Graphene Oxide Nanofluids Research Articles

The effect of boiling in a thermosyphon on surface tension and contact angle of silica and graphene oxide nanofluids

Thermosyphons are heat transfer devices characterised by high efficiency due to simultaneous phase changes occurring in the evaporation-condensation cycle of working fluid. One of the most promising solutions to enhance their heat transfer capacity of the device is the use of nanofluids – suspensions of particles with at least one dimension below 100 nm. It was determined that nanofluid does not influence the work of thermosyphons condenser section and the focus should be put on the boiling process in the evaporator section. During boiling, nanoparticles tend to deposit on the heater’s surface, what alters characteristics of this surface and near surface hydrodynamics. This changes the appearance of nanofluid, but the precise effect on how the deposition of particles affects the properties of nanofluid is unknown. Changes in surface tension and wettability affect boiling regimes (e.g. reduced surface tension reduces the size of departing bubbles and inhibits geysering), and efficiency of heat transfer through the device. Understanding of those parameters is crucial for the development of appropriate models describing heat transfer in thermosyphon working with nanofluids. The main goal of this study is to determine surface tension and contact angle of nanofluids based on silica nanoparticles and nano-sized graphene oxide flakes before and after the experimental boiling cycle in the thermosyphon. Results show that, in comparison with water, silica nanofluid (2 vol%) is characterised by lower surface tension and contact angles on both analysed surfaces. After-use silica nanofluid exhibited noticeably higher averaged surface tension and smaller contact angles in comparison to the fresh working medium. The change was most likely due to the decreased concentration caused by the deposition of nanoparticles during the thermosyphon operation. Still, the differences between before-use and after-use samples were smaller than the measurement uncertainties. Before-use graphene oxide nanofluid already showed surface tension and contact angle similar to water due to low concentration of graphene flakes (0.1 g/L). Consequently, the properties of after-use graphene oxide fluid were also not much different from water. Additional measurements of surface tension for graphene oxide nanofluid with and without addition of sodium dodecyl sulphate surfactant allowed to differentiate the effects caused by graphene flakes and surfactant. The surfactant reduced the surface tension of the nanofluid, but the change was smaller than in case of surfactant addition to pure water.

Synthesis of graphene oxide nanofluid based micro-nano scale surfaces for high-performance nucleate boiling thermal management systems

The objective of this study is to explore the exceptional thermal management ability of Graphene Oxide (GO) nanofluid and microporous surfaces (M) for nucleate pool boiling based thermal management systems. The performance of the designed system has been analyzed for thermal management of concentrated photovoltaics (CPV) system. A detailed analysis has been performed for GO nanofluid, with concentrations; 0.0001%, 0.001%, and 0.01%, and deionized (DI) water-based working fluid over the plane unmodified surface (P) and microporous (M) surfaces. GO nanofluid enhanced critical heat flux (CHF) and the heat transfer coefficient (HTC) over the plane surface. However, over M surface, GO nanofluid resulted in thick layer formation and significantly affected the NBHT performance. The highest CHF of 1850 kW/m2 has been observed for GO over the plane surface, increasing 2.31 times. M surface with deionized water resulted in the highest average HTC of 64.36 kW/m2.K, increasing 3.47 times. GO over the plane surface (Np) based NBHT thermal management system resulted in the highest concentration ratio of 3102 and can be used for CPV system. In comparison, M surface-based thermal management system resulted in the highest efficiency.

