Values Of Pr Research Articles

Remarkably enhanced piezoelectric and ferroelectric characteristics of Er:ZnO upon graphene addition for wearable self-powered piezoelectric sensors

Flexible Er-ZnO/PDMS and Er-GO/ZnO/PDMS nanogenerators with high energy harvesting performance were developed. The output voltage and current density of Er-doped ZnO, Er-doped GO/ZnO (1:10) and Er-doped GO/ZnO (1:5) nanocomposites-based piezoelectric harvesters were (70 V, 1.85 µAcm−2), (80 V, 2.16 µAcm−2) and (100 V, 2.47 µAcm−2), respectively. The Er-doped GO/ZnO wearable sensor showed output voltages of 4 V and 9 V by bending the human wrist and elbow, respectively. In addition, a remarkable improvement of the remnant polarization (Pr) and a favourable reduction of the coercive field (Ec) were achieved for Er-doped ZnO and Er-doped GO/ZnO nanocomposites. The corresponding values of Pr and Ec for pure ZnO, Er-doped ZnO, Er-doped GO/ZnO (1:10) and Er-doped GO/ZnO (1:5) nanostructures were (0.06 μC/cm2, 6.50 kV/cm), (8.75 μC/cm2, 4.74 kV/cm), (13.25 μC/cm2, 3.98 kV/cm) and (8.913 μC/cm2, 3.54 kV/cm), respectively. The enhanced piezoelectric and ferroelectric properties of Er-doped ZnO and Er-doped GO/ZnO nanocomposites make them futuristic hybrids with immense potential for designing pressure biosensors, mechanical energy harvesters and environmentally friendly ferroelectric-based memory devices.

The Potential Value of Ki-67 in Prognostic Classification in Early Low-Risk Endometrial Cancer.

This study aims to determine the optimal cut-off value of Ki-67 to better predict the recurrence of early low-risk endometrial cancer (EC). Seven hundred and forty-eight patients diagnosed with low-risk EC from West China Second Hospital of Sichuan University and the First Affiliated Hospital of Chongqing Medical University were retrospectively analyzed. The receiver operating characteristic curve (ROC) and Youden index were used to calculate the optimal cut-off value of Ki-67 expression. The clinicopathological indexes between two groups divided by cut-off value of Ki-67 were compared. The univariate and multivariate regression analyses were performed to investigate risk factors connected to the recurrence of early low-risk EC. The survival analysis was shown in Kaplan-Meier curve. Thirty-three patients were detected with tumor recurrence after primary surgery (4.4%); 33% was the optimal cut-off value of the Ki-67 index. A high Ki-67 was significantly associated with age (P = .002), myometrial invasion (P < .001), and the expression of P53 (P = .007). The multivariate regression analysis verified that Ki67 ≥ 33% was an independent prognostic factor for predicting recurrence. The recurrence-free survival (RFS) and the overall survival (OS) in high Ki-67 group was significantly lower than that in low Ki-67 group (P < .001 and P = .029, respectively). The prognostic values of ER, PR, and P53 in combination with Ki-67 were superior to each single predictor. The optimal cut-off value of Ki-67 for predicting recurrence is 33%, which quantitatively defines the specific value of Ki-67 that causes high-risk recurrence in early low-risk EC.

Weak nonlinear analysis of nanofluid convection with g-jitter using the Ginzburg--Landau model

Abstract Nanofluid has emerged as a remarkable heat and mass transfer fluid due to its thermal characteristics. Despite this, continuing research is required to address problems in real applications and offer a solution for controlling transfer analysis. Therefore, in this study, the authors intend to model (Ginzburg–Landau equation) and analyze the two-dimensional nanofluid convection with gravity modulation. The perturbed analysis is adapted to convert the leading equations into Ginzburg–Landau equation. Lower amplitude ( δ \delta values from 0 to 0.5) values are taken since they influence transfer analysis. The values of Pr are considered as 0 to 2 to retain the local acceleration term in the system of equations. A lower amount of frequency of modulation ( Ω \Omega values from 0 to 70) is sufficient to enhance the heat and mass transfer rates. It is found that g-jitter and concentration Rayleigh numbers control the stability of the system. The Prandtl number and the amplitude of modulation enhance nano-heat and nano-mass transfer. This shows a destabilizing effect of modulation on nano-convection. Also the nano-Rayleigh number Rn has a dual nature on the kinetic energy transfer for positive and negative signs. A comparison is made between modulated and unmodulated systems, and it is found that the modulated systems influences the stability problem than the unmodulated systems. Finally, it is found that g-jitter influences effectively to regulate the transport process in the layer.

