Stability Of Nanofluids Research Articles

MSG extraction using silicon carbide-based emulsion nanofluid membrane: Desirability and RSM optimisation

Seasonings have become more popular recently as a way to enhance the flavour of food. Seasonings of various types are produced regularly. Uninformed users are unaware of what these flavour enhancers are made of. They are concerned only with eating tasty food and are unconcerned about the effects of these ingredients on their health. These seasonings contain monosodium glutamate (MSG), which adds a lot more flavour to the meal. Membrane processes, among the various methods, offer a wide range of applications over advanced oxidation techniques. MSG was extracted from a simulated aqueous polluted solution using emulsion liquid membrane (ELM). Where, ELM is the highly effective single stage extraction and stripping process. The industrial application of ELM is limited due to the reduced stability of the emulsion. In the current study, the membrane phase of ELM was replaced by the silicon carbide based nanofluid to form the ENM (emulsion nanofluid membrane). Whereas, the enhanced dispersion stability of nanofluid ensured the extraction process's effectiveness. Further, a three level RSM – CCD model was used to optimise the important parameters such as nanofluid concentration– (vol%), ultrasonication time– (min), surfactant concentration– (Triton X-100- vol%), and carrier concentration– (Tri-octylamine -vol%). A higher level of nanofluid concentration and ultrasonication time, according to RSM's desirability study, are critical functions in maintaining maximum desirability. The ENM proved to be the most efficient and recyclable method of MSG extraction.

Impacts of ultrasonication time and surfactants on stability and optical properties of CuO, Fe3O4, and CNTs/water nanofluids for spectrum selective applications

The prime objective of the present experimental work is to evaluate the impact of ultrasonication time and surfactants on the optical characteristics (transmittance and absorbance) and stability of CuO/water, CNTs/water, and Fe3O4/water nanofluids to be used in spectrum selective applications. Two-step method with various ultrasonication times (30 min, 60 min, and 90 min) was employed to prepare nanofluids (having volume fractions of 0.004 % and 0.0004 %). Furthermore, various surfactants (anionic, cationic, and polymer) were added to the base fluid. The study results revealed that surfactants have a significant effect on the stability of nanofluids over ultrasonication time. The nanofluids prepared using sodium dodecylbenzene sulfonate (SDBS) have the highest zeta potential values than other surfactants used in the experimentation. The increase in transmittance of nanofluid was more prominent for lower concentration (0.0004 %) after one week of preparation. The concentration of nanoparticles, ultrasonication time, temperature, and surfactants influenced the optical characteristics of nanofluids. The most stabled CNTs nanofluid with 0.004 % concentration and 90 min of ultrasonication obtained an average of 67.6 % and 74.6 % higher absorbance than stabled CuO and Fe3O4 nanofluids, respectively. The irradiance transmitted through nanofluid was strongly dependent on the concentration and type of nanoparticles.

Experimental investigation of silica nanoparticle assisted Surfactant and polymer systems for enhanced oil recovery

Enhanced oil recovery techniques are commonly used today in oil fields to boost oil production. The objective of the present study is to investigate the use of silica nanoparticles (NPs) with surfactants and polymers to increase the oil recovery from oil fields. Synergistic effects of surfactant, polymer, and nanoparticles on interfacial tension (IFT) reduction, wettability alteration, emulsification, and viscosity improvement are reported in this study. Core flooding experiments were performed in cores with different permeabilities to screen the reservoir on basis of rock properties. The dispersion of NPs in the aqueous solution of surfactant and polymer was characterized by stability analysis, Turbiscan analysis, dynamic light scattering (DLS), and zeta-potential measurements. The nanoparticles were able to further reduce the IFT between the surfactant solution and crude oil. The stability of nanofluids was increased when surfactant was added as evidenced by a higher zeta potential value (−39.6 mV). The addition of polymer led to even higher stability of the nanofluids as observed by the Turbiscan analyzer. A synergistic effect of NPs, surfactant, and polymer was observed in the core flooding experiments. The nanofluid system provided higher incremental oil recovery in high permeability core as compared to low permeability core. Different recovery mechanisms responsible for oil recovery by nanofluids like wettability alteration, disjoining pressure, log jamming, and pore channel plugging phenomena are discussed. The flooding results indicate that the injection of the designed slug increases the oil recovery up to 28% of the original oil in place after conventional water flooding. Therefore, the findings of this study can help for a better understanding of the use of silica NPs with surfactant and polymer as a chemical EOR agent. The result also helps in the screening of sandstone reservoirs where nanofluid could be employed.

