Increasing Nanoparticle Concentration Research Articles

Thermal and rheological behavior of aluminium-doped zinc oxide nanofluids: Experimental study and application of artificial neural network model

In this study, the influence of Al-doping concentration on the thermal and rheological characteristics of pristine zinc oxide (ZnO) nanofluids was investigated across a range of temperatures and nanoparticle concentrations. A multilayer perceptron (MLP) artificial neural network (ANN) with an optimized topology was employed to model the thermal conductivity and viscosity of nanofluids. The addition of 0.13 M of Al-doped zinc oxide nanoparticles at 1 % rate led to a remarkable 64 % increase in the thermal conductivity of the base fluid (50:50 ratio water + ethylene glycol mixture). Furthermore, incorporating 1 % of these Al-doped nanoparticles outperformed pure zinc oxide, resulting in a 44 % boost in thermal conductivity. The enhanced heat transfer capabilities of Al-doped zinc oxide were evident across different doping and nanoparticle concentrations. The viscosity of nanofluids increases with an increase in nanoparticle concentration and decreases with an increase in temperature. ZnO and Al-doped ZnO nanoparticles have been prepared and studied their structural, morphological and elemental properties using XRD, SEM and EDS respectively. The predicted thermal and rheological behaviours are in close agreement with the experimental values.

The Effects of Adding TiO2 and CuO Nanoparticles to Fuel on Engine and Hand–Arm Driver Vibrations

Occupant comfort is a key consideration in automobile dynamics, with vibrations potentially causing long-term physical discomfort, especially for drivers. This study investigates the impact of adding TiO2 and CuO nanoparticles to fuel on engine-induced vibrations. Experiments were conducted at various nanoparticle concentrations (0, 50, 100, and 150 ppm) and engine speeds (1000, 2000, and 3000 rpm). Key performance metrics, including kinematic viscosity, density, heating value, thermal conductivity, and brake power (BP), were analyzed. The results indicated that increasing nanoparticle concentration led to a rise in BP. The highest reduction in root mean square (RMS) vibration accelerations occurred at 3000 rpm and 150 ppm, with vibration reductions of 30.33% for CuO and 28.61% for TiO2. Additionally, 8–10% of engine vibrations were transmitted to the steering wheel. The use of 150 ppm CuO nanoparticles resulted in reduced vibration transmission to the steering wheel at all tested speeds. These findings suggest that nanoparticle-enhanced fuels can significantly reduce engine vibrations, potentially improving driver comfort and reducing wear on vehicle components.

Hydrothermal dynamics of darcy Forchheimer ternary hybrid nanofluid flow past bended surface with active—passive controls

This dynamic study investigates hydrothermal and rheological properties of two-dimensional ternary nanofluid flow by using active passive control mechanisms on nanoparticles navigating a porous curved surface. The working fluid contains nanometer sized spherical shaped particles of three different metals [Formula: see text], which are homogenously and stably dispersed in liquid dihydrogen monoxide as host fluid. A strong magnetic force of strength [Formula: see text] acts along radial direction of curved surface. Thermal radiation term in heat equation suggests a strong heat source in the vicinity. This unique amalgamation, which has not been addressed so far by any researcher incorporates Brownian motion and thermophoresis to construct the hydrothermal framework. The passive control of nanoparticles on surface influenced by Brownian movement and thermophoresis, which is considered more realistic in comparison to constant concentration hypothesis (active control), have been taken into account. The nanoliquid flow is governed by system of Partial Differential Equations (PDEs) that cater thermophysical properties of nanoparticles. After simplifying the system to Ordinary Differential Equations (ODEs) using suitable transform, it is solved numerically using bvp4c in MATLAB 2023a. The obtained graphical and numerical results are discussed in detail to explain physics of observed thermo-rheological behaviour and mass diffusivity. The study reveals that curvature and porosity factors have opposite effects on velocity profile. All involved parameters augment temperature profile for both active and passive controls except curvature factors. In all the cases, active control assures higher temperature over passive control. Dual consequences have been noted for active and passive controls for concentration panels in most cases. Nusselt number is found increasing for increasing nanoparticles concentration with ternary nanofluid having maximum heat transfer rate. This study significantly contributes to the knowledge of ternary nanofluidic thermo-rheological analysis on curved stretching surface having numerous applications in mechanical, thermal and industrial domains. It also offers insights for developing advanced coatings and materials in industrial and engineering context.

