Heat Transfer Field Research Articles

REVIEWING THE IMPACT OF MAGNETIC PRANDTL NUMBER AND MAGNETIC FORCE PARAMETER ON CONVECTIVE HEAT TRANSFER IN BOUNDARY LAYERS

This review paper provides a comprehensive inspection how the magnetic Prandtl number (Prandtl number influenced by a magnetic field) and the magnetic force parameter affect convective heat transfer in boundary layers. The investigation delves into the intricate interplay between these parameters and their implications for heat-transfer phenomena. Understanding the influence of magnetic fields on convective heat transfer holds significant importance for diverse engineering applications such as advanced technologies, heat exchangers, and cooling systems. Through a thorough analysis of existing literature, this review offers valuable insights into the complex relationship between the magnetic Prandtl number, the magnetic force parameter, and convective heat transfer in boundary layers. The main novelty of the current review is based on the perception that this review is very beneficial for the readers to establish future work in the field of magneto-material and magneto heat transfer. This review will provide the clear knowledge about the physical significances of the magnetic Prandtl number and magnetic force parameter on chief physical quantities like velocity profile, temperature distribution, skin friction, and heat-transfer rate.

ИССЛЕДОВАНИЕ ТЕПЛООБМЕНА В АППАРАТАХ С ПЕРЕМЕШИВАЮЩИМ УСТРОЙСТВОМ

This study was carried out with the aim of in-depth analysis of heat transfer processes in chemical and heat apparatuses that use mixing devices. The mixing process plays a key role in various industries, including chemical production, food processing and many others. Mixing is important for uniform distribution of components in reactors, tanks and apparatus, which in turn affects product quality and process efficiency. Heat exchange is a vital element in numerous technological processes and holds a significant role in enhancing efficiency and conserving energy across various industries. This study began with a thorough review of the literature. Further experiments were carried out, including work with different types of apparatuses and stirring devices, with different stirring intensity. Digital prototypes were chosen as the method of research and the ANSYS software package was used. The purpose of this study is to analyze the efficiency of heat transfer in such apparatuses, as well as to identify the factors affecting the intensity of heat transfer. This study addresses following problems: heating water in an apparatus with a stirrer, determining the critical temperature and time to reach steady-state in different mixtures. The study of heat transfer in apparatus with a mixing device is a critical element for optimizing production processes and increasing energy efficiency. According to calculations, faster achievement of the steady-state regime is observed, which indicates more efficient heating of the liquid when using a turbine stirrer. Mathematical calculations confirm that when stirring a mixture of water and glycerin, compared to stirring pure water, a slower and less efficient heating process occurs, due to the higher viscosity of glycerin. This study serves as an important contribution to the field of heat transfer and provides valuable guidelines for further developments and applications.

Analysis of variable inductor employing vegetable-based transformer oil with magnetic nanoparticles

Variable inductors using magnetorheological fluids have recently been successfully applied to power-conversion devices; however, the thermal properties of Vegetable oil-based Magnetic Nanofluids (VMNFs) have not been investigated. In this study, the temperature characteristics of a variable inductor embedded with a VMNF were analyzed by developing a multiphysics analysis method and verified experimentally. To analyze the temperature distribution efficiently, a coupled analysis of the Magnetoquasistatic (MQS) field and steady-state heat transfer field based on the finite-element method was performed. The B-H curves of the VMNF and ferrite core were obtained via magnetic property measurement experiments, and the input waveforms were measured from the current and high-frequency pulse voltages applied to the variable inductor of the DC–DC converter. To predict the temperature rise of the VMNF-gap variable inductor, the power dissipation was determined using the Steinmetz experimental equation modified by the Bertotti model in the electronic system solver and input as a heat source in the steady-state heat-transfer analysis. The temperature increase predicted by the multiphysics analysis method agreed well with the experimental data, and an increasing the concentration of magnetic nanoparticles had a cooling effect. The developed MQS–thermal field coupled analytical method and the cooling properties of VMNFs can be applied to the design of power-conversion devices operating with high-frequency power sources.