Effects of radiation and heat generation for non‐Newtonian fluid flow over slendering stretching sheet: Numerically

AbstractA numerical analysis of MHD 3D second grade fluid over slendering stretching sheet is presented in this study. In addition, heat generation and thermal radiation impacts are included to inspect the heat transfer mechanism. Using the boundary layer approximation, the problem is stated mathematically in the form of PDEs (partial differential equations), which are altered to nonlinear ODEs (ordinary differential equations) by invoking appropriate similarity variables. Solutions of these nonlinear equations are computed by MATLAB bvp4c function. Graphs for involving parameters are plotted to view their impacts on velocity and temperature. Impression of numerous parameters on Skin friction and Nusselt number are also depicted in tables and the results are discussed in detail. The computed values of skin friction revealed constant behavior and Nusselt number depicted increasing performance due to boosting values of Prandtl number Pr. The computed values of skin friction revealed constant behavior and Nusselt number depicted reducing performance due to boosting values of heat generation parameter Q. The computed values of skin friction revealed constant behavior and Nusselt number depicted reducing performance due to boosting values of radiation parameter Rd.

Structural, Dielectric and Ferroelectric Characterizations of Sol-gel Prepared Ba1-xSrxTiO3 Nanoceramics

Ba1-xSrxTiO3 (0.0 ≤ x ≤ 0.5) nanoceramics were synthesized via sol-gel route and the structural and electric properties of the resulting compositions were investigated. revealed A tetragonal crystal structures for x = 0.0 - 0.3 and a cubic structure for x = 0.5 compositions was revealed by X-ray diffraction. The smaller ionic radii of Sr ions resulted in the lowering of c/a ratio with increasing x and a tetragonal to cubic structural transformation was observed at around x = 0.4. The average crystallite size gradually decreased with increasing x from 0 to 0.5. This trend was visible in electron micrographs. The room temperature dielectric constant in these nanoceramics increases with increasing Sr and a maximum value of 1553 was observed for x=0.3. Curie temperature (Tc ) of 125 °C was obtained for x=0.0, which shifted toward lower temperature with increasing x value. The value of Tc was observed as 100 and 75 °C for x = 0.1 and 0.3, respectively. The remnant polarization (Pr ), saturation polarization (Ps ), and coercive field (Ec ) decreased with increasing Sr concentration in BT due to the structural modifications. Value of Pr decreases from 0.637 to 0.229 μC/cm2, Ps decreases from 8.910 to 3.238 μC/cm2 and Ec decreases from 0.631 to 0.255 kV/cm with increasing x from 0 to 0.5.

Entropy generation and thermal performance of tubular heat exchanger fitted with louvered corner-curved V-baffles

The current article deals with an experimental study on entropy generation analysis and thermohydraulic performance of a uniform heat-flux tube equipped with louvered corner-curved baffle tape (LCBT). Air was drawn into the inserted tube for the Reynolds number (Re) between 4760 and 29,300. The V-shaped LCBT arranged by V-tip in downstream direction was introduced with three baffle pitch ratios (PR = 1–2) and six louver angles (θ = 0–90°) for a fixed attack angle (α) of 30° and baffle height ratio (BR = 0.25). The impacts of investigated parameters on the thermal enhancement factor (TEF), Nusselt number (Nu), friction factor (f), and total entropy generation (S˙gen′) were examined. The measurements showed that the LCBT with the smallest values of PR = 1, θ = 0° give the largest Nu and f at about 4.4 and 19.2 times above the plain tube values, respectively. However, the greatest TEF around 2.23 was seen for employing the LCBT at PR = 1, θ = 45°. The entropy analysis also showed that the S˙gen′ is found to decline with the increment of PR and θ, whereas the minimal S˙gen′is at PR = 1, θ = 0° for lower Re but at PR = 1, θ = 45° for higher Re. Furthermore, the Nu and f empirical correlations for employing LCBTs were also proposed.

