Search Results (55)

Water, acetone, and TiO₂/nano-silver water (NSW) nanofluids were investigated as working fluids in loop thermosyphon battery thermal management systems (LTBMS) under simulated electric vehicle (EV) conditions to evaluate scalability and robustness across inclinations (0° to 60°) and ambient temperatures (−10 °C to 20 °C). Experimental conditions were established with 60 °C as the reference temperature, corresponding to the onset of battery thermal runaway, to ensure relevance to critical thermal management scenarios. Results indicate that LTBMS A maintained battery cell temperatures at 50.4 °C with water and 31.6 °C with acetone under a 50 W heat load. In contrast, LTBMS B achieved cell temperatures of 41.8 °C with water and 42.8 °C with 0.01 vol% TiO₂ nanofluid, however, performance deteriorated at higher nanofluid concentrations due to increased viscosity and related thermophysical constraints. In heating mode, LTBMS A elevated cell temperatures by 16 °C at an ambient temperature of −10 °C using acetone, while LTBMS B attained 52–55 °C at a 100 W heat load with nanofluids. The lightweight LTBMS design demonstrated superior thermal performance compared to conventional air-cooling systems and performance comparable to liquid-cooling systems. Pure water proved to be the most effective working fluid, while nanofluids require further optimization to enhance their practical applicability in EV thermal management. Full article

Triply Periodic Minimal Surface (TPMS) heat exchangers have attracted significant attention for their high surface area and effective thermal performance. This study evaluates the performance of TPMS heat exchangers under turbulent flow conditions using aluminum (Al) and silver (Ag) materials with pure water and nanofluid as working fluids. The implementation of Ag TPMS structures resulted in approximately 15% enhancement in thermal performance compared to Al structures due to superior thermal conductivity. The introduction of nanofluid (0.6% volume concentration) improved overall heat transfer efficiency by 12% compared to pure water. Performance evaluation criteria (PEC) analysis demonstrated that Ag TPMS structures achieved up to 30% higher values than Al structures. Temperature homogeneity analyses revealed significant improvements, with Al TPMS structures showing a 24% reduction in temperature variation when using nanofluid, while Ag TPMS structures exhibited up to 40% better temperature uniformity. Computational fluid dynamics analyses validated the experimental findings with deviations less than 7%, confirming the model’s reliability. These results demonstrate the significant potential of TPMS structures in high-performance cooling applications and provide valuable insights for future heat exchanger designs. The enhanced efficiency of thermal management system (TMS) heat exchangers using nanofluids contributes to reduced energy consumption, supporting environmentally conscious decision-making in industrial and energy systems. Full article

This study investigates the thermal performance of heat pipes using nanofluids based on silver (Ag), aluminum oxide (Al₂O₃), and multi-walled carbon nanotubes (MWCNTs) at varying concentrations. Heat pipes, recognized for their efficiency in passive thermal management, face limitations with traditional fluids. Nanofluids, engineered by dispersing nanoparticles in base fluids, were explored as alternatives due to their superior thermal conductivity and convective properties. Nanofluids were prepared using ultrasonication, and their thermal conductivity, viscosity, and stability were evaluated. Experimental tests were conducted under controlled conditions to assess the impact of nanoparticle type, concentration, inclination angle, and fluid filling ratio on performance metrics, including thermal resistance (TR) and heat transfer coefficients (HTCs). The results demonstrated that Ag-based nanofluids outperformed others, achieving a 150% increase in thermal conductivity and an 83% reduction in TR compared to deionized water. HTCs increased by 300% for Ag nanofluids at a 0.5% concentration. Inclination angles and filling ratios also significantly affected performance, with optimal conditions identified at a 70% filling ratio and a 30° inclination angle. The findings highlight the potential of nanofluids in optimizing heat transfer systems and provide a framework for selecting suitable parameters in industrial applications. Full article

This study presents a numerical investigation on the heat transfer and pressure drop characteristics of silver/water nanofluids (0.1–0.5 vol.%) flowing in tubes with four distinct expansion–contraction ratios (ECR = 1.25, 1.50, 1.75, and 2). Additionally, the impact of the distance between expansion and contraction (DEC) within the tubes was examined. The analysis was conducted under turbulent flow conditions and three-dimensional thermal convection in tubes subjected to a constant heat flux of 20 kW/m², with the inlet Reynolds number maintained at approximately 20,000. The nanofluids were considered as single-phase and modeled in the Ansys Fluent 16 software through the finite volume method, and the equations were discretized through the second-order upwind scheme. The nanofluids demonstrated significant potential in enhancing thermal performance, particularly in tubes where the convective heat transfer coefficient was affected by abrupt expansion–contraction ratio (ECR). A maximum increase of up to 24.90% in the average convective heat transfer coefficient compared to the base fluid was observed. Exergy efficiency showed a tendency to increase by up to 29.97% with the use of nanofluids. The findings indicate that the convective heat transfer coefficient can both increase and decrease with the expansion–contraction ratio (ECR) of the tube, as can the pressure drop. Consequently, the application of this passive technique, incorporating silver/water nanofluids, holds promise for use in cooling systems, nuclear reactors, and other similar applications, provided they are meticulously designed. Full article

