Stability Of Nanofluids Research Articles

Combined effect of silica nanoparticles and binary surfactants in enhancing oil recovery: An experimental investigation

Modern oil fields extensively utilize enhanced oil recovery (EOR) techniques to optimize production. This investigation evaluates the potential of silica (SiO2) nanoparticles (NPs) when combined with the SDS-TX100/xanthan gum (XG) binary surfactant/polymer mixture for enhancing oil recovery. The study focuses on examining the synergistic effects of the SDS-TX100 + XG combination and SiO2 NPs on reducing interfacial tension (IFT), altering wettability, and improving viscosity. Core flooding experiments were conducted on low-permeability San Saba sandstone cores. The dispersion and stability of SiO2 NPs in the SDS-TX100 surfactant mixture were evaluated through stability analysis, dynamic light scattering (DLS), Ultraviolet–visible spectroscopy (UV–VIS), and turbidity meter. Notably, the NPs exhibited a significant reduction in IFT between the SDS-TX100 surfactant mixture and crude oil, while the addition of the SDS-TX100 surfactant mixture improved the stability of nanofluids. Core flooding experiments revealed a synergistic effect of SiO2 NPs with the SDS-TX100 + XG mixture, leading to higher incremental oil recovery compared to the SDS-TX100 + XG mixture alone. The study elucidates various mechanisms contributing to oil recovery, including wettability alteration and IFT reduction. The flooding outcomes indicate that injecting SiO2 NPs with the SDS-TX100 + XG mixture increases oil recovery by up to 16 % of the original oil in place (OIIP) after conventional water flooding. This research contributes to a comprehensive understanding of the application of SiO2 NPs with binary surfactant and polymer as a chemical-EOR (CEOR) agent and assists in identifying sandstone reservoirs where nanofluids could be effectively deployed.

A sustainable approach for the preparation and stability of mono and hybrid nanofluids in the milling of Nickel based superalloy

This work is focused on enhancing the sustainability and machinability in finish end-milling of Nimonic 90 superalloy using nanofluid-assisted machining. The research deals with the preparation and analysis of the stability of hybrid nanofluids for the machining of Nimonic 90. The UV–visible absorption of prepared mono and hybrid nanofluids are examined and based on the absorption curves, and 1% of the weight of the nanoparticles is chosen. The samples have been used to estimate the ideal ultrasonication time and its behaviour with various ionic and non-ionic surfactants have been determined. By examining the UV–visible absorption curves, the shelf life of the hybrid nanofluid is obtained, and it is found to be equivalent to that of the freshly prepared nanofluid. When preparing nanofluids based on alumina and hBN, tween 80 and Sodium Dodecyl Sulfate (SDS) has proved to be to be superior surfactants, respectively. Furthermore, toxicity test has revealed that the well-dispersed nanofluid are non-toxic in nature, with hybrid nanofluid exhibiting 84% cell viability. The hybrid nanofluid possesses a zeta potential of −30.8 mV. Additionally, has been observed that all the prepared nanofluids exhibited Newtonian behaviour and that their viscosities are 15%–20% higher than those of the base fluid. During the nanofluid assisted machining with hybrid nanofluid, the machining results of Nimonic 90 superalloy demonstrate the synergistic influence of both nanoparticles. Compared to dry machining, the hybrid nanofluid has a 48.80% reduction in cutting forces, 72.66% reduction in cutting temperature, 63.63% reduction in surface roughness, and 46.03% reduction in flank wear. Additionally, a Pugh matrix assessment score of 9 compared to the score of −5 for dry machining indicates that the usage of hybrid nanofluid as a cutting condition has substantial potential for future sustainable machining methods.

