Non-Newtonian nanofluid characteristics over a melting wedge: A numerical study

A study is conducted to determine the impact of joule heating, thermo-diffusion, and chemical reaction effect on wedge flow with melting. Using similarity transformation, the nonlinear PDEs regulate nanofluid flow is converted to nonlinear ODEs. The MATLAB solver is used to solve the boundary value problem numerically. The interaction of relevant physical entities on nanoparticle concentration, nanofluid temperature, nanofluid velocity, skin friction, rate of heat, and mass transfer is graphically portrayed. This study will aid in the development of cooling devices and various shapes in heat sinks, as well as improving the heat transfer characteristics of Casson flow and strengthening formerly industrial uses. In the limiting situation, current findings are compared to analysis of findings. Flow velocity and concentration compacts in association with enhancing values of chemical reaction factor while temperature increases with enhancing the values of chemical reaction parameter. An upsurge in the temperature of the fluid is seen with the increasing Eckert number. It is found that the melting process increases the thicknesses of Solutal, thermal, and momentum boundary layers while it reduces mass transfer rate, heat transfer rate, and Skin friction. The Casson fluid displays a superior heat transfer mechanism than the Newtonian fluid. This study would be valuable in designing cooling gadgets and heat sinks of various shapes which will enhance the heat transfer properties of Casson nanofluids thereby increasing their applications in industrial perspectives. Moreover, the study reveals the novel applications of Casson nanofluids in cooling devices and heat sinks.     

Effects of nonlinear chemical reactions on the transport coefficients associated with steady and oscillatory flows through a tube

The paper concerns with the determination of effective transport coefficients associated with the oscillatory flow through a tube where a solute undergoes nonlinear chemical reactions both within the fluid and at the boundary. Method of homogenization, a multiple-scale method of averaging, is adopted to derive the transport equation that contains advection, diffusion and reaction. The resultant equation shows how the transport coefficients are influenced by the rate and degree of the nonlinear chemical reaction. Two different nonlinear reactions are considered at the bulk flow and the boundary. The reactions at the boundary may be reversible and irreversible in nature. Several facts are established from the model by fixing the rate or degree of the nonlinear reactions. Results demonstrate that the reaction at the boundary is more influential than the bulk-flow reaction in determining the transport coefficients. Also fluid-phase reaction coefficient diminishes as the nonlinearity increases, whereas the trend is opposite for the nonlinear wall-phase reaction coefficient. Different controlling parameters are found to play significant role on the transport coefficients when the ratio of wall-phase concentration to the fluid-phase concentration is low.     

Unsteady bioconvective squeezing flow with higher-order chemical reaction and second-order slip effects

In this investigation, the foremost aim is to study the impact of a higher-order chemical reaction and second-order slip on the bioconvective nanoliquid flow comprising gyrotactic microorganisms between two squeezed parallel plates. The existence of magnetic strength, thermophoretic, and Brownian migration is considered to model the flow. Similarity transformations are implemented to reduce our mathematical model into a set of nonlinear ordinary differential equations along with the requisite boundary conditions. The classical Runge-Kutta-Fehlberg method technique is employed to avail the numerical outcomes of the aforementioned nonlinear foremost equations correlated with the relevant boundary conditions. Parametric flow discussions, like, velocity profile, thermal profile, and heat and mass transport, have been portrayed through indispensable charts and graphs. Physical quantities, like, skin friction, Nusselt number, Sherwood number, and microorganism density number, have been estimated to analyze their numerous applications. The results communicate that temperature diminishes for squeezing factor and first-order velocity slip parameter, but augments for second-order slip parameter. Mass transport accelerates for chemical reaction but reduces for the order of reaction. Microorganism density number amplifies owing to chemical reaction and Peclet number while it decays for chemical reaction. This has advantageous applications in bio-micro-systems, bioreactors, biosensors, biochromatography, magnetic bioseparation devices, biocoating, and ecological fuels.     

