Copper Nanofluid Research Articles

Numerical investigation of nanofluid laminar forced convection heat transfer between two horizontal concentric cylinders in the presence of porous medium

In this paper, the finite volume method is used to investigate the laminar forced convection of water–copper nanofluid between two porous horizontal concentric cylinders. The effects of Reynolds number, the volume fraction of nanoparticles, the geometry, and the porous medium porosity on heat transfer have been studied. The problem is investigated in two different geometries and Re = 10, 25, 50, 75,100, and volume fraction of nanoparticles 0, 0.2, 0.5, 2, and 5% that were related to Copper nanoparticles and the porous medium porosity of 0.5, 0.9. The results indicated that in each geometry, the corresponding Nusselt number increase in the porosity of 0.9 is greater than that of the case with the porosity of 0.5. The results show that the increase in the heat transfer coefficient in the second geometry is greater than the first geometry and in porosity 0.9 is greater than porosity 0.5. These increase values are 6 and 3%, respectively. The increase in the average temperature of the inner cylinder surface in the five mentioned Reynolds values and both geometries is investigated. This increase in temperature in Re = 10 is greater than other Reynolds numbers. The corresponding temperature increases of Re = 10, for the first and second geometries, are 1.8 and 2.2%, respectively. Investigation of the effects of volume fraction of nanoparticles on Nusselt number and heat transfer coefficient shows that both parameters increase by increasing in the volume fraction of nanoparticles. The results show that the increase in the volume fraction of nanoparticles causes the increase in average temperature of the surface. The results show that these increases of temperature that take place in the volume fractions of 0.5, 2, and 5% of nanoparticles are equal to 0.6, 1.14, and 2.3% and relative to the water, respectively.

Experimental assessment of Al2O3 and Cu nanofluids on the performance and heat leak of double pipe heat exchanger

The aim of the study is to experimentally investigate and compare the influence of two different nanofluids (Cu/water and Al2O3/water) on the performance of a double pipe heat exchanger at different volume concentrations and flow rates. Effect of varying hot-side inlet temperature is also tested for the selected concentrations. The nanofluid, pumped on the shell-side of the heat exchanger, has a Reynolds number ranging from 7000 to 15,000 while, for each Reynolds number, the concentration of the nanoparticles ranges from 0.26% - 0.83% on volume basis. Results indicated that presence of nanoparticles within the base fluid can offer a great potential for energy transfer. Observation of experimental outcomes shows notable enhancement in the Nusselt number when increasing the mass-flow of the nanofluid. The enhancement registered for the above mentioned range of Re and concentration are up to 13% for Al2O3 and 23% for Cu. Experimental results show a considerable improvement in the effectiveness (up to 7% for aluminum oxide and 10% for copper). Also, the performance enhances with the augmentation of the hot-side inlet temperature. Heat leak from the shell-side (cold fluid) to atmosphere is observed to be enlarged when nanoparticle is employed and is proportionally related to the concentration. It is also monitored that the heat leak within aluminum oxide nanofluid is greater than the copper nanofluid.

Heat transport on steady MHD flow of copper and alumina nanofluids past a stretching porous surface

AbstractAn attempt is made to investigate the steady magnetohydrodynamic convective flow of the viscous nanofluid due to a permeable exponentially stretching porous surface. Water is used as a traditional fluid while nanoparticles include copper and alumina. The fluid is electrically conducting, subject to an applied magnetic field with a constant strength. Convective type boundary conditions are employed in modeling the heat transfer process. The nonlinear partial differential equations governing the flow are reduced to an ordinary differential equation by similarity transformations and then solved using the Runge‐Kutta fourth‐order method. A parametric study of the physical parameters is made, and a representative set of numerical results for the velocity and temperature, as well as local shear stress and local Nusselt number, is presented graphically. Hartman number increase diminishes the velocity and has the contrary result in the subjective sense for the mass transfer parameter. An increase in the Prandtl number Pr lessens the temperature and thickness of the thermal boundary layer. The main conclusions have been indicated.