Exploring thermal flow dynamics in pressurized water reactors using hybrid graphene nanoplatelet coolants

AbstractThis study investigates the impact of hybrid nanoparticles on the temperature of nuclear reactor coolant, with a focus on graphene nanoplatelet (GNP)‐based hybrid nanoparticles. Sixteen different hybrid nanofluids were analyzed, and their performance was compared with a standard water‐based coolant. The criticality values were obtained through MCNP modeling, revealing that higher nanoparticle ratios led to increased criticality, with the highest value of 1.3239 observed in GNP‐Fe3O4 + Al2O3 nanofluids (0.05 wt%) and the lowest value of 1.2935 in GNP–Fe3O4 + SiO2 nanofluids (0.001 wt%). Temperature variations showed that increasing nanoparticle concentrations resulted in slightly higher temperatures, with a maximum of 611.97 K for 0.05 vol.% GNP nanoparticles. Additionally, the departure from nucleate boiling ratio values were consistently above the safety threshold of 2.08, with the lowest value of 3.657 for GNP–Fe3O4 + SiO2 nanofluids (0.05 vol.%). These findings suggest that hybrid nanofluids, particularly those with higher nanoparticle ratios, can enhance the thermal performance and safety margins of nuclear reactor coolants, offering a promising avenue for future research and application.

Solar Collectors with Nanofluid for Domestic Applications: A Review

Energy management and the usage of renewable energy sources are essential for a sustainable future. This paper carried out a review and summarize the recent topic of solar collectors heating water for use in a domestic application. Several researchers have studied solar collectors with flat plates, evacuated, and concentrators to improve heat gain for heating water. Entropy is an important function that the attention of investigators to reduce and increase the thermal efficiency of solar collectors. Nanofluid has been selected as have found a new class of thermal efficiency enhancement for this purpose. Thermal performance is enhanced by changing the geometry of the absorber plate of the solar collector and the evacuated tube is the best. It was found that increasing nanoparticle concentration to 4% improves solar collector efficiency to 30%. It was observed that the report of solar-collector enhancement by changing geometry and fluid flow through the solar-collector.

A New Process for Efficient Non-Destructive Metal-Activated Composite Plating of Ni-P-Al2O3 on Titanium Base and Its Performance Research

A new high efficient and non-destructive mental activation process of electroless composite plating was proposed. The process utilized electromagnetic induction equipment to heat the titanium alloy substrate and used its energy to complete the activation process, which could successfully attach the nickel nanoparticles firmly to the surface of the titanium alloy; at the same time, the process pre-activated Al2O3 nanoparticles and added the activated nanoparticles to the plating solution. In the process of plating, the activated titanium substrate was used as the catalytic center of electroless nickel plating (ENP) for electroless composite plating. The new activation process avoided complicated traditional processes such as acid etching and zinc dipping. Such traditional processes require huge doses of chemicals, including various strong acids, so improper waste liquid treatment will cause harm to the environment. The important parameters of the process were optimized by orthogonal experiments. A scanning electron microscope (SEM), an X-ray photoelectron spectroscopy (XPS), an energy dispersive spectrometer (EDS), thermal shock experiments and friction and wear experiments were used to characterize and analyze the surface morphology, composition, binding force and friction coefficient of the coating, and analyze the coating quality by measuring the plating rate and the thickness of the coating. The results showed that the rate of electroless composite plating increased with the increase in Al2O3 nanoparticle concentration. When the concentration of Al2O3 nanoparticles reached 1.5 g/L, the ENP rate decreased with the increase in Al2O3 nanoparticle concentration. The adhesion of the sample was evaluated by the scratch test, which showed that the binding grade of the sample was 0, and the Vickers hardness was 688.5 HV. Results showed that the coating produced by this new process has excellent performance. Therefore, the process is an environmentally friendly and fast activation composite plating process.

