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Accepted Manuscripts

BASIC VIEW  |  EXPANDED VIEW
Discussion  
Asterios Pantokratoras
J. Heat Transfer   doi: 10.1115/1.4040541
The present comment concerns some doubtful results included in the above paper.
research-article  
Andrey Gusarov
J. Heat Transfer   doi: 10.1115/1.4040482
Additively-manufactured cellular and honeycomb structures, foams, and very oblate particles dispersed in matrix are the examples of heterogeneous media with thin-wall morphology. Phase boundaries can also be considered by this approach. Statistical description is proposed to estimate the effective radiative properties of such media. Three orientation models are studied: (i) isotropic, (ii) surface elements parallel to a plane, (iii) surface elements parallel to an axis. Radiative transfer equations are obtained for the three models in the framework of the homogeneous phase approach and the multiphase approach. The radiative thermal conductivity is calculated for a bundle of circular rods, a packed pebble bed, and an open-cell metal foam. The results generally agree with the reference calculations by other methods. Small difference can be explained by different approaches to scattering and assumptions about the temperature distribution. Attenuation of light in a skin tissue is calculated by the diffusion approximation. The attenuation coefficient generally agrees with the reference Monte Carlo simulation. The difference observed at certain combination of parameters can be due to the assumption of regular arrangement of vessels at the Monte Carlo simulation.
TOPICS: Radiative heat transfer, Thin wall structures, Simulation, Radiation scattering, Honeycomb structures, Electromagnetic scattering, Thermal conductivity, Biological tissues, Approximation, Metal foams, Rods, Skin, Temperature distribution, Vessels, Diffusion (Physics), Scattering (Physics), Foams (Chemistry), Particulate matter
research-article  
Ali Riahi, Julien Pellé, Lillia Chouchane, Souad Harmand and Sadok Ben Jabrallah
J. Heat Transfer   doi: 10.1115/1.4040481
This paper presents a numerical and experimental study of a turbulent flow of air in a Tbifurcation. This configuration corresponds to the radial vents placed in the stator vertically to the rotor-stator air gap in the electrical machines. Indeed, our analysis focuses on the local convective heat transfer on the vents internal surface under a turbulent mass flow rate. In order to dimension the cooling installation of this region, computational fluid dynamics (CFD) simulations and an experiment using particle image velocimetry (PIV) have been carried out. The resulting flow generally being the seat of recirculation zones in the various channels. The influence of the flow ratio and the diameter of the bifurcation on the dynamic and thermal behavior of the flow was. To carry out this study, we considered a numerical approach based on the KW-SST turbulence model (using commercial software, "Comsol Multiphysics"), allowing to numerically solve the Navier-Stokes equations and the energy equation in the system under consideration. We describe the different hypotheses necessary to formulate the equations governing the problem, the initial conditions, and the limits. The velocity in the bifurcation obtained using the simulation is compared with that obtained by the experiment and reveals a good agreement. The effect of branch diameter of the bifurcation and the effect of the flow ratio of heat transfer have been particularly analyzed in this paper.
TOPICS: Flow (Dynamics), Heat transfer, Cooling, Machinery, Particulate matter, Turbulence, Dimensions, Air flow, Simulation, Navier-Stokes equations, Computational fluid dynamics, Convection, Rotors, Bifurcation, Computer software, Stators, Vents
PHOTOGALLERY  
Taolue Zhang, Jayaveera Muthusamy, Dr. Jorge L. Alvarado, Anoop Kanjirakat and Reza Sadr
J. Heat Transfer   doi: 10.1115/1.4040393
The objective of this study was to visualize and simulate the thermal physical process during double droplet train impingement for three different horizontal impact spacings (S = 0.65 mm, 1.2 mm and 2 mm). Two identical HFE-7100 droplet trains were produced using a piezoelectric droplet generator at a frequency of 6000 Hz with a corresponding droplet Weber number of 312. A translucent sapphire substrate with a thin film ITO coating was used as heater in the experiments. The heat transfer and hydrodynamics of double droplet train impingement have been visualized using IR thermal imaging and high speed optical imaging techniques, respectively. The double droplet train impingement process was also simulated numerically using the Coupled Level Set-Volume of Fluid (CLS-VOF) approach with dynamic mesh adaption (DMA). Humps were observed both numerically and experimentally between two adjacent impact craters due to the interactions caused by the impinging droplet trains. It was found that the hump height decreased when impact spacing increased. IR images show that higher impact spacing leads to better heat transfer performance, which could be due to the lower hump height at greater impact spacing conditions. It was also observed that higher impact spacing leads to better thermo-hydrodynamics within and outside the impingement zone. In summary, results show that horizontal impact spacing plays a significant role in double droplet train impingement cooling. This work was supported by the National Priority Research Program of the Qatar National Research Fund, Grant No.: NPRP 6-1304-2-525.
