Copper Nanofluid Research Articles

Non-Isothermal Hydrodynamic Characteristics of a Nanofluid in a Fin-Attached Rotating Tube Bundle

In the present study, a novel configuration of a rotating tube bundle was simulated under non-isothermal hydrodynamic conditions using a mixture model. Eight fins were considered in this study, which targeted the hydrodynamics of the system. An aqueous copper nanofluid was used as the heat transfer fluid. Various operating factors, such as rotation speed (up to 500 rad/s), Reynolds number (10–80), and concentration of the nanofluid (0.0–4.0%) were applied, and the performance of the microchannel heat exchanger was assessed. It was found that the heat transfer coefficient of the system could be enhanced by increasing the Reynolds number, the concentration of the nanofluid, and the rotation speed. The maximum enhancement in the heat transfer coefficient (HTC) was 258% after adding a 4% volumetric nanoparticle concentration to the base fluid and increasing Re from 10 to 80 and ω from 0 to 500 rad/s. Furthermore, at Re = 80 and ω = 500 rad/s, the HTC values measured for the nanofluid were 42.3% higher than those calculated for water, showing the nanoparticles’ positive impact on the heat transfer paradigm. Moreover, it was identified that copper nanoparticles’ presence had no significant effect on the system’s pressure drop. This was attributed to the interaction of the fluid flow and circulated flow around the tubes. Finally, the heat transfer coefficient and pressure drop had no considerable changes when augmenting the rotation speed at high Reynolds numbers.

Prediction of velocity profile of water based copper nanofluid in a heated porous tube using CFD and genetic algorithm

The heat transfer improvements by simultaneous usage of the nanofluids and metallic porous foams are still an attractive research area. The Computational fluid dynamics (CFD) methods are widely used for thermal and hydrodynamic investigations of the nanofluids flow inside the porous media. Almost all studies dedicated to the accurate prediction of the CFD approach. However, there are not sufficient investigations on the CFD approach optimization. The mesh increment in the CFD approach is one of the challenging concepts especially in turbulent flows and complex geometries. This study, for the first time, introduces a type of artificial intelligence algorithm (AIA) as a supplementary tool for helping the CFD. According to the idea of this study, the CFD simulation is done for a case with low mesh density. The artificial intelligence algorithm uses learns the CFD driven data. After the intelligence achievement, the AIA could predict the fluid parameters for the infinite number of nodes or dense mesh without any limitations. So, there is no need to solve the CFD models for further nodes. This study is specifically focused on the genetic algorithm-based fuzzy inference system (GAFIS) to predict the velocity profile of the water-based copper nanofluid turbulent flow in a porous tube. The most intelligent GAFIS could perform the most accurate prediction of the velocity. Hence, the intelligence of GAFIS is tested for different values of cluster influence range (CIR), squash factor(SF), accept ratio (AR) and reject ratio (RR), the population size (PS), and the percentage of crossover (PC). The maximum coefficient of determination (~ 0.97) was related to the PS of 30, the AR of 0.6, the PC of 0.4, CIR of 0.15, the SF 1.15, and the RR of 0.05. The GAFIS prediction of the fluid velocity was in great agreement with the CFD. In the most intelligent condition, the velocity profile predicted by GAFIS was similar to the CFD. The nodes increment from 537 to 7671 was made by the GAFIS. The new predictions of the GAFIS covered all CFD results.

Heat transfer properties of metal, metal oxides, and carbon water-based nanofluids in the ethanol condensation process

This work investigates the convective heat transfer enhancement of water-based nanofluids in pipe heat exchanger used for the ethanol condensation process. The nanofluids were produced with different nature of nanoparticles, Cu, Fe3O4, MWCNT, and graphene, in the volume concentration 0.01–0.1%, using different surfactants. These nanoparticles are characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), specific surface area (BET), and Dynamic light scattering (DLS). Density, thermal conductivity, and viscosity of base fluids and nanofluids were experimentally determined at a relevant temperature of 20 °C. Convective heat transfer enhancement under laminar regime was evaluated from a well-designed experimental setup. As the main results, the thermal conductivity of nanofluids increases up to 3–5% and the viscosity can increase or decrease with nanoparticle concentration, showing a lubricating effect of nanoparticles coupled with respective surfactant. It was shown that the heat transfer properties, heat transfer coefficient, and Nusselt number, are increased with nanofluids compared to water and base-fluids, up to 20%, in the range of Pe 2000–10000. Experimental heat transfer properties are shown to be greater than theoretical ones. Finally, copper nanofluid at low concentration appear to be the best candidate for the application and pipe flow geometry considered.