Analysis of nonlinear convection and diffusion in viscoelastic fluid flow with variable thermal conductivity and thermal radiations

The study offers a thorough evaluation of the complex fluid dynamics and heat transfer phenomena in Williamson viscoelastic fluid flow, taking into account thermal radiations and variable thermal conductivity. The paper extends its analysis to include heat transfer effects, which are critical in several engineering and industrial applications, and digs into the complexity of non-Newtonian fluid behavior, with a special focus on thermal radiation, heat production, diffusion and viscous dissipation. The study makes use of mathematical models and numerical method RK4 to clarify the nonlinear interactions between convection and diffusion processes in this viscoelastic fluid. The energy and concentration equations are simulated in the presence of the modified Fourier and Fick laws. Moreover, the predicted heat flow is based on the Cattaneo–Christov theory. This research also sheds light on the interaction between rheological properties and thermal characteristics, providing important new knowledge to the broader field of fluid dynamics and heat transfer.

Multi-effect analysis of nanofluid flow in stenosed arteries with variable pressure gradient: analytical study

This study advances the understanding of nanofluid behaviour within stenosed arteries, highlighting the importance of considering multifaceted effects in the modelling process. It investigates the combined impact of pressure gradient variation, heat transfer, chemical reactions, and magnetic field effects on nano-blood flow in stenosed arteries. Unlike previous studies that made the assumption that the pulsatile pressure gradient remains constant during channel narrowing, this novel investigation introduces a variable pressure gradient. This, in turn, significantly impacts several associated parameters. The mathematical model describing nano-blood flow in a horizontally stenosed artery is solved using perturbation techniques. Analytical solutions for key variables, including velocity, temperature, concentration, wall shear stress, flow rate, and pressure gradient, are visually presented for various physical parameter values.

Numerical simulation to study mixing vane spacer effects on heat transfer performance of supercritical pressure fluid in an annular channel

The spacer represents an essential part in the nuclear fuel rod. Spacer grid with mixing vanes in fuel rod bundle of nuclear reactor core has a significant impact on heat transfer perfor-mance in downstream to grid spacer. Grid Spacers are located on the nuclear fuel rod as-sembly to hold suitable clearance among the rods in a bundle. The objective of this paper is to study the enhanced heat transfer performance of R134a at supercritical pressure 4.5 MPa near downstream to mixing vane spacer in a vertical channel of annular flow. A spacer of 0.38 blockage ratio with mixing vanes, situated at mid-span of an annular channel is used in the present work. Numerical simulations have been accomplished for spacer with mixing vane and spacer without mixing vane in an annular channel by using commercial CFD (Computa-tional fluid dynamics) code ANSYS Fluent. The present investigation represents the compara-tive study for spacer with mixing vane and spacer without mixing vane effects on heat transfer and flow field characteristics in a downstream direction for mass flow-rate 0.41469 kg/s and heat flux 160 kW/m2. The results indicate that spacer with mixing vane has notable influence on heat transfer performance and flow field characteristics downstream of mixing vane spacer as compared to spacer without mixing vane. Wall temperature fall and increase of coefficient of heat transfer are significantly greater adjacent to spacer downstream. Spacer influence in the improvement of the heat transfer is noted up to distance X/D = 40 downstream and then flow is found as fully developed.

Simulation of Electrowetting-Induced Droplet Detachment: A Study of Droplet Oscillations on Solid Surfaces

The electrowetting-induced detachment of droplets from solid surfaces is important for numerous applications in the fields of heat transfer and fluid mechanics. The forced oscillations of droplets on solid surfaces and their ability to detach are studied. In this study, the process is efficiently simulated by implementing a powerful methodology developed by our team. Our results agree with experiments showing that optimal detachment, in terms of actuation energy, is achieved when the application of voltage is synchronized with the spreading time of the droplet. Under these conditions, the droplet oscillates with a period close to that of a mirrored Rayleigh droplet. The relationship between the droplet’s oscillation period and its physical properties is examined. During voltage-droplet synchronization, the droplet’s ability to detach depends mostly on its contact angle, its viscosity, and the applied voltage. An energy analysis is also conducted, revealing how energy is supplied to the droplet by electrowetting-induced detachment.

