Increasing Particle Concentration Research Articles

Where have all the beads gone? Fate of microplastics in a closed exposure system and their effects on clearance rates in Mytilus spp.

The fate of microplastic particles (MP) in exposure experiments is mostly unclear. We measured the recovery of polystyrene (PS) microbeads, which were applied in various concentrations from 0.07 to 47.47 beads/ml, from the different compartments of an experimental system with mussels (Mytilus spp.). At the end of the experiment, we detected a significant loss of MP indicating that the mussels were exposed to less particles than intended. If such a discrepancy remains un-recognized by the experimenter, observed effects are related to an inaccurate particle concentration. Additionally, we observed reduced clearance rates of the mussels in the presence of MP and the effect size increased with increasing particle concentration. This effect was more pronounced in mussels that had recently spawned than in mussels that still had mature gonads. This is a hint that effects of MP may depend on the reproductive status of an organism.

Pore-scale analysis of two-phase nanofluid flow and heat transfer in open-cell metal foams considering Brownian motion

Simultaneous use of porous media and nanofluids will increase the convective heat transfer multiple times compared to non-porous and pure fluid conditions. Heat transfer and flow transport of nanofluids inside porous media are usually simulated in large-scale with average properties, which are typically highly uncertain. Pore-scale simulation as an alternative approach can capture the characteristics of flow and heat transfer more accurately. Only few studies have been conducted to study nanofluid flow through porous media in pore-scale, and most of them employed single-phase approach without focus on different affective forces. This paper uses a pore-scale approach to investigate the flow characteristics and convective heat transfer of two-phase nanofluid flow in open-cell metal foams (OCMFs). Simulation of fluid flow and heat transfer is achieved by Buongiorno’s model. Therefore, a computational code through the OpenFOAM library that operates by a direct numerical simulation (DNS) approach and the finite volume method (FVM) is used. The momentum, energy, continuity, and nanoparticle distribution equations are discretized, and the SIMPLE algorithm is utilized for pressure and velocity coupling. In the present study, three OCMFs with a constant porosity (0.86) and various pore densities are investigated. Also, variations of pressure gradient, Nusselt number, and Darcy velocity are investigated as a function of pore density (as a geometric parameter), nanoparticle diameter, concentration, and Brownian motion force. The results indicate that the Brownian force enhances the heat transfer in OCMFs from 2% by up to 14% for the nanofluid flowing with 3% nanoparticle concentration. Also, increasing the diameter of nanoparticles reduces the Darcy velocity and heat transfer by up to 4%. On the other hand, increasing particle concentration from 3% to 5%, increases heat transfer by up to 10% and reduces the Darcy velocity by up to 9%. Finally, doubling the pore density demonstrates the complex behavior of the flow patterns, in which the heat transfer increases by up to 30% and permeability and velocity are reduced by up to 70%.

Numerical Investigation of Fine Particulate Matter Aggregation and Removal by Water Spray Using Swirling Gas Flow

In this paper, a mathematical model based on the two-fluid frame model coupled with the population balance model which considers the aggregation of particles and droplets in detail for cyclonic spray dedusting is proposed. The model is applied to study the characteristics of multiphase flow field and the effects of the gas velocity, spray volume, and particle concentration on the removal efficiency. In addition, the simulation results are verified by the experimental data. The results suggest that the turbulence kinetic energy increases near the wall as the inlet velocity increases, and the spray region increases as the spray volume increases. This is conducive to turbulent mixing of the particles and droplets, and the agglomeration efficiency of the particles is improved, so the particle size increases, and the particle removal efficiency increases to 99.7% by simulation results are within the allowable range of error (about 99-99.5% in dedusting efficiency by experimental data). As the particle concentration increases, the particle removal efficiency initially increases, then decreases and reaches the highest value at 2 g/m3, which is due to the limited adsorption efficiency of the spray droplets. The results are helpful for providing a theoretical basis for spray to promote agglomeration of particles and improving the dust removal efficiency in the swirl field.