Numerical Simulation of the Thermally Developed Pulsatile Flow of a Hybrid Nanofluid in a Constricted Channel

Heat transfer analysis of the pulsatile flow of a hybrid nanofluid through a constricted channel under the impact of a magnetic field and thermal radiation is presented. Hybrid nanofluids form a new class of nanofluids, distinguished by the thermal properties and functional utilities for improving the heat transfer rate. The behaviors of a water-based copper nanofluid and water-based copper plus a single-wall carbon nanotube, i.e., (Cu–SWCNT/water), hybrid nanofluid over each of velocity, wall shear stress, and temperature profiles, are visualized graphically. The time-dependent governing equations of the incompressible fluid flow are transformed to the vorticity-stream function formulation and solved numerically using the finite difference method. The laminar flow simulations are carried out in 2D for simplicity as the flow profiles are assumed to vary only in the 2D plane represented by the 2D Cartesian geometry. The streamlines and vorticity contours are also shown to demonstrate the flow behviour along the channel. For comparison of the flow characteristics and heat transfer rate, the impacts of variations in Hartmann number, Strouhal number, Prandtl number, and the thermal radiation parameter are analyzed. The effects of the emerging parameters on the skin friction coefficient and Nusselt number are also examined. The hybrid nanofluid is demonstrated to have better thermal characteristics than the traditional one.

Performance Enhancement and Analysis of Shell and Tube Type Heat Exchanger

Nano-fluids are playing a very important role in thermal stream due to its physical and thermal properties. Now a day it was observed that there are lots of papers which have explained the deep study on nanofluids. There are so many areas in which nanofluids are used to increase the thermal efficiency and coefficient of heat transfer. In this review comprehension, many research works which are related to nanofluids used as a working fluid in shell and tube heat exchanger will be summarized in efficient way. And theoretical as well as experimental study is to be performed for shell and tube heat exchanger to determine what the effects on various parameters of graphene nanofluid, silver nanofluid, Al2O3 nanofluid and copper nanofluid. Graphite is the cheapest form of producing flanks of graphene and these samples of produced graphene were optimized with help of different type of methods. To increase the performance of heat transfer of shell & tube heat exchanger, the graphene nanofluid is used as a working fluid rather than any different type of ordinary fluid. The thermal efficiency and the coefficient of heat transfer depend upon the inlet temperature, flow rate, concentration of working fluid. The general outcomes show that by increasing in concentration of nanoparticle and flow rate of working fluids, there will be the increment in heat transfer rate, thermal conductivity and efficiency of heat exchanger.

Stagnation Point Flow in Copper Nanofluid over Slippery Cylinder with Viscous Dissipation

This study investigates the heat transfer dissipation on stagnation point flow over a slippery stretching/shrinking cylinder in a copper nanofluid by considering the effect of viscous dissipation. A system of nonlinear partial differential equations is modelled and transformed into ordinary differential equations using similarity transformations. The governing equations with the corresponding boundary conditions are analysed numerically using a bvp4c solver in MATLAB. The solutions are found to be dependent on the Eckert number and slip parameters. The results are represented by the velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number. Dual solutions are observed for the shrinking cylinder in the presence of Eckert number. Velocity profile and skin friction coefficient consistently increase while temperature profile increases initially and then decreases with the increase of slip parameter for both first and second solutions. Moreover, the presence of copper nanoparticles reduces the thermal boundary layer thickness. This research can be enhanced by using hybrid nanofluids to further improve the heat transfer.