Thermal energy storage, heat transfer, and thermodynamic behaviors of nano phase change material in a concentric double tube unit with triple tree fins

The contribution of this study is the proposal of a synergistic composite enhancement strategy involving tree fins and nanomaterials to improve the low thermal performance of phase change material (lauric acid) in a typical double tube latent heat thermal energy storage unit. The effects of nanoparticle concentrations and tree fin branching angles on the fluid dynamics, melting time, heat transfer, energy storage, and entropy generation characteristics were investigated. By employing tree fins, the melting time was respectively reduced by up to 60.20% and 36.05% compared to the finless case and the rectangular fins, while the energy storage power was respectively boosted by up to 143.36% and 37.45%. The increase of nanoparticle concentration was beneficial for melting heat transfer, and the dendritic fins with a bottom angle of 90° and a top angle of 30° yielded the highest energy storage performance. The total entropy generation of the melting process was mainly governed by the thermal entropy generation, and it showed a decreasing trend with the increase of time. In contrast to the finless configuration, the incorporation of fins diminished the integrated entropy generation value. Similarly, an elevation in nanoparticle concentration also led to a reduction of the integrated entropy generation value.

Extraction evolutionary features of continuous light-induced plasmonic nanobubbles by a dynamic spectral regression model

A comprehensive understanding of the nature of light-induced plasmonic nanobubbles (PNBs) generated around noble metal nanoparticles is essential for optimizing PNB-based applications, such as light-driven microfluidic control. To investigate the overall evolution pattern of plasmonic nanobubbles (PNBs) under continuous light illumination, a computational model based on the least-squares method is established. Meanwhile, the variations in nanofluid transmittance and vaporization mass under continuous light illumination are measured by an immersion fiber and an electronic balance, respectively. The effects of nanoparticle concentration on the nanofluid transmittance and vaporization mass are analyzed. Considering the variations in nanofluid concentration, the overall evolution pattern of PNBs is preliminarily analyzed by monitoring the real-time dynamic change in nanofluid transmittance. The experimental results indicate that the nanoparticle concentration has an important effect on the nanofluid vaporization process. During the illumination stage, an increased nanofluid concentration intensifies the synergistic effect of water vaporization and PNB growth on transmittance reduction. The change in nanofluid transmittance caused by PNB scattering greatly exceeds that caused by increasing nanoparticle concentration. The nanofluid concentration gradually increases and peaks at the end of the cooling stage, and the rate of change of the nanofluid concentration is proportional to the nanofluid concentration. The numerical calculations show that the average size and the range of the PNB size distribution continuously increase with increasing irradiation time, and decrease during the cooling stage. A higher nanofluid concentration corresponds to a wider range of PNB size distribution.

Comparative study of two-phase flow approaches for modeling conjugate heat transfer in a three-dimensional wavy microchannel-heat sink with CuO-water nanofluid

This study aims to numerically investigate the conjugate heat transfer (CHT) and the changes in the hydraulic and thermal terms of laminar flow (300 ≤ Re ≤ 800) in a 3-D wavy microchannel heat sink (MCHS). The obtained results from different nanofluid flow simulated models will be compared. The numerical simulation approaches used include single-phase, mixture, Eulerian, DPM, and DDPM. The effect of adding 1%, 3%, and 6% concentration of CuO nanoparticles (100 nm) in deionized water as the base fluid is examined on various parameters such as local and axial temperature, heat transfer convective coefficient, friction factor, Nusselt number (Nu), velocity distribution, and thermal and hydraulic boundary layer parameters. The substrate surface, due to its larger area surface and the amplitude of the sinusoidal wave, has a greater impact on the nanofluid flow as a channel bottom conjugate surface compared to others. The results obtained from the different models show close agreement with each other for various cases. For example, at Re = 304, the average Nu and friction factor for pure water are approximately 10.43 and 0.0260, respectively. For water with 0.01 concentration of CuO nanoparticles, Nu is found to be in the range of 10.43–10.78, and the friction factor ranges from 0.260 to 0.290, depending on the approach used for simulation. This shows a 2% increase in Nusselt number compared to a 0.05% increase in the friction factor. Moreover, these values increase by approximately 5.7% and 11.3% on average with an increase in CuO nanoparticle concentration to 0.06. Additionally, the DPM and DDPM models show a 15% difference in the scattering of CuO nanoparticles compared to the Eulerian-Eulerian models. The single-phase model presented in this study yields similar results to the multiphase approaches. Furthermore, the PEC parameter increases by about 1.9% with the addition of CuO nanoparticles at a concentration of 0.06.