Mg1-xNixFe2-xCrxO4 synthesis via hydrothermal route: Effect of doping on the structural, optical, electrical, magnetic and photocatalytic properties

A pristine MgFe2O4 and a series of Ni and Cr substituted magnesium ferrite NPs have been fabricated via hydrothermal route. The influence of double ions substitution on MgFe2O4 was examined attributed to structural, optical, electrical, magnetic and photocatalytic properties. X-ray diffraction analysis revealed cubic geometry having fd3m space group with an average crystalline size in 25–33 nm. From hysteresis loop saturation polarization (Ps), coercivity and remanence polarization (Pr)was evaluated and found that the value of Ps and Pr were improved on increasing dopants content. VSM analysis confirms the ferromagnetic behavior of Mg1-xNixFe2-xCrxO4. Furthermore, thedielectric loss decreased by increasing frequency as well as the amount of dopant. UV–Vis absorption spectrum exhibited red-shift and band-gap energy reduced i.e., 2.58 to 2.29 eV. PCA study evaluated using crystal violet (CV) dye and Mg1-xNixFe2-xCrxO4 NPs exhibited higher efficiency and 97 % dye degradation was observed for Mg1-xNixFe2-xCrxO4 versus MgFe2O4 (59 %) under sunlight irradiation in 100 min. Moreover, the stability of NPs was confirmed through recycling experiment and Mg1-xNixFe2-xCrxO4 showed promising stability and reusability. Thus, the enhanced photocatalytic activity under solar light revealed its application for remediation of dyes in industrial waste under sunlight irradiation, it will make the process highly feasible.

Synthesis of Ni doped barium hexaferrite by microemulsion route to enhance the visible light-driven photocatalytic degradation of crystal violet dye

The pristine and Ni doped BaNixFe12-xO19 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) NPs have been fabricated via facile microemulsion approach and the impact of dopants was explored based dielectric, optical, structural and the photocatalytic properties of BaNixFe12-xO19 nanoparticles. X-ray diffraction and Raman study confirmed the formation of regular hexagonal geometry with space group P63/mmc with crystallite size in 32–50 nm range. Functional groups were identified using FTIR analysis. The remanence (Pr), saturation polarization (Ps) and coercivity (Hc) was explored by P-E loop analysis and the value of Pr and Ps was enhanced with the concentration of dopant. According to PL spectra, highly doped materials had a higher charge separation (e−- h+) and low recombination rate, which resulted in higher photocatalytic degradation activity of fabricated nanomaterials. The optical band gap was found to be 1.78 eV versus undoped (2.60 eV for pristine BaFe12O19). Due to polarizations, the dielectric loss, dielectric constant and tangent loss values were declined, while AC conductivity was enhanced. Photocatalytic performance of doped and undoped samples under visible right irradiation was studied for crystal violet dye. For 100 min exposure to visible light, the highly doped catalyst exhibits 97% degradation versus 60% in case of pristine this is attributed to efficient electron-hole pair separation. Furthermore, quenching effect of different scavengers indicated that hydroxyl radical had a main role, and e− or h+ played a minimal role in CV dye degradation. The enhanced properties due to doping make BaNixFe12-xO19 a potential candidate for photocatalytic applications under visible light irradiation.