Efficiency enhancement of an air-conditioner utilizing nanofluids: An experimental study

This paper presents a novel idea of utilizing nanofluid as external cooling jacket around the condenser of an air conditioner. Experimental investigations were carried out to study the influence of two types of nanofluids namely, copper and aluminum oxide nanofluids on the performance of an air conditioner. The nanofluids were used to enhance the heat transfer by means of providing an external nanofluid medium around the condenser section. Both Cu and Al2O3 nanofluids were prepared in three volume fractions of 1%, 2% and 5% with water as the base fluid. The performance of the air conditioner was evaluated by comparing the coefficient of performance when the system is operated with and without nanofluid. Experimental results indicate that employment of Cu and Al2O3 nanofluids causes a significant enhancement in the COP. As the volume fraction was increased, the performance was found to increase. For the highest volume fraction of 5%, Al2O3 nanofluid was found to enhance the COP by a maximum of 22.1% while copper nanofluid exhibited a more significant enhancement by 29.4%.

Experimental Investigation on the Performance of Heat Pump Operating with Copper and Alumina Nanofluids

In the present study, an attempt is made to enhance the performance of heat pump by utilizing two types of nanofluids namely, copper and alumina nanofluids. These nanofluids were employed around the evaporator coil of the heat pump. The nanofluids were used to enhance the heat input to the system by means of providing an external jacket around the evaporator coil. Both the nanofluids were prepared in three volume fractions 1%, 2% and 5%. Water was chosen as the base fluid. The performance of the heat pump was assessed by calculating the coefficient of performance of the system when it was operated with and without nanofluid jacket. A significant enhancement in the coefficient of performance was noticed when copper and alumina nanofluids were employed in the system. Also, the coefficient of performance was found to have a direct relationship with the tested volume fractions. For the highest volume fraction of 5%, the performance of the heat pump was found to enhance by 23% with alumina nanofluid, while for copper nanofluid, a very significant enhancement in performance by 72% was observed. Thus, utilizing of nanofluids in heat pumps can be very beneficial towards performance enhancement and the idea can also be extended to other thermal systems such as steam power plant, automobile radiator, industrial heat exchangers and refrigeration systems.

Analysis of hybrid nanofluids in machining AISI 4340 using minimum quantity lubrication

Abstract Cutting fluids enhance the machining performance due to their ability to provide good lubrication and remove generated heat. Minimum quantity lubrication (MQL) serves as the best alternative for flood machining as it allows a considerable reduction in machining cost along with longer tool life. Nanofluids are fluids having enhanced lubrication and cooling characteristics due to very high surface to volume ratio of nanoparticles. In the present work, machining is performed in dry condition, MQL application of soluble oil without nanoparticles, 0.3 wt% of copper dispersed in soluble oil, 0.3 wt% of graphene dispersed in soluble oil, and 0.3 wt% of graphene and copper (1:1) dispersed in soluble oil (hybrid nanofluid). Turning of AISI 4340 material is performed using uncoated tungsten carbide at varying cutting parameters. Graphene nanofluid as well as hybrid nanofluid showed the least flank wear. Hybrid nanofluid showed the least cutting temperature at higher depth of cut and higher feed while copper nanofluid showed the least cutting temperature at higher cutting velocities.

Influence of load and speed on tribological performance of Cu nanofluids in EHL line contacts

Abstract Nowadays, wear is the leading cause of common machine failure and significant use of lubricants is required to reduce such failure. Lubricants over the years have evolved from animal fats to mineral oils and now nanofluids. Nanofluids are the blend of nanoparticles and base lubricating oil. Copper nanofluids are used as efficient nanolubricants for contacting surfaces because of their high thermal and electrical conductivity. In this paper, influences of applied load and rotational speed on tribological performance of copper nanofluids have been investigated. The effect of viscoelasticity in terms of contact pressure and film thickness in elastohydrodynamic lubrication (EHL) has been also investigated. Experimental tests were performed on multispecimen tribometer machine in pin on roller (line contact) arrangement, using EN31-EN31, EN31-GM, EN31-PB, EN31-Al alloy as tribopairs. Results indicate that both contact pressure and film thickness do not have any significant effect after incorporation of viscoelastic effect in EHL line contacts of copper nanofluids. Coefficient of friction (CoF) for all the tribopairs have been increased with the applied load, with rotational speed for EN31-GM, EN31- Al alloy. However, for EN31-EN31, EN31-PB CoF decreases. Wear has been also shown to be increase with the increase of applied load and rotational speed.