XPS and material properties of raw and oxidized carbide-derived carbon and their application in antifreeze thermal fluids/nanofluids

In this study, the stability, thermal conductivity and viscosity of carbide-derived carbon antifreeze thermal fluids were explored. The study also compares the results between antifreeze suspensions prepared using oxidized CDC and emulsified CDC using gum arabic. At first, the raw CDC was oxidized with oxygen by acid treatment and the Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results revealed an increase in the oxygen content and oxygen functional groups in oxidized CDC. The two-step method was utilized for CDC thermal fluids preparation. Sedimentation visualization and zeta potential testing were employed to investigate stability of nanofluids with time. The stability results revealed that the oxidized CDC has better stability and higher zeta potential values than the emulsified CDCs; however, both mixtures demonstrated stable suspensions for three months. Viscosity measurements showed that the gum arabic CDC suspensions have a higher viscosity than the oxidized CDC; the viscosity was growing with CDC and gum arabic loadings and decreased with temperature. The thermal conductivity analysis was carried out using a lambda analyzer in a temperature range of 288–338 K with a CDC mass loading range of 0.05–0.3 mass%. The experimental outcomes demonstrated that oxidized CDC suspension has better thermal conductivity than gum arabic emulsified CDC. The highest improvement in thermal conductivity was 25.6% using 0.3 mass% of oxidized CDC at 338 K. Moreover, raising the gum arabic mass loading was found to reduce the thermal conductivity enhancement. Therefore, according to the results, the oxidized CDC antifreeze suspensions can perform better than the emulsified CDC.Graphical abstract

Enhanced Antioxidant Ability of PEG-Coated Ce0.5Zr0.5O2-Based Nanofluids for Scavenging Hydroxyl Radicals.

The antioxidant therapy to preserve residual hearing is relatively recent, and the search for effective antioxidants is still ongoing. Though nanoceria has shown promising radical-scavenging capability, improving its antioxidant ability and the dispersion stability of its nanofluid, which is critical to the desired site, i.e., cochlea, still remains a major challenge. The objective of the present work is to study the radical-scavenging capability of poly(ethylene glycol) (PEG)-coated CeO2 and Ce0.5Zr0.5O2 nanoparticles in water and the biologically relevant fluid (PBS buffer). Nanoparticles in the size range of 4.0–9.0 nm are synthesized using the coprecipitation method and characterized using suitable techniques. The scavenging and dispersion stability of the synthesized nanofluid are analyzed using a UV–vis spectrophotometer. It is found that the addition of PEG during the synthesis process promoted the generation of finer nanoparticles with a narrow size distribution and the doping of zirconium produced a large number of defects in the crystallite structure. The PEG coating over the nanoparticles improved the dispersion stability of nanofluids without affecting their surface reactivity, and it is found to be 94 and 80% in water and PBS, respectively, at 500 μM and 60 min, which is maintained till 90 min. The highest scavenging of hydroxyl radicals by PEG-coated Ce0.5Zr0.5O2 is found to be 60%, which is significantly superior to that of CeO2. The scavenging capability is found to be increased with the concentration of nanoparticles, showing the best scavenging activity at 190 and 150 μM for PEG-coated CeO2 and Ce0.5Zr0.5O2, respectively, and the scavenging in water is at par with that of PBS, indicating that these nanoparticles are suitable to be used in sites where a biologically relevant fluid is present, e.g., the cochlea. It is proposed that PEG-coated Ce0.5Zr0.5O2 having an average size of ∼ 4 nm can be a potential antioxidant in relevant biomedical applications.

