Addition Of Solid Particles Research Articles

Innovative fluidized bed flotation column for fine particle separation

Flotation columns are extensively utilized to separate fine mineral particles. In highly turbulent environments, the increased collision efficiency between bubbles and particles can lead to improved flotation efficiency of fine particles. The fluidized bed flotation column (FBFC), a new type of flotation equipment, improves the separation efficiency of fine particles by creating a highly turbulent environment in the fluidized zone through the addition of solid particles. This paper investigated the fluidization characteristics, bubble, and gas hold up of the FBFC, along with the flotation efficiency of fine quartz particles. Experimental results showed that introducing gas enhanced the fluidization process in the fluidized bed. The fluidized zone facilitated the fragmentation of bubbles into smaller ones. With increasing liquid velocity, the bubble diameter decreases before subsequently increasing, while the gas holdup initially rises and then declines. The flotation efficiency of fine quartz particles is superior in FBFC with added particles compared to those without added particles. The flotation efficiency of fine particles increases with the rise in both liquid velocity and gas velocity.

Simultaneous measurement of velocity field of liquid–solid particle flow in pipelines and analysis of flow characteristics

The liquid–solid particle flow within a horizontal pipeline is a typical particle-laden flow. The interplay between loaded particles and carrier phase engenders significant complexities in the dynamic behavior of such flows. We investigated the dynamics of a liquid–solid particle flow featuring dilute, slightly buoyant, hundred-micron-sized spherical particles fully suspended in the turbulent flow in a pipe, where Re is 7038. Cases with solid volume fractions of 0, 2.67 × 10-4, 5.33 × 10-4, 8.00 × 10-4, 1.07 × 10-3 and 1.33 × 10-3 were considered in this study. Experimental measurement techniques were utilized to acquire images of particles in the two-phase flow across the entire flow field via optical field feedback. Particle image velocimetry (PIV) and particle tracking velocimetry (PTV) were employed to simultaneously obtain liquid-phase velocity fields and particle trajectories. This approach allowed for a comprehensive depiction of the velocity field of each phase. Subsequently, a detailed explanation and analysis of the flow characteristics of the liquid–solid particle flow were provided based on the distribution of macroscopic velocity fields, the microscopic vorticity field, particle velocity vectors, and velocity slip. As a result, it was found that with the addition of solid particles and an increase in volume concentration, the drag effect of the solid phase and the trend of accumulation near the lower wall caused a decrease in the liquid phase velocity profile and deformation of the parabolic shape. In the liquid–solid particle flow with a volume concentration of 1.33 × 10-3, compared to the single-liquid phase flow, the standard deviation of velocity in the central region increased from 0.0097 m/s to 0.0159 m/s, and in the near-wall region, it increased from 0.0257 m/s to 0.0347 m/s, representing increases of 1.54 times and 1.26 times respectively. The proportion of medium vortices increased from 17 % to 30 %, nearly doubling. This study actively explores the concurrent measurement and flow characteristics of liquid–solid particle flow.

Direct numerical simulation of three-dimensional particle-laden thermal convection using the Lattice Boltzmann Method

In thermal multiphase flows, the modulation in the heat transfer rate due to the presence of finite-size solid particles attract growing interest in recent years. This study focuses on developing a robust and efficient simulation method for particle-laden Rayleigh-Bénard convection. The present work utilizes the double distribution function-based thermal lattice-Boltzmann method (TLBM), which enables successful simulations of multiphase fluid-thermal interactions. The no-slip boundary of the moving solid particles is handled by the interpolated bounce-back scheme. Additionally, Galilean invariant momentum exchange and heat exchange approaches are employed for hydrodynamic force and heat transfer calculation at the solid boundaries. The accuracy of the current method is verified with several benchmark cases, including three-dimensional single-phase Rayleigh-Bénard convection, as well as the settling of hot and cold spherical particles in a three-dimensional enclosure. Furthermore, we explore the modulation of Rayleigh-Bénard flows due to the presence of freely moving finite-size particles. The simulations are conducted on a distributed memory cluster with a 3D domain decomposition technique facilitated by the MPI library. A brief discussion on the parallel performance of the simulations is provided for both particle-laden and single-phase flow scenarios. Finally, the effects of finite-size solid particles on the overall heat transfer efficiency and modulation to the flow field in three-dimensional particle-laden turbulent Rayleigh-Bénard convection are discussed. The results show that addition of solid particles results in a moderate increase in the overall Nusselt number, and this enhancement is mainly due to the increased heat flux transported by the particles.

