Nanotechnology is widely used in heat transfer devices to improve thermal performance. Nanofluids can be applied in heat pipes to decrease thermal resistance and achieve a higher heat transfer capability. In the present article, a comprehensive literature review is performed on the nanofluids’ applications in heat pipes. Based on reviewed studies, nanofluids have a high capacity to boost the thermal behavior of various types of heat pipes such as conventional heat pipes, pulsating heat pipes, and thermosyphons. Besides, it is observed that there must be a selected amount of concentration for the high-performance utilization of nanoparticles; high concentration of nanoparticles causes a higher thermal resistance which is mainly attributed to increment in the dynamic viscosity and the higher possibility of particles’ agglomeration. Enhancement in heat transfer performance is the result of increasing in nucleation sites and the intrinsically greater nanofluids’ thermal conductivity.

Due to the biological risks of using the conventional lubricants, the vegetable oils have been considered nowadays. Besides, to improve the tribological properties of the vegetable oils in various applications like metal forming processes, nanoparticles have been used as additives. This research evaluated the lubrication performance of the Al₂O₃ and TiO₂ nanoparticles dispersed in rapeseed oil during the parallel tubular channel angular pressing (PTCAP) process. The experimental PTCAP tests have been fulfilled under three lubrication conditions and the comparison between the PTCAP processed tubes has been performed in terms of the maximum forming force, surface roughness, and microhardness. The experimental results indicate that adding the mentioned nanoparticles has caused at least a 50% reduction in the maximum deformation load. Moreover, a remarkable decrement in the surface roughness of the formed tubes has been obtained.

Superalloys are grouped as hard-to-cut materials with relatively poor machinability. Tool wear is considered one of the main machinabiliry attributes in machining superalloys. Although numerous works have been reported on factors governing tool life in machining superalloys, no study was found on the effect of nanoparticles stability on nanofluid performance and consequently resulted tool wear morphologies. In the present work, the nanoparticles were reinforced by means of improving the stability of the base fluid. To that accomplished, the surface active agent (surfactant) was added to the base cutting fluid as a reinforcing element. The effects of new lubricant on the tool wear morphology of A286 works parts were assessed.

Condensation is an important regime of heat transfer which has wide applications in different industries such as power plants, heating, ventilating and air conditioning, and refrigeration. Condensation occurs in two different modes including filmwise (FWC) and dropwise (DWC) condensation. DWC occurring on hydrophobic and superhydrophobic surfaces has a much higher heat transfer capacity than FWC. Therefore, wide investigations have been done to produce DWC in recent years. Superhydrophobic surfaces have micro/nano structures with low surface energy. In this study, a two-step electrodeposition process is used to produce micro/nano structures on copper specimens. The surface energy of specimens is reduced by a self-assembled monolayer using ethanol and 1-octadecanethiol solution. The results show that there is an optimum condition for electrodeposition parameters. For example, a surface prepared by 2000 s step time has 5 times greater heat transfer than FWC while a surface with 4000 s step time has nearly the same heat transfer as FWC. The surfaces of the fabricated specimens are examined using XRD and SEM analyses. The SEM analyses of the surfaces show that there are some micro-structures on the surfaces and the surface porosities are reduced by increasing the second step electrodeposition time.

A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side. Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05, inclination angle of the back and front walls (α) from 5° to 75°, Rayleigh number from 103 to 105, and length of heater changer from 0.1 to 1. The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.

Miniaturization of electronic equipment has forced researchers to devise more effective methods for dissipating the generated heat in these devices. In this study, two methods, including porous media inserting and adding nanoparticles to the base fluid, are used to improve heat transfer in an annulus heated on both walls. To study porous media insert, porous ribs are used on the outer and inner walls independently. The results show that when porous ribs are placed on the outer wall, although the heat transfer enhances, the pressure drop increment is so considerable that performance number (the ratio of heat transfer enhancement pressure increment, P_N) is less than unity for all porous rib heights and porous media permeabilities that are studied. On the other hand, the P_N of cases where porous ribs were placed on the inner wall depends on the Darcy number (Da). For example, for ribs with Da=0.1 and Da=0.0001, the maximum performance number, P_N=4, occurs at the porous ribs height to hydraulic diameter ratios H/D_h=1 and H/D_h=0.25. Under these conditions, heat transfer is enhanced by two orders of magnitude. It is found that adding 5% nanoparticles to the base fluid in the two aforementioned cases improves the Nusselt number and P_N by 10%–40%.

Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces. The aim of this research is to study the influence of nanoparticles volume fraction, nanoparticles type, suction or injection, the heat generation or absorption, the Eckert number, thermal and velocity slip parameters, and radiation on the velocity and temperature fields on the flow and heat transfer over a porous flat plate. Four different types of nanoparticles including metal nanoparticles (Cu), metal oxide nanoparticles (Al₂O₃) and carbon-based nanomaterials (MWCNTs and SWCNTs) which were dispersed in the water (as based fluid) are studied. The governing equations are converted into the ordinary differential equations using similarity solution and solved numerically by the RKF45 algorithm. The results of the simulations showed a contradiction with the results of other researchers who expressed that using nanoparticles with higher thermal conductivity and volume fraction led to increasing heat transfer rate in nanofluids; this study proves that, in some cases, boosting the volume fraction of nanoparticles has a potential to decrease the heat transfer rate due to significant changes in values of some parameters including radiation, heat generation, and viscous dissipation.

The present paper emphasizes the peristaltic mechanism of Rabinowitsch liquid in a complaint porous channel under the influence of variable liquid properties and convective heat transfer. The effect of inclination on the complaint channel walls has been taken into account. The viscosity of the liquid varies across the thickness of the complaint channel, whereas, thermal conductivity varies concerning temperature. The nonlinear governing equations are solved by using perturbation technique under the long wavelength and small Reynold’s number approximations. The expressions for axial velocity, temperature, the coefficient of heat transfer and streamlines are obtained and analyzed graphically. The above said physiological phenomena are investigated for a specific set of relevant parameters on dilatant, Newtonian and pseudoplastic fluid models. The results presented here shows that the presence of variable viscosity, porous parameter and slip parameter significantly affects the flow quantities of dilatant, Newtonian and pseudoplastic fluid models. The investigation further reveals that an increase in the value of variable viscosity and porous parameters enhances the occurrence of trapping phenomenon. Moreover, the size of trapped bolus can be eliminated with suitably adjusting the angle of inclination parameter.

In this study, magneto-hydrodynamics (MHD) mixed convection effects of Al₂O₃-water nanofluid flow over a backward-facing step were investigated numerically for various electrical conductivity models of nanofluids. A uniform external magnetic field was applied to the flow and strength of magnetic field was varied with different values of dimensionless parameter Hartmann number (Ha=0, 10, 20, 30, 40). Three different electrical conductivity models were used to see the effects of MHD nanofluid flow. Besides, five different inclination angles between 0º~90º is used for the external magnetic field. The problem geometry is a backward-facing step which is used in many engineering applications where flow separation and reattachment phenomenon occurs. Mixed type convective heat transfer of backward-facing step was examined with various values of Richardson number (Ri=0.01, 0.1, 1, 10) and four different nanoparticle volume fractions (ø=0.01, 0.015, 0.020, 0.025) considering different electrical conductivity models. Finite element method via commercial code COMSOL was used for computations. Results indicate that the addition of nanoparticles enhanced heat transfer significantly. Also increasing magnetic field strength and inclination angle increased heat transfer rate. Effects of different electrical conductivity models were also investigated and it was observed that they have significant effects on the fluid flow and heat transfer characteristics in the presence of magnetic field.

The present article has been fine-tuned with the investigation of mixed convection Darcy-Forchheimer flow of ZnO-SAE50 oil nanolubricant over an inclined rotating disk under the influence of uniform applied magnetic field applied to various industries. The current study has been enriched with additional consideration of slip flow, thermal radiation, viscous dissipation, Joulian dissipation and internal heating. In view of augmentation of thermal conductivity of nanolubricant, a new micro-nano-convection model namely Patel model has been invoked. The specialty of this model involves the effects of specific surface area and nano-convection due to Brownian motion of nanoparticles, kinetic theory based micro-convection, liquid layering and particle concentration. Suitably transformed governing equations have been solved numerically by using Runge-Kutta-Fehlberg scheme. An analysis of the present study has shown that applied magnetic field, porosity of the medium, velocity slip and inertia coefficient account for the slowing down of radial as well as tangential flow of ZnO-SAE50 oil nanolubricant, thereby leading to an improvement in velocity and thermal boundary layers.