Rheological study of nanoparticle-based cationic surfactant solutions

Worm-like micelles are of special interest among the many forms of surfactant aggregates because of their usefulness in research and technology. Micelles are elongated, flexible aggregates formed by amphiphilic molecules spontaneously self-organizing in liquids. The nature of the surfactant determines its unique shape, which may be altered by mixing it with other substances or changing physicochemical variables like as temperature, pH, or salinity. The rheology of viscoelastic fluid systems is currently being modified using nanoparticles. This method, which was just introduced about 10 years ago, has shown to be highly promising, producing significant improvements in rheological properties, particularly at reservoir temperatures. The goal of this research is to investigate and assess the rheology of an aqueous cationic surfactant solution based on graphene oxide nanoparticles. The thermodynamics, structure, and rheology of nanoparticle-based cationic surfactant solutions were investigated experimentally. According to structural and thermodynamic investigations in surfactant-nanoparticle mixtures, micelle-nanoparticle interactions arise as physical crosslinks between micelles. The existence of these interactions is shown to generate considerable viscosity and viscoelasticity in wormlike micelles, even when the fluid is Newtonian in the absence of nanoparticles. The viscosity, shear modulus, and relaxation time all increase as particle concentration increases. Adding nanoparticles generates a network of micellar entanglements as a result of that. Our results demonstrate that adding nanoparticles to surfactant solutions provides for a one-of-a-kind method of altering fluid rheology under a range of circumstances.

Quantitative and Qualitative Study of Double-Pipe Heat Exchangers Performance Using Water Based Nanofluids

The heat transfer performance of base fluids is greatly improved with suspended nanoparticles in a variety of applications such as solar collectors, heat pipes, nuclear reactors, cooling systems, automotive radiators, and more. In the present paper, the problem of flow of nanofluids with forced convection is studied in detail in three cases, under constant mass flow rates (Case 1), under optimized mass flow rates with two different geometric configuration scenarios of the heat exchangers, N-shaped pipe heat exchanger (Case 2) and M-shaped pipe heat exchanger (Case 3). Numerical results in the previous works, as obtained for water–Al2O3 mixture, have been demonstrated that of nanoparticles into the base fluids fluid led to a significant increase of the heat transfer coefficient, which clearly increases with an increase in particle concentration. However, those particals also caused drastic effects on the wall shear stress that increases correspondingly with the particle loading. Therefore, in the current study the full performance of the different heat exchanger designs will be investigated numerically under the effect of different particle concentrations and different nano materials such as Al2O3, CuO, TiO2 and SiO2. Additionally, the Computational Fluid Dynamics (CFD) single-phase model is adopted for predicting the heat transfer performance in fluent using ANSYS. Therefore, the results show enhancement in heat transfer for the heat exchanger is due to increased volume fraction, and a direct correlation between overall heat transfer effectiveness and volume fraction percentage of nanofluids, while CuO was proven most effective amongst considered nano particles. Besides, adjusting the geometry into an M-shaped pipe had resulted in an enhanced heat transfer effectiveness.

Solvent-free synthesis of superhydrophobic materials with self-regenerative and drag reduction properties

Despite many exquisite properties, the use of superhydrophobic materials have been limited due issues with long-term durability, and use of solvents and chemicals. In present work, cost effective, and solvent-free approach was used to fabricate flexible superhydrophobic composite materials with self-regenerative and low-drag characteristics. Variation in reinforced particle’s fraction directly influenced the morphology, de-wettability and mechanical stability. The increase in particle concentration (polytetrafluoroethylene (PTFE)) resulted in decrease in surface skewness and kurtosis indicating formation of plateau-type morphology. De-wetting and adhesion showed a non-linear trend with minimum values observed for composite with 60 vol% reinforced particles. The composition was optimized based on high de-wetting, low adhesion and high mechanical strength. The optimized composite composition consisted of homogenous globular morphology with advancing and receding angles in excess of 150°, low tilting (5°) angle and lowest adhesion of ∼ 20 µN (more than ten times lower than PTFE). The high de-wetting of the composite was due to presence of stable Cassie state resisting the liquid impalement even against lower surface tension liquids and increased normal loads on droplets. The composite demonstrated both chemical and physical self-regeneration capability in real time during long-term abrasion, maintaining contact angles in excess of 150° and 5° tilting angle. The superhydrophobic material also showed extremely low drag (100 times lower than polydimethylsiloxane) to droplet mobility with friction forces around 5–12 µN, depending upon droplet size. Owing to sustainable nature, the synthesized functional composite can be used in multiple engineering systems.

Phase-Field Simulation on the Effect of Second-Phase Particles on Abnormal Growth of Goss Grains in Fe-3%Si Steels.

