Heat Transfer Characteristics Of Nanofluids Research Articles

Numerical Study of Convection Heat Transfer with Confinement Around a Square Cylinder Submerged in a Water-Based Nanofluid

The novelty of this work lies in the comprehensive investigation of Forced convection heat transfer a square cylinder inclined at 45° using CuO nanofluid employing a single phase approach. A heated square cylinder with constant wall temperature boundary condition, subjected to a flowing nanofluid between two parallel walls, undergoes a laminar, steady and two-dimensional flow within a Reynolds number range of 1 < Re > 40. To obtain solutions for the flow and energy transfer, a Finite Element Method (FEM) is employed to numerically solve the governing differential equations and boundary conditions. The objective of this work is to highlight the effects of Reynolds number (Re), confinement ratio (λ), volume concentration (Φ) and diameter of nanoparticles (dnp) on fluid flow and heat transfer characteristics of nanofluid. To capture the effect of Φ and dnp in nanofluid, the thermo-physical-properties of CuO nanofluid are determined experimentally. In the results, at Re = 40, a secondary separation zone (recirculation zone) is observed near the surface of the channel wall. The drag coefficient value rises as the Φ increases and the vdnp decreases, regardless of other factors such as Re and λ. Conversely, as the confinement ratio and volume fraction of nanoparticles increase, the average Nusselt number also rises, while maintaining a constant value of Re and dnp. In contrast, the size of the nanoparticles exhibits an inverse relationship with the average Nusselt number. The study contributes to the understanding of nanofluid behavior and provides practical insights for applications, supported by correlations and Artificial Neural Network predictions (Parrales et al.).

Enhanced heat transfer in hybrid CNT nanofluid flow over a permeable stretching convective thermal curved surface with magnetic field and thermal radiation

The heat transfer characteristics of nanofluid play an important role in several industries to optimize their performance with the interaction of dissipative heat. However, in energy harvesting its application is vital. Therefore, the current heat transfer analysis was carried out based on the consequence of viscous and Joule dissipation in favour of the hybrid nanofluid flow over an elongating permeable curved convective thermal surface. Additionally, the external heat source and linear thermal radiation influence the flow phenomena whenever the velocity slip and nanoparticle shape effects associated with Hamilton–Crosser thermal conductivity model are significant. The designed equations relating to the flow phenomena are solved numerically using shooting-based Runge–Kutta fourth techniques followed by the similarity transformations used for the nondimensional form of the system of equations. The role of characterizing factors is deployed via graphs and described briefly. The correlation with the earlier investigation for the numerical outcomes of the rate of energy transport is also reported. The major outcomes of the study reveal that the enhanced curvature parameter along with the particle concentrations within their limit overshoots the velocity profiles further, the external heat source combined with thermal radiation also favors in enhancing fluid temperature.

Investigating Heat Transfer Characteristics in Nanofluid and Hybrid Nanofluid Across Melting Stretching/Shrinking Boundaries

Investigating Heat Transfer Characteristics in Nanofluid and Hybrid Nanofluid Across Melting Stretching/Shrinking Boundaries

Important of Slip Effects in Non-Newtonian Nanofluid Flow with Heat Generation for Enhanced Heat Transfer Devices

In various fields such as engineering, nanotechnology, and biomedical sciences, the study of non-Newtonian nanofluid flow with heat generation is becoming increasingly important. However, it is challenging to accurately model such flows due to their complex behavior and slip effects at the fluid-solid interface. This research investigates the impact of first and second-order slip conditions on the flow and heat transfer properties of a non-Newtonian nanofluid using a power law model to describe the fluid's non-Newtonian behavior and numerical methods to solve the resulting equations. To determine the influence of various parameters such as slip parameters, Brinkman number, power law index, and Eckert number on the velocity, temperature, and concentration profiles, which this study examines. The study shows that slip parameters significantly determine the flow and heat transfer properties of non-Newtonian nanofluids, the study also reveals that slip parameters are a crucial factor in understanding the flow and heat transfer characteristics of nanofluids, with the second-order slip condition having a greater impact on velocity and temperature profiles than the first-order slip condition. These findings are valuable for developing and optimizing heat transfer devices that involve non-Newtonian nanofluids with heat generation, which is essential for technological advancements in today's industry.