This study presents the effect of non-uniform heat source on the magneto-hydrodynamic flow of nanofluid across an expanding plate with consideration of the homogeneous-heterogeneous reactions and thermal radiation effects. A nanofluid’s dynamic viscosity and effective thermal conductivity are specified with Corcione correlation. According to this correlation, the thermal conductivity is carried out by the Brownian motion. Similarity transformations reduce the governing equations concerned with energy, momentum, and concentration of nanofluid and then numerically solved. The influences of the effective parameters, e.g., the internal heat source parameters, the volume fraction of nanofluid, the radiation parameter, the homogeneous reaction parameter, the magnetic parameter, the heterogeneous parameter and the Schmidt number are studied on the heat and flow transfer features. Further, regarding the effective parameters of the present work, the correlation for the Nusselt number has been developed. The outcomes illustrate that with the raising of the heterogeneous parameter and the homogeneous reaction parameter, the concentration profile diminishes. In addition, the outcomes point to a reverse relationship between the Nusselt number and the internal heat source parameters.

The optimal design of heating and cooling systems must take into account heat radiation which is a non-linear process. In this study, the mixed convection in a radiative magnetohydrodynamic Eyring-Powell copper-water nanofluid over a stretching cylinder was investigated. The energy balance is modeled, taking into account the non-linear thermal radiation and a thermal slip condition. The effects of the embedded flow parameters on the fluid properties, as well as on the skin friction coefficient and heat transfer rate, are analyzed. Unlike in many existing studies, the recent spectral quasi-linearization method is used to solve the coupled nonlinear boundary-value problem. The computational result shows that increasing the nanoparticle volume fraction, thermal radiation parameter and heat generation parameter enhances temperature profile. We found that the velocity slip parameter and the fluid material parameter enhance the skin friction. A comparison of the current numerical results with existing literature for some limiting cases shows excellent agreement.

Present numerical study examines the heat and mass transfer characteristics of magneto-hydrodynamic Casson fluid flow between two parallel plates under the influence of thermal radiation, internal heat generation or absorption and Joule dissipation effects with homogeneous first order chemical reaction. The non-Newtonian behaviour of Casson fluid is distinguished from those of Newtonian fluids by considering the well-established rheological Casson fluid flow model. The governing partial differential equations for the unsteady two-dimensional squeezing flow with heat and mass transfer of a Casson fluid are highly nonlinear and coupled in nature. The nonlinear ordinary differential equations governing the squeezing flow are obtained by imposing the similarity transformations on the conservation laws. The resulting equations have been solved by using two numerical techniques, namely Runge-Kutta fourth order integration scheme with shooting technique and bvp4c Matlab solver. The comparison between both the techniques is provided. Further, for the different set physical parameters, the numerical results are obtained and presented in the form of graphs and tables. However, in view of industrial use, the power required to generate the movement of the parallel plates is considerably reduced for the negative values of squeezing number. From the present investigation it is noticed that, due to the presence of stronger Lorentz forces, the temperature and velocity fields eventually suppressed for the enhancing values of Hartmann number. Also, higher values of squeezing number diminish the squeezing force on the fluid flow which in turn reduces the thermal field. Further, the destructive nature of the chemical reaction magnifies the concentration field; whereas constructive chemical reaction decreases the concentration field. The present numerical solutions are compared with previously published results and show the good agreement.

In this paper, we have numerically examined the steady boundary layer of a viscous incompressible nanofluid and its heat and mass transfers above a horizontal flat sheet. The boundary conditions considered were a nonlinear magnetic field, a nonlinear velocity and convection. Such nonlinearity in hydrodynamic and heat transfer boundary conditions and also in the magnetic field has not been addressed with the great details in the literature. In this investigation, both the Brownian motion and thermophoretic diffusion have been considered. A similarity solution is achieved and the resulting ordinary differential equations (nonlinear) are worked numerically out. Upon validation, the following hydrodynamic and heat and mass transfers parameters were found: the reduced Sherwood and Nusselt numbers, the reduced skin friction coefficient, and the temperature and nanoparticle volume fraction profiles. All these parameters are found affected by the Lewis, Biot and Prandtl numbers, the stretching, thermophoretic diffusion, Brownian motion and magnetic parameters. The detailed trends observed in this paper are carefully analyzed to provide useful design suggestions.