A phase-field model was revised to study the abnormal growth of Goss grains during the annealing process in Fe-3%Si steels, in which the interaction between the second-phase particles and Goss grain boundaries (GBs) was considered. The results indicate that the abnormal growth of Goss grains occurs due to the different dissolvability of the particles at Goss GBs compared with the other GBs. Moreover, the degree of abnormal growth increases first and then decreases with an increasing particle content. Meanwhile, the size advantage of Goss grain can further promote the degree of abnormal growth. Two types of island grains were found according to the simulated results, which is consistent with the experimental observations. A proper GB dissolvability of particles is the key factor for the formation of isolated island grains, and a higher local particle density at GBs is the main reason for the appearance of serial island grains. These findings can provide guidance for the desired texture control in silicon steels.

The conjoint influence of oxygen and hot extrusion on microstructure and mechanical properties of a powder metallurgy processed aluminum alloy

In this paper, Al-8.3Zn-2.3Mg-2.5Cu alloys with different oxygen contents were prepared through complex techniques including blending or ball milling, cold isostatic pressing, vacuum sintering, hot extrusion, and heat treatment, and their microstructure and mechanical properties were investigated. For the samples containing 0.15 wt% and 0.33 wt% oxygen, the sintered density values are 99.1% and 98.7% of the theoretical density, and the corresponding average grain sizes are 5.60 μm and 4.83 μm. After heat treatment, the average grain sizes of the samples with 0.15 wt% oxygen subjected to the extrusion ratios of 4:1, 9:1, and 17:1 are 5.17 μm, 4.28 μm and 3.83 μm, respectively, and the corresponding yield strengths are 607 MPa, 615 MPa, and 621 MPa. Moreover, the {111}<112> deformation texture changes to {001}<001> and {001}<111> recrystallization textures. In contrast, for the extruded sample (9:1 extrusion ratio) with 0.33 wt% oxygen, the grains are finer, and static recrystallization barely occurs with little variation in texture after heat treatment. This is due to the increase in content of thermostable γ-Al2O3 particles. Accordingly, the sample with high oxygen content exhibits excellent comprehensive mechanical properties with the ultimate tensile strength of 719 MPa, yield strength of 690 MPa, and elongation of 11.5%. Regarding the strengthening mechanism, apart from the common precipitation strengthening, the contributions of dislocation strengthening and grain boundary strengthening are greater in the 0.33 wt% oxygen alloy than in the 0.15 wt% oxygen alloy. This is due to the pinning effect of γ-Al2O3 particles on dislocations and grain boundaries.

Microplastic pollution in small rivers along rural–urban gradients: Variations across catchments and between water column and sediments

The aquatic ecosystems of the world are highly burdened with microplastics (MPs; particles <5 mm). There is a great need for better understanding of patterns of MP pollution across catchments and rivers of different sizes, anthropogenic pressures and hydrogeomorphological features. In this study, we investigated the MP concentrations including their characteristics (polymer type, shape, size and colour), and MP distribution in water and sediments of two hydrogeomorphologically different small-scale catchments (< 800 km2), namely Kamniška Bistrica (KB) and Ljubljanica (LJ), Slovenia. The main objective of this study was to gain a better understanding of how WWTP effluents and catchment urbanisation together with the diversity of natural hydrogeomorphology, affect the quantity and quality of MP pollutants in the rivers with smaller catchments. Significantly different mean MP concentrations were found in the water columns (KB: 59 ± 16 items m−3; LJ: 31 ± 14 items m−3), but not in the sediments (KB: 22 ± 20 items kg−1; LJ: 23 ± 25 items kg−1). A longitudinal gradient with increasing particle concentration was observed in both water and sediment samples and in both catchments. Polyethylene (PE) and polypropylene (PP) particles dominated in all samples. Fibres were predominant in the water column samples, while fragments were more common in the sediment samples. MP particles were mostly coloured, and most of them were smaller than 2 mm in both water and sediment samples. The critical evaluation of the results and previous studies suggest that the characteristics of the catchment (anthropogenic pressures, size, climate, etc.), the hydrogeomorphology of the river (sediment type, discharge, flow velocity etc.), the sampling location along the river, the sampled compartment (water, sediment), the sampling method, and the hydrometeorological characteristics at the time of sampling, are important factors for observed MP concentrations and other characteristics.