Characterization of Local Nano‐Heat Transfer Fluids for Solar Thermal Collection

Performance of organic oils in solar thermal collection is limited due to their low thermal conductivity when they are compared to molten salt solutions. Extraction of organic oils from plants can be locally achieved. The purpose of this study was to investigate the effect of use of copper nanoparticles in some base local heat transfer fluids (HTFs). Addition of volume fraction of 1.2% of the copper nanoparticles to oil‐based heat transfer fluids improved their thermal conductivity as deduced from the thermal heat they conducted from solar radiation. The oil‐based copper nanofluids were obtained by preparation of a colloidal solution of the nanoparticles. Impurities were added to increase the boiling point of the nano‐heat transfer fluids. Stabilizers were used to keep the particles suspended in the oil‐based fluids. The power output of the oil‐based copper nano‐heat transfer fluids was in the range of 475.4 W to 1130 W. The heat capacity of the steam in the heat exchanger was 93.7% dry and had a thermal capacity of 5.71 × 103 kJ. The heat rate of flow of the oil‐based copper nano‐heat transfer fluids was an average of 72.7 Js−1·kg−1 to 89.1 Js−1·kg−1. The thermal efficiency for the oil‐based copper nano‐heat transfer fluids ranged from 0.85 to 0.91. The average solar thermal solar intensity was in the range 700 Wm−2 to 1180 Wm−2. The heat exchanger used in this study was operating at 4.15 × 103 kJ and a temperature of 500.0°C. The heat transfer fluids entered the exchanger at an average temperature of 381°C and exited at 96.3°C and their heat coefficient ranged between 290.1 Wm−2°C and 254.1 Wm−2°C. The average temperatures of operation ranged between 394.1°C and 219.7°C with respective temperature efficiencies ranging between 93.4% and 64.4%. It was established that utilization of copper nanoparticles to enhance heat transfer in oil‐based local heat transfer fluids can mitigate energy demand for meeting the world’s increasing energy uses, especially for areas inaccessible due to poor land terrain.

Mixed convection heat transfer and entropy generation analysis of copper–water nanofluid in a vertical channel with non-uniform heating

This paper reports results of a numerical investigation on mixed convection heat transfer and entropy generation for water–copper nanofluid within a vertical channel. The left wall is subjected to a heat flux density of sinusoidal variation, while the right one is cooled at uniform density. The Buongiorno model is employed to describe the nanofluid flow in order to take into account the thermophoresis effect and the Brownian motion. The governing equations are solved numerically using the finite volume method with the SIMPLE algorithm. The effects of pertinent parameters including the Richardson number (Ri), the heat flux ratio (Rq) and the nanoparticles volume fraction (ϕi) on the flow and thermal fields, as well as the entropy generation are analyzed for both non-uniform and uniform heating. The results show that the heat transfer rate and the various irreversibility modes are increased with the rise of Ri and Rq and the reduction of ϕi. It is also found that a sinusoidal heating is beneficial for the mean Nusselt number but, unfortunately, it is not favorable for the total entropy generation with augmentation rates of up to 7% and 14%, respectively. A map of the flow reversal occurrence is performed and reveals that the latter is strongly affected by the control parameters. In addition, a correlation is proposed to predict the onset of this phenomena with a maximum deviation of 5% compared to the numerical results.

Impact of generalized Fourier’s law and Fick’s law for MHD flow of Ag‒H2O and TiO2‒H2O nanomaterials

Purpose The purpose of this paper is to investigate the effect of inclined magnetic field, variable viscosity and Cattaneo–Christov heat and mass flux theories on the steady MHD free convective boundary layer flow of viscous, incompressible and electrically conducting water-driven silver and titanium-oxide nanofluids over a vertical stretching sheet. Design/methodology/approach The boundary layer equations of momentum, energy and nanoparticle concentration are partial differential equations in nature, which are reduced to nonlinear ordinary differential equations by means of similarity transformations. The resulting nonlinear equations are solved analytically by means of optimal homotopy analysis method. Findings Assessments with numerical results are performed and are found to be in an excellent agreement. Numerical results of the skin friction factor, the local Nusselt number and the local Sherwood number are obtained through tables. The effects of various physical parameters on the velocity, temperature and nanoparticles fraction are incorporated through graphs. The study analyzes the efficiency of heat transfer of nanofluids in cooling plants and rubber sheets. Originality/value No research works have been conducted to evaluate the effects of various physical phenomena on the copper and titanium nanofluids flow.