This research elaborates magnetohydrodynamics (MHD) impact on non-Newtonian (Williamson) fluid flow by stretchable rotating disks. Both disks are rotating with different angular velocities and different stretching rates. Viscous dissipation aspect is considered for energy expression formulation. Entropy generation analysis is described via implementation of thermodynamic second law. Chemical processes (heterogeneous and homogeneous) subjected to entropy generation are introduced first time in literature. Boundary-layer approach is employed for modeling. Apposite variables are introduced for non-dimensionalization of governing systems. Homotopy procedure yields convergence of solutions subjected to computations of highly nonlinear expressions. The significant characteristics of sundry factors against thermal, velocity and solutal fields are described graphically. Besides, tabular results are addressed for engineering quantities (skin-friction coefficient, Nusselt number). The outcomes certify an increment in temperature distribution for Weissenberg (We) and Eckert (Ec) numbers.

This article investigates the colloidal study for water and ethylene glycol based nanofluids. The effects of Lorentz forces and thermal radiation are considered. The process of non-dimensionalities of governing equations is carried out successfully by means of similarity variables. Then, the resultant nonlinear nature of flow model is treated numerically via Runge-Kutta scheme. The characteristics of various pertinent flow parameters on the velocity, temperature, streamlines and isotherms are discussed graphically. It is inspected that the Lorentz forces favors the rotational velocity and rotational parameter opposes it. Intensification in the nanofluids temperature is observed for volumetric fraction and thermal radiation parameter and dominating trend is noted for γ-aluminum nanofluid. Furthermore, for higher rotational parameter, reverse flow is investigated. To provoke the validity of the present work, comparison between current and literature results is presented which shows an excellent agreement. It is examined that rotation favors the velocity of the fluid and more radiative fluid enhances the fluid temperature. Moreover, it is inspected that upturns in volumetric fraction improves the thermal and electrical conductivities.

Three-dimensional Darcy-Forchheimer nanoliquid flow in the presence of rotating frame and activation energy is inspected. Flow is developed through linearly stretching of the surface. Convection of heat and mass exchange is given due consideration. The novel characteristics in regards to Brownian dispersion and thermophoresis are retained. The variation in partial differential framework (PDEs) to nonlinear ordinary differential framework (ODEs) is done through reasonable transformations. Governing differential frameworks have been computed in edge of NDSolve. Discussion regarding thermal field and concentration distribution for several involved parameters is pivotal part. Physical amounts like surface drag coefficients, transfer of heat and mass rates are portrayed by numeric esteems. It is noticed that impacts of porosity parameter and Forchheimer number on the thermal and concentration fields are quite similar. Both temperature and associated thermal layer thickness are enhanced for larger porosity parameter and Forchheimer number. Temperature and concentration fields exhibit similar trend for the higher values of rotational parameter. Effects of thermal and concentration Biot numbers on the temperature and concentration fields are qualitatively similar. Higher Prandtl and Schmidt numbers correspond to stronger temperature and concentration fields. Larger nondimensional activation energy, temperature difference parameter and fitted rate constant yield weaker concentration field. Brownian motion parameter for temperature and concentration has reverse effects while similar trend is observed via thermophoresis parameter.

Present work reports chemically reacting Darcy-Forchheimer flow of nanotubes. Water is utilized as base liquid while carbon nanotubes are considered nanomaterial. An exponential stretchable curved surface flow is originated. Heat source is present. Xue relation of nanoliquid is employed to explore the feature of Cnts (single and multi-wall). Transformation technique is adopted in order to achieve non-linear ordinary differential systems. The governing systems are solved numerically. Effects of involved parameters on flow, temperature, concentration, heat transfer rate (Nusselt number) with addition of skin friction coefficient are illustrated graphically. Decay in velocity is noted with an increment in Forchheimer number and porosity parameter while opposite impact is seen for temperature. Moreover, role of Mwcnts is prominent when compared with Swcnts.