Applying multivariate inverse heat conduction problem to determine thermal contact resistance in aircraft embedded systems

In the field of heat transfer, inverse problems deal with the estimation of parameters that are difficult to measure directly. The usefulness of inverse techniques is such that, due to severe conditions, direct measurement of a certain variable becomes inaccessible. This works aims to perform inverse estimation in two problems. The first case is related to the estimation of the heat flux boundary condition and thermal contact resistance between two SAE 1020 steel plates. The first case is used as validation for the second case and is solved using the finite volume method for the discretization of the diffusion equation and Successive Over Relaxation (SOR) for solving the system of linear eqs. A set of seven one-dimensional experiments were performed varying the roughness and contact pressure at the interface of the samples and, as expected, it was found that the thermal conductance is a function of these parameters. The second case consists in the estimation of three thermal resistances in an aircraft embedded system consisting of four components and ambient air. In this case, the direct problem is solved using fourth-order Runge-Kutta to solve the system of ODEs. In both cases a future times regularization technique approach combined with Markov Chain Monte Carlo (MCMC) optimization method is used to solve the inverse problem. The embedded system inverse problem is also solved using a new and simple approach based on the Quadrilateral Optimization Method (QOM) with future time steps regularization and the result is compared with the MCMC method. The results of this work consolidate a low-cost inverse estimation setup and attest to the capacity of multivariate estimation in inverse heat transfer problems.

Stagnation point flow of magnetized convective nanofluid via porous stretchy surface subjected to ohmic heating and heat generation

ABSTRACT Nanotechnology is progressively deploying more complicated functional nanofluid materials that can be tweaked to improve efficiency. Motivated by these advances, the present simulation has aimed to generalize the steady flow models for nanofluid stagnation point flow through a porous stretchy surface. Additionally, the model enriches by incorporating the impacts of Brownian motion and thermophoresis because of the Buongiorno model process, heat generation and Ohmic heating. The fluid model transformation is done by adopting appropriate similarity variables, and the solutions to the set of ordinary derivative equations are computationally done by employing the Fehlberg Runge-Kutta scheme and the shooting method. The significant structural behaviour of the entrenched fluid quantities is presented graphically and deliberated in the discussion section. Also, some exciting engineering quantities are calculated and offered in tabular form. As revealed, the nanoliquid velocity decays for large numbers of modified convective and magnetic terms. The heat generation, dissipation, magnetic and radiation terms augmented the nanoliquid thermal dispersion. The reverse impact is detected on the heat transfer field and species distribution with rising Brownian movement term. An increasing heat source inspired the thermal gradient along the boundary domain. Finally, to support the current findings, a result verification is conducted with the existing method, which portrays the correctness of the solution approach.

Simulation and experimental study on flow and heat transfer performance of sheet-network and solid-network disturbance structures based on triply periodic minimal surface

Triply periodic minimal surface (TPMS) structures are widely used in the field of flow and heat transfer. In this paper, four TPMS structures, Schwartz Diamond-sheet (D-sheet), Schwartz Diamond-solid (D-solid), Schoen IWP-sheet (IWP-sheet), and Schoen IWP-solid (IWP-solid), are designed based on two structure generation strategies. The above structures all are manufactured through additive manufacturing, and the material is AlSi10Mg. The samples were characterized by X-ray scanning. The flow and heat transfer performance of different TPMS structures was studied by computational fluid dynamics (CFD) and experimental methods. The results show that the pressure drop of sheet-network is larger than that of solid-network for the same TPMS type. With the same structure generation strategy, the pressure drop of Schwartz Diamond (D-type) is greater than that of Schoen IWP (IWP-type). The heat transfer performance of the TPMS structure shows the same results as the pressure drop. The performance enhancement criterion (PEC) of the solid-network TPMS is better than that of the sheet-network structure, and the D-type TPMS structure is better than the IWP-type structure. The average PEC of D-solid and IWP-solid is 31 % and 44 % larger than that of D-sheet and IWP-sheet, respectively. The average PEC of D-sheet and D-solid is 11.8 % and 1.7 % larger than that of IWP-sheet and IWP-solid, respectively. The mechanism of the higher PEC of the solid-network structure is the low pressure drop caused by the high through-hole ratio and relatively concentrated skeleton. Under the same pressure drop, the heat transfer performance of TPMS with D-type sheet structure is better. The research content of the article is mainly applied to fin-enhancement, which can replace fins in traditional heat exchangers. In actual engineering applications, the TPMS structures type is reasonably selected according to the requirements.

