Nanofluid Heat Transfer Research Articles

Comparison of the use of different nanofluids for heat transfer from the outer surface of spiral tubes: Energy, exergy, and exergoeconomic (3E) analysis

Heat exchangers play a crucial role in industrial processes by facilitating the efficient transfer of thermal energy. The thermophysical properties of nanofluids, which consist of nanoparticles dispersed in conventional heat transfer fluids, are enhanced. Their remarkable thermal conductivity and convective heat transfer characteristics have the potential to significantly improve heat transfer processes. In the present investigation, a numerical study has been carried out to investigate the effect of different nanofluids on heat transfer from outer surface of a spiral coil based on the first and second laws of thermodynamics. The numerical solutions are checked against previous experimental and numerical research in the field. Nusselt number, Euler number, exergy efficiency, irreversibility, and equipment cost are studied with respect to concentration, mass flow ratio (Rm), and shell and tube inlet temperature for a variety of nanofluids, including Al2O3/H2O, CuO/H2O, Fe2O3/H2O, and TiO2/H2O. Compared to water, the exergy efficiency is lower while using nanofluids, as shown by the results, especially in higher nanofluid concentrations, and among the different nanofluids, Al2O3–H2O nanofluid was found to have the highest thermodynamics second law efficiency. The exergy destruction rate experiences linear growth by increasing the nanofluid concentration. A higher pressure drop based on the Euler number is expected for nanofluids. In addition, the consumption of nanofluids on the shell side results in a considerable reduction of the purchased equipment cost (PEC) value compared to water. As opposed to the tube-side input temperature, variations in the shell-side inlet temperature found to have a greater impact on the heat exchanger's exergetic performance.

Exact solutions for magnetohydrodynamic nanofluids flow and heat transfer over a permeable axisymmetric radially stretching/shrinking sheet

We report on the magnetohydrodynamic impact on the axisymmetric flow of Al2O3/Cu nanoparticles suspended in H2O past a stretched/shrinked sheet. With the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles, the physical flow process is illustrated. The resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity transformations. The transformed differential equations are solved analytically. Impacts of the magnetic parameter, solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted graphically. The skin friction and Nusselt number were also evaluated. In addition, existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching one. Further, Al2O3/H2O nanofluid flow has better thermal conductivity on comparing with Cu/H2O nanofluid. Furthermore, it was found that the first solutions of the stream are stable and physically realizable, whereas those of the second ones are unstable.

Heat Transfer and Thermal Energy Storage Enhancement by Foams and Nanoparticles

The use of innovative methods for the design of heating, cooling, and heat storage devices has been mainly oriented in the last decade toward the use of nanofluids, metal foams coupled with working fluids, or phase change materials (PCMs). A network of nine Italian universities achieved significant results and innovative ideas on these topics by developing a collaborative project in the last four years, where different approaches and investigation techniques were synergically employed. They evaluated the quantitative extent of the enhancement in the heat transfer and thermal performance of a heat exchanger or thermal energy storage system with the combined use of nanofluids, metal foams, and PCMs. The different facets of this broad research program are surveyed in this article. Special focus is given to the comparison between the mesoscopic to macroscopic modeling of heat transfer in metal foams and nanofluids, as well as to the experimental data collected and processed in the development of the research.

Exploration of entropy analysis and viscous dissipation on radially convective flow of (Cu‐Al2O3:H2O) hybrid nanofluid over a stretching disk