Heat transfer performance of a radiator with and without louvered strip by using Graphene-based nanofluids

The present work is focused on the Graphene-based nanofluids with high thermal conductivity which helps to improve the performance and enhance heat transfer. The thermal systems emphasis on the fluid coolant selection and statistical model. Graphene is a super-material, lighter than air, high thermal conductivity, and chemical stability. The purpose of the research is to work up with Graphene-based Nanofluids i.e., Graphene (G) and Graphene oxide (GO). Nanoparticles are dispersed in a base fluid with a 60:40 ratio Water & Ethylene Glycol and at different volume concentrations ranging from 0.01%-0.09%. Radiator model is designed in modelling software and louvered strip is inserted. The simulation (Finite Element Analysis) is performed to evaluate variation in temperature drop, enthalpy, entropy, heat transfer coefficient and total heat transfer rate of the considered nanofluids, results were compared by with and without louvered strip in the radiator for the temperature absorption. 58-60% enhancement of enthalpy observed when Graphene and Graphene oxide nanofluid was utilized. 1.8% enhancement of entropy is observed in 0.09% volume concentration of the Graphene and Graphene oxide nanofluid when louvered strips are inserted in the radiator tube at a flow rate of 3 LPM. With louvered strip inserted in the radiator, heat transfer coefficient enhanced by 236% for Graphene and 320% enhancement is identified for Graphene oxide nanofluid when compared to without louvered strip insert. The results stated that high performance is observed with the utilization of louvered strip in the radiator tube.

Preparation and application of nanofluid flooding based on polyoxyethylated graphene oxide nanosheets for enhanced oil recovery

In this paper, an innovative polyoxyethylated graphene oxide-based nanofluid (P-GO-O) for enhanced oil recovery was prepared. Transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR), Raman spectra, thermogravimetric analysis (TGA), and UV–vis spectra analysis were used to characterize the P-GO-O nanosheets. Moreover, zeta potential, temperature resistance, and salinity tolerance were evaluated to determine the dispersion stability of the P-GO-O nanofluid. The zeta potential of P-GO-O in deionized water was −39 mV, and the P-GO-O nanofluid exhibited excellent high temperature and high salinity resistance. Benefiting from its structure, the P-GO-O nanofluid was capable of lowering the oil–water interfacial tension to 12.2 mN/m and changing the oil-wet surface to the water-wet surface. In the oil displacement test, the oil recovery ratio of P-GO-O nanofluid (17.2%) was higher than the GO-O (octadecylaminated graphene oxide) nanofluid (6.7%), which was attributed to its better stability and wettability alteration. These results indicated that the P-GO-O nanofluid had the potential for enhanced oil recovery (EOR) application.

Artificial Neural Network Applied to Predicting the Surface Tension of Acoustically Levitated Droplets of Supercooling Nanofluids

Droplet oscillation method is a noncontact experimental approach, which can be used to measure the surface tension of acoustically levitated droplet. In this paper, we obtained huge amounts of experimental data of deionized water and water-based graphene oxide nanofluids within the temperature range of [Formula: see text]8.2–[Formula: see text]C. Based on the experimental data, we analyzed the influence of droplet’s deformation and frequency shift phenomenon on the surface tension of levitated droplet. Eight parameters that strongly correlate with surface tension were found and used as input neurons of artificial neural network model to predict the surface tension of supercooling graphene oxide nanofluids. The experimental data of nonsupercooling graphene oxide nanofluids were used as training set to optimize artificial neural network model, and that of deionized water were served as validation set, which was used to verify the predictive ability of artificial neural network model. The root mean square error of the optimized artificial neural network model to validation set is only 0.2558[Formula: see text]mN/m, and the prediction values of the surface tension of supercooling deionized water were in good agreement with the theoretical values calculated by Vargaftik equation, which indicates that artificial neural network model can deal well with the complex nonlinear relationship. Afterwards, we successfully predicted the surface tension of supercooling nanofluids by means of the optimized artificial neural network model and obviously reduced the dispersion and deviation caused by droplet deformation and other problems during oscillation process.