Investigation of Magneto Hydrodynamics Properties of Reiner–Philippoff Nanofluid with Gyrotactic Microorganism in a Porous Medium

Investigation of Magneto Hydrodynamics Properties of Reiner–Philippoff Nanofluid with Gyrotactic Microorganism in a Porous Medium Nanofluids have many potential applications in engineering, medicine, and biotechnology due to their enhanced thermal, electrical, and optical properties. However, the flow and heat transfer characteristics of nanofluids are influenced by various factors, such as the type and size of nanoparticles, the base fluid, the magnetic field, the radiation, the chemical reaction, and the presence of microorganisms. Therefore, it is important to study the effects of these factors on the nanofluid flow and heat transfer using mathematical models and numerical methods. One of the mathematical models that can describe the nanofluid flow is the Reiner-Philippoff model, which is a classical non-Newtonian fluid model that accounts for the shear-thinning behaviour of some fluids. The Reiner-Philippoff model has been used to study the nanofluid flow over a stretching sheet, which is a simplified model of many industrial processes involving stretching or shrinking surfaces. However, most of the previous studies have neglected the effects of the Arrhenius reaction, thermal radiation, viscous dissipation, and bio-convection on the nanofluid flow over a stretching sheet. The objective of this paper is to fill this gap by conducting a numerical investigation of the effects of the Arrhenius reaction, thermal radiation, viscous dissipation, and bio-convection on a Reiner-Philippoff nanofluid of MHD flow through a stretching sheet. This also considers the effects of thermophoresis and Brownian motion, which are two mechanisms that govern the transport of nanoparticles in nanofluids. The article utilized a similarity transformation to reduce the governing partial differential equations into ordinary differential equations, which are then solved by using the MATLAB computational tool bvp4c technique. The paper also employs a hybrid numerical solution method using Runge-Kutta fourth order with a shooting technique and an optimization technique using the Bayesian regularization method for Runge-Kutta to improve the accuracy of the prediction outcomes. The main finding of this paper is that the Arrhenius reaction, thermal radiation, viscous dissipation, and bio-convection have significant effects on the velocity, temperature, concentration, and motile microorganism profiles of the nanofluid flow over a stretching sheet. The paper also discusses how these effects can be controlled by varying the relevant parameters. This provides graphical results for the profiles of velocity, temperature, concentration, and motile microorganisms for different values of these parameters. The study also compares its results with some existing results in the literature and finds good agreement.

Numerical simulation on thermohydraulic performance of different types of nanofluids in a corrugated-triangular channel

Nanofluids have garnered significant interest as a potential solution to address overheating challenges across diverse industries. Researchers are actively exploring different types of nanofluids to mitigate these issues. In this study, a numerical analysis was conducted using ANSYS software to examine the fluid flow and heat transfer characteristics of nanofluids (ranging from 0 to 4 volume fractions) in a corrugated wavy channel within the turbulent range. Various nanoparticles, including Al2O3, CuO, SiO2, and ZnO, were employed and dispersed in different base fluids such as ethylene glycol, glycerin, and water. The particle size of the nanoparticles ranged from 20 to 70 nm. The results revealed that SiO2/water-based nanofluids provide better heat transfer than all the water-based nanofluids. The maximum average Nusselt number and pressure drop of 200 and 115 Pa, respectively, were observed for SiO2 nanofluid (volume fraction of 0.04) with a particle size of 20 nm. Highlights Al2O3, CuO, SiO2 and ZnO considered in this work. Corrugated plates with three different corrugated angles of 20° to 60° are tested. Eexperiments are performed for different heat flux in turbulent range. Maximum heat transfer obtained for SiO2/water nanofluid.