Cattaneo-Christov Heat Flux Model for Bio-Convective Radiative Eyring-Powell Nanofluid with Viscous-Ohmic Dissipation and Magnetic Dipole Impacts

In this work we studied the solutions of the bio-convected Eyring-Powell nanofluid involving gyrotactic micro-organisms in the presence of viscous-ohmic dissipation, double diffusion, and magnetic field over a stretched sheet under the impacts of nonlinear radiation and Arrhenius activation energy. The magneto-nanoparticles suspension in microorganisms are beneficial in nanofluid stability. Also, they have number of applications in nanosciences, biotech, pharmaceuticals, and mechanical development. The nonlinear coupled PDEs are transformed into ODEs by taking a suitable set of similarity transformations and then computationally solved with MATLAB’s bvp4c and RK4-Shooting technique. The skin friction coefficient, Nusselt number, and Sherwood number are represented in tabular form. The mass and heat transmission rate improve in the presence of gyrotactic microorganisms. The temperature as well as concentration of Eyring-Powell Nanofluid get decreased by accelerating the significant mass and thermal stratification. The concentration profile Φ(η) depreciate for higher Chemical reaction rate (σ), Schmidt number (Sc), and temperature difference (δ1) parameters but rises upon increasing values of Activation energy (Ea). Also, the microorganism concentration difference parameter (β1), bioconvection Lewis number Lb and Peclet number Pe are opposing the motile microorganism density profile.

Review of Ti3C2Tx MXene Nanofluids: Synthesis, Characterization, and Applications

MXene-based nanofluids are important because of their thermal and rheological properties, influencing scientific and industrial applications. MXenes, made of titanium carbides and nitrides, are investigated for nanofluid enhancement. This review covers MXene nanofluid creation, characterization, and application. To produce nanoscale MXene particles, two-dimensional materials are dissolved and dispersed in a base fluid. The stability and efficacy of MXene nanofluids depend on production methods, such as chemical exfoliation, electrochemical etching, and mechanical delamination. Improved heat transfer coefficients and thermal conductivity from MXene nanofluids help resolve heat transfer, energy efficiency, and thermal control problems. This extensive review also addresses long-term safety and the necessity for standardized characterization methodologies, helping researchers optimize MXene-based nanofluids in many technological fields

Thermodynamic Properties of Ferrofluid: Preparation, Stability and Statistical Mechanics

Ferrofluids are known as magnetic liquids that are colloidal suspensions of ultrafine, single domain magnetic particles in either aqueous or non-aqueous liquids. For such fluids, the problem arises in calculating thermal conductivity, viscosity, and thermodynamic properties on nanoparticles and ferrofluids. Thus, the main objective is to determine thermal conductivity and viscosity for ferro-nanoparticles and ferrofluids. For this study, the ZnO and Fe3O4 are checked for mechanical properties such as SEM, TEM and XRD. Then, being suspended into the diesel engine oil SAE-50 as base fluid and surfactant, Triton-100, in preparation of two-step method. Ferrofluids are prepared for 0.1%, 0.4% & 0.7% w/v and stability of nanofluids are being observed for 5 days. From the results obtained experimentally, the nanoparticles were found to be in good stability as no coagulate occur. This is because the EDLRF acts as the opposite to Van der Waals attractive force which separates the particles from each other. Finally, the thermal conductivity and viscosity for ferro-nanoparticles and ferrofluids were successfully obtained and demonstrated. Statistical mechanics are then discussed to calculate the properties of ferrofluids. The analytical results from statistical mechanics are potentially be used to compare with the experiment data.

Compound effect of EHD and nanofluid on flow boiling characteristics in minichannels

In this study, electrohydrodynamic (EHD) and nanofluid were synergistically employed to improve minichannel flow boiling. R141b, TiO2/R141b and TiO2/Span80/R141b nanofluids are employed as working fluids. Flow boiling characteristics in minichannels under electric field were evaluated experimentally. Laser confocal microscope was used to examine the effect of EHD and surfactant on nanofluid stability, particularly nanoparticle deposition on heated surfaces. Electric field can effectively enhance heat transfer, and the enhancement is more significant for nanofluids compared to pure fluid. Heat transfer performance is higher for TiO2/R141b than TiO2/Span80/R141b, while TiO2/Span80/R141b shows higher pressure drop than TiO2/R141b. The maximum enhancement ratio of 1.58 and 1.85 is found for TiO2/R141b and TiO2/Span80/R141b under electric field. Besides, heat transfer mechanism enhanced by EHD and nanofluid was discussed. Nanofluid stabilization induced by electric field and surfactant play crucial role in EHD enhancement for nanofluid. The findings suggest that TiO2/Span80/R141b nanofluid is well-suited for integration with EHD.