Thermo-electro-rheological behaviour of vanadium electrolyte-based electrochemical graphene oxide nanofluid designed for redox flow battery

The use of electrolyte-based nanofluid is a new approach for enhancing the performance of Vanadium Redox Flow Batteries (VRFBs). This paper, for the first time in the literature, presents an experimental study to comprehensively investigate the rheological behaviour, electrical conductivity, and thermal conductivity of a newly prepared electrochemical graphene oxide (EGO)/ vanadium (IV) electrolyte-based nanofluid in different weight concentration and bulk temperatures. SEM, FT-IR and X-ray Diffraction (XRD) characterizations were performed and different functional groups, smooth 2D layered structures, and low crystallinity were detected in our tailored oxidation EGO which are amongst the enhancing features for VRFBs electrode materials. It was observed that the optimum weight concentration of nanoparticles in the electrolyte-based nanofluid is 0.05 wt% with strong colloidal stability, enhanced electrical and thermal conductivities, and an optimal viscosity. The maximum feasible enhancements in electrical and thermal conductivities that were achieved were 12%, and 4%, respectively, which can positively affect the performance of flow battery in terms of electrochemical activity on the electrode surface and thermal management of the flow battery system. In addition, the rheological evaluation showed that the behaviour of the electrolyte-based nanofluid tends to change from Newtonian to non-Newtonian for weight concentrations higher than 0.05%. The results obtained from rheological behaviour can provide useful insights in choosing an optimum pumping system of the flow batteries working with electrolyte-based nanofluid.

Effect of Ultralow Concentrated Reduced Graphene Oxide Nanofluid on Radiator Performance

Abstract Nanocoolants are engineered colloidal suspensions of nanoparticles in a conventional coolant (water–ethylene glycol). Use of metals and metallic oxide nanofluids at concentrations greater than 0.01 vol % has been studied in greater detail compared to functionalized graphene nanofluids. In the present work, an experimental investigation is carried out on an automobile radiator by changing the conventional coolant to reduced graphene oxide (RGO) nanocoolant. The present study focuses on the effect of ultralow nanoparticle concentration (0.002–0.006 vol %), Reynolds number of hot coolant (80–170), Reynolds number of air (210–270), and inlet temperature of hot coolant (40 °C and 60 °C). The effect of these parameters on the performance of the radiator is measured in terms of convective heat transfer coefficient (CHTC), Nusselt number, friction factor, and effectiveness. Results indicate that at 0.006 vol % concentration, there is a maximum increase of 100.5% and 111%, respectively, in CHTC and effectiveness, besides a reduction in friction factor. RGO nanocoolant offers great scope for reducing the radiator size and increasing its performance.

An experimental study on energetic performance evaluation of a parabolic trough solar collector operating with Al2O3/water and GO/water nanofluids

The parabolic trough solar collector (PTSC) is one of the most developed and commercialized technologies in solar heating systems. The main purpose of this study is to utilize two samples of water-based nanofluids (0.2 wt %) made of graphene oxide (GO) and alumina (Al2O3) nanoparticles in a PTSC. First, the stability and thermophysical properties of the nanofluids were investigated by focusing on the morphology of their constituent nanoparticles. In one of the results, the values of thermal conductivity and dynamic viscosity in the GO nanofluid were obtained 9.1% and 23.4% higher than Al2O3 nanofluid. Next, the nanofluids were tested in the PTSC at three volume flow rates (1, 3, and 5 L/min). Compared to pure water, the best enhancement in thermal efficiency was observed at 1 L/min about 63.2% in GO nanofluid and 32.1% in Al2O3 nanofluid. Also, the best energetic performance (the ratio of useful energy provided to pumping energy required) of the system was realized at 1 L/min. The operational effectiveness of the nanofluids in the collector was decreased with increasing flow rate. This behavior was observed more severely in the GO nanofluid, as it showed lower energetic productivity than pure water at flow rate of 5 L/min.