Exergy Analysis of a Single-Shaft Gas Turbine Power Plant with Steam Injection

Exergy analysis has been performed on a single-shaft gas turbine with steam injection upstream (STIG) of the combustion chamber. The analysis will be performed to study the effect of increasing of compressor inlet temperature O1T design compressor pressure ratio cd PR and turbine inlet temperature O3T on the exergy destruction of STIG cycle components. For a specific value of steam mass flow rate: the increasing in O1T has a worthless effect on the exergy destruction of compressor and turbine while leads to increase in the exergy destruction of the combustion chamber. The increasing in cd PR leads to increase in the exergy destruction for all gas turbine power plant components. The increasing in O3 T leads to decrease in the exergy destruction of the combustion chamber, increase in the exergy destruction of the turbine, while has a worthless effect on the compressor. The biggest exergy destruction occurs in the combustion chamber For a specific values of O1T , cd PR , and O3 T steam injection will lead to improve the exergy destruction of the the combustion chamber, while has a reverse effect on the turbine, and has no effect on the compressor.

Optimal Homotopy Asymptotic Analysis of the Dynamics of Eyring-Powell Fluid due to Convection Subject to Thermal Stratification and Heat Generation Effect

In the present study, the effect of thermal stratification and heat generation in the boundary layer flow of the Eyring-Powell fluid over the stratified extending surface due to convection has been investigated. The governing equations of the flow are transformed from partial differential equations into a couple of nonlinear ordinary differential equations via similarity variables. The optimal homotopy asymptotic method (OHAM) is used to acquire the approximate analytical solution to the problems. Impacts of flow regulatory parameters on temperature, velocity, skin friction coefficient, and Nusselt number are examined. It is discovered that the fluid velocity augments with a greater value of material parameter E , mixed convection parameter λ , and material fluid parameter σ . The result also revealed that with a higher value of the Prandtl number Pr and the stratified parameter ε , the temperature and the velocity profile decreases, but the opposite behavior is observed when the heat generation/absorption parameter γ increases. The results are compared with available literature and are in good harmony. The present study has substantial ramifications in industrial, engineering, and technological applications, for instance, in designing various chemical processing equipment, distribution of temperature and moisture over agricultural fields, groves of fruit trees, environmental pollution, geothermal reservoirs, thermal insulation, enhanced oil recovery, and underground energy transport.

MHD Boundary Layer Flow Past an Exponentially Stretching Sheet with Darcy-Forchheimer Flow of Nanofluids

Objectives: To investigate an exponentially stretched sheet with a magnetic force to explore the Darcy-Forchheimer flow of a two-dimensional blood-based nanofluid and the effect of different relevant parameters of the fluid flow assumption for velocity and temperature profiles. Methods: Nanoparticles such as Ag, TiO2 and Fe with base fluid blood are being investigated. The governing equations of the problem, such as continuity, motion, and energy, are derived and translated into ordinary differential equations by employing appropriate optimization techniques. The bvp4c technique is used to perform numerical computations. The impacts of non-dimensional governing factors like the prandtl number (Pr), magnetic field parameter (M), Forchheimer number (Fr), porosity parameter (b ) and nanofluid volume fraction (ϕ ) are determined numerically and displayed through graphs. Tables illustrate and explain the local Nusselt number and skin friction coefficient. Findings: Velocity profile of Ag-blood, TiO2-blood and Fe-blood decreases and temperature profile increases for increasing values of Pr, b , M and Fr. For rising values of M, b , and Fr, the skin friction coefficient increases and the Nusselt number decreases, but the accelerating trend of ϕ exhibits a reversible trend. Novelty: The Darcy-Forchheimer flow of a two-dimensional blood-based nanofluid with a magnetic field is novel in the model. The (Ag-Blood, TiO2-Blood, Fe-Blood) nanofluid flow past an exponentially stretching surface is considered in the present study, while no one has considered these nanofluids for the same model. Keywords: MHD; Bloodbased nanofluid; Nanoparticles; Exponentially stretching surface; Darcy Forchheimer flow; Blood based nanofluid

Magnetohydrodynamic mixed convection flow of liquid metals in a vertical channel: A stability analysis