TOPICS: Hydrodynamics, Heat transfer, Drops, Visualization, Trains, Imaging, Thermohydrodynamics, Thin films, Generators, Sapphire, Impingement cooling, Fluids, Coating processes, Coatings
PHOTOGALLERY  
Dong Hwan Shin, Yeonghwan Kim, Jin Sub Kim, Do Won Kang, Jeong Lak Sohn and Jungho Lee
J. Heat Transfer   doi: 10.1115/1.4040394
Flow visualization was performed to give a physical insight with vortical structures of an axisymmetric impinging jet on a concave surface. High-speed imaging was employed to get clear images with a laser light sheet illumination. An axisymmetric jet is issued into quasi-ambient air through a straight pipe nozzle with fully-developed velocity profile. A regular vertical pattern of an axisymmetric jet was observed with different flow entrainment rate. While an impinged jet turns to convert a wall jet along a concave surface, the flow interaction between the large-scale toroidal vortex and the concave surface was observed in the transition between the stagnation and wall jet zone. The ring-shaped wall eddies induced from a pair of toroidal vortices were also appeared to diverge into the radial direction along the concave surface. As the jet Reynolds number increases, small-scale vortices can be developed to a large-scale toroidal vortex. The location in which a large-scale toroidal vortex strikes is generally identical to the location where the secondary peak in heat transfer occurs. The frequency of large scale toroidal vortex on concave surface is found to be nearly similar as that of wall jet on flat surface. As the nozzle-to-target spacing (L/D) increases, it becomes shorter due to the loss of jet momentum. The flow behavior of axisymmetric impinging jet on a concave surface can be helpful to design the internal passage cooling for gas turbine blade.
TOPICS: Flow visualization, Vortices, Flow (Dynamics), Nozzles, Pipes, Design, Gas turbines, Heat transfer, Cooling, Lasers, Eddies (Fluid dynamics), Reynolds number, Blades, Imaging, Momentum
PHOTOGALLERY  
Jin Sub Kim, Dong Hwan Shin, Wooyong Moon, Jaehun Heo and Jungho Lee
J. Heat Transfer   doi: 10.1115/1.4040395
Condensation behavior on a superhydrophobic microporous surface was visually compared with that on a plain surface in the water saturated at the pressures of 101.3 kPa (Tsat = 100 °C) and 3.2 kPa (Tsat = 25 °C). The microporous surface was formed by sintering copper powders with the average diameter of 50 µm on the bare copper surface, resulting in the coating thickness of approximately 250 µm. The microporous surface was coated with the polytetrafluoroethylene (PTFE) layer by the spray-coating method to change the wettability into superhydrophobic, which was verified from a measured apparent contact angle of above 150°. While dropwise condensation is observed on both bare and hydrophobic plain surfaces at Psat = 101.3 kPa, filmwise condensation is seen on the superhydrophilic plain surface. At the low saturation pressure of 3.2 kPa, condensation behavior on the bare plain surface is changed into the filmwise condensation with improved wettability. In contrast, on the microporous surface, the only superhydrophobic microporous surface shows dropwise condensation behavior, where the surface is considered at the Cassie-state. However, filmwise condensation behaviors are observed on both superhydrophilic and bare microporous surfaces due to the wicking into the pores.
TOPICS: Condensation, Visualization, Film condensation, Water, Pressure, Copper, Coating processes, Coatings, Sintering, Copper powders, Spraying (Coating processes)
PHOTOGALLERY  
Seongchul Jun, Jin Sub Kim, Jungho Lee and Seung M. You
J. Heat Transfer   doi: 10.1115/1.4040396
The hydrophobic, Teflon-coated surfaces on plain copper and Cu-HTCMC (High temperature Thermally Conductive Microporous Coating) compared on pool boiling heat transfer of water. The HTCMC was created by sintering of copper powders with the average particle size of 67 µm and about 300 µm coating thickness that showed a good boiling heat transfer and the CHF enhancement from the previous study at saturation of water [1]. The Teflon-coated surfaces were created by coating of Amorphous Fluoroplastic (AF) 2400 resin on both plain copper and Cu-HTCMC. The static angles of both surfaces showed hydrophobic as about 120-130°. The departure bubble sizes created by merged bubbles of both surfaces are comparable as about 7 mm at 5 kW/m2 and the sizes are increased as heat flux increases. However, unlike to the plain surface, the smaller bubbles on Cu-HTCMC are not observed at the heat flux of 5 kW/m2 because the number of nucleation sites created in the porous structure are huge smaller bubbles are merged as soon as they grow from pores. As heat flux reaches the surfaces are covered by vapor film and reached the critical heat flux (CHF) at much lower heat fluxes compared to hydrophilic surfaces but the CHF values of Teflon-coated Cu-HTCMC is 640 kW/m2 and the value is more than tenfold higher than that of Teflon-coated plain copper.