AbstractThe current research work deals with the impact of suction/injection on the thermally radiating convective flow generated by a nonlinear stretched disk. The energy equation is addressed by the presence of thermal radiation and the energy dissipative function. This work was carried out with the help of the Das and Tiwari (single‐phase nanofluid) models and the Maxwell Garnett and Brinkman nanofluid models for the analysis of entropy generation. In the present model, nanoparticles of copper (Cu) and alumina (Al2O3) are being used with water (H2O) as the base fluid. The governing nonlinear partial differential equations are transformed into ordinary differential equations with the assistance of appropriate similarity variables. These transformed equations are then solved using the bvp4c function, a built‐in function in MATLAB software. The investigation examines the influence of various factors on the velocity and temperature fields, entropy generation, skin friction, and heat transfer rate. The findings show that suction decreases velocity and temperature by 6.59%, while injection has the opposite effect. Viscous dissipation increases velocity by 5.13% and temperature by 17.94% in hybrid nanofluids. Higher Prandtl numbers reduce velocity and temperature by 6% in nanofluids but boost them by 5.45% and 18.81% in hybrid nanofluids with radiation growth. As volume fraction rises, Al2O3/H2O nanofluid speed falls by 5.37%, but Cu‐Al2O3/H2O hybrid nanofluid temperature increases by 13.09% and surface drag force increases by 12%. The entropy of the hybrid nanofluid increases by 5.84%, 8.19%, and 14.04% with Eckert number, suction, and Prandtl number but decreases by 10.08% with temperature difference. The Nusselt number of nanofluid decreases by 10.58% and 12.40% with Eckert number and radiation, but hybrid particles increase it by 10.31% with intensified Prandtl number. These findings offer valuable insights for potential applications of hybrid nanofluids in heat transfer and cooling systems.

Ternary Hybrid Nanofluids Containing Gyrotactic Microorganisms with Magnetohydrodynamics Effect over a Shrinking/Stretching of the Horizontal Plate

Nowadays, ternary hybrid nanofluids have been discovered by the researchers to play an important role in heat transfer systems. This study focuses on the study of heat and mass transfer of ternary hybrid nanofluids over a shrinking/stretching horizontal plate induced by gyrotactic microorganisms with the effects of magnetohydrodynamics (MHD). Motile microorganisms were added to a suspension of nanoparticles in a base fluid and mixed in most microsystems to the enhance the convectional properties of the nanofluids. This research uses water as the base fluid to investigate the effects of silver (Ag), Aluminium Oxide (AI203) and Copper (Cu) nanoparticles. The similarity transformation was used to reduce the partial differential governing equations into ordinary differential equations. The transformed nonlinear ordinary differential equations with appropriate transformed boundary conditions were solved numerically using the bvp4c procedure in the MATLAB software. The combination of the Tiwari and Das with Buongiorno model used in this mathematical equation. The results of the research are illustrated graphically and presented via tables to show the behaviour of velocity, temperature, concentration of nanoparticles, and microorganism density as well as the coefficients of skin friction, Nusselt number, Sherwood numbers, and motile microorganism density for the nanoparticles of the THNF. The results show that, for the shrinking case, the magnetic field parameter increases for skin friction and Sherwood number, while it decreases for the Nusselt number and density of motile microorganisms. The Brownian motion parameter and bioconvection Péclet number are shown to significantly increase the Sherwood Number and density motile microorganisms. Thermophoresis, however, has been proven to lower the Sherwood number and density of motile microorganisms. Then, THNF (water/Ag-AI2O3-Cu) is shown to better compared to nanofluids (water/AI2O3) and hybrid nanofluids (water/Ag-AI2O3) in both cases.

Electroosmotic flow and heat transfer of a hybrid nanofluid in a microchannel: A structural optimization

In microchannels where there is a change in the direction of flow, the difference in path length between the inner and outer walls or boundaries can play an effective role in dispersion. This research focuses on studying the fluid flow and heat transfer of a hybrid nanofluid in a microchannel under electroosmotic flow. A structural optimization is applied to reduce dispersion, and the results of the optimized geometry are compared with the original geometry. The results show that the heat transfer is improved due to the new geometry configuration. If only the study of heat transfer is considered, it is recommended to use the optimal geometry with a low volume fraction and a high electric potential. Although the nanofluid's performance in increasing heat transfer is failed due to the low flow rate, the enhanced heat transfer can be achieved through optimized geometry or high electric potential. The results of this research can be applied to the design of more advanced and efficient microfluidic devices with multifaceted objectives.