Experimental evaluation of a thermosyphon-based heat exchanger working with a graphene oxide (GO) nanofluid in a cogeneration system

Waste heat recovery is an alternative to improve the energy efficiency and decrease the fuel cost in industrial processes. Nanofluids have been considered an alternative to common fluids in heat exchangers in order to increase their heat transfer rate. This experimental study was conducted using graphene oxide (GO) nanofluids in a thermosyphon-based heat exchanger coupled to a diesel electrogene group forming a cogeneration system. The heat exchanger had 47 copper thermosyphons, which were evaluated with water and with a GO nanofluid at a 30% filling ratio. The heat supplied to the evaporator was produced by the exhaust gases of a diesel engine coupled to an electric generator, and the external air flow was used in the condenser. Before the experiments in the heat exchanger, one thermosyphon with the same filling ratio was evaluated using water and the GO nanofluid to compare its thermal performance at lab scale. The results at lab scale showed a decrease in thermal resistance by up to 67% using the GO nanofluid compared to water. However, when the thermosyphon-based heat exchanger was evaluated at real scale with water and the GO nanofluid, its performance was not improved despite the fact that some individual thermosyphons showed lower condenser-evaporator temperature differences.

An experimental study on heat transfer performance of GO and rGO-CuO nanofluids in a heat exchanger

In the present work, we have reported the synthesis and characterization of graphene oxide (GO) and copper oxide functionalized reduced graphene oxide (rGO-CuO) nanomaterials and studied their heat transfer properties. The synthesized materials are characterized using FTIR, XRD, UV–vis spectrophotometry, STM, EDX, SEM, and TEM analysis. Both GO and rGO-CuO nanomaterials are used as water-based NFs to study the heat transfer performance. The maximum enhancement of heat transfer rate and effectiveness of GO-water NF are found to be 18.51% and 24.58% concerning Di-water, respectively. Whereas, in the rGO-CuO-water NFs, maximum enhancement in the heat transfer rate and the effectiveness is obtained as 24.07% and 37%, compared to the Di-water, respectively. The maximum increase in Nusselt number for GO-water NF is found to be 16.48% as compared to Di-water. Whereas, for rGO-CuO-water NF is found to be 23.84% and 6.3% compared to Di-water and GO-water NFs at Reynold numbers 806.67, 1210.48, and 1617.21, respectively. These NFs may be useful in the future for heat exchanger applications.

Enhancement of start-up and thermal performance in pulsating heat pipe with GO/water nanofluid

Graphene Oxide (GO) is a new carbon material with a two-dimensional sheet structure, which has high thermal conductivity and strong hydrophilicity. In this study, influence of GO nanofluid and filling ratio on the start-up performance of a water-based PHP was investigated. The PHP was fabricated with a long copper tube, which was bent into 3 turns, with the inner and outer diameters were 2 mm and 4 mm respectively. The nanofluid was prepared by dissolving GO nanoparticles into the deionized water, with different mass fraction range (ω = 0.02–0.1 wt%), and filling ratios (FR = 20%, 50%, 80%). The evaporation section was electrically heated, with a heating power ranged from 10 W to 30 W, while the condensation section was cooled by the forced convective wind. Results showed that both the filling ratio and the GO concentration had great effect on the start-up performance of the PHP. When the filling ratio was at 20% and 50%, the suitable introduction of GO nanofluid could improve the start-up performance of the water-based PHP, and the best concentration range was about 0.05–0.08 wt%, for the start-up performance optimal. Especially at the filling ratio was 50%, adding 0.05 wt% GO nanoparticles could decrease the start-up temperature and time about 34 °C (41%) and 796 s (58%), respectively, when compared with the deionized water. In contrast, at the filling ratio of 80%, adding GO nanofluid did not significantly improve the start-up performance, even led a deterioration of the performance at a higher concentration (ω = 0.1 wt%). When compared with the GO concentration, the filling ratio had a greater impact on the start-up of PHP. As the filling ratio increased, the minimum starting heat input increased. As for thermal performance, when heat input was 30 W, GO concentration was 0.05 wt% and filling ratio was 50%, it reached the highest thermal performance enhancement rate about 54.34%, when compared with the pure water PHP.