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Metal oxide nanofluid is a new type of heat transfer medium with good thermal performance, which can be used to improve the heat collection and photothermal conversion performance of the collector. The development of new nanofluids with excellent stability, thermophysical and photothermal properties is very important for solar thermal utilization. In this paper, the ZnO nanofluids with SDS/CTAB mixed surfactants were prepared by two-step method. Their stability, thermophysical, optical and photothermal properties were studied based on experimental data. Then, the optimum concentration and preparation conditions of the proposed ZnO nanofluids adding SDS/CTAB with good photothermal performance were obtained. The results showed that the ZnO nanofluids with the addition of SDS/CTAB hybrid surfactant has good dispersion stability and its thermal conductivity can reach 0.772 W/(m·K). The transmittance was as low as 19.0.10% and the extinction coefficient was as high as 7.25 cm−1. In addition, the addition of the SDS/CTAB hybrid surfactant caused the ZnO nanofluids to exhibit better photothermal conversion efficiency up to 87%, which was superior to that of the control group with the addition of other surfactants. Therefore, ZnO nanofluids with the addition of SDS/CTAB have great potential as DASC working fluids.

Enhanced Stability, Superior Anti-Corrosive, and Tribological Performance of Al2O3 Water-based Nanofluid Lubricants with Tannic Acid and Carboxymethyl Cellulose over SDBS as Surfactant

In this research work, the stability, tribological, and corrosion properties of a water-based Al2O3 nanofluid (0.5 wt%) formulated with tannin acid (TA) and carboxymethyl cellulose (CMC) as dispersants or surfactants were investigated. For comparative purposes, sodium dodecylbenzene sulfonate (SDBS) was also incorporated. The stability of the nanofluid was assessed through zeta potential measurements and photo-capturing, revealing the effectiveness of TA and CMC in preventing nanoparticle agglomeration. Tribological properties were examined using a pin-on-disk apparatus, highlighting the tribofilm of Al2O3 that enhanced lubricating properties of the nanofluid by the SEM, resulting in reduced friction and wear of the contacting surfaces. Sample with the addition of both TA and CMC exhibited the best tribological performance, with a ~ 20% reduction in the friction coefficient and a 59% improvement in wear rate compared to neat nanofluid without TA and CMC. Additionally, the corrosion resistance of the nanofluids were evaluated via weight loss and electrochemical impedance spectroscopy. The nanofluid sample containing both TA and CMC exhibited the lowest corrosion rate, with 97.6% improvement compared to sample without them. This study provides valuable insights into the potential applications of TA and CMC-based Al2O3 nanofluids as effective and environmentally friendly solutions for coolant or lubrication in cutting processes.

Field-induced magnetorheological study towards the active magneto-viscoelastic behavior of stable MnFe2O4 magnetic nanofluid

This work presents the fine-tuned synthesis of MnFe2O4 oleic acid-coated magnetic nanoparticles (MNPs) by the chemical co-precipitation method. The X-ray photoelectron spectroscopy (XPS) was utilized to investigate the elemental composition and oxidation state of oleic acid-coated MnFe2O4 MNPs. The Fourier transform infrared spectroscopy (FTIR) spectra were used to confirm the functional groups in the oleic acid-coated MnFe2O4 magnetic nanoparticles. The spherical shape of MnFe2O4 MNPs is confirmed by Field emission scanning electron microscopy (FESEM) and High-resolution transmission electron microscopy (HRTEM) techniques. Zeta potential (ζ) measurements were performed to confirm the stability of MnFe2O4 magnetic nanofluid (MNF). Magnetic measurements (M−vs−H) reveal the saturation magnetization, Ms = 20.3 emu/g and coercivity, HC = 30 Oe, confirming the single domain superparamagnetic nature at 300 K. Field-induced shear thinning behavior of the MnFe2O4 magnetic fluid is confirmed by a power law, η = c γn + n∞ and steady-state behavior measurements. Magneto viscous effect initially increased at a low shear rate of 20 s−1 and then decreased at a higher shear rate of 100 s−1, which confirms the stability of the MnFe2O4 magnetic fluid. Also, the highest deflection angle, θ = 243 m.rad of MnFe2O4 magnetic fluid was observed at a moderate shear rate 100 s−1 and a high magnetic field of 1.2 T, while the lowest value of deflection angle, θ = 65 m.rad was observed in the absence of magnetic field. In contrast, the storage modulus (G') is greater than the loss modulus (G''), in corroboration with the viscoelastic-to-viscous behavior of MnFe2O4 magnetic fluid.

