Investigation of Viscosity and Rheological Properties of Copper/Ethylene Glycol Nanofluid (original) (raw)
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Enhanced thermal conductivity and viscosity of copper nanoparticles in ethylene glycol nanofluid
Journal of Applied Physics, 2008
This study investigates the thermal conductivity and viscosity of copper nanoparticles in ethylene glycol. The nanofluid was prepared by synthesizing copper nanoparticles using a chemical reduction method, with water as the solvent, and then dispersing them in ethylene glycol using a sonicator. Volume loadings of up to 2% were prepared. The measured increase in thermal conductivity was twice the value predicted by the Maxwell effective medium theory. The increase in viscosity was about four times of that predicted by the Einstein law of viscosity. Analytical calculations suggest that this nanofluid would not be beneficial as a coolant in heat exchangers without changing the tube diameter. However, increasing the tube diameter to exploit the increased thermal conductivity of the nanofluid can lead to better thermal performance.
Particle size effects in the thermal conductivity enhancement of copper-based nanofluids
Nanoscale Research Letters, 2011
We present an analysis of the dispersion characteristics and thermal conductivity performance of copper-based nanofluids. The copper nanoparticles were prepared using a chemical reduction methodology in the presence of a stabilizing surfactant, oleic acid or cetyl trimethylammonium bromide (CTAB). Nanofluids were prepared using water as the base fluid with copper nanoparticle concentrations of 0.55 and 1.0 vol.%. A dispersing agent, sodium dodecylbenzene sulfonate (SDBS), and subsequent ultrasonication was used to ensure homogenous dispersion of the copper nanopowders in water. Particle size distribution of the copper nanoparticles in the base fluid was determined by dynamic light scattering. We found that the 0.55 vol.% Cu nanofluids exhibited excellent dispersion in the presence of SDBS. In addition, a dynamic thermal conductivity setup was developed and used to measure the thermal conductivity performance of the nanofluids. The 0.55 vol.% Cu nanofluids exhibited a thermal conductivity enhancement of approximately 22%. In the case of the nanofluids prepared from the powders synthesized in the presence of CTAB, the enhancement was approximately 48% over the base fluid for the 1.0 vol.% Cu nanofluids, which is higher than the enhancement values found in the literature. These results can be directly related to the particle/agglomerate size of the copper nanoparticles in water, as determined from dynamic light scattering.
Analysing the Thermal Performance of Heat Pipe Using Copper Nanofluids
Heat pipes are heat transfer device that do not need external power; as a result, they are used in various thermal systems. Enhancing the performance of heat transfer device is a continues effort. Thus, this study investigates the effect of copper nanofluid on the thermal performance of cylindrical heat pipe (HP) that has screen mesh wick for heat transfer applications. The copper HP consists of 350 mm length and 12.7 mm outside diameter. To investigate its thermal performance mathematical model is developed. Demineralized water based 20 nm copper nanofluids with 0 to 4% particle concentrations were considered in the study. Simulation was done at 100 W heat input and results showed that when the particle concentration increases the evaporator wall temperature drops. At 4% particle concentration nanofluid the HP thermal resistance reduced by 17.5% compared to when the HP uses demineralized water. Furthermore, for a given particle concentration as the heat input increases the temperature change between the evaporator and the condenser increases. The outcome of the investigation can be input to the design of solar heat exchangers that use HPs filled with nanofluids.
Applied Physics Letters, 2001
It is shown that a ''nanofluid'' consisting of copper nanometer-sized particles dispersed in ethylene glycol has a much higher effective thermal conductivity than either pure ethylene glycol or ethylene glycol containing the same volume fraction of dispersed oxide nanoparticles. The effective thermal conductivity of ethylene glycol is shown to be increased by up to 40% for a nanofluid consisting of ethylene glycol containing approximately 0.3 vol % Cu nanoparticles of mean diameter Ͻ10 nm. The results are anomalous based on previous theoretical calculations that had predicted a strong effect of particle shape on effective nanofluid thermal conductivity, but no effect of either particle size or particle thermal conductivity.
NUMERICAL MODELING AND SIMULATION OF COPPER OXIDE NANOFLUIDS USED IN COMPACT HEAT EXCHANGERS
In this paper, a comparison of heat transfer and pressure drop characteristics of CuO/water nanofluids in a helically coiled heat exchanger held in horizontal and vertical positions is presented. heat transfer of Nanofluid is a new environment, usually metallic nanoscale particles suspended in a base fluid composed. Do nanofluidics compared with conventional fluids have higher coefficients of thermal conductivity and displacing. However, due to the increased use of nanofluidics, sometimes leading to excessive pressure drop can be pumped. The theoretical study of this issue using nano-fluids in the heat exchanger tube and shell and tube heat exchangers are widely used in the industry are the purpose of the project is located.
Effect of Copper Nanoparticle Aggregation on the Thermal Conductivity of Nanofluids
Russian Journal of Physical Chemistry A, 2016
—The thermal conductivity of water and glycerol is investigated via the transient hot wire method by adding small amounts of copper nanoparticles to solutions. At a 0.2% copper nanoparticle concentration, the thermal conductivity coefficient rises to 25% for the Cu + glycerol system, and to 35% for Cu + water system. A mechanism and mathematical model for describing the nanoparticle aggregation effect on the thermal properties of nanofluids are proposed, based on an analysis of the accumulated experimental data. It is shown that the enhancement of nanofluid thermal conductivity at low nanoparticle concentrations is directly proportional to their volume fraction and thermal conductivity coefficient, and (in accordance with the literature data) is inversely proportional to the radius and the aggregation ratio. The proposed model describes the existing experimental data quite well. The results from this work can be applied to the rapid cooling of electronic components, in the power engineering for ensuring the rapid and effective transfer of thermal energy in a nuclear reactor, and in the oil industry for thermal stimulation.