Assessment of Stability and Thermophysical Properties of Jojoba Nanofluid as a Metal-Cutting Fluid: Experimental and Modelling Investigation

Nanofluids based on vegetable oil have emerged as ecological alternatives to conventional cutting fluids. Jojoba-seed oil has recently been identified as adequate for use in metal cutting. Aiming to assess the stability and thermophysical properties of jojoba nanofluids, this article reports an experiment- and modelling-based investigation. The stability, viscosity and thermal conductivity of jojoba MoS2 nanofluid were studied across a broad range of temperatures and concentrations of nanoparticles. The functional relationship of the viscosity and thermal conductivity to the temperature and concentration was determined by regression analysis. In addition to confirming known phenomena, vis-à-vis the effect of the concentration and temperature on the viscosity and thermal conductivity, this study shows that the increase in the thermal conductivity in line with the concentration stagnates after an initial sharp rise due to an increase in the attractive forces between the particles. The viscosity displays a second-order interactive relationship with the temperature and concentration of the nanoparticles, whereas thermal conductivity follows a complex third-order interaction model. In addition to being economical, jojoba nanofluid matches or surpasses the nanofluid prepared using commercially available mineral-oil-based cutting fluid (LRT 30)—which is specially designed for the minimum-quantity lubrication method of metal cutting. Conclusively, this investigation paves the way for the shop-floor application of jojoba nanofluid in metal-cutting operations.

Experimental investigations on thermo-physical properties and stability of diamond-alumina based hybrid nanofluids

In recent years, the demand of hybrid nanofluids (HNFs) is growing due to their quintessential thermo-physical properties (TPP) and good stability. In this work, nano-diamond (ND) (<10 nm) and nano-alumina (Al2O3) (<80 nm) based mono and HNFs are taken in to consideration. Good thermal conductivity (TC) of ND particles and good physical properties of Al2O3 particles combine to form better HNF when dispersed in water. In-depth and critical experimental investigation has been conducted on TPP and stability analysis of nanofluids. Particle characterization is performed with Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM) assisted with energy dispersive analysis of X-rays (EDAX). Two-step method is employed for constructing Al2O3/water, ND/water, ND-Al2O3/water nanofluids at different weight fractions (0.01–0.3 wt.%). KD2 Pro TC analyzer and Anton Paar MCR 302e rheometer are used for determining TC and viscosity of nanofluids, respectively. The maximum enhancement of 4.2%, 16.93%, and 22.93% are observed in TC at 80 °C for 0.3 wt.% of Al2O3/water, ND-Al2O3/water, and ND/water nanofluids, respectively in comparison with that of distilled water. Correlations are developed for TC and viscosity and compared with experimental values. For evaluating stability of nanofluids, three methods applied such as visual inspection, UV–vis spectroscopy, and zeta-potential (ZP) are used. Stability period of nanofluids represented as ND/water (55 days) > ND-Al2O3/water (45 days) > Al2O3/water (30 days). Both TPP and stability enhanced for ND-Al2O3/water (hybrid) nanofluid compared to Al2O3/water (mono) nanofluid, thus used in various thermo-fluidic industries.

Synthesis and characterization of goethite (α-FeOOH) magnetic nanofluids

Magnetic nanofluids consisting of goethite nanoparticles in aqueous suspensions have been successfully synthesized using two sodium-free routes. Nanoparticle morphology, nanofluid stability and optical properties have been studied and compared with a goethite nanofluid whose nanoparticles are synthesized with a different protocol using NaOH. The synthesis procedure determines the nanoparticle size and morphology, which, in turn, is connected to optical properties and their sensitivity to external magnetic fields. The highest sensitivity is shown by the sample synthesized with NaOH, which is characterized by the largest nanoparticles (261±5 nm hydrodynamic size) and whose absolute transmittance values increase or decrease by about 11% and 20%, respectively, depending on to the mutual directions of magnetic field and electromagnetic wave polarization/wave vector, for an applied magnetic field of 5.60 mT. Nanoparticles in the fluid are therefore able to discriminate both the absolute value and the direction of the magnetic field and, moreover, being their response non-spectrally flat, specific spectral ranges exist where their response is maximized.