This article concentrates on the properties of three-dimensional magneto-hydrodynamic flow of a viscous fluid saturated with Darcy porous medium deformed by a nonlinear variable thickened surface. Analysis of flow is disclosed in the neighborhood of stagnation point. Features of heat transport are characterized with Newtonian heating and variable thermal conductivity. Mass transport is carried out with first order chemical reaction and variable mass diffusivity. Resulting governing equations are transformed by implementation of appropriate transformations. Analytical convergent series solutions are computed via homotopic technique. Physical aspects of numerous parameters are discussed through graphical data. Drag force coefficient, Sherwood and Nusselt numbers are illustrated through graphs corresponding to various pertinent parameters. Graphical discussion reveals that conjugate and constructive chemical reaction parameters enhance the temperature and concentration distributions, respectively.

Model of Casson nanofluid flow over a nonlinear shrinking surface is considered. Model of Tiwari and Das is applied to nanofluid comprising of sodium alginate with copper and silver. The governing nonlinear equations incorporating the effects of the viscous dissipation are transformed into boundary value problems (BVPs) of ordinary differential equations (ODEs) by using appropriate similarity transformations. The resulting equations are converted into initial value problems (IVPs) using the shooting method which are then solved by Runge-Kutta method of fourth order. In order to determine the stability of the dual solutions obtained, stability analysis is performed and discovered that the first (second) solution is stable (unstable) and physically realizable (unrealizable). Both the thickness of the thermal boundary layer as well as temperature increase when the Casson parameter (β) is increased in the second solution.

The main goal of this paper is to investigate natural convective heat transfer and flow characteristics of non-Newtonian nanofluid streaming between two infinite vertical flat plates in the presence of magnetic field and thermal radiation. Initially, a similarity transformation is used to convert momentum and energy conservation equations in partial differential forms into non-linear ordinary differential equations (ODE) applying meaningful boundary conditions. In order to obtain the non-linear ODEs analytically, Galerkin method (GM) is employed. Subsequently, the ODEs are also solved by a reliable numerical solution. In order to test the accuracy, precision and reliability of the analytical method, results of the analytical analysis are compared with the numerical results. With respect to the comparisons, fairly good compatibilities with insignificant errors are observed. Eventually, the impacts of effective parameters including magnetic and radiation parameters and nanofluid volume fraction on the velocity, skin friction coefficient and Nusselt number distributions are comprehensively described. Based on the results, it is revealed that with increasing the role of magnetic force, velocity profile, skin friction coefficient and thermal performance descend. Radiation parameter has insignificant influence on velocity profile while it obviously has augmentative and decreasing effects on skin friction and Nusselt number, respectively.

Application of nanofluids in heat pipes usually presents satisfactory experimental results regarding a thermal resistance reduction of the heat pipe. However, the existing computational studies connecting heat pipes and nanofluids lack a deeper discussion regarding the validity of the models currently used for representing the behaviour of a nanofluid in a heat pipe, particularly for unusual base fluids and nanoparticles such as carbon nanotubes or ethylene glycol. Thus, this comparative study presents the results of a set of computational simulations using pre-established equations for modelling a nanofluid in a heat pipe with experimental data from the literature. The results show agreement with the expected behaviour qualitatively and the presented maximum variations between 1.5% and 23.9% in comparison to the experimentally measured average temperatures. Also, the experimentally obtained temperature distribution of a heat pipe could not be reached numerically only with the use of adequate thermal properties, indicating that the boiling phenomenon is more complex than the current model used for computational simulations. Moreover, the existence of an optimal particle volume fraction for using nanofluids in this application could be observed by combining different properties models.

The pump performance parameters, such as pump pressure, plunger friction and pump valve resistance, are fundamental parameters of optimal design of pump efficiency and sucker rod pumping system (SRPS). In this paper, considering the characteristic of geometrical nonlinear and rheology property of multiphase fluid, the pump performance parameters are studied. Firstly, a dynamics model of annular fluid flow is built. In the detail, a partial differential equation of annular fluid is established and a computing model of fluid pressure gradient is built. Secondly, the simulation models of plunger friction and hydraulic resistance of pump valve are built. Finally, a novel simulation method of fluid pressure in annular space is proposed with software ANSYS. In order to check up the correction of models proposed in this paper, the comparison curves of experiment and simulation results are given. Based on above model, the whole simulation model of plunger pump is simulated with Visual Basic 6.0. The results show that the fluid friction of pump plunger and instantaneous resistance of pump valve are nonlinear. The impact factors of pump performance parameters are analyzed, and their characteristic curves are given, which can help to optimize the pump motion parameters and pump structural.