Recent development in fluid-flow problems: A brief review

This particular article is a collection of some recent research articles on fluid flow problems. The present article summarizes the recent research developments regarding the experimental and theoretical examination about thermal conductivity of different nanofluids. The current investigate analyzes several factors those strongly affecting thermal conductivity of nanofluids include temperature, solid volume fraction, particle type, particle size, particle shape, magnetic field, different base fluids, pH, ultrasonic time and surfactant. Other than, different justifiably attractive models contributing enlargement of thermal conductivity of nanofluids are invoked. Lastly, major heat transfer mechanisms namely Brownian motion, thermophoresis, nanoclustering, interfacial nano-layer and osmophoresis responsible for remarkable role in upgrade the thermal conductivity. Hence the heat transfer characteristics of nanofluids are considered.

Computational fluid dynamics approaches: An overview

This special article is a collection of 28 review articles from different fluid flow approaches. The present article summarizes the recent research developments regarding the theoretical and experimental investigations about thermal conductivity of different nanofluids. The current study analyzes several factors those strongly affecting thermal conductivity of nanofluids include solid volume fraction, temperature, particle size, particle type, particle shape, different base fluids, magnetic field, pH, surfactant and ultrasonic time. In addition, different reasonably attractive models contributing augmentation of thermal conductivity of nanofluids are invoked. Finally, important heat transfer mechanisms namely Brownian motion, nanoclustering, thermophoresis, osmophoresis and interfacial nano-layer responsible for significant role in ameliorating the thermal conductivity and therefore the heat transfer characteristics of nanofluids are discussed.

Heat transfer mechanism for abnormal enhancement of thermal conductivity in a nanofluidic system by molecular dynamics

Molecular dynamics simulation was used to investigate effects of microscopic characteristics of interfacial layer of ZnO/W and Zn/W nanofluids to reveal abnormal enhancement of thermal conductivity. The thermal conductivities of ZnO/W nanofluids were higher than those of Zn/W nanofluids. It was found that fewer water molecules with slower velocities leave the interfacial layer and trajectory lines of water molecules are more concentrated to form a more stable interfacial layer in the ZnO/W nanofluidic system. A higher number of nanoparticle atoms and the probability of finding molecules evaluated by mean square displacement and radial distribution function, lead to the formation of a more stable interfacial layer. This study presents a new parameter S to evaluate the stability of the interfacial layer to determine the effect of its on the thermal conductivity and a new perspective to improve the heat transfer characteristics of nanofluids.

Analytical analyzing mixed convection flow of nanofluid in a vertical channel using python approach

This study uses analytical methods to investigate the impact of parameters on the mixed convection flow of nanofluid in a vertical channel. The research aims to explore the heat transfer characteristics of nanofluids for more efficient heat transfer in devices. The study analyzes the influence of the Reynolds, Grashof, and Prandtl numbers on nanofluid flows. It also examines the effects of temperature and nanoparticle concentration distributions on parameters such as Brownian motion (Nb), thermophoresis (Nt), and Lewis number (Le). The presence of nanoparticles significantly enhances the heat transfer characteristics in the flow problem. Reynolds number, Grashof number, and Prandtl number significantly impact flow behavior. Velocity, temperature, and nanoparticle volume fraction profile trends are thoroughly investigated and found to vary. Akbari-Ganji's method (AGM) and the homotopy perturbation method (HPM) demonstrate the potential of computational tools in analyzing nanotechnology fluid dynamics. The accuracy and reliability of the proposed analytical techniques are confirmed through comparisons with a numerical method. The novelty of this research lies in its comprehensive analysis of parameter effects on the mixed convection flow of nanofluid, the enhanced heat transfer characteristics in the presence of nanoparticles, and the unique contributions offered by the utilization of Python programming in this field. The outcomes of this study provide insights for designing and optimizing heat transfer systems using nanofluids, contributing to advancements in nanotechnology.