Numerical and experimental analysis of performance in a compact plate heat exchanger using graphene oxide/water nanofluid

Purpose This study aims to present the experimental and computational performance analysis in compact plate heat exchanger (PHE) using graphene oxide nanofluids at different concentrations and flow rate. Design/methodology/approach Field emission scanning electron microscope and X-ray diffraction were used to characterize graphene oxide nanoparticles. The nanofluid samples were prepared by varying volume concentration. Zeta potential test was done to check stability of samples. The thermophysical properties of samples have been experimentally measured. The experimental setup of PHE with 60° chevron angle has also been developed. The numerical analysis is done using computational fluid dynamics (CFD) model having similar geometry as of the actual plate. Distilled water at fixed temperature and flow rate is used in hot side tank. Nanofluid at fixed temperature with varying concentration and flow rate is used in cold side tank as coolant. Findings The numerical and experimental results were compared and found that both results were in good agreement. The results showed ∼13% improvement in thermal conductivity, ∼14% heat transfer rate (HTR), ∼9% in effectiveness and ∼10% in overall heat transfer coefficient at cost of pressure drop and pumping power using nanofluid. Exergy loss also decreased using nanofluid at optimum concentration of 1 Vol.%. Originality/value The CFD model can be significant to analyze temperature, pressure and flow distribution in heat exchanger which is impossible otherwise. This study gives ease to predict PHE performance with high accuracy without performing the experiment.

Thermal Performance of Thermosyphons Intended for Evacuated Tube Solar Collector Using Graphene Oxide Nanofluids

Vacuum tube solar collectors are composed by two concentric glass tubes with the annular space evacuated. At the inner tube a thermosyphon is placed inside a metallic fin in order to absorb sun’s irradiation and heat running water placed at a manifold. Thermosyphons are passive heat transfer devices that absorb heat at the evaporator region, evaporating the working fluid that reaches the condenser in the form of steam. At the condenser, heat is dissipated to the environment, condensing the working fluid that returns to the evaporator, closing the thermodynamic cycle. In this study, thermosyphons with three different working fluids (5 and 10% graphene oxide nanofluids and distilled water) were built and experimentally tested. The evaporator and the adiabatic section have an outer diameter of 8.33mm and lengths of 1,600mm and 40mm, respectively. The condenser has an outer diameter of 13.40mm and a length of 35mm. The filling ratio used was 50% of the evaporator’s volume. A resistive tape wrapped at the evaporator and connected to a power supply was responsible for heating the working fluid by Joule effect, and water flow rates of 0.50, 0.75, and 1.00L/min were responsible for condensing the working fluid at the condenser. Heat loads of 35, 55, and 75W were applied to the devices and K-type thermocouples were responsible for acquiring temperature data from the thermosyphons, allowing the thermal analysis based in the temperature distribution and thermal resistance for each working fluid. The best working fluid for the conditions proposed, out of the three investigated, was 5% graphene oxide.

Experimental investigation of specific heat of aqueous graphene oxide Al2O3 hybrid nanofluid

The specific heat of aqueous graphene+Al2O3 (1:1) hybrid nanofluid was measured using the cooling method. The influence of nanoparticle mass fraction and temperature on the specific heat capacity of the hybrid nanofluids was investigated, the specific heat of the hybrid nanofluid was compared with that of aqueous graphene oxide nanofluid and Al2O3 nanofluid. A fitted formula of the specific heat of the hybrid nanofluid was proposed based on the experimental data. It indicates that the specific heat reduction ratio increases with increase of nanoparticle fraction and the maximum reduction ratio is 7% at 0.15 wt.% at 20?C. The mass fraction of nanoparticle affects the specific heat of hybrid nanofluid more significantly at lower temperature. Temperature impacts the specific heat more distinctly than the nanoparticle fraction. The specific heat increases with temperature and the maximum specific heat reduction ratio of the hybrid nanofluid diminishes from 7% at 20?C to 2% at 70?C at the mass fraction of 0.05%.