Finite element analysis of couple stress micropolar nanofluid flow by non‐Fourier's law heat flux model past stretching surface

Numerical analysis has been done to investigate magnetohydrodynamics nonlinear convective flow of couple stress micropolar nanofluid with Catteneo‐Christov heat flux model past stretching surface with the effects of heat generation/absorption term, chemical reaction rate, first‐order slip, and convective boundary conditions. The coupled highly nonlinear differential equation governing the steady incompressible laminar flow has been solved by a powerful numerical technique called finite element method. The impacts of diverse parameters on linear velocity, angular velocity (microrotation), temperature, concentration profile, local skin friction coefficient, local wall couple stress, local Nusselt number, and Sherwood number are presented in graphical and tabular form. The result pointed out that the enhancement in material parameter β increases the velocity of the fluid while the couple stress parameter K has quite opposite effect. Heat and mass transfer rate of the fluid are enhanced by increasing material parameter while couple stress parameter shows the opposite influence. Moreover, heat and mass transfer rate are higher with the Catteneo‐Christov heat flux model than Fourier's law of heat conduction. The accuracy of the present method has been confirmed by comparing with previously published works.     

Flow of three-dimensional radiative Williamson fluid over an inclined stretching sheet with Hall current and nth-order chemical reaction

In the current communication, three-dimensional Williamson fluid flow past a bidirectional inclined stretching plate with novel Hall current, nonuniform heat source/sink, and nth-order chemical reaction features are investigated. Rosseland's diffusion model is defined for the radiation heat transfer. The nonlinear governing derivative equations satisfying the flow are transmuted to the coupled derivative equations by employing the local similarity quantities and then solved numerically through the Runge–Kutta–Fehlberg method utilizing the shooting quadrature. An inclusive analysis is reported via graphs for the flow rate field, temperature, and concentration distributions for different evolving terms of immense concern. Wall dragging effect and wall heat gradient and wall concentration gradient have been examined, plotted, and described. The detailed geometry reveals that dimensionless velocity field is monotonically rising as the Hall parameter rises. The chemical reaction concentration for the Williamson fluid is enhanced with expanding values of the magnetic field parameter. Transitional values of wall stress components upturn with an increase in Hall parameter while the Williamson term is boosted. Nusselt number is reduced as the Williamson term rises and the Sherwood number enhances with a rising chemical reaction term. The results are verified for limiting cases by comparing with various investigations and found to have excellent accuracy.     

Magnetically driven chemically reactive Casson nanofluid flow over curved surface with thermal radiation

During this exploration, Casson nanofluid is taken over a sheet that is curved and stretching in nature and its flow equations are analyzed. Radiation and slip provisions are also taken into consideration. A magnetic field of uniform rate is provided. Convective heat and mass transference extract dominant conclusions from the system. The Brownian migration together with thermophoresis is also included in the flow structure. Moreover, the chemical reaction of higher-order within the nanoingredients also generates interest. Guiding equations furnished by the selected model are resettled to ordinary differential equations of nonlinear type by significant similarity transformation. We have worked on MAPLE-19 software to work out this with a suitable accuracy rate. Upshots are shown with diagrams and tables. Corresponding physical consignment such as Nusselt number has been analyzed. Determination of skin friction and moreover Sherwood's number is also in the area of interest. Magnificent advancement in heat sifting is dealt with by magnetic and Brownian motion specification. The graphs prescribed the upshots of thermophoresis and slip parameters. Outcomes convey that temperature together with concentration are reduced for stretching parameters but velocity lines are enhanced. Heat transport goes up for magnetic and Brownian motion framework but elevated outcomes are spotted for radiative flow in contrast to nonradiative flow. Mass transfer is reduced for chemical reaction components but the rate of augmentation is elevated for higher-order chemically reactive flow. Mass Biot number and temperature Biot number both increase the concentration and temperature transport, respectively.     