Thermal transport in porous media has stimulated substantial interest in engineering sciences due to increasing applications in filtration systems, porous bearings, porous layer insulation, biomechanics, geomechanics etc. Motivated by such applications, in this article, a numerical study of entropy generation impacts on the heat and momentum transfer in time-dependent laminar incompressible boundary layer flow of a Casson viscoplastic fluid over a uniformly heated vertical cylinder embedded in a porous medium is presented. Darcy’s law is used to simulate bulk drag effects at low Reynolds number for an isotropic, homogenous porous medium. Heat line visualization is also included. The mathematical model is derived and normalized using appropriate transformation variables. The resulting non-linear time-dependent coupled governing equations with associated boundary conditions are solved via an implicit finite difference method which is efficient and unconditionally stable. The outcomes show that entropy generation and Bejan number are both elevated with increasing values of Darcy number, Casson fluid parameter, group parameter and Grashof number. To analyze the heat transfer process in a two-dimensional domain, plotting heat lines provides an excellent approach in addition to streamlines and isotherms. It is remarked that as the Darcy number increases, the deviations of heat lines from the hot wall are reduced.

The present exploration is conducted to describe the motion of viscous fluid embedded in squeezed channel under the applied magnetics effects. The processes of heat and mass transport incorporate the temperature-dependent binary chemical reaction with modified Arrhenius theory of activation energy function which is not yet disclosed for squeezing flow mechanism. The flow, heat and mass regime are exposed to be governed via dimensionless, highly non-linear, ordinary differential equations (ODEs) under no-slip walls boundary conditions. A well-tempered analytical convergent procedure is adopted for the solutions of boundary value problem. A detailed study is accounted through graphs in the form of flow velocity field, temperature and fluid concentration distributions for various emerging parameters of enormous interest. Skin-friction, Nusselt and Sherwood numbers have been acquired and disclosed through plots. The results indicate that fluid temperature follows an increasing trend with dominant dimensionless reaction rate σ and activation energy parameter E. However, an increment in σ and E parameters is found to decline in fluid concentration. The current study arises numerous engineering and industrial processes including polymer industry, compression and injection shaping, lubrication system, formation of paper sheets, thin fiber, molding of plastic sheets. In the area of chemical engineering, geothermal engineering, cooling of nuclear reacting, nuclear or chemical system, bimolecular reactions, biochemical process and electrically conducting polymeric flows can be controlled by utilizing magnetic fields. Motivated by such applications, the proposed study has been developed.

This study presents the deep removal of copper (II) from the simulated cobalt electrolyte using fabricated polystyrene-supported 2-aminomethylpyridine chelating resin (PS-AMP) in a fixed-bed. The effects of bed height (7.0–14.0 cm), feed flow rate (4.5–9.0 mL/min), initial copper (II) concentration of the feed (250–1000 mg/L), feed temperature (25–40 °C) and the value of pH (2.0–4.0) on the adsorption process of the PS-AMP resin were investigated. The experimental data showed that the PS-AMP resin can deeply eliminate copper (II) from the simulated cobalt electrolyte. The bed height, feed flow rate, initial copper (II) concentration of the feed, feed temperature and feed pH value which corresponded to the highest removal of copper (II) were 7.0 cm with 35 mm of the column diameter, 4.5 mL/min, 40 °C, 1000 mg/L and 4.0, respectively. The breakthrough capacity, the saturated capacity of the column and the mass ratio of Cu/Co (g/g) in the saturated resin were correspondingly 16.51 mg/g dry resin, 61.72 mg/g dry resin and 37.67 under the optimal experimental conditions. The copper (II) breakthrough curves were fitted by the empirical models of Thomas, Yoon-Nelson and Adam-Bohart, respectively. The Thomas model was found to be the most suitable one for predicting how the concentration of copper (II) in the effluent changes with the adsorption time.