Evacuated tube solar collector performance using copper nanofluid: Energy and environmental analysis

The effect of metallic copper nanoparticles on the thermal efficiency of an evacuated tube solar collector was studied. Different volume concentrations of copper nanoparticles e.i. 0.01%, 0.02% and 0.03% were examined to explore the effect of nanoparticles on evacuated solar collector performance. The tests were performed at three volume flow rates of 0.6 L/min, 0.7 L/min and 0.8 L/min. The results demonstrate a 50% increase in the output temperature. Also, the heat energy incremented from 417 W to 667 W, which is equivalent to 34% area reduction for the same energy production. The remarkable enhancement in the heat removal factor to reach a value of 0.97. Copper nanoparticles played a significant role to increase both the absorbed energy and the removal energy parameters. Their maximum values were found for a volume concentration of 0.03% and at the volume flow rate of 0.8 L/min to be 0.83 and 21.66, respectively. Finally, environmental analysis is carried out to find the role of copper nanoparticles in CO2 reduction. The comparison between current results with reported results in the literature for other types of nanoparticles, show the high potential of copper nanoparticles for solar collector applications.

An experimental investigation into heat transfer characteristics of aqua based Cu nanofluid for automobile radiator

In this experimental research work, heat transfer characteristics of water based copper (Cu) nanofluids has been investigated and compared with conventional fluids for an automobile radiator under the laminar flow regime. In this study, 37 verticals with cross section of stadium shaped tubes and having multi louvered fins inaugurated on their outer body act as a radiator. Forced air with constant velocity flowing through bunches of fins becomes potential factor for heat transfer. The variation in liquid flow rate through radiator has been kept in the range of 2-5LPM. Three different volumetric concentrations (0.3%, 0.6% and 1.0%) of water based copper nanofluids have been prepared for use. Also, the inlet temperature has been varied in the range of 45-55° C to investigate the effect of inlet temperature of the coolant fluids over Nusselt number. The maximum enhancement of 39.53% in Nusselt number has been observed as compared to that for distilled water and accordingly, its effectiveness got raised by 10.73% at 1.0% volumetric concentration of the nanoparticles. The salient feature of this experimental study is that water based copper nanofluids come out as suitable and better coolant for the radiator.

Experimental study on thermal performance of copper nanofluids in a miniature heat pipe fabricated by wire electrical discharge machining

A cylindrical miniature heat pipe (MHP) with a diameter of 1.9 mm and a length of 130 mm was designed and fabricated via wire electrical discharge machining in this study. A special elastic fixture was designed for the micro grooves machining process. Water based copper nanofluids with mass concentrations ranged from 0.5 wt% to 1.5 wt% were prepared and tested in the MHP. Both the transient response and heat transfer capability of the MHP with copper nanofluids and DI water were studied experimentally. The MHP with nanofluids had a slightly slower startup response compared to the one with DI water. However, the heat transfer capability of the MHP with nanofluids was greatly improved to 250 mW (q = 8.82 W/cm2), while that of the MHP with the basefluid (DI water) was only 100 mW (q = 3.53 W/cm2). At the heat load of 150 mW, the MHP with 0.5 wt% nanofluid showed a minimum thermal resistance of 0.33 °C/W. The effects of mass concentration, filling ratio and heat load were investigated as well.

Numerical study of thermal radiation and suction effects on copper and silver water nanofluids past a vertical Riga plate

PurposeThe purpose of this paper is to explore the flow of Cu-water and Ag-water nanofluids past a vertical Riga plate. The plate is infinite in height and has zero normal wall flux through its surface. Influence of thermal radiation, slip, suction and chemical reaction on the flow characteristics are reported.Design/methodology/approachNon-dimensional forms of the flow governing equations are obtained by means of a set of similarity transformations. Numerical solution is obtained with the help of fourth-fifth-order Runge–Kutta–Fehlberg method with shooting procedure. Comparison of solution profiles of Cu-water and Ag-water nanofluids are presented graphically and with the help of tables. Influence of pertinent parameters on skin friction and heat transfer rate is also reported.FindingsResults reveal that the skin friction coefficient is more prominent in the case of Ag-water nanofluid for an increase in thermal radiation and volume fraction. The role of suction and slip is to increase velocity but decrease the temperature in both nanofluids. Temperature and velocity of both nanofluids increase as volume fraction and thermal radiation values are augmented. Heat transport increases with thermal radiation. Region near the plate experiences rise in nanoparticle concentration with an increase in chemical reaction parameter.Originality/valueA complete investigation of the modeled problem is addressed and the results of this paper are original.