Slurry and liquid impingement erosion behavior of low-temperature plasma carburized AISI 420 martensitic stainless steel

The impact of plasma carburizing treatment on the erosion wear resistance of AISI 420 martensitic stainless steel (MSS) was studied. Experiments were carried out varying a broad spectrum of erosion parameters, including impact velocity, impact angle, and exposure duration. Both slurry and liquid impingement erosion were employed in the experiments, with testing conducted using both distilled water and saline solutions to assess the combined effects of corrosion and erosion wear. Compared to untreated samples, a significant improvement in the erosion wear resistance of AISI 420 MSS due to low-temperature plasma carburizing treatment was observed for all tested conditions. The observed performance enhancement can be attributed to the formation of the carburized layer, constituted of the α'C and Fe3C phases. Results also highlighted that the severity of the tribosystem was significantly influenced by the test solution characteristics. A marginal increase in severity was observed upon introducing the saline solution, while a more substantial severity increase occurred with the addition of solid particles in the test fluid. The specimens' mass loss was increased by increasing impact velocity, following a simple potential relationship, and with impact angle, following a first-degree linear equation. In the case of the exposure time, the mass loss curves depended on the test environment. For solutions containing quartz particles, an additional final stabilization stage was observed in addition to the acceleration stage observed in the absence of abrasive component. This phenomenon was attributed to surface work hardening induced by the impact of solid particles. Regarding wear mechanisms, samples tested only with distilled water displayed erosion flow marks. Those containing distilled water and NaCl exhibited not only flow marks but also pits. Lastly, solutions containing solid particles additionally presented features of plastic deformation, lip formation, craters, indentations, and extruded material.

Characterization of a CrN/Cr gradient coating deposited on carbon steel and synergistic erosion-corrosion behavior in liquid‒solid flow impingement

Erosion-corrosion resistance is a critical factor in the service life extension of metallic structural materials in front of complex flow and solid impingement. To improve the erosion-corrosion resistance, a CrN/Cr gradient coating was fabricated on carbon steel by the double glow plasma alloying technique. The CrN/Cr gradient coating mainly consists of the CrN phase and (Fe, Cr) metal phase. Debye rings from the X-ray pattern illustrated that the coating was under a compressive stress of 868 MPa. Residual stress and fine toughness of the gradient structure enhanced its adhesion strength, endowing it with the potential to accommodate strains caused by external forces. The potentiodynamic polarization test illustrated that the addition of solid particles and the increase in flow velocity severely weakened the protective ability. The mass loss rate results illustrated that the synergistic effect made the greatest contribution to the erosion-corrosion damage of the CrN/Cr gradient coating, while its proportion increased as the flow velocity increased. Compared to the substrate, the gradient structure of the coating facilitated interruption of the sharp interfaces, thereby reducing the deformation mismatch and enhancing the damage tolerance of the coating.

A Model of Froth Flotation with Drainage: Simulations and Comparison with Experiments

The operation of a froth flotation column can be described by a nonlinear convection–diffusion partial differential equation that incorporates the solids–flux and drift–flux theories as well as a model of foam drainage. The resulting model predicts the bubble and (gangue) particle volume fractions as functions of height and time. The steady-state (time-independent) version of the model defines so-called operating charts that map conditions on the gas and pulp feed rates that allow for operation with a stationary froth layer. Operating charts for a suitably adapted version of the model are compared with experimental results obtained with a laboratory flotation column. Experiments were conducted with a two-phase liquid–bubble flow. The results indicate good agreement between the predicted and measured conditions for steady states. Numerical simulations for transient operation, in part for the addition of solid particles, are presented.