Maximizing heat transfer potential with graphene nanofluids along with structured copper surfaces for pool boiling

Increasing the demand and depletion of energy sources confront every technological development with energy conversation and its utilization. Boiling heat transfer is the most applicable heat transfer method in many industries, from electronic chip manufacturing to heavy nuclear power plants. Hence, the augmentation of it is of prime importance for future requirements. The present investigation focused on the augmentation of boiling heat transfer by considering a novel V-pattern staggered copper surface for pool boiling in graphene nanofluid media. The study encompasses a detailed exploration of nanofluid concentrations ranging from 0.1% to 0.40 vol% prepared in equal volumes of dimethylformamide and distilled water. The nanofluid's stability is observed to be quite promising, and the results are presented. The wall superheat was drastically reduced to 48.73%, and the maximum heat transfer coefficient enhancement of 83.47% was achieved for 0.04% concentration of graphene nanofluid with a V-pattern surface compared to a smooth copper surface with water. This is due to the micro-level structured convection patterns promoted by the microstructures. The thermophysical properties of nanofluid and peculiar microstructures enhanced the relative heat transfer coefficient by 63.37%. On the other hand, two popular machine learning models, Random Forest Regression (RFR) and Multi-Layer Perceptron (MLP), are used to predict the boiling heat transfer coefficient. Moreover, it is observed that the RFR model fitted the data well and yielded the lowest mean absolute percentage error within the bounds of computational time.

Synthesis and characterization of Al2O3-methanol nanofluid and its usage in bubble column for an improved mass transfer rate

Methanol-based physical absorption, known for its effective CO2 capture ability, has been employed in acid gas removal (AGR) unit. However, the high energy consumption associated cooling methanol and acid gas hampers its widespread adoption. To address this challenge, numerous studies have explored the use of nanoparticles to enhance the CO2 absorption at room temperature, thereby reducing the energy requirements. In this study, the objective is to synthesize and characterize the Al2O3-methanol nanofluid and investigate its application in a bubble column for improved mass transfer rates during CO2 absorption. The methanol based Al2O3 nanofluid was prepared using the two-step method with ultrasonication technology and CO2 absorption in the resultant product was investigated. Initially, 0.001 vol%, 0.01 vol % and 0.1 vol% Al2O3 nanoparticles was added to methanol solution and to mixture them well via ultrasonication technology. The static settlement method and zeta potential analysis were utilized to characterize the stability of the as-prepared nanofluid. Both impact of sonication power and time on the stability of nanofluid were discussed as well. Then, numerical simulations was employed to investigate the mass transfer coefficient for CO2 absorption and the numerical uncertainty was carefully analyzed to verify the reliability of the numerical method. It revealed a 7.3%, 29.2% and 60.7% enhancement in mass transfer coefficient during CO2 absorption for 0.001 vol%, 0.01 vol% and 0.1 vol% nanoparticles under room temperature, respectively. The visualized reason for this improvement was related to the enhanced bubble breakup and coalescence after adding nanoparticles to methanol. The expanded interfacial area between gas and liquid plays a vital role in the mechanism of this improvement.

Experimental measurement of thermal conductivity and viscosity of Al2O3-GO (80:20) hybrid and mono nanofluids: A new correlation

This study examines the thermophysical properties of Aluminum oxide (Al2O3) and graphene oxide (GO) based mono and hybrid nanofluid mixture at different volume concentrations for heat transfer application. Firstly, Al2O3 and GO nanoparticles were mixed with base fluid (deionized water) separately at 1.0 % of volume concentration for mono nanofluid preparation. Then, Al2O3-GO hybrid nanofluid (80:20) was prepared for volume concentrations of 0.25 %, 0.5 %, 0.75 % and 1.0 %. The stability of both nanofluids was evaluated based on Zeta potential and pH measurements. Meanwhile, the viscosity and thermal conductivity were investigated for temperatures starting from 30 °C to 50 °C. The experimental thermal conductivity and viscosity measurements were correlated using the analytical regression method to predict the thermal conductivity and dynamic viscosity of Al2O3-GO hybrid nanofluid. The maximum thermal conductivity improvement of hybrid Al2O3-GO nanofluid (1 %) was about 4.30 % and 4.34 % higher than Al2O3 and GO mono nanofluid, respectively. In contrast, the viscosity of 1 % Al2O3-GO hybrid nanofluid showed the least reduction of 4.6 %, which is 4.1 % and 6.6 % less than both Al2O3 and GO mono nanofluids. Compared to experimental values, the new model resulted in a high level of predictive accuracy for both thermal conductivity and viscosity, with a maximum error of 6 % and 4 %.