Triply periodic minimal surfaces (TPMSs) show potential as porous materials in different engineering applications. Amongst them, heat sink is the subject of this paper. The advantage of such a structure is the ability to design it based on the intended applications. In the present paper, an attempt is made to experiment with a better understanding of the performance of TPMSs in heat sink applications. The experiment was conducted for different flow rates, and two heat sink materials, aluminum and silver, were used. In addition, two fluids were used experimentally: The first was water, and the second was a mixture of water containing 0.6% aluminum nanoparticles and identified as a nanofluid. The applied heat flux was maintained constant at 30,800 W/m². The results reveal experimentally and confirm numerically that the TPMS structure secures a uniform heat extraction in the system. The development of the boundary layer in the porous structure is reduced due to the current structure design. A higher Nusselt number is obtained when the nanofluid is used as the circulating fluid. The performance evaluation criteria in the presence of the nanofluid exceed 100. Full article

This study aims to investigate the thermohydraulic performance of silver nanofluids with different surface modifications (citrate, lipoic acid, and silica) in turbulent convective heat transfer applications. Three silver nanofluids were prepared, each modified with citrate, lipoic acid, or silica coatings. The nanofluids were characterized for stability using zeta potential measurements and evaluated in a smooth brass tube under turbulent flow conditions. The experimental setup involved measuring the temperature, pressure, and flow rate to assess heat transfer coefficients, pressure drops, and friction factors. The results were compared with distilled water as the base fluid and validated against theoretical models. The silica-shelled nanofluid (Ag/S) exhibited a significant 35% increase in the average heat transfer coefficient compared to distilled water, while the citrate-coated (Ag/C) and lipoic acid-coated (Ag/L) nanofluids showed slight decreases of approximately 0.2% and 2%, respectively. The Ag/S nanofluid demonstrated a 9% increase in the mean Nusselt number, indicating enhanced heat transfer capabilities. However, all modified nanofluids experienced higher pressure drops and friction factors than the base fluid, with the Ag/S nanofluid showing the highest increase in viscosity (11.9%). Surface modifications significantly influence the thermohydraulic performance of silver nanofluids. The silica-shelled nanofluid shows the most substantial enhancement in heat transfer, making it a promising candidate for applications requiring efficient thermal management. However, the increased hydraulic costs associated with higher-pressure drops and friction factors must be carefully managed. Further research is needed to optimize these nanofluids for specific industrial applications, considering long-term stability and the effects of different nanoparticle concentrations and geometries. Full article

Understanding of dusty fluids for different Brinkman numbers in porous media is limited. This study examines the Darcy–Brinkman model for two-dimensional magneto-hydrodynamic fluid flow across permeable stretching/shrinking surfaces with heat transfer. Water was considered as a conventional base fluid in which the copper (Cu), silver (Ag), and titanium dioxide ($Ti{O}_2$) nanoparticles were submerged in a preparation of a ternary dusty nanofluid. The governing nonlinear partial differential equations are converted to ordinary differential equations through suitable similarity conversions. Under radiation and mass transpiration, analytical solutions for stretching sheets/shrinking sheets are obtained. Several parameters are investigated, including the magnetic field, Darcy–Brinkman model, solution domain, and inverse Darcy number. The outcomes of the present article reveal that increasing the Brinkman number and inverse Darcy number decreases the velocity of the fluid and dusty phase. Increasing the magnetic field decreases the momentum of the boundary layer. Ternary dusty nanofluids have significantly improved the heat transmission process for manufacturing with applications in engineering, and biological and physical sciences. The findings of this study demonstrate that the ternary nanofluid phase’s heat and mass transpiration performance is better than the dusty phase’s performance. Full article

Magnetic fluids, a new type of energy transfer fluid with tunable properties, have garnered significant interest from researchers worldwide. Hybrid magnetic fluids prepared by adding different types of nanoparticles exhibit superior thermophysical properties and functional characteristics. In this paper, we prepared a water-based magnetic fluid loaded with multi-walled carbon nanotubes (MCNTs), silver (Ag), and copper (Cu) to enhance thermal conductivity. Using a transient double hot-wire method, we designed and built an experimental measurement system for the thermal conductivity of magnetic fluids with an average measurement error of less than 5%. We studied the thermal conductivity of hybrid magnetic fluids under different conditions and evaluated the advantages and disadvantages of various models, including the Maxwell model, H&C model, Tim model, Y&C model, and Evans model. Our results show that MF+MCNTs, MF+Ag, and MF+Cu nanofluids can all improve the thermal conductivity of the carrier fluid, with MF+MCNTs exhibiting the best improvement effect of 10.93%. Among the five models evaluated, the Evans model had the best predictive effect with a deviation range within 5%. This work provides theoretical and practical reference for enhancing the thermal conductivity of magnetic fluids and provides a more accurate theoretical model for calculating the thermal conductivity of hybrid magnetic fluids. Full article

