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Variation of viscosity of propylene glycol-based graphene nanofluids with mass concentration at 50 ℃
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This study determined the optimal dispersion conditions of nanofluids by orthogonal experiments. Stable graphene/propylene glycol nanofluids are successfully prepared by a "two-step method" using a 60 wt % propylene glycol deionized water solution as the base fluid, and its thermal conductivity and viscosity are evaluated. Additionally, the effects...
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![Fig. 5. Thermal conductivity enhancement in different nanofluids [66].](profile/Mohammad_Abdelkareem/publication/349633738/figure/fig2/AS:1017180250468353@1619526078382/Thermal-conductivity-enhancement-in-different-nanofluids-66_Q320.jpg)
![Fig. 7. Classification and forms of graphene and graphene derivatives [93].](profile/Mohammad_Abdelkareem/publication/349633738/figure/fig4/AS:1017180250447877@1619526078484/Classification-and-forms-of-graphene-and-graphene-derivatives-93_Q320.jpg)
Heat transfer operations are very common in the process industry to transfer a huge amount of thermal energy, i.e., heat, from one fluid for different purposes. Many fluids are used as heat transfer fluid (HTF), in which water is the most common HTF due to its high specific heat, availability, and affordability. However, conventional HTFs, includin...
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... These wavy patterns offer promising applications in heat transfer augmentation, particularly in heat sinks, enabling electronic chips to operate optimally even under higher thermal loads. Dong et al. [8] studied the TC and viscosity of a nanofluid based on 60:40% PG and water-GN and found that these properties improved with increasing dispersion of particles. Sundar et al. [9] found that nano diamond-based nanofluids at 1 vol% nanoparticle concentration have higher TC and dynamic viscosity than base fluids. ...
The present study aimed to evaluate the heat transfer performance of three different mixtures of propylene glycol and De ionized water-based nanofluids in a mini hexagonal tube heat sink (MHTHS), as well as the influences of particle volume fraction and temperature on the thermo physical properties of nanofluids. The three different nanoparticles such as MgO, ZnO, and Al2O3 were dispersed in a mixture of Propylene Glycol (PG) and De ionized water (DIW) at four different volume fractions of 0.01, 0.02, 0.03, and 0.04 respectively. In colder regions, propylene Glycol was used as a better heat transfer fluid in miniature devices due to its anti-freezing properties. In this study, the experiment was conducted under two conditions First, the flow rate of DIW was maintained at 20L/h and the flow rate of three different nanofluids varied from 20 L/h to 50 L/h. Secondly, mixture proportions of 20%(PG)/80% (DIW) and 40% (PG)/60% (DIW) were taken as base fluids. The measurements of thermal conductivity and viscosity were also investigated. Experiments were performed to determine the heat transfer coefficient, Nusselt number, friction factor, and pressure drop of three different nanofluids flowing in an MHTHS were also investigated. Experimental results indicate that heat transfer coefficients and Nusselt number intensify with an increase in Volume fractions and Reynolds number. Consequently, friction factor and pressure drop were also investigated. The results revealed MgO-PG (20%)/DIW (80%) with 0.04VF results in a 36.6% enhancement in heat transfer rate compared to the base fluid. The Nusselt number for MgO-PG (20%)/DIW (80%) at 0.04VF showed an enhancement of 25.6% compared to the base fluid. ZnO-PG (40%)/DIW (60%) had a higher friction factor and pressure drop than the base fluid. Finally, the Reynolds number of nanofluids for selected velocity and contour escalated with increasing temperature and decreased with higher volume fraction. By optimizing the volume fraction of MgO-PG (20%)/DIW (80%) based nanofluids, the performance and longevity of miniature devices in colder regions can be effectively enhanced by providing an efficient cooling solution.
... Common materials are metals or metal oxides, as originally experimented with by Choi and Eastman [2]. Additionally, advanced carbon-based materials such as nanodiamonds, graphene, and carbon nanotubes are taken advantage of [9][10][11]. The base fluids used in nanofluids are generally similar to working fluids that have been previously applied in thermal management systems, including water, ethylene glycol, and oils [12,13]. ...
... where Pr is defined as shown in Equation (10), and Re is defined as: ...