Numerical study on Fe3O4 nanoparticle separation from water flow using magnetic field: A 3D simulation

The development of magnetic separation technology using magnetic nanoparticles offers a promising avenue for targeted drug delivery and dealing with the upcoming water crises, environmental pollution and the gradual mineral resource depletion. In this study, a three-dimensional Lagrangian Discrete Phase Model (DPM) is carried out to simulate the performance of Fe3O4 nanoparticles to improve the separation process under the influence of an external magnetic field within a horizontal pipe. The crucial role of the drag force in capture efficiency (CE) prompted its examination, simulating various drag models for groups of particles. The Stokes-Cunningham model, showing a 3.59% average error is a suitable choice compared to experimental results. The research examines the impact of effective parameters, including flow velocity, magnetic field intensity, wire location, particle size and mass flow rate, and pipe diameter on CE and flow pattern. The results show that increasing nanoparticle concentration reshapes the flow pattern due to secondary flows without significantly changing separation efficiency. Moreover, decreasing flow velocity, diminishes drag force and enhances magnetic force impact. Specifically, reducing the velocity to a third increases CE by 37%. Furthermore, capture capacity varies approximately linearly with electric current. Due to the magnetic force’s role as a volumetric force in interphase momentum transfer, the increase in particle size from 200 to 500 nm at 3 × 105 A enhances CE by nearly 50%. However, increasing the pipe diameter diminishes particle capture, attributed to higher Reynolds numbers. According to the results, the impact of increasing magnetic field intensity and particle size on CE improvement is notably more pronounced compared to the effect of flow velocity reduction. A comparative analysis of three injection types reveals that using the group injection type helps to select an appropriate injection location to increase CE and identify the final positions of nanoparticles.

Determination of operational flow regime and heat transfer performance optimization of mono and hybrid nanofluids using FOM and sensitivity analysis

Nanofluids are considered as the most suitable replacement for conventional coolants due to their augmented thermal properties. The current study focuses on the operational suitability of different nanofluids (45 nanofluids) and estimates their heat transfer performance through Figure of merit (FOM) analysis. To perform an FOM-based ranking of these nanofluids, the heat transfer coefficient, friction factor, and pumping power of several nanofluids were also calculated. The effect of varying the volumetric concentration (0.01–1 vol%) on the pumping power, heat transfer coefficient, and thermo-physical characteristics of several nanofluids was examined. Different process and design parameters like pressure drop, flow velocity, mass flow rate, internal channel diameter, fluid temperature gradient, and wall temperature of the system were varied to check their effect on heat transfer coefficient, friction factor, and pumping power. Based on the FOM analysis, the authors determined that the majority of the nanofluids (26 nanofluids) investigated can be used in both laminar and turbulent flow regimes. The heat transfer coefficient decreases with increasing nanoparticle concentration. Therefore, it is essential to keep the concentration at an optimum level to attain the desired heat transfer performance. Among various key findings from the study, authors reported that the friction factor and pumping power of the nanofluid increases when the pressure drops and the channel’s internal diameter increases, while with increasing flow velocity, the friction factor and pumping power decrease. The authors also suggest that the pressure drop should be limited to 1–1.003 bar, the flow velocity should be greater than 1.4–1.5 m/s and the internal diameter should be 0.02 m to maintain the friction factor below 0.1. The aforementioned parameters are crucial when optimizing the heat transfer performance of a cooling system using nanofluid as a coolant.

Optimizing heat transport in a permeable cavity with an isothermal solid block: Influence of nanoparticles volume fraction and wall velocity ratio

Abstract This study examines the influence of wall velocity ratio on mixed convective heat transport in a permeable cavity containing an isothermal solid block at its center. The analysis considers the characteristics of various flow variables, i.e., Darcy number, wall velocity ratio, Richardson number, and volume fraction of suspended nanoparticles, on heat transport and material flow characteristics. The principal equations are solved implementing the semi-implicit method for pressure linked equations algorithm, and the outcomes are compared with existing literature. The study shows that rising estimations of Darcy number, velocity ratio, Richardson number, and nanoparticles volume fraction lead to improved heat transfer rates. For example, at high Richardson number (100) and solid volume fraction (0.05), increasing the velocity ratio from 0.5 to 1.5 results in a 6% (5%) upsurge in heat transport rate. Conversely, at smaller Richardson number (0.01), the heat transport rate upsurges by 29% (28%). Similarly, at high Darcy numbers and low wall velocity ratios, a 3% (4%) escalate in heat transport rate is observed with an increase in nanoparticles concentration from 0 to 0.05, while a 9% (8%) increase in thermal performance is achieved at low Darcy numbers. The study emphasizes the importance of optimizing the combination of nanoparticles volume fraction, Darcy number, velocity ratio, and Richardson number to maximize thermal performance in the porous cavity.