The new wave structures to the perturbed NLSE via Wiener process with its wide-ranging applications

This article extracts stochastic soliton waves for the perturbed nonlinear Schödinger’s equation (PNLSE) forced by multiplicative noise through the Itô sense by utilizing two unified solver methods. The presented solutions involve three types: rational function, trigonometric function, and hyperbolic function solutions. These stochastic solutions are critical for studying numerous complicated phenomena in heat transfer, new physics, and many other fields of applied science. We demonstrate the effect of multiplicative noise on the solution of the stochastic PNLSE, which have never been studied before. The study and acquired solutions clarify that the unified solver technique is sturdy and efficient. Finally, several 2D and 3D graphs for selected solutions are shown.

Two-scale data-driven design for heat manipulation

Data-driven methods have gained increasing attention in computational mechanics and design. This study investigates a two-scale data-driven design for thermal metamaterials with various functionalities. To address the complexity of multiscale design, the design variables are chosen as the components of the homogenized thermal conductivity matrix originating from the lower scale unit cells. Multiple macroscopic functionalities including thermal cloak, thermal concentrator, thermal rotator/inverter, and their combinations, are achieved using the developed approach. Sensitivity analysis is performed to determine the effect of each design variable on the desired functionalities, which is then incorporated into topology optimization. Geometric extraction demonstrates an excellent matching between the optimized homogenized conductivity and the extraction from the constructed database containing both architecture and property information. The designed heterostructures exhibit multiple thermal meta-functionalities that can be applied to a wide range of heat transfer fields from personal computers to aerospace engineering.

Aerothermal characteristics past a matrix structure inside a rectangular serpentine passage

A matrix structure can offer a high heat transfer and improved structural rigidity to the gas turbine's aerofoils. The earlier matrix studies are limited to presenting aerothermal behavior within the matrix structures. Thus, there is a scope to investigate the aerothermal characteristics downstream of a matrix geometry. The present experimental effort seeks to characterize the detailed flow and heat transfer downstream of the matrix and at the bend for Re = 800 and 6500. The heat transfer and flow fields are captured in various planes using liquid crystal thermography and stereoscopic particle image velocimetry techniques. The results show that the matrix ejects a highly turbulent vortical flow in the form of two co-rotating vortices, which further diffuse and merge in downstream. The matrix offers a very high average augmentation (Nu¯/Nu¯0) in the first pass for Re = 800 (varies from 12 to 4), but it shows a poor heat transfer (Nu¯/Nu¯0 < 1) at the bend region, which can generate local hot spots for Re = 800. In contrast, for Re = 6500, the matrix offers a stable augmentation throughout the first pass and bend region, i.e., Nu¯/Nu¯0≈ 2.4–1.

Radiation and Nanoparticles Shape Effect on Aligned MHD Jeffrey Hybrid Nanofluids Flow and Heat Transfer over a Stretching Inclined Plate

The study through a stretching medium is a topic in the field of fluid dynamics and heat transfer. It involves investigating the behaviour of fluid flow and heat transfer phenomena in situations where a medium, such as a solid surface, is continuously stretched or deformed. Jeffrey fluid are found in the applications in various fields, including engineering, materials science, and biomedical engineering. Water was combined with copper (Cu) and aluminium oxide (Al2O3) is used in this study by considering the influence of nanoparticles shape which are spherical, brick, cylindrical, platelet and blade. The Keller Box method is used to solve numerically the Jeffrey hybrid nanofluid's governing nonlinear partial differential equations (PDEs) to nonlinear ordinary differential equations (ODEs) using similarity transformation. The results for both the velocity and temperature profiles of Jeffrey hybrid nanofluids (Deborah number, β) as well as the skin friction and Nusselt number are presented graphically and in tabulated form. The result shows that the momentum boundary layer thickness is decrease for any increment of the value alignment angle of the magnetic field parameter, the interaction of the magnetic field parameter, alignment angle of the incline plate, the mixed convection parameter, the radiation parameter, and the nanoparticles shape except the value of the volume fraction of the nanoparticles for the increasing value of Deborah number (β). The skin friction is increases as any increment value of an alignment angle of magnetic field, interaction of magnetic parameter, radiation parameter and volume fraction of nanoparticles increase, while the Nusselt number is decrease for the value of radiation parameter. It also observed that the factor of nanoparticles shape result is significant with the Jeffrey hybrid nanofluids which is the nanoparticles shape with the highest skin friction coefficient and Nusselt number is blades shape.

