole as the exclusive product. The above selectivities were not clearly distinct when the corresponding alkylamides were treated either in the presence or absence of the ligand. A number of o-halophenyl alkylamides provided either exclusively o-dehalogenated products or a mixture of o-dehalogenated and o-hydroxylated products, but none gave 2-alkylbenzoxazoles. In addition to the above selectivities, the use of an environmentally friendly solvent (water) and base, and the recyclability of the catalyst make this procedure a benign alternative to the existing methods for the synthesis of these molecules, viz. o-hydroxybenzamides and o-arylbenzoxazoles.

A Simple Ball Milling Method for the Preparation of <I>p</I>-CuO/<I>n</I>-ZnO Nanocomposite Photocatalysts with High Photocatalytic Activity

The p-n junction photocatalyst, p-CuO/n-ZnO, was prepared via ball milling of ZnO and CuO nanoparticles in water. The structural, optical, and surface properties of the p-n junction photocatalyst p-CuO/n-ZnO were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy, and Zeta potential analyzer. The Photocatalytic activity of the photocatalyst was evaluated via photocatalytic oxidation of Methylene Blue (MB) in the presence of UV light. This study demonstrates a novel p-n junction oxide photocatalyst p-CuO (wt. 10%)/n-ZnO having superior photocatalytic activity (PCA) for the degradation of model dye under the illumination of UV-Vis light. The MB solution was only PCA, degraded by 100% within 15 min by the use of CuO (wt. 10%)/ZnO photocatalyst. Effectivley 365% increase in degradation rate constant was noticed for CuO (10 Wt.%)/ZnO nanocomposite as compared to that of pure ZnO nanoparticles. The enhanced PCA is anticipated from the presence of many micro p-n junctions formed between ZnO-CuO nanoparticles upon ball milling, which helps in efficient electron/hole pair charge separation upon excitation. The study highlights the fact that PCA of p-n junction CuO/ZnO photocatalyst can be effectively tuned by manipulating the interface of the heterostructure and by adjusting the parameters affecting the PCA. The result obtained from PCA is further verified by the zeta potential study.

Scale formation and subcooled flow boiling heat transfer of CuO–water nanofluid inside the vertical annulus

The forced convective and subcooled flow-boiling heat transfer of CuO/water nanofluid as well as fouling rate of nanofluid are experimentally quantified for different dilute concentrations of CuO nanoparticles in water over a range of mass fluxes (353kg/m2s<G<1059kg/m2s). Stabilization of nanofluid was also carried out using pH control method and examined using time-spend experiment. In the best case of stabilization (about 216h), experimental results demonstrate that two discrete regions of heat transfer are seen namely force convective and nucleate boiling. Results also show that when concentration of nanofluid increases, heat transfer coefficient in both regions significantly decreases in comparison to pure water. Beside, results reveal that increase of heat and mass flux significantly increases the heat transfer coefficient in both heat transfer mechanisms. In the range of these experiments; nanoparticles have an insignificant effect on the flow pressure drop with the CuO/water nanofluid. Beside, Influence of some operating conditions on flow boiling heat transfer coefficient and fouling rate is discussed.

Experimental study on CuO nanoparticles in distilled water and its effect on heat transfer

The pool boiling characteristics of dilute dispersions of CuO nanoparticles in water were studied using a 36 gauge NiCr wire at atmospheric pressure. Significant enhancement in critical heat flux (CHF) can be achieved at modest nanoparticle concentrations (< 0.1% by volume) without facing any problem of agglomeration and fouling. During experimentation and subsequent inspection, formation of a porous layer of nanoparticles on the heater surface was observed. Boiling of nanofluid resulted in nanoparticle deposition smoothing the surface at lower concentration. To substantiate the nanoparticle deposition and its effect on critical heat flux, investigation was done by measuring the surface roughness and SEM images of the wire surface. While SEM images revealed particle coating, measurement of surface roughness indicated surface modification. Formation of the porous layer on the heater surface as revelled by SEM images provided an excellent location for nucleation sites and subsequent bubble formation. Flow visualisation of the CuO nanofluid (0.1 g/l) up to critical heat flux gave an idea of bubble growth. The experimental results showed the evidence of nanoparticle deposition on the wire surface enhancing critical heat flux.

Experimental study on CuO nanoparticles in distilled water and its effect on heat transfer on a vertical surface

The pool boiling characteristics of dilute dispersions of CuO nanoparticles in water were studied at atmospheric pressure on a vertical heating surface. Experimental investigation of different weight concentrations of nanoparticles revealed significant enhancement in heat flux and deterioration in pool boiling. Out of many reasons, nanoparticles coating the heater surface was believed to be the reason behind this. Subsequent inspection of the heater surface showed nanoparticles coating the surface, forming a porous layer. To substantiate the nanoparticle deposition and its effect on heat flux, an investigation was performed by measuring the surface roughness of the heater surface before and after the experiment. While SEM images of the heater surface revealed nanoparticle deposition, measurement of surface roughness of the heater surface confirmed it. Formation of the porous layer on the heater surface as revealed by SEM images provided an excellent location for nucleation sites enhancing heat transfer. However, deterioration in nucleate boiling at different weight concentrations indicated some phenomenon is working behind this.

Heat transfer characteristics in double tube helical heat exchangers using nanofluids

In the present work a three-dimensional analysis is used to study the heat transfer characteristics of a double-tube helical heat exchangers using nanofluids under laminar flow conditions. CuO and TiO 2 nanoparticles with diameters of 24 nm dispersed in water with volume concentrations of 0.5–3 vol.% are used as the working fluid. The mass flow rate of the nanofluid from the inner tube was kept and the mass flow rate of the water from the annulus was set at either half, full, or double the value. The variations of the nanofluids and water temperatures, heat transfer rates and heat transfer coefficients along inner and outer tubes are shown in the paper. Effects of nanoparticles concentration level and of the Dean number on the heat transfer rates and heat transfer coefficients are presented. The results show that for 2% CuO nanoparticles in water and same mass flow rate in inner tube and annulus, the heat transfer rate of the nanofluid was approximately 14% greater than of pure water and the heat transfer rate of water from annulus than through the inner tube flowing nanofluids was approximately 19% greater than for the case which through the inner and outer tubes flow water. The results also show that the convective heat transfer coefficients of the nanofluids and water increased with increasing of the mass flow rate and with the Dean number. The results have been validated by comparison of simulations with the data computed by empirical equations.