Experimental study on thermal conductivity of ethylene glycol based nanofluids containing Al2O3 nanoparticles (original) (raw)
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International Journal of Heat and Mass Transfer, 2009
Experimental investigations have been carried out for determining the thermal conductivity of three nanofluids containing aluminum oxide, copper oxide and zinc oxide nanoparticles dispersed in a base fluid of 60:40 (by mass) ethylene glycol and water mixture. Particle volumetric concentration tested was up to 10% and the temperature range of the experiments was from 298 to 363 K. The results show an increase in the thermal conductivity of nanofluids compared to the base fluids with an increasing volumetric concentration of nanoparticles. The thermal conductivity also increases substantially with an increase in temperature. Several existing models for thermal conductivity were compared with the experimental data obtained from these nanofluids, and they do not exhibit good agreement. Therefore, a model was developed, which is a refinement of an existing model, which incorporates the classical Maxwell model and the Brownian motion effect to account for the thermal conductivity of nanofluids as a function of temperature, particle volumetric concentration, the properties of nanoparticles, and the base fluid, which agrees well with the experimental data.
Thermal conductivity and specific heat capacity measurements of Al2O3 nanofluids
Journal of Thermal Analysis and Calorimetry, 2012
Thermal conductivities and specific heat capacities of nanoparticles of Al 2 O 3 dispersed in water and ethylene glycol as a function of the particle volume fraction and at temperatures between 298 and 338 K were measured. The steady-state coaxial cylinders method, using a C80D microcalorimeter (Setaram, France) equipped with special calorimetric vessels, was used for the thermal conductivities measurements. The heat capacities were measured with a Micro DSC II microcalorimeter (Setaram, France) with batch cells designed in our laboratory and the ''scanning or continuous method.'' The Hamilton-Crosser model properly accounts for the thermal conductivity of the studied nanofluids. Assuming that the nanoparticles and the base fluid are in thermal equilibrium, the experimental specific heat capacities of nanofluids are correctly justified.
In the present paper, the effects of temperature and volume fraction on thermal conductivity of SWCNT– Al 2 O 3 /EG hybrid nanofluid are investigated. Single-walled carbon nanotube with outer diameter of 1–2 nm and aluminum oxide nanoparticles with mean diameter of 20 nm with the ratio of 30 and 70%, respectively, were dispersed in the base fluid. The measurements were conducted on samples with volume fractions of 0.04, 0.08, 0.15, 0.3, 0.5, 0.8, 1.5 and 2.5. In order to investigate the effects of temperature on thermal conductivity of the nanofluid, this characteristic was measured in five different temperatures of 30, 35, 40, 45 and 50 °C. The results indicate that enhancement of nanoparticles' thickness in low volume fractions and at any temperature causes a considerable increment in thermal conductivity of the nanofluid. In this study, the highest enhancement of thermal conductivity was 41.2% which was achieved at the temperature of 50 °C and volume fraction of 2.5%. Based on the experimental data, an experimental correlation and a neural network are presented and for thermal conductivity of the nanofluid in terms of volume fraction and temperature. Comparing outputs of the experimental correlation and the designed artificial neural network with experimental data, the maximum error values for the experimental correlation and the artificial neural network were, respectively, 2.6 and 1.94% which indicate the excellent accuracy of both methods in prediction of thermal conductivity.
Applied Physics Letters, 2014
In the present work, the temperature and concentration dependence of thermal conductivity (TC) enhancement in ethylene glycol (EG)-based amorphous and crystalline Al 2 O 3 nanofluids have been investigated at temperatures ranging from 0 to 100 C. In our prior study, nanometer-sized particles of amorphous-, c-, and a-Al 2 O 3 were prepared via a simple sol-gel process with annealing at different temperatures and characterized by various techniques. Building upon the earlier study, we probe here the crystallinity, microstructure, and morphology of the obtained a-Al 2 O 3 nanoparticles (NPs) by using X-ray powder diffraction with Rietveld full-profile refinement, scanning electron microscopy, and high-resolution transmission electron microscopy, respectively. In this study, we achieved a 74% enhancement in TC at higher temperature (100 C) of base fluid EG by incorporating 1.0 vol. % of amorphous-Al 2 O 3 , whereas 52% and 37% enhancement is accomplished by adding cand a-Al 2 O 3 NPs, respectively. The amorphous phase of NPs appears to have good TC enhancement in nanofluids as compared to crystalline Al 2 O 3. In a nutshell, these results are demonstrating the potential consequences of Al 2 O 3 NPs for applications of next-generation efficient energy transfer in nanofluids. V
Journal of Nanoparticle Research, 2010
We present new data on the thermal conductivity of nanofluids consisting of alumina nanoparticles dispersed in water, ethylene glycol, and ethylene glycol ? water mixtures. We also demonstrate that our previously published model is able to describe the temperature, particle size, and particle volume fraction dependence of these nanofluids without any adjustable parameters, irrespective of the base fluid used (water, ethylene glycol, or water ? ethylene glycol mixtures). Furthermore, we demonstrate how the model may be used to check the consistency of literature data on all alumina nanofluids.