Microscopic mechanism of nanofluids electrospray: A molecular dynamics study

Cone-jet electrospray is widely used in various fields, such as electrospinning, nanostructured porous coating preparation, and inkjet printing, for which it can produce a large number of monodisperse and high charge-to-mass ratio droplets. A molecular dynamics method is employed to investigate the cone-jet electrospray emission behavior of nanofluids, where the microscopic mechanism of cone-jet electrospray including the formation of the cone, disintegration of the jet, stability of hydrogen bond, and interactions between molecules is revealed. In this paper, the influence of operating parameters and liquid physical properties were numerically conducted and extensively analyzed. The results show that the cone-jet electrospray only occurs in a certain range of applied voltage and flow rate, and the temperature and concentration of nanoparticles have a great effect on the jet length and the number of clusters produced by jet disintegration. When the electric field intensity increases, the length of the jet and the number of clusters increase. However, regardless of the electric field intensity, the maximum axial density is always located near the capillary outlet and the maximum radial density is located at the central axis of the capillary. As the temperature increases, the number of clusters increases significantly due to the synthetical effect of electric field-induced disintegration and evaporation, whereas the jet length is reduced. With an increase in concentration of nanoparticles at room temperature, the Taylor cone not only appears earlier but also has a larger angle. Meanwhile, the non-bonded interactions between ethanol molecules become stronger. This work provides microscopic mechanisms of nanofluids cone-jet electrospray and is potentially useful to optimize the design parameters of industrial applications.

Advanced electrochemical synthesis and characterization of Al2O3 nanoparticles embedded in polyaniline matrix for optoelectronic applications

Nanocomposite materials, featuring conducting polymers and aluminum oxide nanoparticles (Al2O3-NPs), are revolutionizing various fields including biomedicine, optoelectronic devices, and dye adsorption. In this study, we report on the synthesis of Al2O3 nanoparticles embedded in a Polyaniline (PANI) matrix for the fabrication of Al2O3/PANI nanocomposite films. The electrodeposition method was employed to deposit these films onto ITO-glass substrates, with concentrations ranging from 5 % to 20 %. The optical properties of the nanocomposites were analyzed using UV–Vis spectroscopy, allowing the determination of the refractive index and absorption coefficients. In addition, the Scherrer equation was used to calculate the average crystallite size, providing insight into the microscopic, ordered regions within the material. With increasing nanoparticle concentration in PANI-Al2O3 nanocomposites, Tauc plots revealed an increase in energy band gaps from 3.70 eV to 3.85 eV. Additionally, optical bandgap energies increased in PANI- Al2O3 nanocomposites, while electrical conductivities decreased with higher Al2O3 NPs content. Incorporation of Al2O3 NPs reduced the degree of conjugated π-bonds in PANI and disrupted the ordered structure of polymer chains. Moreover, the SEM analysis confirmed that the nanocomposite films had a dense, fiber-like structure. Further analysis of FTIR and XRD data revealed interactions between Al2O3 nanoparticles and PANI chains. At lower concentrations, minimal interaction was observed, while higher concentrations resulted in enhanced molecular interactions, leading to improved chain stretching, molecular packing, and larger crystallite sizes. As a result of Al2O3 nanoparticle incorporation, the nanocomposites exhibited conductivity values ranging from 0.12 to 0.02 S cm−1. These engineered nanocomposite films, characterized by high crystallinity, varied electrical conductivities, and controlled band gaps, show promising potential as active components in next-generation optoelectronic devices.