Nanomaterials have been the focus of intense study and growth in the modern era across the globe because of their outstanding qualities, which are brought about by their nanoscale size; for instance, increased adsorption and catalysis capabilities plus significant reactivity. Multiple investigations have verified the fact that nanoparticles may successfully remove a variety of pollutants from water, and, as a result, they have been utilized in the treatment of both water and wastewater. Therefore, the current research intent is to examine the nonlinear heat source/sink influence on the 3D flow of water-based silver nanoparticles incorporated in an Eyring–Powell fluid across a deformable sheet with concentration pollutants. Silver particles have been used intensively to filter water, due to their potent antibacterial properties. The leading equations involving partial differential equations are renewed into the form of ordinary ordinary differential equations through utilizing the appropriate similarity technique. Then, these converted equations are solved by utilizing an efficient solver bvp4c. Visual displays and extensive exploration of the different impacts of the non-dimensional parameters on the concentration, temperature, and velocity profiles are provided. Also, the important engineering variables including skin friction, the rate of heat, and mass transfer are examined. The findings suggest that the mass transfer rate declines due to pollutant parameters. Also, the results suggest that the friction factor is uplifted by about 15% and that the heat transfer rate, as well as the mass transfer rate, declines by about 21%, due to the presence of the nanoparticle volume fraction. We believe that these results may improve the flow rate of nanofluid systems, improve heat transfer, and reduce pollutant dispersal. Full article

The novel class of fluids known by nanofluids is composed of colloidal suspensions of solid nanoparticles dispersed in a base fluid. When the solid nanoparticles are made of noble metals they can be named as noble metals nanofluids or noble nanofluids for short. This review attempts to offer a comprehensive survey along with a critical analysis of the noble metals nanofluids and their hybrids. Hence, the nanofluids having gold, silver, palladium, platinum, iridium, among others, nanoparticles are overviewed, giving emphasis to their superior thermophysical characteristics, stability, synthesis easiness, and potential applications. This work summarizes the published research findings about the noble metal nanofluids including the synthesis methods, heat transfer underlying mechanisms, and their performance evaluation in heat transfer and thermal energy storage purposes. This work intends also to provide practical insights in applications like Concentrated Solar Power systems, transformers, heat exchangers and heat pipes, cooling of electronics, among others. Also, it is highlighted the impact of the different formulations, temperature and pH values, and surfactants in the thermal conductivity, specific heat, and viscosity of these nanofluids. Besides, the interactions between the metal nanostructures and the base fluid molecules as viscosity and thermal conductivity determiners are discussed. Finally, the limitations, challenges, and prospects of the noble nanofluids are addressed such as their scalability and investment cost in large-scale applications. Full article

Nanoscience and nanotechnology have been rapidly developing due to the increased use of nanoparticles in several fields including health (antibacterial agents), medicine, chemistry, food, textiles, agricultural sectors, and nanofluids. The study aimed to biologically synthesize AgNPs using leaf and stem extracts of Tabernaemontana ventricosa. The AgNPs were successfully synthesized and verified using UV-visible spectroscopy; however, the synthesis of the AgNPs was more efficient using the leaf extracts rather than the stem extracts. The energy-dispersive X-ray (EDX) analysis showed that the elemental silver (Ag) content was much higher using leaf extracts compared to the stem extracts. The AgNPs synthesized using both leaf and stem extracts were analyzed using scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM), and images displayed spherical, ovate, and triangular-shaped nanoparticles (NPs), which varied in particle size ranging from 16.06 ± 6.81 nm to 80.26 ± 24.93 nm across all treatments. However, nanoparticle tracking analysis (NTA) displayed much larger particle sizes ranging from 63.9 ± 63.9 nm to 147.4 ± 7.4 nm. The Fourier transform infrared (FTIR) spectral analysis observed functional groups such as alcohols, phenolic compounds, aldehydes, alkanes, esters, amines, and carboxylic acids. Our study suggests that medicinal plant extracts can be used for the effective economical production of AgNPs due to their efficient capping; however, further studies are necessary to determine the possible function groups and phytochemicals within T. ventricosa that are responsible for the synthesis of AgNPs. Full article