Supervised learning method for prediction of heat transfer characteristics of nanofluids

Supervised learning method for prediction of heat transfer characteristics of nanofluids

Numerical investigation of forced convection flow characteristics on hydrophobic surface with nanofluid

In the present study, the flow resistance and heat transfer characteristics of nanofluid flowing through the channel with hydrophobics surfaces are investigated based on mixture multiphase model. A new model is built to exhibit the comprehensive performance of four structured hydrophobic surfaces under different parameters, and one structure with best thermos-hydraulic performance is chosen for the next step. Then, the Al2O3–water nanofluid is added to fluid domain and the flow characteristics is discussed in detail. The results show that the square posts structure has the best comprehensive performance. The overall performance of hydrophobic surfaces has been greatly improved after adding nanofluid, due to the slip-velocity produced by hydrophobic surface and increased fluid thermal conductivity by nanofluid. In addition, the value of performance evaluation criterion is steadily improved as the contact angle and volume fraction are both increasing, which can be increased to 20%, compared with smooth plate, due to the combined effect of hydrophobic surface and nanofluid.

Heat transfer characteristics of nanofluid under the action of magnetic field based on molecular dynamics and flow states

Theoretical analysis, numerical simulations, and experimental studies are used to comprehensively investigate the changes in the heat transfer characteristics of Fe3O4–water magnetic nanofluid under different types of magnetic fields and the heat transfer mechanism, providing new ideas for its practical application. By combining the fundamental conservation theorem and the Boussinesq approximation, dimensionless control equations have been established. The analysis of the variation pattern of the calculated values of the source terms under different boundary conditions, as well as the order of magnitude analysis, concludes that: the enhanced trend of Brownian motion and thermophoretic motion is the main reason for the enhanced heat transfer capability of the magnetic nanofluid; where the thermophoretic motion contributes slightly more to the heat transfer; the increase in Joule heat is the reason for the further enhancement of the heat transfer capability by the magnetic field. Volume fraction, temperature, and magnetic field strength are positively correlated with the average convective heat transfer coefficient. The reason for magnetic fields to enhance heat transfer is revealed by the deflection of the magnetic nanofluid by the magnetic body flow under local magnetic fields to form localized reflux. The alternating magnetic field further enhances the ability of magnetic fields to enhance heat transfer in magnetic nanofluids. Overall, the effect of the applied magnetic field on the motion of the magnetic nanoparticles causes the disruption of the thermal boundary layer, which is responsible for the enhanced heat transfer capacity of magnetic nanofluids.

MHD Casson nanofluid boundary layer flow in presence of radiation and non-uniform heat source/sink

<abstract><p>On stretched magnetic surfaces, we present a numerical study of Casson nanofluids moving through porous materials. The Casson liquid model explains how non-Newtonian liquids behave. Numerical techniques are utilized to solve the nonlinear partial differential equations produced by similarity transformations. Results are gathered for the Nusselt number, skin friction coefficient, temperature and velocity. The impacts of physical variables on the flow and heat transfer characteristics of nanofluids are depicted in graphs. They include the Prandtl number, magnetic parameter, radiation parameter, porosity parameter and Casson parameter. Findings indicate that as the Casson nanofluid parameters are increased, the temperature profile rises but the velocity field decreases. With increasing magnetic parameters alone, it is possible to see a decrease in the thickness of the pulse boundary layer and an increase in the thickness of the thermal boundary layer. All the results are depicted in graphical representations.</p></abstract>

Numerical Simulation of the Natural Convective Heat Transfer of Nanofluids in a Square Cavity Based on Different Predictive Models for Single-Phase and Multiphase Flow Mixtures