Novel antimicrobial applications of copper oxide nanoparticles after combination with tissue conditioner used in complete prostheses

BackgroundTissue conditioners are used for treating and improving the tissues supporting complete dentures. On the other hand, recent advances in nanotechnology have revolutionized various fields of science, including dentistry. The present study aimed to investigate novel antimicrobial applications of copper oxide nanoparticle-based tissue conditioner used in complete prostheses.MethodsThe present experimental study included 126 tissue conditioner samples with different concentrations of copper oxide nanoparticles (20%, 10%, 5%, 2.5%, 1.25%, 0.625%, and 0% w/w). The samples were incubated with Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans in 24-well plates for 24 h. Then, samples from the wells were re-incubated for 24 h, and the microorganisms were counted.ResultsThe culture media containing E. faecalis and P. aeruginosa showed significantly different growth between different nanoparticle concentrations following 24 h (P < 0.001), showing a reduction in bacterial growth with increased nanoparticle concentration. Both bacteria did not show any growth at the 20% concentration. However, C. albicans showed significant differences in growth between different nanoparticle concentrations following 48 h (P < 0.001), showing a reduction in growth with increased nanoparticle concentration. Also, the least growth was observed at the 20% concentration.ConclusionsIn conclusion, the CuO nanoparticles were prepared using a green synthesis methon in the suitable sizes. Moreover, the tissue conditioners containing CuO nanoparticles showed acceptable antimicrobial properties against E. faecalis, P. aeruginosa, and C. albicans.

Investigation on the synergistic effect and thermal properties of poly-hydroxyethyl methacrylate encapsulated graphene quantum dot-paraffin hybrid nanofluid

In this study, a novel water-based hybrid nanofluid was developed using poly-hydroxyethyl methacrylate-encased graphene quantum dot-paraffin nanocomposite (HEMA GQD-P). Graphene quantum dots (GQD) with an average size of 10 to 15 nm were synthesized by citric acid nucleation and the HEMA GQD-P nanocomposites were synthesized by an emulsion polymerization reaction. The emission spectra of GQD obtained using photo-luminescent spectroscopy confirm the occurrence of quantum confinement effect. The synthesis of HEMA GQD-P was carefully carried out to ensure its optimal properties. The synergistic effect due to high thermal conductivity of GQD and high latent heat capacity of paraffin were recognized in the enhanced properties of nanocomposite and hybrid nanofluid. The latent heat capacity of the synthesized nanocomposite was found to be 21.8 % higher than the pure paraffin. The prepared hybrid nanofluid possesses high dispersion stability at pH 7 and the thermal conductivity of the hybrid nanofluid enhances with an increase in nanoparticle concentration. A maximum thermal conductivity enhancement of 53 % (±2) was obtained for the hybrid nanofluid (0.3 vol%) at 30 °C. The present work reveals that the encapsulation of GQD-paraffin in a poly-hydroxyethyl methacrylate shell creates nanocomposites with high heat transfer properties. The synergistic effect of the HEMA GQD-P enhances their potential in the preparation of hybrid nanofluids with enhanced properties for desired thermal management applications.

Effect of Graphene Oxide Incorporation on the Strength of Denture Repair Resin

To evaluate the effect of incorporating graphene oxide nanoparticles (GO NPs) and graphene sheets on the flexural strength of an auto-polymerized (AP) acrylic resin-repaired denture. 60 heat-activated (HA) resin specimens were fabricated and randomly divided into 6 groups (n = 10). The specimens in Group I were kept intact. 50 specimens were cut into two parts with a 45-degree bevel. Group II specimens were repaired with AP resin and Group III specimens were repaired with HA resin. In the repair of Group IV, Group V, and Group VI specimens, 1%, 2% GO NPs, and graphene sheets were added to AP resin, respectively. A 3-point bending test with a universal test device measured the flexural strength. Statistical analyses of the results were performed with the Kruskal Wallis H-test. (α = 0.05) The flexural strength of Group I (130.05 ± 20.20 MPa) was the highest among all groups. The flexural strength of Group IV (67.49 ± 12.70 MPa) was significantly higher than Group V (50.87 ± 15.02 MPa) and Group VI (44.77 ± 10.70 MPa). The lowest strength value was obtained in Group VI. Adding 1% GO NPs to AP acrylic resins increases flexural strength. However, the increase in nanoparticle concentration and the addition of graphene sheets negatively affect strength.