Nanofluid Flow in a Porous Channel with Suction and Chemical Reaction using Tiwari and Das's Nanofluid Model

In this paper, an analysis is made for a nanofluid flow in a porous channel by introducing the conservation equation of nanoparticle volume fraction into Tiwari and Das's nanofluid model. The suction and chemical reaction are also considered in this work. The governing partial differential equations are simplified by employing a new variable and transformed into a system of high‐order nonlinear ordinary differential equations by similarity transformations. The Keller box method is used to solve this problem numerically. In addition, the influences of significant physical parameters on the distributions of the velocity and temperature as well as nanoparticle concentration are graphically presented and discussed in detail. It is found that there exists a critical value of the permeable parameter which determines the influence law of nanoparticle volume fraction parameter on skin friction coefficient and local Sherwood number. The results also indicate that the concentration increases sharply with the Schmidt number and chemical reaction parameter.     

Influence of viscous dissipation and spanwise cosinusoidally fluctuating temperature on MHD free convective boundary layer flow with radiation absorption and chemical reaction

The current reconnaissance emphasis on spanwise cosinusoidally fluctuating temperature along with time deepened as well as radiation absorption on unsteady magneto-hydrodynamics free convective heat and mass transfer boundary layer flow with viscous dissipation, constant suction normal to an infinite hot vertical porous plate in the existence of chemical reaction by means of heat generation. The analytical solution of nonlinear PDE's governing the flow has been accomplished by employing a second-order multiple regular perturbation method within the stipulated boundary conditions. Velocity, temperature, concentration as well as Sherwood have been exemplified graphically; along with Skin friction, and Nusselt numbers are ascertained in tabular form. Eventually, it was found that velocity, temperature, and Skin friction accelerated with the accumulative values of Eckert number and radiation absorption, but conflicting results emerged in the case of Prandtl number. Contemporaneously Sherwood's number depreciated with the magnification of the chemical reaction parameter as well as the Schmidt number.     

MHD nonlinear radiative flow of Carreau nanofluid with variable chemical reaction: An approach to control global warming

Solar energy is a significant source of clean and renewable energy, which can be harnessed to control global warming/pollution levels. Carreau nanofluid models have been used in the cooling of solar devices so as to upgrade the efficiency of solar energy systems. The energy equation is modeled by adopting nonlinear thermal radiation because it has a major role on the solar energy absorption capacity of nanofluid. Diffusion of species involving chemical reactions in boundary layer flow finds overwhelming applications in pollution studies, polymer production, in the design of chemical processing equipments, and so forth. In view of this, the present article is developed to evaluate the impact of nonlinear thermal radiation, chemical reaction, and applied magnetic field to the flow of Carreau nanoliquid induced by exponentially extendable surface. The outcomes of the preset study include that more magnetized the conducting fluid contributes more controlled motion of both shear thinning and shear thickening fluids. Axial and transverse surface viscous drag forces, rate of heat, and mass transportation augment with raising Weissenberg parameter while temperature and concentration fields attain a descending trend due to it. In addition, augmented temperature ratio parameter upgraded the thermal field.     

Radiative unsteady hydromagnetic 3D flow model for Jeffrey nanofluid configured by an accelerated surface with chemical reaction

The current exploration reveals the unsteady three‐dimensional flow of Jeffrey nanofluid over a bidirectional oscillatory stretching surface. The Brownian motion and thermophoresis phenomenon has been scrutinized by utilizing Buongiorno's nanofluid model. The heat transfer analysis is carried out in the presence of thermal radiation and heat generation/absorption features. Furthermore, chemical reaction and magnetic effects are also deliberated. The flow has been generated by a bidirectional periodically accelerated heated surface. The formulated nonlinear problem is condensed into a dimensionless form via apposite transformations, and then analytic series solution is computed via homotopic technique. Comprehensive graphical evaluations for numerous prominent flow constants on associated profiles are performed. In addition, the tabulated numerical calculations for the local Nusselt and Sherwood numbers are also presented. The current analysis reported that both components of velocities have an increasing tendency for higher Deborah number, whereas an adverse influence is observed for the ratio of relaxation and retardation times parameter. Moreover, the concentration profile diminishes for the increasing variation of the chemical reaction parameter.     