Ultra-stable carbon quantum dot nanofluids for direct absorption solar collectors

Nanofluids show great interest in the direct absorption solar collector (DASC) due to their excellent optical, thermal, and flow properties. However, the stability of nanofluid in the terms of the long period and the working temperature has limited its commercial application in DASCs. In this work, ultra-stable carbon quantum dot (CQD) nanofluids were prepared by microwave heating polyethylene glycol 200 (PEG-200), which shows excellent stability over a long period (such as 30 days) and repeatable performance at the working temperature. The solar thermal conversion efficiency η increases with extending the microwave duration t, and η can reach 81% at 1 sun and t = 24 min, which is triple the base fluid PEG-200 (η = 27%). In addition, the solar intensity and working temperature have little effect on η due to the ultra-stability of CQD nanofluids. Finally, η can be further enhanced by changing the base fluid or mixing with the plasmonic nanofluids. These results show that the CQD nanofluids can be a potential working fluid used in solar thermal applications.

Review on aqueous graphene nanoplatelet Nanofluids: Preparation, Stability, thermophysical Properties, and applications in heat exchangers and solar thermal collectors

Nanofluids of graphene nanoplatelets (GNP) have superior thermal performance characteristics and good stability, are relatively affordable, and can easily be prepared by the two-step method. This review performs an in-depth analysis of the preparation, stability, and thermophysical properties of GNP nanofluids, and their applications in heat exchangers, solar thermal collectors, and heat pipes. This study analyses in detail the performance improvements achieved with pristine, covalent functionalised, and non-covalent functionalised GNP nanofluids compared to water. Covalent functionalisation was found to be superior to non-covalent functionalisation in terms of stability and heat transfer coefficients. Functionalisation by electrophilic addition and free-radical grafting were found to be more environmentally friendly compared to acid treatment. In terms of convective heat transfer coefficient, pristine GNP outperformed functionalised GNP, but both types showed large improvements compared to water. It was found that stability and heat transfer performance improved as particle size was decreased, while thermal conduction and convection coefficients increased with nanofluid concentration and temperature. Thermal conductivity improvements of over 30% were found for both pristine and covalently functionalised GNP nanofluids at 0.1 wt% concentration. A maximum convection heat transfer coefficient increase of 200% was achieved using 0.1 wt% pristine GNP nanofluid. By comparison, a maximum improvement of 119% was achieved using covalently functionalised GNP. The convective heat transfer enhancement seemed to increase with decreasing tube diameter. In flat plate solar collector applications, efficiency improvements over 20% were obtained for covalently functionalised GNP nanofluids at 0.1 wt%, while an efficiency improvement of over 65% was obtained using pristine GNP in an evacuated tube solar collector. Applications in cooling, heat pipes, and direct absorption solar collectors were also reviewed. From this study, it could be inferred that GNP nanofluids are a viable alternative working fluid. Further research is needed to optimise their performance.

An Detailed Study on Nano Fluids and Its Applications in Energy Sector

Nano liquids are primarily used as coolants for their advanced heat properties in heat exchangers such as Electronic cooling systems (Like flat plates) and radiators. Heat transfer on a flat plate has been analyzed by several researchers. The nanofluid is prepared by suspending small nanoparticles in basic Water and ethylene glycol Such as fluids with or without stabilization techniques. The average size of nanoparticles is less than 100 nm, and The nanoparticles used in nano liquids are usually. The base fluid is a Well stimulant treatment fluid used in cosmetics Continuous phase fluid. Continuous phase fluid may be added, But it is not defined as water, and whether it is liquid or hydrocarbon May be without hydrocarbon gas. Well-induced therapy More than one base fluid can be used. The atomic number can Derived from the dimensional analysis of the Fourier law, because it is equal to the dimensionless temperature gradient at the surface: q Heat transfer rate, k is the constant heat. Conductivity and T is the temperature of the liquid. Sodium benzoic sulfate (SDBS) Water is used as a surfactant in the preparation of nano liquids. Cu nanoparticles with demonized water Nano-liquid samples of three-volume fractions are prepared; the average diameter of the nanoparticles is 25 nm. Many researchers have called the validity stability of nanofluids. The scattering behavior of various non-substances in the solvent varies and depends on many factors. A complete understanding of particle-particle-particle interaction to create a stable fluid. Electronics heat management and increasing the efficiency of fluids for transfer from air to liquid cooling systems. Improving the energy efficiency of electronic systems. Improving rack density for computer systems by reducing computers to sub-1U operating systems. Improvement in Power Module Life (MTPF). A nanofluid is a liquid containing particles the size of nanometers. The Nano liquids are obtained by scattering. Non-aqueous fluid (NAF) is a water-based permeable fluid. Commonly used NAF systems are reverse emulsions based on diesel oil, mineral oil or synthetic fluid. In NAF systems, the water level is emulsified in a continuous oil phase, also known as water-in-oil emulsion or reverse emulsion. Nusselt A is the number Is the dimensionless number closest to the pocket number. Both numbers are held inside the fluid Will be converted to a liquid with thermal energy Used to describe the ratio of thermal energy.