Heat transfer enhancement with nanofluid in an open enclosure due to discrete heaters mounted on sidewalls and a heated inner block

Purpose The purpose of this study is to explore the heat transfer enhancement in copper–water nanofluid flowing in a diagonally vented rectangular enclosure with four discrete heaters mounted centrally on the sidewalls and a square-shaped embedded heated block in the influence of a static magnetic field. Design/methodology/approach Four discrete heaters are mounted centrally on each sidewall of the rectangular enclosure that embraces a heated square block. A static transverse magnetic field is acting on the vertical walls. The Navier–Stokes equations of motion and the energy equation are modified by incorporating Lorentz force and basic physical properties of nanofluid. The derived momentum and energy equations are tackled numerically using the successive over-relaxation technique associating with the Gauss–Seidel iteration technique. The effects of physical parameters connected to dynamics of flow and heat convection are explored from streamlines and isotherms graphs and discussed numerically in terms of Nusselt number. Findings The effect of the embedded heated square block size and its location in the enclosure, nanoparticles volume fraction and the intensity of the magnetic field on flow and heat transfer are computed. Compared with the case when no heated block is embedded in the enclosure, in free convection at Ra = 106, the average local Nusselt number on the wall-mounted heaters is attenuated by 8.25%, 11.24% and 12.75% when the enclosure embraced a heated square block of side length 10% of H, 20% of H and 30% of H, respectively. An increase in Hartmann number suppresses the heat convection. Research limitations/implications The enhancement in the convective heat is greater when the buoyancy effect dominates the viscous effects. Placing the embedded heated block near the inlet vent, the lower temperature zone has reduced while the embedded heated block is at the central location of the enclosure, the high-temperature zone has expanded. The external magnetic field can be used as a non-invasive controlling device. Practical implications The numerically simulated results for heat convection of water-based copper nanofluid agreed qualitatively with the existing experimental results. Social implications The models could be used in designing a target-oriented heat exchanger. Originality/value The paper includes a comparative study for three locations of the embedded heated square. The optimal results for the centrally located heated block are also performed for three different sizes of the embedded block. The numerically simulated results are compared with the published numerical and experimental studies.

Entropy generation in electromagnetohydrodynamic water based three Nano fluids via porous asymmetric microchannel

Nanofluids are of immense importance to the researchers as they have significant uses industrially due to their high heat transfer rates. This new model is employed to examine the electroosmotic flow of magnetohydrodynamic nanofluids through an asymmetric microfluidic channel. Microchannel flow is driven by the electroosmosis and peristalsis mechanisms. Nanoparticles (copper, alumina and titania) with water as a base fluid have been considered. The effects of Joule heating, mixed convection, permeability of the porous medium and dissipation of energy are considered. Besides, velocity slip conditions are also encountered at the walls. Electroosmotic phenomenon is modeled through Poisson equation and Nernst–Planck equation. Debye–Hückel approximation is considered to obtain Boltzmann distribution of electric potential across electric double layer. The emerging non-linear mathematical model is solved numerically by the built-in scheme of working software. The table is inserted for numerical values of heat transfer rate at the upper wall for three different type of water-based metallic nanofluid. To verify the accuracy of results, the comparison of solutions is also shown. Entropy generation in terms of Bejan number under different parameters is also investigated. The influence of physical factors on the characteristics of heat transfer has been pointed out. Water-based copper and titania nanofluids have relatively higher temperature and heat transfer rate when compared to the alumina-water nanofluid. Porosity decays the temperature throughout the microchannel. Moreover, temperature is strongly increased for higher values of the Joule heating parameter γ, in presence of Cu-water nanofluid. The current analysis is related to bio-inspired electrokinetic nanofluidic micropump models and incipient nanomedicine technologies.