Thermal analysis of buoyancy-motivated Casson fluid flow with time-independent chemical reaction under Lorentz forces

The present research study examines the magneto-hydrodynamic natural convection visco-elastic boundary layer of Casson fluid past a nonlinear stretching sheet with Joule and viscous dissipation effects under the influence of chemical reaction. To differentiate the visco-elastic nature of Casson fluid with Newtonian fluids, an established Casson model is considered. The present physical problem is modeled by utilizing the considered geometry. The resulting system of coupled nonlinear partial differential equations is reduced to a system of nonlinear ordinary differential equations by applying suitable similarity transformations. Numerical solutions of these reduced nondimensional governing flow field equations are obtained by applying the Runge-Kutta integration scheme with the shooting method (RK-4). The physical behavior of different control parameters is described through graphs and tables. The present study describes that the velocity and temperature profiles decreased for increasing values of Casson fluid parameter. Velocity field diminished for the increasing nonlinear parameter whereas velocity profile magnified for increasing free convection parameter. Thermal field enhanced with increasing magnetic parameter in the flow regime. The concentration profile decreased for the rising values of the chemical reaction parameter. The magnitude of the skin-friction coefficient enhanced with increasing magnetic parameter. Increasing Eckert number increases the heat transfer rate and increasing chemical reaction parameter magnifies the mass transfer rate. Finally, the similarity results presented in this article are excellently matched with previously available solutions in the literature.     

Crude Oil Fouling in a Pilot-Scale Parallel Tube Apparatus

Maya crude oil fouling reveals a seemingly straightforward dependency of initial fouling rate on surface temperature, but a maximum is found in the initial fouling rate–velocity relationship, which mirrors that found in a model chemical system of styrene polymerization. The linear dependency of the logarithm of the pre-exponential factor on apparent activation energy for the crude oil is also found in the styrene system. The apparent activation energy for the crude oil ranged from 26.4 kJ/mol at 1.0 m/s to 245 kJ/mol at 4.0 m/s. Such strong dependencies of apparent activation energy on velocity, even at high velocity, are consistent with Epstein's mass transfer reaction attachment model. Surface temperatures at which the fouling rate becomes velocity independent are 274°C and 77°C for Maya crude oil and styrene, respectively. For surface temperatures in excess of this isokinetic temperature, an increase in velocity would lead to an increase in the rate of fouling.     

The capric and lauric acid mixture with chemical additives as latent heat storage materials for cooling application

The mixture of capric acid and lauric acid (C-L acid), with the respective mole composition of 65% and 35%, is a potential phase change material (PCM). Its melting point of 18.0°C, however, is considered high for cooling application of thermal energy storage. The thermophysical and heat transfer characteristics of the C-L acid with some organic additives are investigated. Compatibility of C-L acid combinations with additives in different proportions and their melting characteristics are analyzed using the differential scanning calorimeter (DSC). Among the chemical additives, methyl salicylate, eugenol, and cineole presented the relevant melting characteristics. The individual heat transfer behavior and thermal storage performance of 0.1 mole fraction of these additives in the C-L acid mixture are evaluated. The radial and axial temperature distribution during charging and discharging at different concentrations of selected PCM combinations are experimentally determined employing a vertical cylindrical shell and tube heat exchanger. The methyl salicylate in theC-L acid provided the most effective additive in the C-L acid. It demonstrated the least melting band width aimed at lowering the melting point of the C-L acid with the highest heat of fusion value with relatively comparable rate of heat transfer. Furthermore, the thermal performance based on the total amount of transferred energy and their rates, established the PCM’s latent heat storage capability.     