Experimental examination of the properties of Fe3O4/water nanofluid, and an estimation of a correlation using an artificial neural network

Currently, considering that the addition of solid particles to normal fluids directs to a considerable increase in thermal conductivity, the utilization of nanofluids rather than typical liquids is extremely customary. This paper provides an experimental evaluation of the viscosity and thermal conductivity of Fe3O4/water nanofluid and provides an estimation model using an artificial neural network (ANN) and margin of deviation. For this purpose, Fe3O4 nanoparticles were synthesized by the co-precipitation method, and the size of nanoparticles was investigated by the XRD test. Also, the Fe3O4/water nanofluid was prepared in a two-step method and the stability of the nanofluid was evaluated by the zeta potential test. Then, thermal conductivity and viscosity of nanofluid were measured at temperatures of 25, 30, 35, 40, 45, and 50°Celsius and volume fractions of 0.1, 0.2, and 0.3%. The outcomes of this experiment indicated that the volume fraction of nanoparticles and temperature have an immediate relationship with the thermal conductivity coefficient of nanofluids because, with the increase of these two parameters, the thermal conductivity coefficient increases and vice versa. Also, the viscosity of the nanofluid decreases with the decrease in volume fraction of nanoparticles and increases with the decrease in temperature.Because of the absence of an exact and proper correlation to predict the viscosity and thermal conductivity of this nanofluid, two correlations are presented as a subordinate of temperature and volume fraction. Also, a analogy was made among the results of the experiment and the output of the proposed relationship and it was found that the maximum margin of deflection for thermal conductivity is equal to 0.42% and for viscosity is 0.06%. Toward the end of this research, the laboratory results were analyzed by neural networks. The designed neural network was compared with the values obtained from the suggested relationship and the outcomes indicated that in predicting the viscosity and thermal conductivity of nanofluids, the neural network has fewer blunders and higher accuracy.

Erosion-Corrosion of Gathering Pipeline Steel in Oil-Water-Sand Multiphase Flow

This work studies a series of factors influencing erosion-corrosion in oilfield gathering pipelines steel using the home-made testing pipe flow loop. Results showed that steel was corroded in oil-water flow. The corrosion rate increased with the flow velocity on the whole, and the addition of solid particles would intensify the localized corrosion. For the erosion-corrosion test added with 2 wt% quartz sand at the velocity of 2 m/s, the portion of pure corrosion and pure erosion accounted for 47.50% and 70.83%, respectively. The erosion-enhanced corrosion was 16.67% of the total weight loss, while the corrosion inhibiting the damage from erosion accounted for 35.00%, so negative synergistic effects appeared in the oil-water-sand multiphase flow conditions.

Experimental assessment of thermal and rheological properties of coconut oil-silica as green additives in drilling performance based on minimum quantity of cutting fluids

Conventional metal working fluids are prepared from petroleum based mineral oils with toxic, carcinogenic, non-biodegradable and unsustainable additives, which can cause serious environmental contamination and health risks to operators. Formulations with non-toxic emulsifiers and natural additives such as vegetable oils are currently being considered for further development and use of non-toxic tribological products. This study is concerned with the thermal and flow properties of a cutting fluid (taladrine, T) mixed with a phase change material (PCM) coconut oil (CO) in a proportion of 1:9 (CO-0.1T) and hydrophilic silica in 0.01, 0.03 and 0.05 vol fractions. The thermal properties were evaluated by differential scanning calorimetry (DSC) and thermal conductivity measurements while the flow properties were assessed by viscosity temperature curves. The addition of solid particles has demonstrated an enhancement of the thermal conductivities with small differences in the latent heat. The microstructure of the suspensions was established from the DSC cooling dynamic thermogram and the rheological measurements. These results were confirmed by the images of optical polarized microscopy in which plate-like needles were observed. The suspension of 0.03 silica in CO-0.1T demonstrated an adequate gel strength and produced a reduction of 11 °C in drilling performance. A Minimum Quantity of Cutting Fluid (MQCF) of 2 g as an alternative for dry machining and flood cooling. It also prevented evaporative loss and removed metal chips, as a high viscosity complex fluid. In this work the use of phase change materials filled with solid particles as a way of sustainable eco-friendly toxic waste removal in drilling was justified.