An experimental investigation of the convective heat transfer augmentation in U-bend double pipe heat exchanger using water-MgO-Cmc fluid

One of the major problems of using nanofluids in heat exchange applications is the forming and deposition of nanoparticles on the inner surface of the heat exchanger. In this paper, Water-Cmc fluid is used as a surfactant for nanoparticles to prevent deposition and congregation. The pressure drops and heat transfer in U-bend double pipe heat exchanger based on water-MgO-Cmc fluid, are examined. Nanoparticles of Magnesium Oxide (MgO) and Carboxymethyl Cellulose (Cmc) are used with pure water as a base fluid. The experimental rig and procedures are designed to facilitate various operational conditions such as flow rate, volume concentration of MgO particles and weight concentration of Cmc particles. Furthermore, convective heat transfer coefficient, heat exchanger effectiveness, pressure drop, friction factor, under different conditions, are measured. The results demonstrate convective heat transfer coefficient of U-bend double pipe heat exchangers is enhanced by 35% for 1 MgO vol.% and 0.2 Cmc wt.% compared to base fluid (Water-Cmc). It is concluded that pressure drops are directly proportion to the increase of MgO nanoparticles at same Cmc concentration by 23% at 0.2 wt.%. Whilst, friction factor of the system is inversely proportion to the increase of volumetric flow rate of water-MgO-Cmc fluid. An increase in MgO nanoparticle concentration increases the friction factor, hence maximum friction factor enhancement by 38% for MgO concentration of 1 vol.%. The effectiveness of heat exchanger is slightly increased by 8% with increase of MgO concentration and flow rate. Finally, thermo-physical characteristics of water-MgO-Cmc fluid at various temperatures, are measured

Study of heat transfer in trihybrid nanofluid (Cu/Ag/Al2O3 with H2O) in Hele-Shaw cell and square enclosure with throughflow

The stability analysis of trihybrid nanofluid (Cu/Ag/ A l 2 O 3 as nanoparticles and H 2 O as base fluids) with spherical, brick, and cylindrical shapes, respectively, are examined theoretically and analytically with throughflow. Normal mode techniques have been used for linear stability analysis, and truncated Fourier series is carried out for nonlinear analysis. Comparison of Hele-Shaw cell and Square enclosure is performed in both linear and nonlinear analysis. Square enclosures are found to prevail in heat and mass transfer. Hele-Shaw number (HS number) has destabilizing behavior. Increase in concentration of nanoparticle increases the heat and mass transfer. Cylindrical shapes particles are found to have earlier rate of convection in both the system. Furthermore, throughflow exhibits destabilizing behavior. Hele-Shaw cell prevail heat and mass transfer on comparing for regular fluid. In all the three phases Prandtl number enhances the heat/mass transfer due to increase in momentum diffusivity of the fluid.

Comet Assay and Micronucleus Test in Circulating Erythrocytes of Ctenopharyngodon idella Exposed to Nickel Oxide Nanoparticles.

The number of pollutants released into freshwater and marine environments has increased due to the widespread use of nanoparticles. Nickel oxide nanoparticles (NiO-NPs) were tested for genotoxicity in fish fingerlings of the species Ctenopharyngodon idella. For 7, 14, and 21days, fingerlings were exposed to NiO-NPs with each increasing concentrations of 2.25mg/L, 4.50mg/L, and 6.75mg/L, respectively. The micronuclei assay and comet assay were used to evaluate the DNA damage. The experiment revealed that with the increase in nanoparticle concentration and exposure duration, the level of DNA damage also increased. The experiment resulted to be time and dose dependent, and the damage was found as follows: 6.75mg/L > 4.50mg/L > 2.25mg/L against each exposure period. In terms of comet assay, the results showed that after 7days, the level of DNA damage in all the concentrations was highly significant (P < 0.001). Increased DNA damage was calculated at the higher administered dose of 6.75mg/L for 21days of exposition, followed by 14 and 7days, respectively. The second high toxic effect was observed in the fish blood at the exposure concentration of 4.50mg/L for 21days, followed by 14 and 7days, respectively. The micronuclei induction in the nanoparticle's administered blood could be detected only for a 7-day exposition period. Whereas for the exposed duration of 14 and 21days, the entire red blood cells of the grass carp were completely destroyed demonstrating the ability of the nanoparticles to cause anomalies in aquatic life.