EFFECTIVENESS AND THERMAL PERFORMANCE ANALYSIS OF COPPER NANOFLUIDS FLOW IN A U-BEND DOUBLE-PIPE HEAT EXCHANGER

EFFECTIVENESS AND THERMAL PERFORMANCE ANALYSIS OF COPPER NANOFLUIDS FLOW IN A U-BEND DOUBLE-PIPE HEAT EXCHANGER

Unsteady Free Convection Flow of Nanofluid with Dissipation Effect over a Non-Isothermal Vertical Cone

This paper investigated unsteady free convection flow of nanofluid with dissipation effect over a non-isothermal vertical cone. The dimensional governing equations that consists of continuity, energy and momentum equations are reduced by using appropriate dimensionless variables along with variable wall temperature as its initial and boundary conditions. The case when water is the base fluid has been considered and the effects of the solid volume fraction on the flow and heat transfer characteristics are determined for Silver (Ag), Copper (Cu), Alumina (Al2O3) and Titanium oxide (TiO2) nanofluids. The purpose of the study is to investigate numerically the mathematical model by using the Crank-Nicolson method. The discretization equations were computed, and numerical results were plotted using MATLAB software. It has been shown that when the nanoparticles volume fraction increases, the NuX increases and the velocity profile decreases. Moreover, for Silver(Ag), Copper(Cu) and Titanium oxide (TiO2) nanoparticles, the thermal boundary layer decreases at first but later started to increase at certain values as the nanoparticles volume fraction increases. However, for Alumina (Al2O3) nanoparticles, the temperature profile increases as the nanoparticles volume fraction increases. It has also been found in this problem that the Alumina (Al2O3) nanoparticles have the highest heating performance while Silver (Ag) nanoparticles have the highest cooling performance.

Experimental investigation on stability and thermal conductivity of dodecanethiol-coated copper nanofluids

Nanofluids were prepared by dispersing dodecanethiol-coated copper nanoparticles (~ 50 nm average diameter) in toluene. The stability and thermal conductivity of the nanofluids were investigated for various particle volume concentrations (0.09–1.5 vol%) and temperatures (293–333 K). The amount of dodecanethiol surfactant coated on the nanoparticle surface was determined by thermogravimetric analysis (TGA), and the chemical structure of adsorbed surfactant molecules was characterized by Fourier transform infrared spectroscopy (FT-IR). UV-vis absorbance analysis of the nanofluid was undertaken to determine the optimum ultrasonic vibration time for stability enhancement. The modeling study generated a new semi-practical correlation as a function of particle volume concentration and temperature for an existing Brownian motion–based thermal conductivity model, which demonstrated good compatibility with the present experimental measurements compared with other models.

Experimental heat transfer studies on copper nanofluids in a plate heat exchanger

The objective of the present work is to study the influence of copper nanoparticle concentration on heat transfer performance of a mixed base fluid. In the present study, the performance of copper nanoparticles in ethylene glycol (eg) + propylene glycol (pg) + water (W) base fluid was analyzed in the chevron- type plate heat exchanger. The sol-gel method was used to prepare copper nanoparticles (100 nm), dispersed in two different mixed base fluids of volume fractions 5%EG + 5%PG + 90%W and 15%EG + 5%PG + 80%W. Experiments were performed by varying the nanoparticle concentration from 0.2 to 1.0 vol.%. Three different hot fluid inlet temperatures were used (55, 65 and 75 ?C). It is revealed from the study that the rate of heat transfer increased significantly with the mixed base fluid. Result shows that at 75 ?C, 9 and 14.9% enhancement in the Nusselt number is obtained for 5%EG + 5%PG + 90%W and 15%EG + 5%PG + 80%W base fluid, respectively, for the nanoparticle concentration of 1%.