Study of the Mechanical Properties of a CMDB Propellant Over a Wide Range of Strain Rates Using a Group Interaction Model

Composite modified double base (CMDB) propellants are heterogeneous propellants in which properties are significantly improved by adding solid particles into the polymer matrix. A molecular group interaction model that can predict the mechanical properties of polymers through a molecular structure is used to predict the viscoelastic behavior of the CMDB propellant. Considering that the addition of solid particles will improve the crosslinking degree between polymer molecules and reduce its secondary loss peak, the input parameters of the model are modified through dynamic mechanical analysis (DMA) experimental data. By introducing the strain rate into the expression of model glass transition temperature, the mechanical properties of propellant over a wide strain range ( 1.7 × 10 − 4 s-1 ~ 3000 s-1) are obtained. The reliability of the model is verified by comparison with uniaxial compression test data. By modifying the input parameters of the model, the effects of different mass ratios of nitrocellulose (NC)/nitroglycerin (NG) on the mechanical properties of the CMDB propellant were analyzed. The results show that the glass transition loss increases with increasing mass ratio of NC/NG, while Young’s modulus and yield stress decrease.

Thermophysical properties of graphene-based nanofluids

• Nanofluids have enhanced thermophysical properties with improved heat transfer efficiency. • Graphene-based nanofluids have an outstanding thermal conductivity. • The main challenge with graphene-based nanofluids are the cost, stability, and high viscosity. • Graphene-based nanofluids have lower environmental impacts. Heat transfer operations are very common in the process industry to transfer a huge amount of thermal energy, i.e., heat, from one fluid to another for different purposes. Many fluids are used as heat transfer fluid (HTF), in which water is the most common HTF due to its high specific heat, availability, and affordability. However, conventional HTFs, including water, have a lower thermal conductivity, which is the most critical thermophysical property, hence decreased heat transfer efficiency. The addition of solid particles of highly thermally conductive material, specifically at nano-size, i.e., nanoparticles NPs, result in nanofluid NF, which has evolved over the last two decades as efficient HTF and have been investigated in a wide range of applications. Among NPs, graphene (Gr) based materials have shown very high potential as NF due to the very high thermal conductivity up to 5,000 W/m.K, hence higher thermal conductivity NF. This work aims to thoroughly discuss the thermophysical properties of Gr-based NFs, including thermal conductivity, heat capacity, density, and viscosity. The discussion focus on the thermophysical properties as it is the ultimate determinator of the heat transfer characteristics of the HTF, such as the convective and the overall heat transfer coefficient as well as the heat transfer capacity of the NF. The discussion expands to the relative enhancement in such thermophysical properties reaching up to a 40% increase in thermal conductivity, as the most critical thermophysical property. The discussion shows that Gr-based NF has a much higher thermal conductivity relative to widely studied metal oxide NF and at much lower content, and lower density and viscosity increase, which is critical for determining the pumping power requirements. Critical challenges facing the application of Gr-based NFs such as cost, stability, increased density and viscosity, and environmental impacts are thoroughly discussed with mitigation recommendations given.