International Journal of Heat and Mass Transfer, 2017
Experimental study has been carried out to determine the thermal conductivity of five different nanofluids containing aluminum oxide, copper oxide, zinc oxide, silicon dioxide and titanium dioxide nanoparticles dispersed in a base fluid of 60:40 (by mass) propylene glycol and water mixture. The effect of particle volumetric concentration up to 6% was studied with temperatures ranging from À30°to 90°C. Experiments showed an increase in thermal conductivity of nanofluids with increasing concentration and temperature. The thermal conductivity of nanofluids showed a strong dependence on particle volumetric concentration, particle size, properties of particles and the base fluid and temperature. Several existing theoretical models for thermal conductivity of nanofluids were compared with the experimental data, but they all showed disagreement. From comparisons, the most agreeable model was selected and a curve-fit constant was derived to match the data of propylene glycol nanofluids. This model expresses the thermal conductivity of nanofluids as a function of Brownian motion, Biot number, fluid temperature, particle volumetric concentration, and the properties of the nanoparticles and the base fluid. This model provided good agreement with 600 experimental data points obtained from five different nanofluids with an average absolute deviation of 1.79 percent. Because of the enhanced thermal conductivity with increasing temperature, nanofluids should be more beneficial at higher temperature applications.
A comparative study of nanofluid (Al2O3) and distilled water in terms of thermal conductivity
International Journal of Chemical Studies
The transfer of heat energy between fluids is frequently used in various processes in industries. The subject of potential heat energy enhancement is great attention in research. With increase in thermal conductivity of fluid, the efficiency of heat transfer in machines can be improved. In this research work, a comparative study is carried out to investigate the effect of Al2O3 Nanofluid on the thermal conductivity with distilled water. KD2 pro thermal property analyzer is used in this work to measure the thermal conductivity. The Al2O3 nanoparticles of the nanofluid have been characterized by using Scanning Electron Microscope, Transmission Electron Microscope, UV-VIS-NIR. Experimentally, it is found that maximum enhancement in thermal conductivity was 8.7% at 80 °C of 0.1 wt % concentration.
ScienceDirect, 2017
In this study, thermal conductivity of Silica and Water-Ethylene glycol as the base nanofluid, was measured within the temperature range of 25-50 °C for samples with volume fractions of 0.1, 0.5, 1, 1.5, 2, 3, and 5%. According to our measurements, thermal conductivity increased with increasing temperature and volume fraction. In comparison , volume fraction showed a greater incremental effect on thermal conductivity. Measurements showed that the highest thermal conductivity (45.5%) occurred in the volume fraction of 5% at 50 °C. Due to the lack of a precise and appropriate equation for the prediction of thermal conductivity of Silica/Water-Ethylene glycol nanofluid, an equation was provided based on the measurement results, which was a function of volume fraction and temperature. Investigations showed that maximum value for the margin of deviation for the proposed equation was equal to 2.2%, which is acceptable for an experimental equation.
A comprehensive review of last experimental studies on thermal conductivity of nanofluids
Journal of Thermal Analysis and Calorimetry, 2015
C p,nf Specific heat capacities of nanofluid C p,np Specific heat capacities of nanoparticle C p,bf Specific heat capacities of base fluid t Time T Temperature (°C) a Aspect ratio of nanoparticles Nanoparticles Base fluid Al 2 O 3 Water Fe 3 O 4 Oil (engine oil) ZnO (zinc oxide) Diesel CuO Glycol TiO 2 Ethylene glycol SiO 2 Polyethylene glycol (PEG)
Japanese Journal of Applied Physics, 2011
Nanofluids, a mixture of nanoparticles and fluids, have exceptional potential to improve their effective thermal conductivity and thermal diffusivity, aluminum and aluminum oxide nanofluids with five different volume fractions of nanoparticle suspensions in different base fluids, i.e., distilled water, ethylene glycol (EG), and ethanol were prepared by mixing nanopowder and base fluids. Sonication with high-powered pulses was used to ensure the dispersion of nanoparticles in good uniformity in the base fluids. The hot wire-laser beam displacement technique was used to measure thermal conductivity and thermal diffusivity of the prepared nanofluids. The effects of the volume fraction concentration and particle materials on the thermal conductivity and thermal diffusivity of nanofluids were determined. The results showed that the thermal conductivity and thermal diffusivity increased linearly with increasing volume fraction concentration of nanoparticles in the respective base fluids. In addition, the thermal conductivity and thermal diffusivity increased faster in the Al 2 O 3 nanofluids than in all the three base fluids.