Abstract The flow and heat transfer characteristics of nanofluids in a square cavity were simulated using single-phase and mixed-phase flow models, and the simulation results were compared with the corresponding experimental values. The effects of different prediction models for the thermal properties of nanofluids, Grashof number, and volume fraction on the Nusselt number were analyzed. The velocity and temperature distributions of the nanofluid and de-ionized water in the square cavity were compared, and the effects of the temperature and flow fields on the enhanced heat transfer were analyzed according to the field synergy theory. The results show that for the numerical simulation of convective heat transfer in water, both the single-phase flow models and multiphase flow mixing models had high prediction accuracy. For nanofluids, single-phase flow did not reflect the heat transfer characteristics well, and the simulation results of the single-phase flow model relied more strongly on a highly accurate prediction model for the physical parameters. The multiphase flow mixing model could better reflect the natural convective heat transfer properties of the nanofluids in a square cavity. The nanofluid could significantly improve the flow state in the square cavity, thereby facilitating enhanced convective heat transfer. When the concentration is 2% (Grashof number is 1 × 106), the average Nusselt number of the nanofluid is increased by 19.7% compared with the base fluid.

Influence of nanoparticle and channel arc structure on comprehensive performance of nanofluids in curved tiered microchannel heat sinks

AbstractIn order to improve the heat dissipation of the electrical components, a curved tiered microchannel heat sink (TMCHS) was proposed and optimized and applied to cool the electrical components together with nanofluids. Influence of channel radian (φ = 0°, 75°, 135°, 180°), arc number (n = 0, 2, 3, 4), and nanoparticle concentration (w = 0.0%, 0.1%, 0.3%, 0.5%) on flow and heat transfer characteristics of nanofluids in curved TMCHS was numerically investigated. Comprehensive evaluation coefficient comprehensive evaluation factor (PEC) was used to evaluate the thermo‐hydraulic performance of TMCHS and nanofluids. Results indicated that the greater the radian and arc number, the better the thermal performance of TMCHS. The overall performance of TMCHS is the best when the radian is 180° and the arc number is 4. Results in this paper provide important technical guidance for the application of curved tiered microchannel heat sinks and nanofluids to the field of thermal management of electronic components.

Numerical analysis of unsteady mixed convection heat transfer characteristics of nanofluids confined within a porous lid-driven L-shaped cavity

The numerical analysis of unsteady combined convective heat transfer properties of kerosene-alumina nanofluid restricted in an L-shaped porous lid-driven cavity has been examined in this research. Fluid flow governing equations and conjugate heat transport along with the corresponding boundary conditions are used to express the physical problem mathematically. Firstly, boundary conditions and governing equations are transformed into non-dimensional forms using a series of appropriate transformations. Later on, the transformed non-dimensional equations are solved by utilizing the Finite Element Method based on the Galerkin residuals. A comparison with earlier available work is shown and turned out to be a great agreement. Numerical solutions are acquired in a wide variety of governing variables. The governing variables in this study are the Darcy number ( Da ), Reynolds number ( Re ), Richardson number ( Ri ), solid volume fraction (δ), time parameter (τ), etc. The numerical findings of flow and thermal fields are represented graphically in respect of isotherms, streamlines, and average Nusselt number at the hot surface of the cavity. The Re and Da are found to have an extensive impact on the isotherms and streamlines in the cavity, and also in determining the average heat transmission rate.

Impact of the Thermophysical Properties of a Cuo-H<sub>2</sub>O-Based Nanofluid on the Performance of a Cylindrical Solar Concentrator