Structure optimization and cooling performance of a heat sink with discontinuous arc protrusions impacted by nanofluid confined slot jet impingement

PurposeThe purpose of this paper is to improve the overall heat transfer performance and the temperature uniformity of the heat sink and to explore the effects of the jet Reynolds number and the nanoparticle volume fraction of the nanofluids on the flow and heat transfer performance.Design/methodology/approachA heat sink with discontinuous arc protrusions in the wall jet region is proposed for confined slot jet impingement. A sloping upper cover plate is added to improve the heat transfer effect in this area. An Al2O3–water nanofluid is selected as the working fluid of the jet for better heat transfer. The Standard k-e turbulence model is used for numerical calculation. The key structural parameters of the heat sink are optimized by the response surface method and a genetic algorithm. The effects of the jet Reynolds number (Re) and the nanofluid concentration (ϕ) on the flow and heat transfer performance of the optimized heat sink are investigated.FindingsThe average Nusselt number of the optimal heat sink is 8.2% higher and the friction resistance is 5.9% lower than that of the initial flat plate heat sink when ϕ = 0.02 and Re = 8,000. The discontinuous arc protrusions and the sloping upper cover plate substantially enhance the heat transfer in the later stage of jet development, improving the temperature uniformity of the heat sink. The maximum temperature difference of the optimal heat sink is 28.1% lower than that of the flat plate heat sink at the same nozzle height. As the jet Reynolds number and the nanofluid particle concentration increase, the Nusselt number of the optimized heat sink and the friction coefficients increase, resulting in a decrease in the evaluation coefficient. However, the overall temperature uniformity of the heat sink is improved under all conditions.Originality/valueThe novel heat sink structure provides a new way to enhance the heat transfer and temperature uniformity of confined slot jet impingement. The flow and heat transfer performance of the heat sink impinged by confined slot jet of nanofluids are obtained. The combination of response surface method and genetic algorithm can be applied to the multi-objective optimization of heat resistance and flow resistance of heat sink.

VMD analysis of pulsating flow pressure signal of oil with different particle concentration

The Variational Mode Decomposition (VMD) method was used to decompose the oil pressure signals containing different particle concentrations; the number of components of VMD decomposition is determined by using the criterion of joint comparison between the slope of the center frequency of each component and the main frequency of the component of VMD decomposition, and a method for determining the main components of the signal is proposed by the average energy value; the Hilbert envelope demodulation analysis was carried out for the maximum energy component of each pressure signal. The results showed that the larger the particle concentration in the oil, the greater the number of main components obtained by VMD decomposition, and the proportion of the main components per unit concentration showed a monotonically decreasing trend. The main frequency of the main component is the fundamental frequency of its signal or the multiplication frequency combined with the rotating shaft frequency; there is an amplitude modulation relationship between any components; with the increase of particle concentration, the fundamental frequency of the pressure signal decreases successively; the maximum energy component of each pressure signal has the characteristics of amplitude modulation and frequency modulation in different degrees.

Refractive index and temperature coefficient of refractive index of Al2O3- and SiO2-water nanofluids

• Measurements are made of the refractive index and temperature coefficient of refractive index (∂n/∂T) for two nanofluids, Al 2 O 3 -water and SiO 2 -water. • For both nanofluids, the refractive index decreases with increasing temperature and increases with increasing particle concentration. • The variation of refractive index is approximately linear with concentration. • ∂n/∂T for Al 2 O 3 -water nanofluids can be approximated as that of water with an accuracy better than ±5% for a concentration φ < 1%. • For SiO2-water nanofluid, ∂n/∂T can be approximated as that of water with an accuracy of better than ±5% for a concentration φ < 4%. Measurements are made of the refractive index and temperature coefficient of refractive index (∂n/∂T) for two nanofluids, Al 2 O 3 -water and SiO 2 -water, over the temperature range 20–40°C at a wavelength of 632.8 nm. These optical properties are needed for refractive index-based temperature and heat transfer measurements, particularly laser interferometry. A laser beam deflection technique is used to measure the refractive index of the nanofluids. The temperature coefficient of refractive index is determined by measuring the phase change with temperature, using Mach-Zehnder interferometry. Measurements are made for Al 2 O 3 -water nanofluids up to a weight-based concentration of ϕ = 20% and for SiO 2 -water nanofluids up to a weight-based concentration of ϕ = 40%. The refractive index data are used to quantify the errors in interferometric temperature measurements produced by non-homogenous nanofluid suspensions. In the literature, the optical properties of dilute water-based nanofluids are sometimes assumed to be equal to those of water for interferometry experiments. The limits of this approximation are estimated. The current measurements indicate that ∂n/∂T for Al 2 O 3 -water nanofluids can be approximated as that of water with an accuracy better than ±5% for a concentration ϕ < 1%. For SiO 2 -water nanofluid, ∂n/∂T can be approximated as that of water with an accuracy of better than ±5% for a concentration ϕ < 4%.