CFD simulations of stirred-tank reactors for gas-liquid and gas-liquid-solid systems using OpenFOAM®

Abstract An open-source CFD software OpenFOAM® is used to simulate two multiphase stirred-tank reactors relevant to industrial processes such as slurry polymerization and fuel production. Gas-liquid simulations are first performed in a single-impeller stirred-tank reactor, studied experimentally by Ford, J. J., T. J. Heindel, T. C. Jensen, and J. B. Drake. 2008. “X-Ray Computed Tomography of a Gas-Sparged Stirred-Tank Reactor.” Chemical Engineering Science 63: 2075–85. Three impeller rotation speeds (200, 350 and 700 rpm) with three different bubble diameters (0.5, 1.5 and 2.5 mm) are investigated. Flow patterns compared qualitatively to those from experiments. Compared to the experimental data, the simulations are in relatively good agreement for gas holdup in the reactor. The second multiphase system is a multi-impeller stirred-tank reactor, studied experimentally by Shewale, S. D., and A. B. Pandit. 2006. “Studies in Multiple Impeller Agitated Gas-Liquid Contractors.” Chemical Engineering Science 61: 486–504. Gas-liquid simulations are performed at two impeller rotation speeds (3.75 and 5.08 RPS). The simulated flow patterns agree with published pictures from the experiments. Gas-liquid-solid simulations of the multi-impeller stirred-tank reactor are also carried out at impeller rotation speed 5.08 RPS. The addition of solid particles with a volume fraction characteristic of slurry reactors changes the flow pattern significantly. The bottom Rushton turbine becomes flooded, while the upper pitched-blade downflow turbines present a radial-pumping flow pattern instead of down-pumping. Nonetheless, the solid phase has a similar flow pattern to the liquid phase, indicating that the particles modify the effective density of the fluid.

Experimental and Computational Determination of the Wear Resistant Coefficient for Coatings with Nanodispersed Carbide Particles Added by Laser Surfacing

The results of domestic and foreign investigations into the laser surfacing of coatings containing a strengthening carbide phase, as well as metallographic and tribological investigations of coatings by alloy powders of the Ni–Cr–B–Si system, including the addition of nanodispersed titanium and tungsten carbide particles, are presented. Values of the wear resistance coefficient (Kw) of coatings during abrasive wear testing according to the Brinell–Haworth scheme are determined. The use of Kw makes it possible to determine coefficient C when performing a scratch test of the coatings, which depends on the coating hardness, treatment modes, and addition of solid particles. It is found that the magnitude of C is affected by a series of factors such as the processing speed, input laser power density, base melting depth, and carbide phase presence and content. The larger the melting depth is, the lower the coating wear resistance is, which is associated with mixing the base material and surfaced coating. Introducing tungsten carbide nanoparticles in an amount from 3 to 7% makes it possible to increase the coating wear resistance by a factor of 1.5–2.0 when compared with the surfaced powder coating made of the PR-HKh15SR2 alloy and by a factor of 4.6–7.1 with respect to the base material—steel 40Kh. Microhardness of the initial powder is 6400–6600 MPa and increases with the introduction of carbides into it. For example, microhardness reaches 7620–9160 MPa with a WC content of 7% in the coating. Positive surfacing results are found with the emission power density up to 50 W s/mm2, but its further increase leads to the burnout of alloying elements and dissociation of carbides.

Relative Effect of Additional Solid Media on Bubble Hydrodynamics in Bubble Column and Airlift Reactors towards Mass Transfer Enhancement