Theoretical Examination of the Volume Concentration and Nanoparticles Density Influence on the Convective Heat Transfer Enhancement of Nanofluid in 2D Cavity Including the Square Heater

Nanofluid is one of the solutions of heat transfer, which can apply in devices fields as nuclear power, Nano-electronics systems, and solar fluid heating. In this work, the natural convection of Cuwater nanofluid is examined using the Lattice Boltzmann Method (LBM) as a mesoscopic approach. The main objectives of this work are to study the performance and pattern of Cu-water nanofluid and to demonstrate that the nanofluids behave differently while improving their energy transfer compared to pure fluids. The set goal was achieved by solving the tasks: based on the streamlines and isotherms profiles to demonstrate how the convection process and temperature gradients improve. Also, conducting study on heat transfer of nanofluid by calculate the Nusselt number. Depending on the nanoparticle volume percentage, the Grashof number Gr , and the hot obstacle have a significant impact on the convection flow and rate of heat transfer. The most important result is the enhancement of heat transfer with the increasing of volume fraction for a particular Grashof number, also it improves with the rising of Grashof number for a particular nanoparticles volume fraction. Therefore, the aspect ratios of the enclosure have played a significant part in Nusselt number variation. In addition, we found that the Nusselt number avg Nu is higher in the case of cavity without hot obstacle more than for cavity with hot obstacle, so the heat transfer improves in the case of cavity without hot obstacle. The significance of the obtained results consists that the nanofluid is one of the ways to improve heat transfer due to its specific characteristics and properties.

A numerical study on the thermal response of biodegradable ferrous oxide/aluminium oxide nanofluid flow past an unsteady contracting permeable cylinder: A comparative analysis

Esters that are considered natural come from renewable sources like vegetable or animal oils or other bio-based materials. Due to natural esters' great biodegradability, lack of toxicity, and high flash point, their use in industrial applications has been expanding quickly in recent years. The current study, thus numerically investigates an unsteady laminar flow and heat transfer of biodegradable nanofluids past over a shrinking cylinder of time dependent radius. Natural Ester (NE) is used as the base fluids, and two nanoparticles such as Fe3O4 (ferrous oxide) and Al2O3 (aluminium oxide) are used to create different combinations of nanofluids. The unsteady Navier-Stokes equations are used to model it, and similarity solutions are introduced to solve the problem. A MATLAB built-in package BVP4c has been employed to tackle the problem. The physical behavior of the solution has been explored in terms of parametric analysis and graphical demonstration and the validation of present solutions is reported by the comparative benchmark with already available results in a limiting sense. Our findings demonstrate that Fe3O4 biodegradable nanofluids are capable of carrying and dispersing thermal energy more effectively, resulting in improved heat transfer rates compared to Al2O3 biodegradable nanofluids.

Effect of Nanoparticle Material, Porosity and Thermal Radiation on Forced Convection Heat Transfer of Cu-Water and CuO-Water Nanofluids over a Stretching Sheet

Effect of Nanoparticle Material, Porosity and Thermal Radiation on Forced Convection Heat Transfer of Cu-Water and CuO-Water Nanofluids over a Stretching Sheet

Analysis of periodic pulsating nanofluid flow and heat transfer through a parallel-plate channel in the presence of magnetic field

Analysis of periodic pulsating nanofluid flow and heat transfer through a parallel-plate channel in the presence of magnetic field

Effect of thermal instability on heat transfer of micropolar nanofluid saturated in porous medium with rotation

This article investigate the impact of thermal instability on heat transfer of micropolar nanofluid saturated in porous medium with rotation in linear and nonlinear ways. The truncated Fourier series approach is used to analyze nonlinear stability, while analytical evaluation of linear stability is performed with normal mode methodology. Based on outcomes, the micropolar and rotation parameter has stabilizing effect in the system. As opposed to that, nanoparticle Rayleigh number, porosity parameter and Lewis number accelerate the start of convective motion inside the system. Some parameters play a significant influence in transport of heat and mass in non-linear analysis. The rotation parameter, micropolar parameter, perform a major contribution in heat/mass transfer in the system. Mass/heat transfer in the system is analyzed by two different approaches, Mathematica NDSolve and Runge-Kutta-Fehlberg method(RKF-45), and it is found that the rate of mass/heat transfer is exactly the same in both cases.