Effect of a porous medium on flow and mixed convection heat transfer of nanofluids with variable properties in a trapezoidal enclosure

In the present study, the flow field and heat transfer of a water–copper nanofluid with variable properties in a trapezoidal enclosure saturated with porous media are studied. The governing equations are solved by finite volume method and the SIMPLER algorithm. The nanofluid flow is assumed to be laminar, steady and incompressible. Simulations are performed for sidewall (trapezoid legs) angles of 30°, 45° and 60° with respect to horizontal axis, Reynolds numbers from 10 to 1000, Darcy numbers of 10−2, 10−3, 10−4 and volume fractions of 0 to 0.04 of nanoparticles. Numerical results show that the average Nusselt number increases with increasing volume fraction of nanoparticles for all studied Darcy numbers. The convection and motion of the nanofluid decrease by reducing the Darcy number which leads to a reduction in the velocity and local Nusselt number. The average Nusselt number increases by increasing the Darcy number for all aspect ratios. Also, the average Nusselt number increases with increasing Reynolds number for all Darcy numbers, aspect ratios and volume fractions of nanoparticles.

Computational study of unsteady couple stress magnetic nanofluid flow from a stretching sheet with Ohmic dissipation

To provide a deeper insight of the transport phenomena inherent to the manufacturing of magnetic nano-polymer materials, in the present work a mathematical model is developed for time-dependent hydromagnetic rheological nano-polymer boundary layer flow and heat transfer over a stretching sheet in the presence of a transverse static magnetic field. Joule heating (Ohmic dissipation) and viscous heating effects are included since these phenomena arise frequently in magnetic materials processing. Stokes’ couple stress model is deployed to simulate non-Newtonian microstructural characteristics. The Tiwari–Das nanoscale model is adopted which permits different nanoparticles to be simulated (in this article, both copper–water and aluminium oxide–water nanofluids are considered). Similarity transformations are utilized to convert the governing partial differential conservation equations into a system of coupled, non-linear ordinary differential equations with appropriate wall and free stream boundary conditions. The shooting technique is used to solve the reduced non-linear coupled ordinary differential boundary value problem via MATLAB symbolic software. Validation with published results from the literature is included for the special cases of non-dissipative and Newtonian nanofluid flows. Fluid velocity and temperature profiles for both copper and aluminium oxide (Al2O3) nanofluids are observed to be enhanced with greater non-Newtonian couple stress parameter and magnetic parameter, whereas the opposite trend is computed with greater values of unsteadiness parameter. The boundary layer flow is accelerated with increasing buoyancy parameter, elastic sheet stretching parameter and convection parameter. Temperatures are generally increased with greater couple stress rheological parameter and are consistently higher for the aluminium oxide nanoparticle case. Temperatures are also boosted with magnetic parameter and exhibit an overshoot near the wall when magnetic parameter exceeds unity (magnetic force exceeds viscous force). A decrease in temperatures is induced with increasing sheet stretching parameter. Increasing Eckert number elevates temperatures considerably. With greater nanoparticle volume fraction, both skin friction and Nusselt number are elevated, and copper nanoparticles achieve higher magnitudes than aluminium oxide.

Accurate measurement of nanofluid thermal conductivity by use of a polysaccharide stabilising agent

Measuring the thermal conductivity of low viscosity fluids such as aqueous nanofluids is challenging due to the formation of convection currents. In the current work, a modification of the transient hot-wire thermal conductivity measurement technique was investigated to address this problem. The polysaccharide agar was used as a gelling agent to prevent the formation of convection currents, thereby enabling measurement of thermal conductivity. The experimental method was validated by comparison of experimentally measured thermal conductivity values with published reference values over a range of temperatures for two reference fluids stabilised by agar: water and an ethylene glycol/water solution. The precision of thermal conductivity measurements was found to be significantly improved by use of this gelling agent. These findings indicate that agar, or a similar gelling agent, can be used to enable accurate measurement of the thermal conductivity of aqueous fluids. This measurement technique was utilised to accurately measure the thermal conductivity enhancements of copper and alumina aqueous nanofluids with low nanoparticle concentrations, over a range of temperatures. The thermal conductivities of these nanofluids were found to be within ±2% of those predicted by the Maxwell model.