The impact of applied magnetic field on liquid metal flows has good prospects for the industry. For a better understanding of flow dynamics, the stability analysis of liquid metal flows through a confined transverse magnetic field is of fundamental importance in designing advanced magnetohydrodynamic (MHD) devices for the next generation. In this paper, we report the linear stability analysis of mixed convection flow of electrically conducting liquid metals with low Prandtl number (Pr) in a vertical channel under a transverse magnetic field. The flow is described by quasi-static MHD approximation. The instability properties are examined numerically through a spectral collocation method. The influence of magnetic field on instability mechanism is examined for a good range of Pr. The results demonstrate that the growth of the infinitesimal disturbance decreases with increasing strength of the applied magnetic field due to the effective Lorentz force exerted on the flow, i.e., stability of the flow increases. In contrast, the stability of the basic flow decreases on increasing the value of Pr, except for a small range of Pr, where it increases. The kinetic energy balance shows that for very small values of Pr, the shear instability dominates the flow, whereas for relatively larger values of Pr, thermal-buoyant instability plays a significant role in the instability mechanism. The dissipation of energy in the kinetic energy balance occurs prominently due to the presence of the applied magnetic field. The secondary flow pattern shows that the applied magnetic field suppresses the disturbance in the vicinity of channel walls. In contrast, a decrease in thermal diffusivity provokes instability by inviting a strong disturbance cell in the middle portion of the channel. The energy dissipation in the kinetic energy balance occurs mainly due to the presence of the magnetic field.

Solar radiation over a roof in the presence of temperature-dependent thermal conductivity of a Casson flow for energy saving in buildings

Non-Newtonian Casson fluid has great importance in biomechanics, processing of polymer, and industries. Therfore,in the current study, the solar radiation effects onCasson fluid flow and heat transfer over an exponentially stretching sheet in the presence of the influence of the temperature-dependent thermal conductivity are investigated. The propsoed mechanism is given a mathematical form in terms of partial differential equations. Using appropriate similarity variables for similar solutions, a set of partial differential equations are then reduced into set of ordinary differential equations. The solutions of transformed equations are determined by employing the MATLAB built-in function bvp4c. The solutions of velocity distribution, temperature field, and concentration profile are computed against sundry parameters and portryed in graphs. The skin friction, heat transfer rate, and mass transfer rate versus pertinent parameters are displayed in tables. The numerical outcomes show that as Casson parameter β and radiation parameter N are augmented velocity field rises and reduces with increasing values of Prandtl number Pr and thermal conductivity variation parameter γ. The temperature of fluid is enhaced as N is raised and revese trend is noted for increasing values of β, Pr, and γ. Concentration profile grows well with augmentation in N and γ and reverse behavior is observed for augmenting values of β and Pr. A comparision of present and existing results is given to validate of current solutions.

Numerical investigation of double diffusion heat flux model in Williamson nanofluid over an exponentially stretching surface with variable thermal conductivity

This investigation examines the Williamson nanofluid flow over an exponentially stretched surface with variable thickness. Cattaneo-Christov double diffusion (CCDD) heat flux model is applied while examining two cases of heat transfer, i.e., prescribed exponential surface temperature (PEST) and prescribed exponential heat flux (PEHF). A mathematical model of the problem based on momentum, mass, and energy conservation. The governing non-linear partial differential equation (PDEs) are converted into non-linear ordinary differential equations (ODEs) via similarity transformations. The velocity, temperature, and concentration profiles are obtained numerically. Additionally, the impacts of numerous physical parameters of engineering significance are visually depicted through graphs and tables. It is noted that by raising the thermal relaxation parameter γ 1 , the temperature profile decreases. When the concentration relaxation parameter γ 2 rises, then the concentration distribution also decays. When the magnetic parameter M increases, then the velocity profile decreases. For the selected numeric values of the Prandtl number Pr , the temperature profile decreases for both PEST and PEHF cases.