Many researchers have focused on multi-phase reactor development for improving mass transfer performance. However, solid particle addition in gas–liquid contactor for better oxygen mass transfer performance is still limited. Hence, this study aims to analyze the relative effect of different types of local solid media on the bubble hydrodynamic characteristics towards mass transfer enhancement in bubble columns (BCR) and airlift reactors (ALR). This was investigated by varying solid media types (ring, sphere, cylinder, and square), solid loadings (0%–15%), and superficial gas velocities (Vg) (2.6–15.3 × 10−3 m/s) in terms of the bubble hydrodynamic and oxygen mass transfer parameters. The result showed that bubble size distribution in BCR and ALR with additional plastic media was smaller than that without media addition, approximately 22%–27% and 5%–29%, respectively, due to the increase of the bubble breaking rate and the decrease of the bubble rising velocity (UB). Further, adding media in both reactors significantly decreased the UB value. Since media increased flow resistance, resulting in decreased liquid velocity, it can also be the moving bed to capture or block the bubbles from free rising. Therefore, oxygen mass transfer performance was investigated. The oxygen transfer coefficient (KLa) in BCR with solid media addition was enhanced up to 31%–56% compared to a non-addition case, while this enhancement was greater at higher solid loading due to its higher effective surface, resulting in a higher bubble break-up rate compared to the lower loading. In ALR, up to 38.5% enhanced KLa coefficient was archived after adding plastic media over the non-addition case. In conclusion, ring and cylinder media were found to be the most significant for improving KLa value in BCR and ALR, respectively, without extra energy.

Experimental determination and calculation of wear resistance coefficient for coatings with added nanodispersed carbide particles during laser deposition

The paper presents the results of domestic and foreign studies on laser deposition of coatings using hardening carbide phases, as well as metallographic and tribological studies of coatings with Ni-Cr-B-Si alloy powders and with the addition of nanodispersed particles of titanium and tungsten carbides. Wear resistance coefficients of coatings (K w ) were determined in Brinell-Haworth abrasive wear tests. The K w value was used in coating scratch tests to determine the coefficient С that depends on the coating hardness, treatment modes and addition of solid particles. It was found that the С value is influenced by a number of factors: processing speed, input laser power density, base penetration depth, carbide phase presence and content. The higher the penetration depth, the lower the coating wear resistance due to the mixing of the base material and the deposited coating. The introduction of tungsten carbide nanoparticles in the amount from 3 to 7 % increased the coating wear resistance by 1.5-2.0 times compared to the deposited PR-NiCr15BSi2 coating powder and by 4.6-7.1 times in relation to the base material - 40Cr steel. The microhardness of the initial powder coating was 6400-6600 MPa, and it increases with the introduction of carbides. For example, microhardness reaches 7620-9160 MPa at a WC content of 7 % in the coating. Positive deposition results were obtained at radiation energy density up to 50 W•s/mm 2 , but its further increase leads to the burnout of alloying elements and dissociation of carbides.

Experimental and numerical study of cavitating particulate flows in a Venturi tube

Cavitating Venturi tubes play a significant role in mineral processing and their performance depends to a great extent on the presence of solid particles. This work is devoted to experimental and numerical studies of cavitation phenomena in a Venturi tube with different solid mass concentrations (Ws = 5–30 wt%). Numerical simulation is carried out with an axisymmetric 2D CFD-based model available in the commercial CFD software ANSYS FLUENT 16.2. The simulation is conducted using the Eulerian-Eulerian approach. A new four-phase global model was developed based on a simpler engineering approach and validated against experimental data. Predictions of the pressure drop obtained from the CFD model are generally in good conformance with experimental measurements. Both the numerical and experimental studies reveal that the addition of solid particles in the cavitating Venturi tube has significant effects on the generation of cavitation. The outcomes show that the higher solid mass concentration is of benefit to cavitation intensity. The proposed CFD model has proved to be an efficient and reliable tool in predicting the cavitation activities and performance characteristics of the cavitating Venturi tube.

Experimental investigation of hydrodynamics and mass transfer in a slurry multistage internal airlift loop reactor