Melting heat transfer analysis of electrically conducting nanofluid flow over an exponentially shrinking/stretching porous sheet with radiative heat flux under a magnetic field

Modern magnetic nanomaterial processing operations are progressing rapidly and require increasingly sophisticated mathematical models for their optimization. Stimulated by such developments, in this paper, a theoretical and computational study of a steady magnetohydrodynamic nanofluid over an exponentially stretching/shrinking permeable sheet with melting (phase change) and radiative heat transfer is presented. Besides, wall transpiration, that is, suction and blowing (injection), is included. This study deploys Buongiorno's nanofluid model, which simulates the effects of the Brownian motion and thermophoresis. The transport equations and boundary conditions are normalized via similarity transformations and appropriate variables, and the similarity solutions are shown to depend on the transpiration parameter. The emerging dimensionless nonlinear coupled ordinary differential boundary value problem is solved numerically with the Newton-Fehlberg iteration technique. Validation with special cases from the literature is included. The increase in the magnetic field, that is, the Hartmann number, is observed to elevate nanoparticle concentration and temperature, whereas it dampens the velocity. Higher values of the melting parameter consistently decelerate the boundary layer flow and suppress temperature and nanoparticle concentration. A higher radiative parameter strongly increases temperature (and thermal boundary layer thickness) and weakly accelerates the flow. The increase in the Brownian motion reduces nanoparticle concentrations, whereas a greater thermophoretic body force strongly enhances them. The Nusselt number and Sherwood number are observed to be decreased with an increasing Hartmann number, whereas they are elevated with a stronger wall suction and melting parameter.     

Mechanism optimization based on reaction rate rules

Accurate chemistry models form the backbone of detailed computational fluid dynamics (CFD) tools used for simulating complex combustion devices. Combustion chemistry is often very complex and chemical mechanisms generally involve more than one hundred species and one thousand reactions. In the derivation of these large chemical mechanisms, typically a large number of reactions appears, for which rate data are not available from experiment or theory. Rate data for these reactions are then often assigned using so-called reaction classes. This method categorizes all possible fuel-specific reactions as classes of reactions with prescribed rules for the rate constants. This ensures consistency in the chemical mechanism. In rate parameter optimizations found in the published literature, rate constants of single elementary reactions are usually systematically optimized to achieve good agreement between model performance and experimental measurements. However, it is not kinetically reasonable to modify the rate parameters of single reactions, because this will violate consistency of rate parameters of kinetically similar reactions. In this work, the rate rules, that determine the rates for reaction classes are calibrated instead of the rates of single elementary reactions leading to a chemically more consistent model optimization. This is demonstrated by optimizing an n-pentane combustion mechanism. The rate rules are studied with respect to reaction classes, abstracting species, broken C–H bonds, and ring strain energy barriers. Furthermore, the uncertainties of the rate rules and model predictions are minimized and the pressure dependence of reaction classes dominating low temperature oxidation is optimized.     

What are the resource benefits of circulating fluidized bed power generation technology? Take some key thermal power units in China as an example

Efficient use of natural resources is an important part of China's energy industry to achieve sustainable development. The promotion of circulating fluidized bed (CFB) boilers is an important way to save coal and other resources from the source. This article first analyzes the connotation of resource benefits generated by CFB boilers. From the perspective of CFB technology used for low-calorific value coal recycling, coal recovery rate and sustainable development of coal resources (mainly coal can extend mining time), the resource benefits obtained by CFB are analyzed. The resource benefits obtained were analyzed. Second, based on the input-output nonlinear optimization theory, aiming at maximizing the resource benefits of CFB technology, constructing a CFB technology resource benefit nonlinear optimization model, measuring output benefits-added value, that is, the extension time of coal years and coal mining recovery rate increased value. Finally, based on the installed capacity data of China's CFB technology units from 1990 to 2015, the model designed two scenarios for China's future CFB technology development, and predicted China's 2020 CFB machine assembly capacity and power generation. On this basis, by analyzing the degree of coal resource conservation and the extension of the exploitable years, the model derives the resource benefits generated by CFB technology under different scenarios and the impact on the sustainable development of China's coal resources. These conclusions provide a quantitative basis for China's future CFB technology development.     