The focus of this paper was to develop a comprehensive nanofluid thermal conductivity model that can be applied to nanofluids with any number of distinct nanoparticles for a given base fluid, concentration, temperature, particle material, and particle diameter. For the first time, this model permits a direct analytical comparison between nanofluids with a different number of distinct nanoparticles. It was observed that the model’s average error was ~5.289% when compared with independent experimental data for hybrid nanofluids, which is lower than the average error of the best preexisting hybrid nanofluid model. Additionally, the effects of the operating temperature and nanoparticle concentration on the thermal conductivity and viscosity of nanofluids were investigated theoretically and experimentally. It was found that optimization of the operating conditions and characteristics of nanofluids is crucial to maximize the heat transfer coefficient in nanofluidics and microfluidics. Furthermore, the existing theoretical models to predict nanofluid thermal conductivity were discussed based on the main mechanisms of energy transfer, including Effective Medium Theory, Brownian motion, the nanolayer, aggregation, Molecular Dynamics simulations, and enhancement in hybrid nanofluids. The advantage and disadvantage of each model, as well as the level of accuracy of each model, were examined using independent experimental data.
... Suganthi et al. [2] prepared CuO-propylene glycol nanofluids and determined its thermal conductivity, which presents an enhancement of 38% at = 1.5% compared to base fluid data. Shylaja et al. [3] conducted thermal conductivity experiments for iron-oxide Dong et al. [7] investigated the thermal conductivity and viscosity of graphene/60:40% ...
Second law efficiency (exergy) was studied experimentally for transition flow in a tube of 40:60% (weight) propylene glycol and water mixture based nanodiamond nanofluid. Prior to prepare the stable nano-diamond (ND) nanofluid, its soot was rinsed by strong chemicals. The experiments were carried out for several values of particle loading (0.2% to 1.0%) and of Reynolds number (2000 to 8000). The experimental analysis was also conducted for the heat transfer, friction factor and pumping power characteristics of the ND nanofluid. By increasing the values of particle concentration and Reynolds number, the results indicate an increase of heat transfer, Nusselt number, friction factor, pumping power and thermal performance factor, and a decrease of the thermal entropy generation. In comparison with the base fluid data, the heat transfer coefficient, Nusselt number, pressure drop, pumping power, friction factor and the thermal performance factor of the ND nanofluid augment by 36.83%, 24.16%, 15.38%, 13.18%, 19.9%, and 16.94%, respectively, and the thermal entropy generation decreases by 26.92% for 1.0 vol. % and Reynolds number of 5321.16.
In response to rising power demands and cooling loads in thermal systems, new technologies have been adopted to enhance heat transfer characteristics. A suspended nanosized particle that has high thermal conductivity in conventional heat transfer fluids is called a nanofluid. Several studies have investigated the effects of graphene-based nanofluids on thermophysical parameters such as thermal conductivity and viscosity. The paper also highlighted potential benefits of nanofluid in terms of energy conservation, reduction of material consumption and sustainability in the preparation of high thermal conductivity fluid. Also, many numerical and experimental studies have been done for heat transfer characteristics using different graphene-based nanofluids. This review examines the preparation, thermophysical properties, and heat transfer characteristics of graphene-based nanofluids, including graphene nanoplatelets, graphene oxide, and graphene composites, across various thermal systems.
Nanofluids, comprising nanoparticles and a base fluid, have captured substantial interest due to remarkable enhancements in thermal conductivity and other crucial thermophysical properties. These advancements facilitate diverse applications across various industrial processes, including biomedical and drug research. This review centers on non-Newtonian nanofluids, which diverge from Newton's law of viscosity, rendering them more adaptable and versatile. Through a comprehensive examination of the latest research, preparation methods, including both one-step and two-step techniques, and their formulations in oil-based, water-based, and ethylene glycol-based solutions are systematically explored. The study synthesizes findings that highlight significant improvements in heat transfer efficiency and introduces novel applications in sectors, such as biomedical engineering and energy systems. Furthermore, an in-depth characterization of non-Newtonian nanofluids is provided, covering their rheological, dispersion, transport, magnetic, optical, and radiative properties. These fluids are increasingly utilized in heat exchangers, automotive radiators, engines, solar collectors, and electronic coolants, demonstrating their broad spectrum of practical applications. This review shows that the ongoing challenges are primarily centered on the preparation, stability, and commercialization of non-Newtonian nanofluids. Conclusively, the paper underscores the potential of non-Newtonian nanofluids to revolutionize various technological areas and advocates for continued research to develop more stable and efficient formulations, paving the way for innovative industrial and scientific applications.