Performance Evaluation of a Direct Absorption Collector for Solar Thermal Energy Conversion

The solar absorption efficiency of water as a base-fluid can be significantly improved by suspending nanoparticles of various materials in it. This experimental work presents the photo thermal performance of water-based nano-fluids of graphene oxide (GO), zinc oxide (ZnO), copper oxide (CuO), and their hybrids under natural solar flux for the first time. Nanofluid samples were prepared by the two-step method and the photothermal performance of these nanofluid samples was conducted under natural solar flux in a particle concentration range from 0.0004 wt % to 0.0012 wt %. The photothermal efficiency of water-based 0.0012 wt % GO nanofluid was 46.6% greater than that of the other nanofluids used. This increased photothermal performance of GO nanofluid was associated with its good stability, high absorptivity, and high thermal conductivity. Thus, pure graphene oxide (GO) based nanofluid is a potential candidate for direct absorption solar collection to be used in different solar thermal energy conversion applications.

Thermal performance enhancement studies on a circular finned coil-in-shell heat exchanger using graphene oxide nanofluid

The objective of this study is to investigate the effect on heat transfer augmentation by the combined effect of circular fins directly attached to the helical surface of the coil in two different orientations (45° and 90°) and Graphene Oxide nanofluid as a heat transport agent, in a coil-in-shell heat exchanger. The attached circular fins not only act as turbulators on the shell side but could also add to heat transfer from the hot side to the cold side, by a combined mechanism of conduction and convection. The experiment is conducted at constant heat flux, with the cold nanofluid in the coil side and hot air in the shell side. Test runs are taken by varying hot air velocities from 1 m/s to 5 m/s, keeping fixed volume concentration of nanofluid (0.05–0.15%) and flow rate (500 ≤ Re ≤ 5500) one at a time. Experimental results indicated significant enhancement in heat transfer performance for the finned configuration. For 90º and 45º fin orientation—0.15% volume concentration of nanofluid, the maximum heat transfer increase is by 78.46%, and 82.22%, Nusselt number increase is by 32.57%, 60.79% respectively, at a hot air velocity of 3 m/s. The coil side pressure drop and friction factor increased to 32.72% and 24.64% for 0.15% GO nanofluid when compared to pure water at the maximum flow rate. The thermal–hydraulic performance improvement is nearly two-fold with 45º fin orientation-GO nanofluid combination.

Blood-based graphene oxide nanofluid flow through capillary in the presence of electromagnetic fields: A Sutterby fluid model

Pumping devices with the electrokinetics phenomena are important in many microscale transport phenomena in physiology. This study presents a theoretical and numerical investigation on the peristaltic pumping of non-Newtonian Sutterby nanofluid through capillary in presence of electromagnetohydrodynamics. Here blood (Sutterby fluid) is taken as a base fluid and nanofluid is prepared by the suspension of graphene oxide nanoparticle in blood. Graphene oxide is extremely useful in the medical domain for drug delivery and cancer treatment. The modified Buongiorno model for nanofluids and Poisson-Boltzmann ionic distribution is adopted for the formulation of the present problem. Constitutive flow equations are linearized by the implementation of approximations low Reynolds number, large wavelength, and the Debye-Hückel linearization. The numerical solution of reduced coupled and nonlinear set of equations is computed through Mathematica and graphical illustration is presented. Further, the impacts of buoyancy forces, thermal radiation, and mixed convection are also studied. It is revealed in this investigation that the inclusion of a large number of nanoparticles alters the flow characteristics significantly and boosts the heat transfer mechanism. Moreover, the pumping power of the peristaltic pump can be enhanced by the reduction in the width of the electric double layer which can be done by altering the electrolyte concentration.