Upcycling Different Particle Sizes and Contents of Pine Branches into Particleboard.

A growing world population means that demand for wood-based materials such as particleboard is constantly increasing. In recent years, wood prices have reached record highs, so a good alternative can be the utilization of branches, which can reduce the cost of raw materials for particleboard production. The goal of the study was to confirm the feasibility of using an alternative raw material in the form of Pinus sylvestris L. pine branches for the production of three-layer particleboard. Characterization of the alternative raw material was also carried out, and the bulk density was determined. As part of the research, six variants of particleboard, 0%, 5%, 10%, 25%, and 50%, w/w, and two variants where the first one had the face layer made of branch particles and the core layer made of industrial particles, and the reverse variant (all produced panels were three-layer) were produced and then their physical and mechanical properties were studied. The results show that even if the bulk density of branch particles is significantly higher than industrial material, the internal bond and water absorption rises as branch particle content increases. In the case of bending strength and modulus of elasticity, these were decreased with a branch particle content increase. The conducted tests confirmed the possibility of using the raw material, which was usually used as fuel or mulch, to produce particleboards even in 50% content. The present solution also contributes to the positive phenomenon of carbon storage, due to incorporating the branches' biomass into panels rather than burning it. Further research should be focused on the modification of particle production from branches to obtain lower bulk density and to reach fraction shares closer to industrial particles. Furthermore, the chemical characterization of the pine branch particles (cellulose and lignin content, extractives content, pH value) would provide valuable data about this potential alternative raw material.

Role of particles and lattice rotation in tension–compression asymmetry of aluminium alloys

Plastic deformation of aluminium alloy AA6061 under tension and compression is investigated using a strain gradient crystal plasticity model implemented with the finite element method. This approach takes into account the microstructure as determined experimentally by electron backscatter diffraction (EBSD). The asymmetry of stress strain curves in loading of tension and compression (TC) is revealed for the FCC crystal structure. Plastic slip on activated slip systems leads to lattice rotation of crystal matrix and particles towards specific orientations, resulting in variation of moduli. The evolution of two different types of dislocations, statistically stored dislocations (SSD) and geometrically necessary dislocations (GND), is investigated to reveal the TC asymmetry due to slip resistance. It is found that the TC asymmetry at the yield strain is caused by lattice rotation of both crystal matrix and particles. When strain increases, the TC asymmetry is due to a combination of lattice rotation of crystal matrix and particle and variation of the GND density. As particle content increases, the TC asymmetry is mainly attributed to lattice rotation of particles at large strain.

Influence of low-temperature polyurethane solid-solid PCMs particles on the pavement performance of asphalt mixtures

In order to slow down the cooling rate of the mixture and reduce the low temperature cracking of asphalt pavement in large temperature difference areas, low-temperature polyurethane solid-solid phase change materials (LPSPCMs) were prepared by prepolymer method. The researches show that LPSPCMs have good phase change heat storage performance and thermal stability performance, and can be applied to hot mix asphalt mixtures. The LPSPCMs particles were incorporated into the asphalt mixture, and the road performance of the LPSPCMs particulate asphalt mixture was tested and analyzed and found: as LPSPCMs particles change the abrasion resistance and embedded effect between asphalt mixes, with the increase of LPSPCMs particles, the high-temperature performance of asphalt mixes first increased and then decreased. The water stability of asphalt mixtures gradually decreases with the increase of LPSPCMs particles content because relative to limestone aggregates, LPSPCMs particles adhere poorly to asphalt. The thermal stress restrained specimen test (TSRST) showed that the cracking temperature of the asphalt mixture gradually decreased with the increase of LPSPCMs particles contents because of the phase change temperature control effect of LPSPCMs particles indicated that LPSPCMs particles improve the low-temperature performance of asphalt mixtures. On this basis, the correlation between the evaluation index of the phase change temperature adjustment effect and the improvement effect of the low-temperature performance of the mixture was established.

How the presence of particles at the interface influences the droplet deformation in a simple shear flow?