Enhanced thermal and mass transfer of harnessing microbial mediation in electrically conducting Oldroyd-B nanofluid flow: Eukaryotes microorganisms in biological applications

In bioremediation, pollutants are broken down or detached from an atmosphere using microorganisms like bacteria or fungus. These bacteria can either ingest contaminants or be enzymatically converted into innocuous molecules. Bioremediation can be enhanced by several techniques, such as bioaugmentation (the introduction of specific microorganisms), biostimulator (the provision of nutrients to stimulate microbial activity), and bioventing (the provision of air or oxygen to encourage microbial growth). The creation and dissipation of heat in a convective non-Newtonian Oldroyd-B fluid flow across a nonlinear stretching sheet in a three-dimensional boundary layer is examined in this study. The boundary layer flow's highly nonlinear partial differential equations are transformed into ordinary differential equations in the study via similarity transformations. The bvp4c technique of MATLAB is then used to resolve these equations. The study looks at some variables, including as temperature, concentration, the presence of microorganisms, velocity, heat transfer rate, and shear stress. These parameters are evaluated graphically and presented in tabular form, with a focus on the local Deborah numbers (β₁ and β₂), the local buoyancy parameters (λ₁ and λ₂), the Prandtl number (Pr), the Schmidt number (Sc), the Bio-convection Schmidt number (Sb), and the Peclet number (Pe). The results show that raising the local buoyancy parameter improves the boundary layer flow's velocity field and rate of heat transfer. Visual representations of the effects of non-dimensional factors on non-dimensional velocity, concentration, motile microorganism, and temperature profiles help to comprehend the underlying physical properties clearly.

Thermal evaluation of MHD boundary‐layer flow of hybridity nanofluid via a 3D sinusoidal cylinder

AbstractThe study of the boundary layer is considered one of the most important theories in the field of heat and mass transfer because of its important explanation that shows us the behavior of different surfaces while they are under the influence of the flow accompanied by different thermal forces. The study of corrugated surfaces is one of the engineering applications, such as flow in heat exchangers or solar cells or cooling processes during surface heat treatments. This model is also used in medical applications such as flow in arteries or movement in the intestines. So, the work deals with investigating the boundary layer surrounding a three‐dimensional sinusoidal pipe; the boundary layer was assumed to be filled with a hybrid nanofluid consisting of water +Cu nanoparticles as the main fluid, supported by a small concentration of Al2O3 or Ag nanoparticles. The boundary layer is described by a set of nonlinear partial differential equations due to the continuity, momentum, and energy equations, which are transformed into a set of dependently coupled nonlinear ordinary differential equations. The obtained system of equations was solved using numerical techniques. The behavior of the boundary layer under the varying types and concentrations of nanoparticles and the influence of the magnetic field has been depicted by a set of graphs and tables. With reference to some results, it is found that using 5% of nanoparticles of aluminum oxide raises the rate of cooling by 8% and using 5% of silver nanoparticles increases it by 5%.

Numerical study of entropy generation in magneto-convective flow of nanofluid in porous enclosure using fractional order non-Darcian model

The present numerical work examines the effect of fractional order parameter on heat transfer and entropy generation for a thermo-magnetic convective flow of nanofluid (Cu-water) in a square porous enclosure that contains semi-circular bottom wall. The Darcy–Brinkmann–Forchheimer model is utilized to evaluate the momentum transfer in porous media, and the Caputo-time fractional derivative term is introduced in momentum as well as in the energy equation. Further, non-dimensional governing equations are simulated through the penalty finite element method, and the Caputo time derivative is approximated by L1-scheme. The study is carried out for various parameters, including Rayleigh number (Ra), Darcy number (Da), radius of the semicircle (r), fractional order (α), and Hartmann number (Ha). The comprehensive results are presented by the contour variation of isotherms, streamlines, and total entropy generation at the selected range of parameters. In addition, thermal transport and irreversibilities due to heat transfer, fluid friction, and magnetic field have been accounted through the numerical variation of mean Nusselt number (Num) and Bejan number due to heat transfer (Beht), fluid friction (Beff), and magnetic field (Bemf), respectively. The key findings of the present study reveal that during the initial evolution period, the Num value increases as α→1. Additionally, time taken to achieve the steady state condition varies and depends on fractional order α. Furthermore, in the absence of Ha, the heat transfer and entropy generation intensifies with augmentation of Ra and Da for all α, while, the increasing value of Ha shows an adverse impact on the heat transfer rate.