The comparison of colloidal, optical, and solar collection characteristics between Fe2O3 and Fe3O4 nanofluids operated in an evacuated tubular volumetric absorption solar collector

BackgroundThe iron oxide nanoparticles as low-cost, eco-friendly, and efficient nanomaterials exhibit interesting optical properties which make them valuable for nanofluids-based volumetric absorption solar collectors. MethodsThe first aim of this study is to experimentally compare the colloidal stability and optical properties of Fe2O3 and Fe3O4 nanofluids in three volume fractions of 0.005, 0.01, and 0.02%. To the following, it is intended to examine the energy conversion efficiency of these nanofluids in an evacuated tubular volumetric absorption solar collector according to the ASHREA standard. Significant findingsBased on the results, the size and morphology of the iron oxide nanoparticles were nearly similar together, but when dispersed in water they exhibited different colloidal and optical properties. For example, the Fe2O3 nanofluids showed considerable spectral extinction coefficients in the visible range, while the Fe3O4 nanofluids presented limited extinction coefficients in the ultraviolet region with the lower values. At penetration depth of 4 cm, the 0.02%-Fe2O3 nanofluid resulted in a 100% solar weighted absorption fraction in comparison to 83.2% of the Fe3O4 nanofluid with the same volume fraction. According to the collector results, the Fe2O3 nanofluids displayed greater enhancement in the solar to thermal energy conversion than the Fe3O4 nanofluids. The maximum efficiency was 73% at 0.02%-Fe2O3 nanofluid and 51% at 0.02%-Fe3O4 nanofluid.

Hybrid nanofluids development and benefits: A comprehensive review

Hybrid nanofluids (HNFs) have received the prominent attention of researchers due to their improved thermophysical properties than conventional liquids and single-phase nanofluids. Such high potential heat transfer fluids are obtained from the suspension of two or more dissimilar nanoparticles in a regular heat transfer liquid. Owing to the high heat transfer properties of hybrid nanofluid, these are widely used in industrial processes, manufacturing processes, and biomedical engineering. This framework presents a detailed review of hybrid nanofluids preparation, stability, thermophysical properties, and importance in various engineering fields. Furthermore, present analysis addresses the pH control and ultrasound intensity of hybrid nanofluid. This analysis also manifests a hybrid nanofluid preparation method and suitable nanoparticles mixers for various industrial uses. This study reveals some future trends and possibilities related to HNF and a few suggestions regarding the scope in the future research in this area. A big impact with small particles for coming years. The hybrid nanofluid are having higher thermal conductivity which affects significantly to machining output response variables. By hybridizing the suitable combination of nanoparticles, the required heat transfer effect can be obtained still at low particle concentrations.

A study of nanofluid stability in low–salinity water to enhance oil recovery: An extended physicochemical approach

We examined the stability of SiO2 and Al2O3 NPs in both deionized (DI) water and low–salinity water (LSW). Stability was evaluated by measuring absorbance, hydrodynamic diameter, and zeta potential. NP stability was also manipulated by dispersion techniques and surfactant addition. To shape our experiments and explain results, we relied on an extended version of Derjaguin, Landau, Verwey, and Overbeek theory that accounts for hydrophobic and steric interactions. We attribute the observed stability of the examined NPs in DI to their highly negative zeta potential, which maintained absorbance and hydrodynamic diameter and produced a high energy barrier (EB). In LSW, SiO2 was stable because of its hydrophilicity, which maintained the EB, while Al2O3, which is naturally hydrophobic, strongly aggregated when a decrease in zeta potential decreased the EB. After applying various dispersion methods to Al2O3, including ultrasonication, surfactant addition, heat agitation, and pH control, we observed that the best stability occurred at pH 2 with cationic and nonionic surfactant. Although Al2O3 did not show an EB under any conditions, stability nevertheless occurred after surfactant addition, which we attribute to the steric interaction and manipulation of the primary minima. In sum, our physiochemical analysis produced stable nanofluids with potential LSW flooding applications.