One of the cleanest and most efficient solar collector systems is the flat plate collector, which has applications in hot water production, drying, among others. Flat plate collectors have improved in terms of both their structural configurations and working fluids. Several studies have verified the comparatively higher efficiency of nanofluid-based flat plate collectors, relative to that of water and other thermal oils. Additionally, the influence of several nanofluid synthesis factors, such as volume fraction, pH, type of base fluid, hybridization, surfactants, and sonification, on the performance of these collectors has been highlighted in the literature. However, the effect of nanoparticle size on collector performance has received minimal research interest, despite its significant effect on both the cost of synthesis and the thermophysical properties of nanofluids. The uncertainties regarding the effect of nanoparticle size on thermal collectors have limited their practical applications. This study numerically investigates the effect of the nanoparticle size of silver (Ag) nanofluid with nanoparticle sizes between 20 nm and 100 nm on the performance of flat plate collectors. The effect of nanoparticle size on the mean fluid temperature resulted in a maximum temperature of 45.8 °C for the Ag-100 nm. An increase of 0.25 °C for the Ag-20 nm was recorded, relative to the Ag-100 nm. In addition, the Ag-100 nm was calculated to have resulted in the highest reduction in collector size (18.30%), relative to that of water. Full article

Magneto-plasmonic Ag/Ni and Ag/Fe nanoparticles (NPs) were synthesized in this work using the environmentally safe and contaminant-free dual-pulsed Q-switched Nd:YAG 1064 nm laser ablation method. The optical and magnetic characteristics of synthesized nanomaterials were investigated using a vibrating sample magnetometer and an ultraviolet-visible absorption spectrometer. According to transmission electron microscopy (TEM), the shape of Ag/Ni and Ag/Fe NPs seems to be spherical, with mean diameters of 7.3 nm and 11.5 nm, respectively. X-ray diffraction (XRD) was used in order to investigate and describe the phase structures of the synthesized nanomaterials. The synthesized NPs reached maximum temperatures such as 48.9, 60, 63.4, 70, 75, and 79 °C for Ag/Ni nanofluid and 52, 56, 60, 68, 71, and 72 °C for Ag/Fe nanofluid when these nanofluids were subjected to an NIR 808 nm laser with operating powers of 1.24, 1.76, 2.36, 2.91, 3.5, and 4 W, respectively. Because of the plasmonic hyperthermia properties of nanoparticles, nanofluids display higher temperature profiles than pure water. According to these findings, plasmonic nanoparticles based on silver might be used to treat hyperthermia. Full article

This paper aims to investigate free convection heat transmission in hybrid nanofluids across an inclined pours plate, which characterizes an asymmetrical hybrid nanofluid flow and heat transfer behavior. With an angled magnetic field applied, sliding on the border of walls is also considered with sinusoidal heat transfer boundary conditions. The non-dimensional leading equations are converted into a fractional model using an effective mathematical fractional approach known as the Prabhakar time fractional derivative. Silver (Ag) and titanium dioxide (TiO₂) are both considered nanoparticles, with water (H₂O) and sodium alginate (C₆H₉NaO₇) serving as the base fluids. The solution of the momentum, concentration, and energy equation is found by utilizing the Laplace scheme, and different numerical algorithms are considered for the inverse of Laplace, i.e., Stehfest and Tzou’s. The graphical analysis investigates the impact and symmetry of significant physical and fractional parameters. Consequently, we surmise that water-based hybrid nanofluid has a somewhat higher velocity than sodium alginate-based hybrid nanofluid. Furthermore, the Casson parameter has a dual effect on the momentum profile. Furthermore, the memory effect reduces as fractional restriction increases for both the velocity and temperature layers. The results demonstrate that increasing the heat transmission in the solid nanoparticle volume fractions enhanced the heat transmission. In addition, the numerical assessment examined the increase in mass and heat transmission, while shear stress was increased with an increase in the Prabhakar fractional parameter α. Full article

Hydrate-based technology has yet to find its way to commercial applications due to several issues, including formation conditions and slow kinetics. Several solid particles were introduced to speed up hydrate formation. However, these solid compounds have given contradictory results. This study investigated the effect of high thermal conductive metallic nanofluids of silver (Ag) and copper (Cu) on CH₄ and CO₂ hydrates. The solid particles were suspended in a 0.03 wt% SDS aqueous solution, and the results were compared with the 0.03 wt% SDS and deionized water samples. A stirred tank batch reactor was used to conduct the thermodynamic and kinetic experiments. The thermodynamic study revealed that 0.1 wt% of solid particles do not shift the equilibrium curve significantly. The kinetic evaluation, including induction time, the initial rate of gas consumption, half-completion time, t₅₀ and semi-completion time, t₉₅, gas uptake, and storage capacity, have been studied. The results show that the Ag and Cu promote CH₄ hydrates while they inhibit or do not significantly influence the CO₂ hydrates formation. A predictive correlation was introduced to get the apparent rate constant of hydrate formation in the presence of metal-based fluid at the concentrations range of 0.005–0.1 wt%. Full article