Water-based Copper Research Articles

Stagnation Point Flow Over a Stretching or Shrinking Cylinder in a Copper-Water Nanofluid

The problem of steady stagnation-point flow over a stretching or shrinking cylinder in a water-based Copper (Cu) nanofluid is considered in this study. The governing partial differential equations in cylindrical form are reduced to ordinary differential equations using a similarity transformation. The resulting system issolved numerically by using shooting method with Prandtl number Pr = 6.2. The skin friction coefficient, Nusselt number, and the velocity and temperature profiles are presented graphically and discussed. The governing equation of the problem show that the flow and heat transfer characteristic depend on the effects of the curvature parameter, stretching or shrinking parameter and nanoparticle volume fraction parameter. It is found that the solutions for a shrinking cylinder are non-unique which differ from a stretching cylinder. It is observed that the surface shear stress and the heat transfer rate at the surface increase as the curvature parameter increases.

Surfactant-Based Cu–Water Nanofluid Spray for Heat Transfer Enhancement of High Temperature Steel Surface

Spray cooling is critical in many industrial applications to extract large heat fluxes from metal parts, such as hypervapotron in nuclear fusion reactors, heat treatment of steel plates in run-out table (ROT), electronic parts, and many more. The objective of the present study is to enhance the heat dissipation in transition and nucleate boiling regimes using an air-atomized water spray with water-based copper nanofluid as a coolant. The nanoparticle used in this study is energetic metal Cu, which has been prepared by mechanical milling (MM) process. The nanofluid has been prepared by suspending 0.1 vol. % Cu nanoparticles in water, with or without a dispersing agent (surfactant). The effect of type of dispersing agent on augmentation of boiling heat transfer has also been studied. The spray cooling experiments are conducted on a 6 mm thick stainless steel plate of initial temperature above 900 °C. The transient surface heat flux and temperatures are estimated using commercial inverse heat conduction software named intemp. The experimental results illustrated that transition and nucleate boiling heat flux as well as critical heat flux (CHF) increased significantly using nanofluid spray. A maximum ultrafast cooling (UFC) rate of 267 °C/s is achieved using surfactant-based nanofluid spray, which is 31.53% and 59.88% higher as compared to the nanofluid without any dispersant and pure water sprays, respectively. Overall, the surfactant-based copper nanofluid spray can serve as a better coolant on the ROT of steel processing industry.

A Study on the Heat Transfer Enhancement of Miniature loop Heat Pipes by Using the Cu Nanofluids

An experimental study was carried out to understand the heat transfer performance of a miniature loop heat pipes using water-based copper nanoparticles suspensions as the working fluid. The suspensions consisted of deionized water and copper nanoparticles with an average diameter of 80 ㎚. Effects of the cupper mass concentration and the operation pressure on the average evaporation and condensation heat transfer coefficients, the critical heat flux and the total heat resistance of the mLHPs were investigated and discussed. The pressure frequency also depends upon the evaporator temperature which has been maintained from 60℃ to 90℃. The Investigation shows 60% filling ratio gives the highest inside pressure magnitude of highest number pressure frequency at any of setting of evaporator temperature and 5wt% results the lowest heat flow resistance.

Investigation on Copper Nanofluid Obtained through Micro Electrical Discharge Machining for Dispersion Stability and Thermal Conductivity

Nanoparticles show a practical way of exhibiting enhanced size-dependent properties compared to extremely fine or larger particles of the same material. Nanofluids consist of nanoparticles dispersed in base fluid and are usually used for enhancing thermal conductivity in various systems. This study investigates the dispersion stability and thermal conductivity of copper based nanofluids obtained by generating copper nanoparticles using micro electrical discharge machining (micro-EDM) process in both, de-ionized (DI) water and de-ionized water with polyethylene glycol (PEG) stabilizing agent. Micro-EDM was performed with various operating parameters such as the voltage, current, pulse width and duty factor. The generated nanoparticles in the base fluid were examined by energy dispersive analysis by X-rays (EDAX) and transmission electron microscope (TEM) to evaluate their chemical nature, size and morphology. The size distributions of the copper particles in PEG-based nanofluid were determined resulting in average particle size of around 6nm. The experimental results show that the dispersion stability of PEG- based copper nanofluid as compared to DI water-based copper nanofluid is improved as discussed in the following sections of the paper. It was also found that the thermal conductivity of copper-water nanofluid and copper-water with PEG nanofluid are higher than that of pure DI water.