Sustainability in energy production, energy security, and global warming are major concerns facing the globe today. Cylindrical Solar Concentrator is extensively utilized for technologically advanced processes, heat, and power plant applications by utilizing daylight sunshine at no running cost. Numerous inputs and characteristics impact the concentrator's performance, with the type of heat transfer fluid and its mass flow rate being two of the most important. This paper gives a numerical investigation of the influence of thermo-physical attribute of CuO water-based nanofluids on the effectiveness of the Parabolic Trough Solar Concentrator in Ogbomosho weather condition (lat. 8o011, long. 4o111).The governing equations of nanofluids with laminar flow and steady state, using iterative relaxation techniques, as well as the efficiency of the concentrator, were solved. A C++ simulation program was developed to investigate the impacts of thermo physical parameters on concentrator efficiency, with nanoparticle sizes ranging from 1 to 10 percent and mass flow rates of 0.1 kg/s, 0.15 kg/s, and 0.2 kg/s, at a constant incident solar insolation flux of 186 W/m2. The results demonstrated that increasing the mass flow rate of the nanofluids improves the heat transmission properties. The thermo physical properties of CuO-based nanofluids and its effects on the performance of the solar parabolic trough collector are being examined. The impact of thermophysical attributes on thermal effectiveness results in improved thermal efficacy, heat transfer characteristics of nanofluids, and factors influencing its features in solar collectors, which determines its usability. The Parabolic Trough Collector system based on nanofluids is a promising technology with applications in green surroundings.

Thermophysical and transient heat transfer characteristics of aqueous SiO2 nanofluid in energy management applications

The development and implementation of transient heat transfer characteristics of nanofluids in energy management were studied. Ultrasonic-assisted SiO2/water nanofluids with 0.1–1.5 wt. % were prepared using polyvinyl alcohol (PVA) surfactant. The stability of nanofluids was tested and confirmed using zeta potential and light absorbance measurement. Thermophysical properties of nanofluid were investigated at various weight concentrations from 0.1 to 1.5 wt. % in a temperature range of 25–70°C. Transient heat transfer characteristics of nanofluids were examined. Thermophysical properties were enhanced by adding nanoparticles to base fluid. A major enhancement in transient heat transfer characteristics was obtained by applying SiO2/water nanofluids. The convective heat transfer coefficient (CHTC) was increased up to 2.37 times compared to water. The heat absorbance efficiency of the system is increased by a maximum of 24.54%. Finally, a new CHTC correlation has been proposed.

Review on Thermal Performance of Nanofluids With and Without Magnetic Fields in Heat Exchange Devices

Addition of nanoparticles into a fluid can improve the heat transfer performance of the base fluid in heat exchangers. In this work, the preparation method and process of nanofluids are introduced, and thermal properties of nanofluids, such as thermal conductivity and viscosity, are discussed deeply. This paper summarizes various theoretical models of thermal conductivity and viscosity of nanofluids. A comprehensive literature survey on applications and limitations of nanofluids has been compiled. This paper also aims to review the natural and forced convective heat transfer characteristics of nanofluids with and without magnetic fields. The discussion for the natural convective heat transfer of nanofluids focuses on the heat transfer performance of non-conventional enclosures and electric heaters. The effects on heat transfer due to variations of heated walls are also investigated. Specific applications of nanofluids in a tube with trapezoidal ribs, double-tube heat exchangers, and plate heat exchangers have been reviewed and presented in a discussion about forced convective heat transfer. The previous results show that the inlet temperature of nanofluids obviously affects the heat transfer characteristics of double-tube heat exchangers, whereas a multi-walled carbon nanotube–water nanofluid shows significant advantages in plate heat exchangers. Finally, this paper studies natural convective heat transfer of magnetic fluids in a square cavity and forced convection heat transfer in a straight tube and a corrugated structure under the action of magnetic fields. It is found that the heat transfer performance of an Fe3O4–water nanofluid is enhanced when a magnetic field is applied to the corrugated plate heat exchangers, and the pressure drop can be reduced by around 10%. It is recommended that natural convection of magnetic fluids needs to be investigated experimentally in a real cavity and a corrugated channel under the influence of a magnetic field. In addition, studies of alternating magnetic field are recommended to reveal any improvements of thermal performance of magnetic fluids in heat exchange devices. This review puts forward an effective solution for improvement of the thermal performance of heat transfer equipment and serves as a basic reference for applications of nanofluids in heat transfer fields.