Heat transfer of water–graphene oxide nanofluid magnetohydrodynamic flow through a channel in the presence of the induced magnetic field

In the present study, the heat transfer of nanofluid magnetohydrodynamic (MHD) fluid flow through a channel with radiation and viscous dissipation effect is considered. Also, the induced magnetic field is considered. The main aim of the study is to obtain the impact of the induced magnetic field, nanoparticle volume fraction, non-electrically conducting, and conducting walls on the MHD nanofluid flow and heat transfer. Hence, the governing equations include momentum, energy, and induced magnetic field equations that are transformed into non-dimensional forms. The analytical least square method (LSM) and numerical finite element method (FEM) effectively conducted for solving the problem. The results of LSM and FEM are compared, and it is observed that there is an excellent agreement. The effect of several parameters such as Hartmann number, suction/injection parameter, magnetic Prandtl number, radiation parameter, Eckert number, and nanoparticle volume fraction are demonstrated and discussed. It can be concluded that the augmentation of the Hartmann number reduces the value of velocity by up to 50%, and the magnetic Prandtl number augmentation reduces the non-dimensional velocity value of about 10% but increases the induced current density value more than twice. Moreover, the increase of radiation parameter, Eckert number, and nanoparticle volume fraction enhance the heat transfer by 20–50%. Besides, the absolute value of the induced magnetic field increases when the Hartmann number rises. Further, the injection parameter decreases the value of velocity and induced magnetic field by 40–50%; whereas, the value of temperature increases by about 40%, and the induced current density increases by 5–7 times. The suction parameter has the contrary effect.

Heat transfer analysis of looped micro heat pipes with graphene oxide nanofluid for Li-ion battery

Li-ion batteries play a vital role in electromechanical devices. The heat load on such batteries varies with time and application which falls as high temperature rise and it causes severe damages on a device and reduces the life cycle. It will be a big challenge in future decades of electronic devices and the electric car revolution. To overcome such difficulties, this work is considered for thermal management of small Li-ion batteries to check the possibilities through the micro heat pipe. Due to the high impact of nanotechnology in heat transfer science, acetone, deionized water, and tetrahydrofuran fluids are blended with graphene oxide nanoparticles to prepare the nanofluids by ultrasonic method. Here, tetrahydrofuran is a new combination of nanoworking fluid and not addressed by pre-researchers. Tet-rahydrofuran-graphene nanofluid provides 61% of improved thermal conductivity than the other two fluids which accelerates the heat transfer rate with reduced thermal resistance in the range of 0.09-0.64?C/W. To validate the experimental results, a real-time study has been done on Li-ion batteries for a day and ensured the reduction of overheat issues. Hence, the present work will support the Li-ion battery to work in an optimal temperature range in a new way of micro heat pipe with nanofluid.

Heat transfer and mechanical friction reduction properties of graphene oxide nanofluids

A large amount of energy consumption has been caused by friction and inefficient heat transfer in the industry. Current research suggests a promising future for graphene nanofluids. In this paper, graphene oxide-deionized water (GO-DI) nanofluids with both friction reduction and high efficiency heat transfer properties was prepared by a two-step method in this paper. The graphene oxide was characterized using FTIR spectroscopy, Raman spectroscopy, XPS and SEM. The dispersion stability of nanofluids was analyzed by dynamic light scattering. An experimental system for measuring the convective heat transfer coefficient of nanofluids was established. The convection heat transfer and friction properties of GO-DI nanofluid were tested. The experimental results show that the addition of GO nanoparticles to the base fluid increases the convective heat transfer coefficient. The proportion of Nunf/Nuf of nanofluids increases from 1.02 to 1.18 as volume fraction rises. For GO-DI nanofluids, the friction coefficient decreased 71% compared to deionized water, when 0.1 vol% of GO and 3 N normal load were applied. The abrasion loss in 0.05 vol% GO-DI nanofluids was 18.5% less than that in deionized water. The association equation for calculating the convective heat transfer coefficient was proposed and the friction reduction mechanism of GO-DI nanofluids was elucidated.