Natural convection heat transfer in a cavity filled with electrically conducting nano-particle suspension in the presence of magnetic field

This work reports the effect of uniform magnetic field on the heat transfer behavior in the natural convection of electrically conducting but non-magnetic nano-particle suspensions. The experiments are carried out in a differentially heated cubical cavity with two opposite vertical faces at a different uniform temperature kept in a uniform magnetic field. The Rayleigh number range for the present experiment is between 1 × 106 and 1 × 107. To investigate the effect of volume fraction and the type of nanofluid, three different volume fractions of multi-wall carbon nanotubes, graphene, copper, and silica nanofluid are tested at different strengths and directions of the magnetic field. The presence of magnetic field deteriorates the heat transfer which depends upon the direction, strength of the magnetic field and type, and volume fraction of the nanofluid used. The role of magnetic field in the suppression of heat transfer in the presence of magnetic field is explained by a theory involving the interaction of moving electrically conducting particles with the uniform magnetic field.

Analysis of EN24 steel in turning process with copper nanofluids under minimum quantity lubrication

Minimum quantity lubrication (MQL) is a method which consumes lubricant at a minimum level. In this research work, the usage of copper nanofluids with MQL in turning on EN24 steel is presented. The experiments were performed based on L18 orthogonal arrays by varying the cutting speed, feed rate and environment such as oil with flood lubrication (Oil + FL), oil with minimum quantity lubrication (Oil + MQL) and nanofluids with minimum quantity lubrication. To evaluate the effect of process parameters, the responses, namely, surface roughness and tool wear, were examined. In this study, complex proportional assessment method is used to determine the optimal combination in reducing the surface roughness and tool wear. The results showed that suggested method is appropriate in deciding the best cutting conditions and that nanofluid is the most significant parameter on reducing the surface roughness and tool wear. Further, scanning electron microscope was used to examine the tool wear and chip morphology. Atomic force microscope was also used to observe the three-dimensional view of the machined surface.

Heat Transfer of Mixed Convection Electroconductivity Flow of Copper Nanofluid with Different Shapes in a Porous Micro Channel Provoked by Radiation and First Order Chemical Reaction

Heat Transfer of Mixed Convection Electroconductivity Flow of Copper Nanofluid with Different Shapes in a Porous Micro Channel Provoked by Radiation and First Order Chemical Reaction

Experimental Assessment of the Thermo-Hydraulic Performance of Automobile Radiator with Metallic and Nonmetallic Nanofluids

The overall heat transfer of a cross flow heat exchanger can be enhanced by using the nanofluids as coolant, which finds application in reducing the size and weight of automobile radiator. However, improving the heat transfer using nanofluids can be accompanied by simultaneous variations in the required pumping power. This study experimentally evaluates the thermo-hydraulic performance of three nanofluids—metallic (copper, aluminum) and nonmetallic (multiwalled carbon nanotube (MWCNT))—as coolant for an automobile radiator by utilizing an in-house test rig. An enhancement in overall heat transfer coefficient can be observed with nanocoolants (nanofluid as coolant), compared to the de-ionized water at the same Reynolds number. The maximum enhancement in the overall heat transfer coefficient was observed to be 40, 29, and 25% for MWCNT, copper, and aluminum nanofluids, respectively. The thermal performance of coolants was also compared with the same pumping power criterion. The overall heat transfer coefficient of nanofluids were higher than basefluid at low pumping power range and the trend changes with increase in the pumping power. The present study shows that the heat transfer characteristics at the same Reynolds number as well as at the same pumping power needs to be considered for the selection of appropriate nanocoolant for automobile radiator application.