Thermal design of a spherical electronic device naturally cooled by means of water–copper nanofluid saturated porous media

The present work deals with thermal regulation of a spherical electronic device used in naval navigation techniques. Cooling is achieved by means of porous media saturated with water–copper nanofluid contained in another sphere kept isothermal. Nanofluid volume fraction varies between 0 (pure water) and 5%, Rayleigh number ranges from 6.5 × 106 to 1.32 × 109, while ratio between the thermal conductivity of the porous material’s matrix and that of water varies in the 0–40 range. Results for different configurations obtained through variation of these three influencing parameters show that the thermal conductivity ratio has a strong influence on the component’s average surface temperature, while the fraction volume has a moderate influence throughout the range of the considered Rayleigh number. Evolution of the average temperature versus the Rayleigh number is conventional of the power type. It can be calculated through the correlation proposed in this work for any combination of the three influencing parameters. This work complements a recent study where heat transfer occurring around the active sphere is quantified. This optimizes the thermal sizing of the assembly and enhances its reliability.

Entropy optimization in Darcy–Forchheimer MHD flow of water based copper and silver nanofluids with Joule heating and viscous dissipation effects

The irreversibility examination in steady flows of water based silver and copper nanofluids between two rotating disks is presented in this paper. The Darcy–Forchheimer relation is applied to the fluid flow. The two disks are kept at constant temperatures and are rotating with angular velocities. A magnetic field along radial and tangential directions is also applied. Moreover, viscous dissipation, heat generation, and Joule heating influences are taken in the nanofluid flows. The modeled problem is treated with the homotopy analysis method (HAM) and shooting techniques. The deviations in both nanofluids due to embedded factors are shown in graphs. The HAM and shooting techniques are compared and are shown with the help of figures and tables. The leading arguments of the current study are stated in the concluding section.

G-Jitter effect on heat and mass transfer of 3D stagnation point nanofluid flow with heat generation

Abstract The dynamics of viscous copper nanofluid double diffusion problem driven at three-dimensional stagnation point flow induced by heat generation under microgravity environment was analyzed numerically. The nature of the flow was interpreted into a system of differential equation. By imposing Keller box approach, profiles and physical quantities of principle interest result were analyzed. Profiles results showed a natural convection pattern and satisfied the boundary condition. Besides that, curvature ratio gives a significant effect on skin friction. Larger size of frequency of oscillation reduce the peak values of all physical quantities. The analysis on Nusselt shows an enhancement with the additional of nanoparticles into the conventional fluid. Meanwhile, additional resistance at the boundaries was produced due to the presence of copper nanoparticles. A heat source was produced from the heat generation effect inside the fluid reduced the rate of heat transfer at the body due to the additional temperature at the fluid.

Using nanofluid saturated porous media to enhance free convective heat transfer around a spherical electronic device

The thermophysical properties of the nanofluid saturated porous media are used in this work to optimize the thermal design of a spherical electronic device. Quantification of free convective heat transfer has been numerically determined by means of the finite volume method using the SIMPLE algorithm. The Rayleigh number based on the component diameter and water characteristics varies between 6.5x106 and 1.32x109, given the power generated during operation of this active component. The latter is disposed in the center of another sphere maintained isothermal. Its cooling is achieved by means of a porous medium saturated with a water based - Copper nanofluid whose volume fraction varies between 0 (pure water) and 10%. The thermal conductivity of the porous material's matrix ranges from 0 to 40 times that of the base fluid (water). Results of this work show that convective heat transfer systematically increases with this ratio according to a function depending on the Rayleigh number in the whole range of the considered volume fraction. The average Nusselt number also increases with the Rayleigh number according to a conventional power type law while influence of the fraction volume is moderate in the 2-10% range. The results are in agreement with those of previous works for particular thermal conditions. In order to optimize the thermal design of this electronic device, a correlation is proposed, allowing determination of the Nusselt number for any combination of the three influencing parameters for applications in various engineering fields, includind electronics.