Stability enhancement of Al2O3, ZnO, and TiO2 binary nanofluids for heat transfer applications

Abstract Primary goal of this research is to enhance stability of nanofluids which is vital for maintaining consistent thermophysical properties during various applications. Nanofluid stability is essential for obtaining the uniform thermophysical properties during its application. X-ray diffraction and zeta potential were performed to characterize three nanoparticles, namely TiO2, Al2O3, and ZnO. Experimental work was carried out under several trials to enhance the stability of nanofluids. Initially, deionized water was used as base fluid for stability analysis, but nanoparticles agglomerate within after 5 h. Second, alkaline water was selected as base fluid at different pHs ranging from 7 to 14 to analyze the stability of the nanofluids. Finally, the effect of surfactant addition on the stability of prepared nanofluids was also investigated. Observations revealed that at pH 11, nanoparticles exhibited enhanced stability compared to other pH levels. This stability can be attributed to the high zeta potential, fostering electrostatic repulsion between individual particles. It was concluded from the results that zeta potential increases in cases of (TiO2 + ZnO) and (Al2O3 + ZnO) from −44.2 to −47.8 mV and −42.4 to −44.1 mV with the addition of surfactant, respectively. In the case of (Al2O3 + TiO2), zeta potential decreases slightly from −47.7 to −44.9 mV with the addition of surfactant.

Enhancing the dynamic thermal stability of metal oxide oil-based nanofluids through synchronous chemical modification and physical coating

The stability of oil-based nanofluid, especially dynamic thermal stability, hinders its practical application in industries. To enhance the stability of oil-based nanofluids, an excess amount of hexadecyl trimethoxysilane was employed to synchronously achieve chemical surface modification and physical coating of metal oxide nanoparticles. This process can efficiently render the nanoparticle surface lipophilic while introducing steric hindrance. The dynamic thermal stability and long-term durability of the nanofluids were confirmed through extended resting and thermal cycling experiments. Additionally, various characterization methods were employed to examine certain properties of the modified nanoparticles. The results reveal that the modified nanoparticles exhibit lipophilic characteristics, effective dispersion, and robust thermal stability. The nanofluids prepared using these modified nanoparticles remained stable for 3 months during resting periods and withstood 21 days of thermal cycling at 130 °C. This positions them as promising heat transfer mediums for mid-temperature industries. Importantly, this stabilization technique exhibits potential applicability across a wide range of hydrophilic metal oxide oil nanofluids, as suggested by mechanistic analysis. The exploration of dynamic thermal stability mechanisms is of great practical significance in promoting the large-scale application of nanofluids in industry and provides insights that could potentially resolve the longstanding challenge of nanofluid stability.

Su Bazlı Nanoakışkanların Hazırlanmasında Kullanılan Yeni Yüzey Modifiye Fe3O4 Nanopartiküllerinin Uzun Vadeli Kararlılıklarının İncelenmesi

Nanofluids are produced by suspending different solid nano-size materials (metal and nonmetal) in a base liquid and are often used in energy systems to increase thermal performance and heat transfer rate. The main problem observed in nanofluids used in heat transfer applications is their instability. Researchers have developed and proposed some solutions to obtain stable nanofluids. One of the most important solutions, is the nanoparticles surface modification method. In this work, Fe3O4 nanoparticles were subjected to chemical processes and their surfaces were modified. Three different modified nanoparticles were synthesized, which are Fe3O4@SiO2@Si(CH2)3-IM [Cl], Fe3O4@Si(CH2)3-IM [Cl], and Fe3O4@SiO2&Si(CH2)3-IM [Cl] nanoparticles. The nanofluids were prepared in 0.2% Vol. fraction by using the produced particles in base fluid which was distilled water, and stability of nanofluids were observed for 3 months. Nanofluids were subjected to ultrasonication for 3.5 h to obtain homogeneous nanofluid. Not modified water-based Fe3O4 nanofluid completely collapsed in approximately 1 week. In modified nanofluids, although sedimentation occurred, it was observed that a certain amount of the particles remained suspended even after 3 months. The most important analyses in this study are Scanning Electron Microscope, X-Ray Diffraction, and Transmission Electron Microscope.