Study on the Characteristics of the Dispersion and Conductivity of Surfactants for the Nanofluids.

Given the importance of nanofluid dispersion and stability, a number of approaches were proposed and applied to the nanofluid preparation process. Among these approaches, the noncovalent chemical process was intensively utilized because of its effective dispersion ability. For the noncovalent dispersion method, polymers and surfactants are typically used. In order to find an effective noncovalent dispersion method, several types of solutions were prepared in this study. The widely used naturally cellulose nanocrystal (CNC) aqueous solution was compared with several surfactant aqueous solutions. The dispersion characteristics of the prepared fluids were examined by UV/VIS spectroscopy at operating wavelengths ranging from 190 to 500 nm. Furthermore, the heat capacity and the electrical and thermal conductivity of the fluids were analyzed to evaluate their heat transfer performance and conductivity. The Lambda system was utilized for thermal conductivity measurement with operation at proper temperature ranges. The electrical conductivity of the fluids was measured by a conductivity meter. This experimental study revealed that the cellulose nanocrystal was an effective source of the noncovalent dispersion agent for thermal characteristics and was more eco-friendly than other surfactants. Moreover, cellulose aqueous solution can be used as a highly thermal efficient base fluid for nanofluid preparation.

Heat transfer performance of an automotive radiator with MWCNT nanofluid cooling in a high operating temperature range

• An update review on nanofluids in an automotive radiator is presented. • Evaluation of the nanofluid stability using the UV–vis spectrophotometric method. • Thermophysical properties of MWCNT water/EG nanofluids are experimentally investigated. • Thermal performance of MWCNT nanofluids in a temperature range of 80–105 °C. • Observed agglomeration and sedimentation after experimental test in high temperature. This study investigates the heat transfer performance of multiwalled carbon nanotube nanoparticles (MWCNT) dispersed in a binary mixture of water-EG (ethylene glycol) at a volumetric ratio of 50:50 in an automotive radiator. The nanofluids were prepared using the two-step synthesis method at volumetric ratios of 0.025%, 0.05% and 0.1%. The UV–vis spectrophotometry method was used to evaluate the colloidal stability of the samples, reporting the absorbance-concentration relationship according to the Beer-Lambert law. Thermophysical properties such as thermal conductivity and viscosity were measured experimentally and compared with correlations in the literature. The influence of nanoparticle concentration as well as the coolant inlet temperature, of up to 105 °C, on the heat transfer rate and in the overall heat transfer coefficient were evaluated experimentally. The air velocity was maintained constant at 2 m/s and the coolant mass flow rate ranged between 0.09 kg/s and 0.11 kg/s. The maximum increases for the heat transfer rate and for the overall heat transfer coefficient were 4.6% and 4.4%, respectively. The results show that the increase in the concentration of nanoparticles can improve the performance in heat transfer, although the performance decrease for high nanofluid inlet temperatures in the radiator was significant. Finally, the stability of the nanofluids was reassessed after performing tests on the radiator, demonstrating high aggregation and sedimentation of nanoparticles.

Thermal stability of hybrid nanofluid with viscous dissipation and suction/injection applications: Dual branch framework

The thermal stability of nanomaterials is quite necessary for controlling the heat and cooling phenomenon. It is worthy observed that much research has been focused scientists towards the thermal significance of nanoparticles with multidisciplinary engineering and industrial applications. On this end, this report explores the improved thermal mechanism water base material with interaction of hybrid nanofluid stretching and shrinking surface. The cooling and heat phenomenon is observed in presence of viscous dissipation. The hybrid nanofluid characteristics are inspected with combination of copper (Cu) and aluminum oxide (Al2O3) nanoparticles with stable prospective. The consideration of such hybrid nanoparticles is due to impressive thermal characteristics and stable thermal performances. Although some studies are focused by researchers on hybrid nanofluid, however the measurement of thermal stability is not claimed yet. The stretching and shrinking configuration specify the porous medium features. The problem is compiled into dimensionless structure which is further preceded via bvp4c scheme. The resultant ODEs are successfully numerically solved using the bvp4c solver technique. Under restricting conditions, numerical findings are compared to previously published results. Non-dimensional profiles of velocity and temperature are shown graphically. Furthermore, graphs and tables show the effects of the physical parameters used on the reduced skin friction and heat transfer rate. Dual branches are found in specified domain of suction factor.