Water-Based Carbon-Coated Copper Nanoparticle Fluid—Formation of Conductive Layers at Low Temperature by Spin Coating and Inkjet Deposition

Water-Based Carbon-Coated Copper Nanoparticle Fluid—Formation of Conductive Layers at Low Temperature by Spin Coating and Inkjet Deposition

Thermal performance of screen mesh wick heat pipes using water-based copper nanofluids

Fairly stable surfactant free copper–distilled water nanofluids are prepared using prolonged sonication and homogenization. Thermal conductivity of the prepared nanofluid displays a maximum enhancement of ∼15% for 0.5 wt% of Cu loading in distilled water at 30 °C. The wall temperature distributions and the thermal resistances between the evaporator and the condenser sections of a commercial screen mesh wick heat pipe containing nanofluids are investigated for three different angular position of the heat pipe. The results are compared with those for the same heat pipe with water as the working fluid. The wall temperatures of the heat pipes decrease along the test section from the evaporator section to the condenser section and increase with input power. The average evaporator wall temperatures of the heat pipe with nanofluids are much lower than those of the heat pipe with distilled water. The thermal resistance of the heat pipe using both distilled water and nanofluids is high at low heat loads and reduces rapidly to a minimum value as the applied heat load is increased. The thermal resistance of the vertically mounted heat pipe with 0.5 wt% of Cu–distilled water nanofluid is reduced by ∼27%. The observed enhanced thermal performance is explained in light of the deposited Cu layer on the screen mesh wick in the evaporator section of the heat pipe.

Inkjet printing using copper nanoparticles synthesized by electrolysis

A modified electrolysis method was employed to synthesize copper nanoparticles for mass production. Processing parameters including electrolyte temperature, pH and reduction agents were controlled in order to synthesize the particles continuously and directly from copper plates. As a result, well-dispersed copper nanoparticles with an average diameter of 15nm were obtained and the oxidation of these particles was prevented by controlling the parameters. Using an amphiphilic surfactant, a water-based copper nano-colloid was prepared and printed onto a polyimide substrate using a conventional ink-jet printer. Copper patterns sintered at 230°C showed a resistivity of 5.4μΩ-cm (bulk resistivity; 1.67μΩ-cm).

Axisymmetric mixed convection boundary layer flow past a vertical cylinder in a nanofluid

A numerical study has been conducted to investigate the steady axisymmetric mixed convection boundary layer flow past a thin vertical cylinder placed in a water-based copper (Cu) nanofluid. Using appropriate transformations, the system of partial differential equations is transformed into an ordinary differential system of two equations, which is solved numerically using bvp4c function from Matlab. Numerical results are obtained for the skin-friction coefficient and Nusselt number as well as for the velocity and temperature profiles for some values of the governing parameters, namely, the nanoparticle volume fraction parameter ϕ, mixed convection parameter λ and the curvature parameter γ with the Prandtl number Pr = 6.2 (water). The results indicate that dual solutions exist when the surface of the cylinder is cooled (opposing flow, λ < 0 ). It is shown that for a regular fluid ( ϕ = 0) a very good agreement exists between the present numerical results and those reported by Mahmood and Merkin [8].

Influence of moisture content on EPR parameters of copper in impregnated wood

Influence of moisture content on Electron Paramagnetic Resonance (EPR) spectra of spruce wood impregnated with different, water-based copper solutions.

Raman study of ionic water-based copper and zinc ferrite magnetic fluids

Raman spectroscopy is used to investigate the OH-bending and OH-stretching modes of chemisorbed OH-groups in copper-ferrite and zinc-ferrite water-based magnetic fluid samples. Room-temperature Raman spectra were taken from diluted magnetic fluid samples and compared with the spectrum taken from liquid water. The suppression of the symmetric OH-stretching Raman modes from the ionic magnetic fluid sample spectra is discussed in terms of the replacement of a hydrogen atom from the water molecule by the nanoparticle surface. Moreover, changes on the area ratio between hydrogen bonded and nonhydrogen bonded OH-Raman peaks in the ionic magnetic fluid samples, as compared to the OH-Raman peaks from liquid water, are discussed in terms of changes on the hydrogen bond strength.

Modified solution for filling MRI coordinate indicators for the ZD stereotactic frame.

Increased use of magnetic resonance imaging and magnetic resonance angiography in stereotactic planning highlight some technical problems in imaging. Visualization of markers during imaging are vital in stereotactic planning. In magnetic resonance imaging-guided stereotaxy, specially designed plates are used that contain water-based copper sulfate solutions as a marker. Replacement of copper sulfate solution is usually required after some time due to precipitation and leaking. The refilling procedure is quite cumbersome and can cause technical problems in imaging. In this study, we describe copper sulfate solution mixed with a water-soluble gel as a simple but useful alternative to water-based copper sulfate resolution to ease the refilling procedure and to overcome the air bubbles.