Cu-Graphene water-based hybrid nanofluids: synthesis, stability, thermophysical characterization, and figure of merit analysis

Hybrid nanofluids are emerging as an alternative to conventional heat transfer fluids and nanofluids for improving the thermal efficiency of heat exchanging devices synergistically due to their outstanding thermophysical properties associated because of the dispersion of different types of nanoparticles as compared to mono nanofluids. This will help in optimizing fluid characteristics in different flow regimes for several applications. However, enhancing the thermal energy efficiency of heat exchangers is challenging owing to the deprived stability of hybrid nanofluids at greater volume concentrations. This work concentrated on the synthesizing, thermophysical depiction, and thermal performance estimation of stable water-based Cu-graphene hybrid nanofluids using very low volume concentrations of Cu and graphene hybrid nanostructures. Cu-graphene hybrid nanofluid was successfully synthesized by dispersing the synthesized Cu and graphene nanostructures (keeping the Cu concentration constant at 0.04 vol % and varying the graphene concentration from 0.01 to 0.1 vol %) in water. Hybrid nanofluids display excellent stability against aggregation for up to 7 weeks, as proven by higher zeta potential values. Thermophysical characteristics of the prepared hybrid nanofluids were effectively measured. The thermal conductivity of Cu-graphene hybrid nanofluids shows exceptional enrichment (~ 35%) at minimal concentrations of hybrid nanostructures. Viscosity of the water-based hybrid nanofluids shows remarkable enhancement as compared to water and represents the increasing trend in viscosity of the base fluid with respect to the increase in concentration of hybrid nanostructures. The thermal and rheological properties of hybrid nanofluids are effectively validated with existing theoretical models. In addition, the specific heat and pumping power of Cu-graphene hybrid nanofluids with respect to the volume concentration of hybrid nanostructures are calculated using the existing theoretical equations. A figure of merit (FOM) analysis was conducted for the synthesized hybrid nanofluids to gauge thermal efficiency and evaluate the applicability of these hybrid nanofluids under laminar and turbulent flow conditions.

The effects of Multiwalled Carbon Nanotube to the performance of a refrigeration system

By incorporating nanofluid technology and nanolubricants into compressors, the performance can be enhanced while also lowering worldwide fuel consumption and aiming at developing cleaner, more efficient energy sources and uses. The globe is being confronted with energy security issues and heating, cooling and HVAC systems highly contribute to it. Hence, it is critical to save energy and improve the efficiency of the refrigeration cycle. This study presents experimental and theoretical findings in order to investigate the effect of Polyester (POE)-oil based multiwalled Carbon Nanotube (MWCNT) nanolubricant on the Coefficient of Performance (COP) of a refrigeration system. The objectives of this study is to analyze the stability of MWCNT nanofluids, to obtain the COP of a refrigeration cycle run with pure POE oil and MWCNT nanofluids with different concentrations respectively. The experiment was conducted by preparing 0.55, 0.65 and 0.70 g/l MWCNT nanofluid by using the two step method. The most effective concentration used in the refrigeration system was referred to the one that resulted in the highest COP. It was determined from the experiment that 0.55 g/l MWCNT nanofluid resulted in a higher COP of 5.766 as compared to the other two concentrations. Besides, it showed an improvement of 34.6% in COP as compared to the COP of using pure POE oil in the refrigeration system, which was found to be 4.285. The 0.65 g/l and 0.70 g/l concentration of MWCNT resulted in a COP of 5.618 and 5.617, respectively. The compressor work was also analyzed and was found to be reduced noticeably after adding MWCNT nanoparticles. Hence it can be concluded that the increment of MWCNT concentration in nanofluids increases the COP of the refrigeration system but only up to a certain limit of concentration.