Analysis of Casson Nanofluid Flow and Heat Transfer Across a Non-linear Stretching Sheet Adopting Keller Box Finite Difference Scheme

Analysis of Casson Nanofluid Flow and Heat Transfer Across a Non-linear Stretching Sheet Adopting Keller Box Finite Difference Scheme

Numerical investigation of nanofluid buoyant flow behavior and heat transfer characteristics in annular-shaped enclosure with internal baffle

PurposeNatural convection in finite enclosures is a common phenomenon in various thermal applications. To provide the thermal design guidelines, this study aims to numerically explore the potential of using internal baffles and nanofluids to either enhance or suppress heat transport in a vertical annulus. Furthermore, the annular-shaped enclosure is filled with aqueous-silver nanofluid and the effects of five distinct nanoparticle shapes are examined. In addition, the influence of baffle design parameters, including baffle position, thickness and length, is thoroughly analyzed.Design/methodology/approachThe finite difference method is used in conjunction with the alternating direction implicit and successive line over relaxation techniques to solve nonlinear and coupled partial differential equations. The single phase model is used for nanofluid which is considered as a homogeneous fluid with improved thermal properties. The independence tests are carried out for assessing the sufficiency of grid size and time step for obtaining results accurately.FindingsThe baffle dimension parameters and nanoparticle shape exhibit significant impact on the convective flow and heat transfer characteristics, leading to the following results: sphere- and blade-shaped nanoparticles demonstrate around 30% enhancement in the heat transport capability compared with platelet-shaped nanoparticles, which exhibit the least. When considering the baffle design parameter, either a decrease in the baffle length and thickness or an increase in baffle height leads to an improvement in heat transport rate. Consequently, a threefold increase in baffle height yields a 40% improvement in thermal performance.Originality/valueUnderstanding the impact of nanoparticle shapes and baffle design parameters on flow and thermal behavior will enable engineers to provide valuable insight on thermal management and overall system efficiency. Therefore, the current work focuses on exploring buoyant nanofluid flow and thermal mechanism in a baffled annular-shaped enclosure. Specifically, an internal baffle that exhibits conductive heat transfer through it is considered, and the impact of baffle dimensions (thickness, length and position) on the fluid flow behavior and thermal characteristics is investigated. In addition, the current study also addresses the influence of five distinct nanoparticle shapes (e.g. spherical, cylindrical, platelet, blade and brick) on the flow and thermal behavior in the baffled annular geometry. In addition to deepening the understanding of nanofluid behavior in a baffled vertical annulus, the current study contributes to the ongoing advancements in thermal applications by providing certain guidelines to design application-specific enclosures.

Unsteady gyrotactic microorganisms and magnetic nanofluid heat and mass transfer analysis inside a chamber with thermal radiation

ABSTRACT In this examination, we predetermined to investigate the consequence of prescribed gyrotactic microorganism, thermal radiation on unsteady mixed convention flow of Buogiorno model nanofluid inside the square cavity. The combination of suitable momentum, temperature, concentration and concentration of microorganism of nanofluid has been solved numerically via Finite Element method. Pictorial illustrations have been used to predict the sway of sophisticated parameters on fluid flow, temperature, concentration and gyrotactic microorganism set up: Radiation , Brownian motion , Rayleigh number , Thermophoresis , Buoyancy ratio , Lewis number , Peclet number and Bio-convection Rayleigh number . Convergence analysis is presented via grid independence approach. The skin-friction coefficient, average Nusselt number, nanoparticle Sherwood number and microorganism Sherwood number of involved parameters are also plotted through graphs. It is observed through present investigation that isotherm patterns decline with higher choices of radiation parameter. Furthermore, the numerical codes of microorganism mass transport rate impede inside the cavity region with an intensifying values of thermophoresis parameter.