Fouling Behavior and Dispersion Stability of Nanoparticle-Based Refrigeration Fluid

Nanofluids as heat transfer fluids have been acquiring popularity ever since their beginning. Therefore, the refrigeration research could not keep itself away from the ever-rising horizon of nanofluid applications. On the other hand, nanofluid stability remains the critical bottleneck for use. A significant reduction in nanofluids’ performance can derivate from instability phenomena. Looking to industrial applications, nanofluid long-term stability and reusability are crucial requisites. Nanoparticles’ deposits induce microchannel circuit obstruction, limiting the proper functioning of the device and negating the beneficial characteristics of the nanofluid. The aggregation and sedimentation of the particles may also determine the increased viscosity and pumping cost, and reduced thermal properties. So, there is a need to address the features of nanofluid starting from realization, evaluation, stabilization methods, and operational aspects. In this review, investigations of nanorefrigerants are summarized. In particular, a description of the preparation procedures of nanofluids was reported, followed by a deep elucidation of the mechanism of nanofluid destabilization and sedimentation, and finally, the literature results in this field were reviewed.

Thermal performance of stable SiO2 nanofluids and regression correlations to estimate their thermophysical properties

The present work investigates the best mix ratio of Glycerol in Water as a medium to prepare a stable nanofluid. Increasing the proportion of glycerol enhances the aqueous mix's dynamic viscosity and improves the prepared nanofluid's stability. The thermal conductivity and viscosity of the Glycerol and Water mixtures determination were undertaken at various Glycerol ratios. The best percentage of glycerol in the mixture is found to have the least amount of thermal conductivity loss and the optimum viscosity gain. Silica (SiO2) nanofluid of 0.25%, 0.5%, 1%, and 1.5% weight concentrations was prepared with this optimal mixture of Glycerol and Water. The stability of these SiO2 nanofluids is evaluated by determining the zeta potential at different time intervals. The nanofluids prepared were observed to be stable for one month. The thermal conductivity and viscosity of the nanofluids are measured between the temperature limits of 30°–70°C. A peak increment of 32.1%and 46.3% in thermal conductivity and viscosity is observed. Furthermore, when the percentage enhancement ratio (PER) and Mouromtseff ratio of these nanofluids is examined, it is observed that they have more excellent thermal performance at higher temperatures. Regression correlations are developed to estimate the thermal conductivity and viscosity of the prepared nanofluids with a maximum deviation of 9%.

Janus sulfonated graphene oxide nanosheets with excellent interfacial properties for enhanced oil recovery

In this article, we prepared Janus sulfonated graphene oxide nanosheets (JSGO) by a facile method for large-scale production. Unlike previous single-sided modifications of graphene oxide (GO), the smart JSGO nanofluid that can automatically find oil was obtained by modifying the double sides of GO. Benefiting from the introduction of sulfonic acid groups, JSGO had outstanding dispersity and stability under extreme conditions. Furthermore, JSGO exhibited excellent interfacial properties due to its amphiphilic characteristic. On the one hand, JSGO can reduce interfacial tension by 71% and form a strong interfacial film at the oil–water contact, achieving piston displacement with high sweep efficiency. On the other hand, JSGO had a strong ability in wettability reversal that can turn the hydrophobic surface into completely hydrophilic. These excellent properties of JSGO nanofluid contributed to obtaining an additional 18.4% recovery factor at low concentration (100 mg/L) and low injection volume (0.3 pore volume). As a result of the simple preparation, high performance, and excellent dispersion stability of JSGO nanofluid, it can be utilized as a chemical agent to enhance oil recovery in the harsh environment of reservoirs.