Nanofluid performance in a solar LFR system involving turbulator applying numerical simulation

• Innovative swirl flow tapes have been utilized in LFR system. • Hybrid nanoparticles (Al 2 O 3 + CuO) were dispersed considering homogeneous model. • Inclusion of hybrid nanomaterial makes Nu to intensify around 5.26%. • As Q increases, Nu intensifies about 60.21%. • With augment of Q and T in , η t declines around 15.35% and 0.304%. With involving innovative swirl flow tapes through the absorber tube in LFR system, the productivity of unit was improved in present study. To grow the thermal feature of water, hybrid nanoparticles (Al 2 O 3 + CuO) were dispersed. For designing current solar unit, 12 mirrors, one absorber tube and secondary reflector have been used. To calculate the heat source in solid zone of tube, SolTrace has been applied. Because of low fraction of each type of nano-sized material, single phase formulation were utilized. For analyzing the 3D turbulent flow of hybrid nanomaterial within the tube, FVM was chosen with incorporating K-ε formulations. Effects of inlet flow rate (Q) and its temperature (T in ), pitch ratio (PR = 0.147059 to 0.5) and height ratio (BR = 0.16 to 0.24), have been examined in outputs. Three important functions which were calculated for all cases were: Nusselt number ( Nu ), thermal productivity ( η t ) and Darcy factor ( f ). Inclusion of hybrid nanomaterial causes Nu , f and η t to intensify around 5.26%, 4.67% and 0.316% when Q = 15, PR = 0.5, BR = 0.24. As greater value of PR has been chosen, Nu , f and η t enhance around 22.27%, 112.45% and 0.514% when Q = 15, BR = 0.16. Intensify of BR creates more secondary flow and Nu , f and η t augments about 6.36%, 48.7% and 0.06%, when Q = 15, PR = 0.5. With augment of Q and T in , η t declines around 15.35% and 0.304%. As Q increases, Nu intensifies about 60.21% but f declines about 11.1% when PR = 0.5, BR = 0.24.

Dual Solution with Heat Transfer through Moving Porous Plate of an Unsteady Incompressible Viscous Fluid

We examine graphically the behavior of the dual solution of an unsteady incompressible viscous flow with heat transfer due to a moving porous surface. The mathematical model is developed with the implementation of conservation laws which are then tackled numerically, and the simulations are performed through the Keller–Box technique. Application of the Keller–Box technique allows the non-linear differential equations to transform to a scheme of linear differential equations which are easier to illuminate. Outcomes of velocity and thermal behavior are shown graphically for certain values of the dimensionless parameters. It is obvious from the results that temperature of fluid decreases with the increasing values of dimensionless Prandtl number Pr, whereas the velocity enhances for blowing situations.

Effect of dopant on ferroelectric, dielectric and photocatalytic properties of Co–La-doped dysprosium chromite prepared via microemulsion route

In the current study, pristine and a series of La and Co-doped dysprosium chromite (Dy1-yLayCr1-xCoxO3) nanoparticles have been fabricated via a facile microemulsion technique. The influence of doping was evaluated based on structural, ferroelectric, dielectric, and photocatalytic properties. The prepared nanoparticles were characterized by XRD, SEM, Raman, and UV–Vis techniques. XRD patterns confirm the synthesis of a monophase orthorhombic structure with space group Pbnm with an average crystalline size in the 18–37 nm range. The saturation polarization (Ps), remanence (Pr), and coercivity (Hc) were determined using a hysteresis loop, and it was observed that by increasing the concentration of dopants, the value of Ps and Pr were improved. According to the PL spectra, highly substituted materials had a low recombination rate and higher charge separation (e− - h+), which was ultimately accountable for higher photocatalytic activity. The dielectric loss decreases with frequency and dopant concentration. The photocatalytic activity of Dy1-yLayCr1-xCoxO3 was investigated against Crystal Violet (CV) dye under sunlight irradiation. The Dy1-yLayCr1-xCoxO3 furnished a 70% dye degradation in 90 min, which is attributed to the tunned bandgap and efficient electron-hole pair separation and the photocatalytic activity under visible light making Dy1-yLayCr1-xCoxO3 a promising photocatalyst for dye removal from wastewater.