Effect of external electric field on agglomeration characteristics of Cu nanoparticles: A molecular dynamics study

In order to study the effect of electric field on the stability of Cu nanoparticles in water, molecular dynamics method was used to simulate the agglomeration characteristics of Cu nanoparticles. The microscopic agglomeration characteristics of nanoparticles by electric field were analyzed using the distribution and collision of nanoparticles in water at different times, as well as the potential energy, kinetic energy, diffusion coefficient and radial distribution function of the system. The results show that the collision of Cu nanoparticles was inhibited in the presence of both uniform and alternation electric fields. The total potential energy of the system decreases with each collision of particles. When all of the particles are agglomerated, the total potential energy of the system remains constant. According to the radial distribution function, when the electric field intensity increases, the degree of aggregation of water molecules on the particle surface strengthens and then weakens as the electric field strength. Meanwhile, the degree of aggregation decreases with the increasing frequency of the alternating electric field. The effect of electric field frequency on the diffusion coefficient of nanofluid is insignificant. However, as the strength of the electric field increases the diffusion coefficient of the nanofluid decreases, while the resistance coefficient of water molecules increases, and the presence of the electric field inhibits the movement of water molecules. The influence of electric field on the heat transfer and deposition characteristics of nanofluids can be obtained by experiments, but the influence mechanism is difficult to be analyzed by experimental means. The molecular dynamics method also provides a new idea to reveal the influence mechanism of electric field.

Mathematical model for a thermal cooling system with variable viscosity and thermal conductivity over a rotating disk

Mathematical models involving rotation of the disks and the flow of fluid over these serve as a prototypical representation of electronic devices including rotational components. The rotation results in substantial heat generation and the excessive heat buildup can affect performance and reliability, and can cause failure. Therefore efficient cooling mechanisms are essential to dissipate the generated heat and maintain the devices’ temperature within safe operating limits. In this research paper, the focus is on investigating the magnetohydrodynamic (MHD) slip flow and heat transfer of power-law nanofluid over an infinite rotating disk. The study incorporates numerical methods to analyze the system, considering the variable thermal conductivity and viscosity as a function of velocity gradients, and employing velocity slip conditions at the boundary. To facilitate the analysis, the similarity transformation technique is applied, which effectively reduces the governing boundary value problem to a set of nonlinear ordinary differential equations (ODEs). The research explores the dependence of the velocity and temperature profiles on various parameters, including the nanofluid volume concentration parameter, power-law index, magnetic parameter, and velocity slip parameters. Through the numerical results, the influence of these parameters on the flow and heat transfer characteristics is presented and thoroughly discussed. The outcomes of the study are presented in the form of graphs and tables, providing valuable insights into the behavior of the power-law nanofluid flow and heat transfer over the rotating disk.

Property of water-nanoparticle flow and heat transfer in the double-tube heat exchanger with nanofluid