Impact of surfactant on Al2O3/water nanofluids stability for cooling the central processing unit of computer

In order for a computer to perform well, it is important to keep the central processing unit (CPU) cool, and this can be accomplished by using a liquid coolant. This study was conducted to investigate how effective nanofluids could be as a coolant for a water block used in CPU cooling. The nanofluids used in the experiment contained Al2O3 nanoparticles and SDS surfactant in a mixture in water at volume fractions of 0.5%. They were prepared using an ultrasonic cleaner, and then tested to determine how well they transferred heat and the amount of pump power needed. The findings suggest that nanofluids with higher concentrations have better convection coefficient values and are more efficient at reducing the temperature of the water block, but they require more pumping power. It was concluded that the Al2O3 nanofluid with SDS surfactant could be used as a coolant for CPU cooling because of its effectiveness in lowering the temperature of the water block. The present work results are agreed with data available in the literature.

Study on thermo-electrical performance of spray-cooled concentrating photovoltaic system using oleic acid modified nanofluid

In the utilization of solar photovoltaics, concentrated photovoltaic technology can effectively improve the efficiency of solar cells, but it is limited by the problems of contact thermal resistance and low thermal conductivity of working fluid in cooling technology. This article proposes a modified nanofluid spray cooling HCPV system, which not only overcomes the low heat carrying capacity of traditional working fluids, but also solves the problem of contact thermal resistance in the heat transfer process, further reducing the cell temperature to achieve higher heat transfer efficiency and electrical efficiency. At first, oleic acid (OA)-modified Al2O3 nanofluids (OA-Al2O3-H2O/C2H6O) were prepared. Otherwise, stability test methods and spray cooling heat transfer test benches were developed and built. Finally, the stability of nanofluids, the temperature field distribution and electrical efficiency of solar cells under high energy current density were tested, and the effects of flow rate and base-liquid ratio on system performance were analyzed. The results showed that: OA can keep Al2O3-H2O/C2H6O nanofluids more than 48 h, and the surface temperature is stable at 40 °C. Meanwhile, the electrical efficiency is always above 27 %, up to 29.37 % and 1.3 % higher than working fluid water.

Thermal performance of Joule heating in radiative Eyring-Powell nanofluid with Arrhenius activation energy and gyrotactic motile microorganisms

BackgroundBioconvection is the term for macroscopic convection of particles accompanied by a variable density gradient and a cluster of swimming microorganisms. The accumulation of gyrotactic microbes in the nanoparticles is important to exaggerate the thermal efficacy of various structures for instance, germs powered micro-churns, microbial fuel cubicles, micro-fluidics policies, and chip-designed micro plans like bio-microstructures. PurposeHere approach in the current effort is to present an innovative study of bio-convection owing to gyrotactic microbes in a nanofluid comprising non-uniform heat source/sink, space and temperature-dependent viscosity and Joule dissipation. The physical constraints such as convective-surface and new mass flux conditions are examined for 3D Eyring-Powell magneto-radiative nanofluid via porous stretched sheet. Methodology: Over suitable similarity alterations, the related non-linear flow, temperature, and concentration phenomena, equations are altered into non-linear equations. By combining the shooting methodology with the Runge-Kutta fourth-order technique is applied to get numerical solutions. A thorough investigation for the impact of important non-dimensional thermophysical parameters regulating flow characteristics is carried out. MotivationLots of the studies on nanofluids realize their performance therefore that they can be exploited where conventional heat transport development is paramount as in numerous engineering uses, micro-electronics, transportation in addition to foodstuff and bio-medicine. The gyrotactic microbes flow in nanofluids has attained great devotion amongst researchers and the scientist community because of its works in numerous areas of bio-technology. The benefits of counting nanoparticles in mobile microbe's deferral can be established in micro-scale involvement and stability of nanofluid. Significant resultsFor a few chosen parameters, the computed results for friction factor and transport for motile microorganism values are shown. The computed numerical results for parameters of engineering interest are given using tables. Furthermore, the recent solutions are stable with the former stated results and excellent association is found. The temperature of the fluid exaggerates for higher values of thermo-Biot and radiation parameter; however, Peclet and bio-convective Lewis's factor decay the motile microorganisms' field of Eyring-Powell fluid. The concentration field also enhances the activation energy parameter.