Unsteady Ohmic dissipative flow of ZnO-SAE50 nanofluid past a permeable shrinking cylinder

The laminar boundary layer flow of a Zinc Oxide-Society of Automotive Engineers 50 alias nano-lubricant () past a permeable shrinking cylinder is investigated. The flow is unsteady, incompressible, and Ohmic dissipative. The present study holds immense significance in different engineering as well as scientific domains. It combines research on nanoparticle effects, unsteady flows, and solid surface interactions. The study claimed that the use of nanofluid in the unsteady flow past a permeable shrinking cylinder led to significant heat transfer enhancement. The acquired results from the study would be fruitful in the fields of thermal engineering and heat transfer. The findings of the study can aid in optimizing cooling systems, heat exchangers, and energy-efficient designs. A governing model has been achieved for the flow and heat transfer by using conservation laws related to mass, momentum, and energy. Governing system of partial differential equations is solved to a nonlinear system of ordinary differential equations by using similarity transformation, which is later on solved with the help of the Shooting method and RK-Fehlberg duos. Plots are shown for both velocity and temperature profiles, to display the impacts of involved dimensionless parameters. Additionally, graphs for Nusselt Number have also been represented which shows the local rate of heat transfer. It is examined that the Ohmic dissipation as well as the volumetric ratio of the nanoparticles greatly influence the overall thermal performance of the system.

Synchronized measurement of instantaneous convective heat flux and velocity fields in wall-bounded flows

This work presents an experimental setup for acquiring synchronized wall and flow field measurements in a turbulent boundary layer (TBL). Instantaneous measurements of the convective heat transfer distribution at the wall and of the flow field are carried out simultaneously, using synchronized wall-parallel planar particle image velocimetry and infrared thermography. A low-thermal-inertia heated-thin-foil sensor is embedded in the wall beneath the TBL to measure the wall temperature maps with enough temporal resolution. The unsteady energy balance of the heated foil can be solved to restore the instantaneous value of the convective heat transfer coefficient on the wall. A detailed description of the sensor design is included. Furthermore, owing to the relatively low signal-to-noise ratio of instantaneous temperature fluctuation measurements, a recipe for data processing is proposed. A study to characterize the uncertainty of the experimental setup design is also performed. The overall agreement in the correlation between wall heat transfer and velocity fields with the literature supports the validity of the proposed approach. This solution is potentially interesting for flow control purposes, where sensing is performed at the wall.

Performance of supercritical carbon dioxide heat transfer in several enhanced tubes under external high-temperature airflow

A precooler is installed in the Synergetic Air-Breathing Rocket Engine to ensure the compressor operates properly at high Mach numbers. To better fit the actual precooler scenario, the present study simulated the flow and heat transfer fields of supercritical carbon dioxide (sCO2) in a horizontal tube in which hot air counterflows outside. In the coolant channel, two types of ribs were selected and added, including rectangular ribs as well as isosceles triangular ribs. The geometry parameters of the rib and its configuration on the flow and heat transfer characteristics of sCO2 were examined in detail. Results show that six out of eight cases revealed an increase in Nut over 100% in the triangular rib, making it the optimal enhanced structure. Compared to rectangular ribbed tubes, triangular ribbed tubes display a different variation trend in Nut with rib height due to the combined effects of fluid disturbance and recirculation zone. Both types of ribs increase their Nut first and then decrease it with the rise of rib pitch, which may be due to the fact that high turbulence zones require several distances to develop. This research can provide theoretical foundations and data support for the design of high-efficiency air-precoolers in the future.