The three-dimensional numerical simulation is conducted to study the impact of Al2O3/water nanofluid on the flow property and heat transfer of a counter flow double-tube heat exchanger where a laminar flow of cold water is in the outer tube, and in the inner tube there is a turbulent flow of hot nanofluid with particle volume concentrations ranging from 0.05% to 3%. The effects of temperature, flow rate, and particle volume concentration on the property of nanofluid flow and heat transfer are explored. The results show that the friction factor decreases with the increase of temperature and flow rate, and the pressure drop increases with increasing particle volume concentration. The temperature of the nanofluid at the outlet first decreases rapidly with time and then increases gradually to a stable value. Along the flow direction, the temperature of nanofluid decreases slowly at x/D < 10, and the axial temperature gradient increases at the full development stage. At a constant Reynolds number, the lower the temperature or the larger the particle volume concentration, the stronger the heat transfer. The local heat transfer coefficient on the wall of the inner tube decreases rapidly after reaching the peak x/D = 2.3, and then increases slowly until the outlet. The particle number density decreases sharply at x/D < 5, and then slowly decreases, while the change of the geometric mean diameter of particles is just the opposite. Increasing the flow rate or the temperature will strengthen particle coagulation, resulting in the decrease of particle number density and the increase of geometric mean diameter of particles.

Physical insight into thermal analysis of magnetohydrodynamic stagnation point flow of micropolar nanofluid across a flexible surface equipped with porous medium and Fourier and Fick's law

AbstractNanofluids represent a novel heat transfer liquid, making them an efficient medium for enhancing energy transmission. Nevertheless, significant knowledge gaps still exist concerning current strategies for improving heat transfer in nanofluids, underscoring the necessity for comprehensive research on these fluid systems. Therefore, this study considered theoretical analysis retrieves the influence of radiative two‐dimensional stagnation point flow of second‐grade micropolar fluid flow about an elongated channel surface implanted in porous media with magnetic effect, and modified heat and mass flux is under consideration. The major novel effect of the current study is to analyze the activation energy and thermal aspect of the system in the presence of nonlinear radiation effects that are considered in the revised mathematical framework by utilizing the boundary layer theory. The resulting set of coupled partial differential equations is further reduced and transformed into a dimensionless system of ordinary differential equations through appropriate scaling invariants. We initiate the RKF‐45 investigation scheme to numerically analyze the transformed dimensionless system, considering relevant parameters. The computational algorithm is implemented using MATLAB programming syntax. Plotted visuals are revealed for leading parameters against pertinent flow profiles graphically and with numerical data. Additionally, the convergence analysis of the numerical results for various flow profiles of the fluids were compared to establish the authenticity of the proposed flow problem. These research findings play a significant role in controlling heat transfer rates and fluid velocities in diverse manufacturing processes and industrial applications, ultimately aiding in achieving the desired product quality.

Computational Study on the Influence of Non-Newtonian Nano fluids in Fluid Flow and Heat Transfer over a Permeable Surface with Injection and Suction

Computational Study on the Influence of Non-Newtonian Nano fluids in Fluid Flow and Heat Transfer over a Permeable Surface with Injection and Suction

Irreversibility analysis of Magnetohydrodynamic (MHD) mixed convection flow of viscoelastic hybrid nanofluid flow in a channel

This manuscript delves into the analysis of irreversibility in Magnetohydrodynamic (MHD) mixed convection flow of a viscoelastic hybrid nanofluid within a vertical channel. The study adopts a parallel plate configuration and employs Aluminum oxide (Al2O3) and Titanium oxide (TiO2) nanoparticles dispersed in a Carboxymethyl cellulose (CMC)-water base fluid. Utilizing similarity transformations, the governing partial differential equations (PDEs) are converted into a set of ordinary differential equations (ODEs), streamlining the mathematical model. These ODEs are then solved using the homotopy analysis method via Mathematica software for various governing parameter values. Key parameters including the Brinkman number, volume fractions of nanoparticles, magnetic effects, and wall temperature parameter are systematically investigated. Noteworthy insights include that volume fraction and magnetic parameter augments velocity at the left wall and slows down it toward the right wall; Brinkman number and wall temperature parameters significant in elevating temperature; Entropy and Bejan number respond differently to variations in the Brinkman number. Entropy escalates with increasing magnetic parameter, while the Bejan number declines. Illustrated through graphs, these findings enrich the comprehension of MHD mixed convection flow and heat transfer in viscoelastic hybrid nanofluids, elucidating irreversibility aspects tied to such systems.