Investigating heat transfer properties of copper nanofluid in ethylene glycol synthesized through single and two-step routes

Thermal efficiency improvement in conventional cooling fluids like water and ethylene glycol (EG) is a fundamental requirement in various industrial applications. Copper-EG nanofluid can be considered for this purpose; thus synthesized through single-step and two-step procedures using chemical reduction method in this study. Thermal properties of copper-EG nanofluid were investigated in both cases. Pure nano-copper was synthesized without inert environment using sodium hypophosphite as the reducing agent and Polyvinylpyrrolidone (PVP) and glycerol as capping agents resulting in 25 and 34.5 nm average size nanoparticles, respectively. A simple and low-cost synthesis route for pure and stable nano-copper in glycerol was provided that seems promising for large scale production. Heat transfer coefficient (HTC) calculations were performed at 68, 94.8 and 125.5 Reynolds numbers and 0.01, 0.03 and 0.05 wt% in a designed heat exchanger setup. The highest HTC enhancement of the two-step nanofluid occurs at 0.03 wt%. HTC of the one-step nanofluid is significantly increased compared with the base-fluid and increasing the nanofluid concentration leads to higher HTC values. The highest HTC enhancement was 73.34% at Re = 68 for the 0.05 wt% nanofluid.

Natural convective cooling of electronics contained in tilted hemispherical enclosure filled with a porous medium saturated by water-copper nanofluid

Purpose The purpose of this study is to determine the thermal behavior of a hemispherical electronic device contained in a concentric hemispherical enclosure, cooled by means of free convection through a porous medium saturated with a water–copper nanofluid. Influence of various parameters on the thermal state of this device is processed in this work. The high power generated by the dome leads to a Rayleigh number varying in the 5.2 × 107-7.29 × 1010 range. The volume fraction of the monophasic nanofluid varies between 0 (pure water) and 10 per cent while the base of the hemispherical cavity (disc) is inclined between 0° (horizontal disc with dome facing upward) and 180° (horizontal disc with dome facing downward). Design/methodology/approach The three-dimensional numerical approach is carried out by means of the volume control method associated to the SIMPLE algorithm. Findings The work shows that the average temperature of the active component increases with the Rayleigh number according to a conventional law of the power type. The increase in the angle of inclination also goes with a systematic rise in the average temperature. However, increasing the ratio of the solid–fluid thermal conductivities decreases the average temperature of the component, given the respective contributions of the conductive and natural convective phenomena occurring through the nanofluid saturated porous media. The values of this ratio vary in this work between 0 (interstice between the two hemispheres without porous medium) and 70. Originality/value The correlation proposed in this work allows to calculate the temperature of the active electronic component for all the combinations of the four influence parameters which vary in wide ranges.

Experimental determination of viscosity of Water-Glycerine based Cu nano-fluids

Abstract Dispersion of nano sized metallic particles in to conventional base fluids, called nano-fluids, is expected to yield enhanced heat transfer properties. Experimental determination and subsequent correlations of thermo-physical properties such as viscosity, thermal conductivity, specific heat capacity etc., of these nano-fluids become necessary to estimate the heat transfer performance of these nano-fluids. Cu nano-fluids in Water-Glycerine base fluids are prepared at different volume concentrations of Cu nano particles. Two step dispersion synthesis method, without using any surfactant, is used to prepare nano-fluids consisting of Cu nano-particles in Water-Glycerine base fluid. Viscosity of these nano-fluids is determined experimentally at different temperatures of 20, 40, 60 and 80 °C using Brookfield Viscometer. Three different volume concentrations of Cu-based nano-particles in the base fluid are taken as 0.2%, 0.6% and 1.0%. SEM and EDS images show the particle size distribution and elemental analysis of Cu nano-particles. It has been observed that viscosity of nano-fluids increased with increase in particle volume concentration and decreased with increase in fluid temperature. Maximum viscosity value of 3.76 cP for 1.0% vol. concentration at 20 °C and minimum viscosity value of 0.94 cP at 80 °C for 0.2% vol. concentration is obtained for copper nano-fluids. Viscosity for Water-Glycerine base fluid also measured at different temperatures of 20, 40, 60 and 80 °C. This viscosity data of will be useful for the aspiring researchers to predict heat transfer properties of copper nano-fluids.