Darcy–Forchheimer flow of Ree–Eyring fluid over an inclined plate with chemical reaction: A statistical approach

In spite of various reports on non-Newtonian fluids, little is known on the impact of chemical reaction on the Darcy–Forchheimer flow of Ree–Eyring fluid when Cattaneo–Christov (C-C) heat flux (HF) is significant. The inclusion of porous medium occurs in various procedures which include heat transfer, geophysics design, and so forth. It also influences oil production recovery, energy storage units, solar receivers, and many others. The Darcy–Forchheimer flow model is important in the fields where a high flow rate effect is a common phenomenon, for instance, in petroleum engineering. In this study, we aim to analyze the dissipative Darcy–Forchheimer flow of Ree–Eyring fluid by an inclined (stretching) plate with chemical reaction. We have included the C-C HF model to investigate the heat transfer characteristics of the fluid. Equations in the mathematical model are metamorphosed as ordinary differential equations and then unriddled with the aid of shooting strategy. The main advantage of the shooting method is that it is easy to apply. The shooting method requires good initial guesses for the first derivative and can be applied to both linear and nonlinear problems. Results are explicated through graphs. We took the help of a statistical tool, that is, correlation coefficient to analyze the impression of crucial parameters on surface friction drag (skin friction coefficient), heat and mass transfer rates. The main inferences of this study are porosity parameter and Forchheimer numbers deprecate the fluid velocity, Eckert number ameliorates fluid temperature and concentration minifies with larger chemical reaction parameter. It is discovered that the Forchheimer and Weissenberg numbers deprecate the surface friction drag. Mass transfer rate has a substantial positive relationship with Schmidt number and chemical reaction. Furthermore, the heat transfer rate has a substantial positive correlation with the thermal relaxation parameter and a substantial negative correlation with the Eckert number.     

Multi-criteria optimization in a methanol process

Opportunities for additional profit in retrofits depend very much on the existing plant structure, its parameters and energy system. Combined production of heat flow rate, power and chemical products can improve process efficiency. This paper presents an application of the nonlinear programming (NLP) optimization techniques, including increased chemical product output, heat integration and electricity cogeneration by changing amount flow ratios of raw material, and modifying the separation and reaction systems. The existing NLP model has been extended with basic chemical kinetics, including the effects of changing raw material flow rate ratios on product yield.A case studied methanol plant was optimized using the NLP model developed earlier by including an additional flow rate of hydrogen (H₂), decreasing flow rate of high-pressure steam in crude methanol recycling, and increasing methanol production by 2.5%. The potential additional profit from the cogeneration and additional methanol production was estimated to be 2.51 MEUR/a.     

Numerical simulation of complex flow and heat transfer induced by localized laser heating on a urethane-coated substrate

A three-dimensional numerical simulation is conducted for complex flow and heat transfer that incorporate solid–liquid–vapor phase change and surface chemical reaction induced by localized laser heating on a urethane-coated stainless-steel substrate. The surface chemical reaction due to laser irradiation on the urethane-coated stainless-steel substrate, and heat and mass transfer due to melting/vaporization of the stainless steel are considered. The entire problem is solved within one computational domain that includes two solid regions and one gaseous region through a penalty method. One of the solid region is the paint that will decompose via chemical reaction to generate gaseous products and then mix with the air, and the other one is the stainless steel that melting and vaporization can occur due to extremely high temperature in the process. Moreover, the gas phase is considered as a multicomponent system that consists of O₂, N₂, CO₂, H₂O, NO₂, binder vapor, and stainless-steel vapor. In the present multiphysics simulation, the process of melting, vaporization and chemical reaction and the splash of the melted paint and stainless steel into the gas is observed.