INVESTIGATION OF NANOFLUIDS BEHAVIOR IN HEAT EXCHANGERS
The purpose of this paper is to present this new class of fluid called nanofluid and its feasibility for use in industrial heat exchangers. Aiming to analyse the behaviour of the thermophysical properties of nanofluids of alumina oxide and nanofluids copper oxide. Also, checking the reduction in the proposed design of a heat exchanger, hoping to find a good reduction in the use of this novel class of fluid.
The performance of the Alumina/water and copper oxide/water nanofluids in a heat exchanger is experimentally investigated for particle weight concentrations ranging from 0.02 wt% to 0.5 wt%. The alumina/water and copper oxide/water nanofluids were prepared using two-step methods in an aqueous solution with 0.01 wt% CTAB (Cetyl Trimethyl Ammonium Bromide) as a surfactant at different concentrations and were characterized using HRTEM (High-Resolution Transmission Electron Microscopy) technique. Laminar forced convective heat transfer analysis using alumina and copper oxide nanoparticles suspended in water in a circular horizontal tube under constant heat flux boundary conditions was performed. The effect of various flow conditions and weight concentrations in the local heat transfer coefficient and pressure drop of both the nanofluids were investigated. Reynolds number varied from 1275 to 2200. Results show that 12.7 & 14.5 % thermal performance enhancement was observed with 0.5 wt% of Al2O3 and CuO nanofluids. Maximum, 50.62 % enhancement was observed in the average heat transfer coefficient by Al2O3 nanofluids, whereas 52.74 % was observed using CuO nanofluids using 0.5 wt% concentrations of the nanofluids and at Reynolds number of 2200. Correlations were proposed for thermal conductivity, viscosity, and Nusselt number for both the nanofluids with the maximum and minimum deviations of ±9 % and ±10 %, respectively.
Thermophysical properties of water based Cu nanofluid used in special type of coil heat exchanger
Applied Thermal Engineering, 2017
The study shows the results of the investigation into thermophysical properties of water based copper nanofluid designed for a special type of coil heat exchanger requiring a specific working liquid. The nanofluid considered, characterized by low particle concentrations, was proposed as this liquid. The exact determination of its properties was the basis for further experimental and numerical examination of the exchanger. One of the exchanger's heating coils was filled with a refrigerant. In order to prevent a possible refrigerant leakage a special buffer layer filled with the water based Cu nanofluid was mounted in the coil. The thermophysical properties of the nanofluid might lead to heat transfer enhancement in the buffer layer and thus improve the thermal characteristics of the exchanger. The density, viscosity and thermal conductivity of the Cu/water nanofluid were measured experimentally. Spherical copper Highlights Thermophysical properties of Cu/water nanofluid were measured Experiments were performed with nanofluid up to 0.101 vol% concentration Thermal conductivity enhancement of 0.101% nanofluid was 11.5% at 23 °C Relative viscosity of 0.101% nanofluid changes from 2.5% to 27% with temperature Experimental results were compared with classical models
In industries such as power generation, chemical production, air conditioning, transportation, and microelectronics the cconventional heat transfer fluids such as water, mineral oil, and ethylene glycol are used to transfer heat from one fluid to another. The low thermal conductivity of conventional fluids increase the size of the heat transfer device for the given heat transfer. So there is a need to develop energy-efficient heat transfer fluids that are required in a plethora of heat transfer applications. Modern materials technology provided the opportunity to produce nanometer-sized particles which are quite different from the parent material in mechanical, thermal, electrical, and optical properties. The heat transfer properties of these conventional fluids can be significantly enhanced by dispersing nanometer-sized solid particles such as Al 2 O 3 , Cu, CuO and Fe 2 O 3. The suspended nano-sized metallic and metal oxide particles change the transport properties and heat transfer characteristics of the base fluid. Thus the preparation of nanofluids using metal and metal oxide nanoparticleswill play an important role in developing the next generation of cooling technology. The CuO nanoparticles are prepared by adopting sol-gel techniquein the present work. The CuO nanoparticles are prepared from copper nitrate by passed it through different stages such as dissolving, preparation of solution, formation of gel, filtration and drying to get the nano-sized CuO particles. The nanoparticles are sintered for 3 hours at a temperature of 200 0 C in the furnace to remove the liquid traces completely from nanoparticles. TheCuO-water nanofluids are prepared at different volumetric concentration of CuO nanoparticle in the base fluid. To find the heat transfer rates of CuO-water nanofluid for different Reynolds numbers and for different volume fractions of nano-particles in the base fluidthe experiments are conducted in a double pipe counter flow heat exchanger. The experimental overall heat transfer coefficients calculated are compared with the base fluid water. Also the theoretical overall heat transfer coefficients of CuO-water nanofluid are determined by evaluating the physical and thermal properties of nanofluid with the correlations available in the literature.