Hydrodynamics and mass transfer of gas-liquid-solid slurry flow in a simple pilot multistage internal airlift loop reactor with a classic stage clearance are investigated experimentally. The presence of a critical superficial gas velocity to keep the multistage internal airlift loop reactor operating normally without particle deposit was first observed at a certain solid concentration and a fixed height of stage clearance, and an empirical model related to solid concentrations for a constant stage gap is also put forward here to predict the minimum critical superficial gas velocity in the slurry multistage internal airlift loop reactor. The results showed that compared to hydrodynamics and mass transfer in the gas-liquid two-phase flow at the same conditions, the solid concentration and the superficial gas velocity have some distinct effects. The increment of superficial gas velocity can increase the gas holdup, circulating liquid velocity, and volumetric mass transfer coefficient and at the same time decrease the mixing time, while the addition of solid particles would get the opposite effects. Additionally, compared to the two-phase flow, reverse tendencies of the gas holdup and circulating liquid velocity in different stages in the three-phase slurry multistage internal airlift loop reactor are first observed due to axial non-uniform distribution of solid particles. Therefore, solid particles can change the nature of multiphase flow in the multistage internal airlift loop reactor, and some critical information for designing this type of reactor was provided in this work.

Flow attenuation due to the addition of rigid rod-like particles

Interactions between fluid flow, in particular, turbulent flow, and solid particles are complex because many parameters control the interactions. In experiments of particle-laden turbulent flow, it is difficult to identify the scale of vortices which interacts strongly with the particles, since vortices of various scales coexist in turbulence. We, therefore, focus on the effect of the addition of solid particles to a single-scale vertical flow. More concretely, in our experiments, we use a container with a spherical cavity of 180 mm diameter. The container is filled with water and many rigid rod-like particles (the length is 12 mm and the diameter is 2 mm) are laden. We rotate the container at a constant angular velocity to create a swirling flow. This flow would be the solid-body rotation if the particles were not added. Our experiments show that the flow velocity in a central region of the cavity is drastically reduced when we add particles with a density slightly higher than that of the working fluid. We aim to explore the physical mechanism of this suppression phenomenon. For this purpose, we quantify the suppression rate by using particle tracking velocimetry (PTV) and reveal the condition when the addition of rod-like particles suppresses the swirling flow.

Atomization of Gel Fuels with Solid Particle Addition Utilizing an Air Atomizing Nozzle

Microscopic high-speed imaging is used to experimentally measure the velocity and size of droplets of gelled RP-1 based fuels with a solid particle additive. The gels are atomized using an air atomizing nozzle. The droplet diameter and velocity at a fixed position 20 cm from the nozzle on the centerline of the spray are measured at air mass flow rates of 1.5, 3 and 5 g/s. A parametric study is conducted to study the effect of gas mass flow rate, boron particle content, and species of the solid particle on the droplet characteristics. The results indicate that the droplet size decreases with the increasing of gas mass flow rate and boron particle content. Gel fuels with an aluminum particle are observed to produce smaller droplets at a low gas mass flow rate than that with a boron particle. The implication of these observations is that the atomization processes for gelled fuels with an additive of solid particles is controlled by the velocity difference between the gas and the droplets.

Analysis and predictive modeling of nanofluid-jet impingement cooling of an isothermal surface under the influence of a rotating cylinder

In this paper, numerical study and thermal prediction for a nanofluid jet impingement cooling of an isothermal hot surface with an adiabatic rotating cylinder were performed. Finite volume method was used for the solution of resulting governing equations along with the boundary conditions. Influence of various pertinent parameters such as Reynolds number (between 100 and 400), angular rotational velocity of the cylinder (between −0.1 and 0.1), horizontal location of the cylinder (between 0 and 3.75w) and solid particle volume fraction (between 0 and 0.04) on the fluid flow thermal characteristics were examined. It was observed that cylinder rotation and its location affect the cooling performance of the hot surface. It can be used as control element for heat and fluid flow. At the highest angular rotational speed as compared to motionless cylinder case, average Nusselt number reduces by about 20.16% for clockwise rotation. Solid particle addition to the base fluid affects the variation of first and secondary peaks in the Nusselt number along the hot wall. At the highest solid when the cylinder is away from the inlet slot and average Nusselt number enhancement is by about 8.08% at the highest volume fraction. An efficient modeling strategy was developed based on proper orthogonal decomposition and radial basis neural networks for thermal predictions. Accurate and fast results were achieved as compared to high fidelity computational fluid dynamics simulation results.