Elementary School Students' Waste Management Behavior Determinant in Kerinci Regency in 2021

The existence of waste at this time was still a problem that hit almost all regions in Indonesia. Keliling Danau Districts in 2019 has produces 33,311 m3 of waste per year with a population of 22,207 people. The purpose of this study was to determine the determinants behavior of waste management in elementary school students at Kerinci Regency, 2021. This study aims to determine the relationship between knowledge, attitudes, and Availability of Facilities with Waste Management in State Elementary School 52 of Koto Dian students, Kerinci Regency. This research is quantitative with a cross sectional research design. Sampling using random sampling technique with a total sample of 44 students consisted of class III, IV, V to class VI. Data was collected by distributed of questionnaires. Analysis used chi-square test. The results of this study indicate that 18 of 44 (40.9%) respondents with poor behavior of waste management and 26 (59.1%) respondents with good behavior waste management. From the results of the bivariate test, it was found that Knowledge has a PR value = 3.33 CI = 1.73-6.39 and a p-value of 0.001 indicates that there is a relationship between knowledge and behavior of waste management. Attitude has a value of PR = 3.75 CI = 1.62-8.68 and a p-value of 0.001 indicates that there was a relationship between attitude and behavior of waste management and there was not relationship between availability of facilities and behavior of waste management with a p-value of 0.222. The conclusion of this study is that there is a relationship between knowledge and attitudes with behavior waste management. And the availability of facilities has no relationship between behavior of waste management in elementary school students.

Computational analysis of the transient mixed convective flow of nanofluid in the plume regions

Computer microchips and many other electrical devices that use microfluidics use nanofluids as coolants. Nanofluids have a higher thermal conductivity due to the volumetric proportion of nanoparticles. Thus, as the nanofluids in engineering and industrial process have a significant role, the current study aims to focus on the transient mixed convective flow of nanofluid in the plume regions. The numerical solutions for the transient mixed convection flow in the form of amplitude and phase angle are performed reasonably. The desired nonlinear mathematical model is created by incorporating periodic behavior into conservation equations and appropriate boundary conditions. Using appropriate scaling variables, the dimensioned equations are transformed into dimensionless ones. Solutions for the values of Prandtl number Pr, Schmidt number Sc, thermophoretic parameter Nt, Brownian motion parameter Nb and mixed convection parameters and show that the coupling between the fluid and heat transfer can have dramatic effects on the transient shear stress heat and mass transfer. The buoyancy force acting on the heated boundary layer of nanofluid can also have a significant impact on transient skin friction, heat and mass transfer. The governing process is accelerating or depending upon the position of the sphere.

Solvent extraction with a three-dimensional reticulated hollow-strut SiC foam microchannel reactor

• A novel 3-D reticulated microchannel reactor based on the hollow-strut SiC foam for rare earths extraction. • High extraction efficiency and excellent mass transfer performance at high flow rate. • The structure-performance relationship of the foam was studied by extraction experiments combined with numerical simulations. Recently, there has been considerable interest in the use of microchannel reactors for hydrometallurgy of rare earths (REs). Here, a novel integrated microchannel reactor based on the hollow-strut SiC foam material is presented and demonstrated to extract Ce 3+ and Pr 3+ using 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (P507) as the extractant. The typical three-dimensional reticulated structure of the hollow-strut SiC foam was characterized by scanning electron microscopy and X-ray micro computed tomography. Since the reactor’s structure plays a key role in fluid mixing and mass diffusion during the extraction process, the structure-performance relationship of the foam was studied by extraction experiments combined with numerical simulations. Using the foam with the optimal structure, the influence of the flow rate Q 0 of the two liquid phases on the extraction efficiency η and overall volume mass transfer coefficient K L a was discussed. For both RE ions, with increasing Q 0 , η decreases while K L a increases. For the total flow rate of the two phases of 4 ml⋅min −1 , the η values of Pr 3+ and Ce 3+ reached 98.7% and 97.0%, respectively. For the total flow rate of 36 ml⋅min −1 which was much higher than that of many other microchannel reactors reported in the literatures, the η values of Pr 3+ and Ce 3+ still reached 92.2% and 86.9%, respectively, and the K L a values of Pr 3+ and Ce 3+ were 0.198 and 0.161 s −1 , respectively, similar to the high values reported for other microchannel reactors studied in previous work. These findings indicate that the hollow-strut SiC foam microchannel reactor is suitable for use in REs extraction.