A lattice Boltzmann method is presented to simulate a particle-laden droplet subject to a simple shear flow, where the effect of particle concentration, viscosity ratio of droplet to ambient fluid and particle inertia on droplet deformation and particle movement is explored. With the increase of particle concentration, droplet deformation increases because of reduced interfacial free energy caused by reduced fluid-fluid interface length. When a sufficient number of particles are added to interface, droplet deformation monotonically decreases with viscosity ratio, but first rises and then declines for clean interface. This difference is attributed to an increased apparent viscosity of the ambient fluid by added particles. The particle inertia enhances droplet deformation remarkably only when the Reynolds number is relatively high. In addition, particles are found to revolve around the deformed droplet along the interface with a period, which is determined solely by deformation parameter at the viscosity ratio of unity. • A LBM is developed to simulate the fluid-fluid-solid three-phase flows. • The particle's revolution period can be determined by the droplet deformation. • The deposition of particles at the interface can enhance the droplet deformation.

Modeling and analysis of fluid rheology effect on sand screen performance

This paper presents a numerical study of the sand retention process over premium square mesh screens, with special reference to the effect of fluid rheology. This is done by the combined approach of computational fluid dynamics (CFD) and discrete element method (DEM). The fluid viscosity μ f is described by the power-law model ( μ f = K γ ̇ n − 1 ), and the fluid drag force is calculated by a recently developed drag correlation. The model, after validation, is used to study the effects of flow behavior index n , consistency index K , and temperature corresponding to specific rheological properties. The numerical results show that the sand production reduces with increasing n or K but increases with increasing temperature. The increase in n or K or decrease in temperature increases the fluid viscosity. Correspondingly, the particle descending velocity magnitudes decrease, and thus the particle concentration increases. Consequently, the particle-particle interactions near pores become stronger, accounting for faster sand retention. • Non-Newtonian suspension flows through screens are modeled by a CFD-DEM model. • It is equipped with the power-law rheology model and a recent drag correlation. • Effects of power-law constants and temperature on sand production are quantified. • The role of fluid rheology is elucidated in terms of flow and force structures.

Microstructure, phase transformation and mechanical properties of NiMnGa particles/Cu composites fabricated by SPS

Microstructure, phase transformation and mechanical properties of NiMnGa particles/Cu composites prepared by spark plasma sintering method were investigated by SEM, EDS, XRD, susceptibility measurements and mechanical tests. The NiMnGa particles were found to react with Cu matrix and the composites exhibited a similar crystal structure to the Cu matrix. The martensitic transformation and Curie transition of the composites were weakened due to the composition change of NiMnGa particles caused by reactions. With increasing NiMnGa particles content, the martensitic transformation and Curie transition of the composites were enhanced to some extent. However, the martensitic transformation temperature and Curie transition temperature were decreased by ~50 K as compared to those of the original NiMnGa particles. The compressive strength of the composites increased with the increase of NiMnGa particles content, whereas the compressive strain was decreased gradually.

In situ experimental study on fracture toughness and damage mechanism of TiB2‐reinforced steel matrix composites

AbstractIt is crucial to obtain better fracture property of particle‐reinforced metal matrix composites (PRMMCs) for application in structural parts. In this study, three‐point bending tests are conducted on a TiB2‐reinforced steel matrix composites (SMCs) with 9% and 13% TiB2 volume fractions to understand the effect of hot rolling and particle content on fracture toughness. Results show that increasing particle content has a negative effect on the fracture toughness of SCMs as a whole. Many microcracks induced by large‐size particle fracture initiate in the front of crack tip and coalesce with one another are observed, thus accelerating the main crack propagation. However, hot rolling can effectively improve the fracture toughness and hardness of SMCs with two particle contents. Particle characteristics and matrix plasticity of the SMCs are optimized by hot rolling, which finally enhances the crack propagation resistance. The present work provides guiding suggestions for effectively improving fracture properties of PRMMCs.

Numerical Analysis on Convective Heat Transfer of water Based Hybrid Nanofluid (Alumina-Copper) In a Horizontal Annulus

Numerical inspection of natural thermally induced flow in horizontal annulus has been carried out. The annulus taken under consideration is the circular annulus. By applying heat flux to the inner tube, the inner wall of the annulus is kept at high temperature and the outer wall of the annulus is maintained at constant low temperature. The numerical simulations were accomplished by varying concentrations of the hybrid nanofluid of a hybrid alumina-copper various for each Rayleigh number (4 x 104 &lt; Ra &lt; 4 x l05). Heat transmission through natural convection using air as convective fluid, in the body of horizontally placed annulus resided between two same hollow cylinders, is calculated. The influence of the Rayleigh number along with particle concentration on heat transmission characteristics, change in fluid flow and effective thermal conductivity of an annulus has been studied. The results showed a proportional rise in the heat transfer performance and effective thermal conductivity with the increasing particle concentration and Rayleigh numbers.