TOPICS: Copper, Water, Nucleate boiling, Critical heat flux, Bubbles, Coating processes, Coatings, Heat flux, Heat transfer, Vapors, High temperature, Heat, Sintering, Copper powders, Flux (Metallurgy), Nucleation (Physics), Boiling, Particle size, Pool boiling, Resins
Guest Editorial  
Chang Kyoung Choi and Nenad Miljkovic
J. Heat Transfer   doi: 10.1115/1.4040397
The 25rd Heat Transfer Photogallery was sponsored by the K-22 Heat Transfer Visualization Committee for the 2017 International Mechanical Engineering Congress and Exhibition (IMECE) held in the Tampa Convention Center, Tampa, Florida, November 3 - 9, 2017. Ten entries were submitted into the Photogallery sessions and the peer-reviewed evaluation conducted by both the participants and selected HTD K-22 Technical Committee members has identified the four final entries for publication in this ASME Journal of Heat Transfer August issue of 2018. The purpose of publishing these entries is to draw attention to the innovative features of visualization techniques and esthetic qualities of heat and mass transport phenomena. This Photogallery issue covers multiscale visualizations of gas dynamics, impinging jets, condensation and boiling heat transfer on nanoengineered surfaces, and droplet-surface interactions. To focus on visualization images and schematics for each entry, the text is kept to a minimum and further details should be found directly from the authors. Our wish is that the journal readers enjoy viewing these collections, acquire knowledge of the state-of-the-art visualization techniques, and also promote their participation in the future Photogallery sessions in the SHTC and ASME-IMECE conferences.
TOPICS: Heat transfer, Visualization, Transport phenomena, Heat, Condensation, Mechanical engineering, Drops, Gasdynamics, Jets, Boiling
research-article  
Caixi Liu, Shuai Tang, Yuhong Dong and Lian Shen
J. Heat Transfer   doi: 10.1115/1.4040347
We study the effects of particle-turbulence interactions on heat transfer in a particle-laden turbulent channel flow using direct numerical simulation for turbulence and Lagrangian tracking for particles. Our study focuses on the modulations of the temperature field and heat transfer process by inertial particles with different particle momentum Stokes numbers (St), which in combination of the particle-to-fluid specific heat ratio and the Prandtle number results in different particle heat Stokes numbers. It is found that as St increases, while the turbulent heat flux decreases, the particle feedback heat flux increases significantly and results in an increase in the total heat flux. Moreover, by taking advantage of the ability of numerical simulation to address different momentum and heat processes separately, we investigate the different roles played by the particle-to-fluid momentum feedback and heat feedback. It is found that the momentum feedback increases the fluid temperature fluctuation while the heat feedback decreases it, and both reduce the turbulent heat flux. The analyses of simulation data illustrate the two processes of particles affecting heat transfer, namely the direct effect of particle thermal feedback to the fluid and the indirect effect of the modulation of turbulent heat flux due to the suppression of wall-normal turbulence velocity fluctuation by the particles. Our results indicate that both the momentum feedback and the heat feedback are important when the particle inertia is large, suggesting that both feedback processes need be taken into account in computation and modeling.
TOPICS: Particulate matter, Turbulence, Heat transfer, Channel flow, Feedback, Heat flux, Momentum, Heat, Fluids, Temperature, Computer simulation, Simulation, Specific heat, Modeling, Computation, Inertia (Mechanics)
research-article  
Loong Ee Loh, JIe Song, Fenglin Guo and Guijun Bi
J. Heat Transfer   doi: 10.1115/1.4040256
Selective laser melting (SLM) has received increasing attention in recent years as an innovative manufacturing technique. The present SLM process only uses a single laser beam to melt and consolidate the powder which may result in excessive evaporation. In this paper, a double beam scanning strategy is investigated in which the first laser beam pre-heats the powder just below the sintering point while the second laser beam completely melts the powder. An analytical solution on the temperature distribution heated by a moving laser beam in the powder-bulk domain is derived and is used to determine the critical radius of the first laser beam. The single and double beam scanning strategies are compared numerically and it is found that double beam scanning can effectively reduce material evaporation and increase the amount of powder melted in the SLM process.
TOPICS: Lasers, Laser beams, Melting, Temperature distribution, Evaporation, Manufacturing, Sintering
research-article  
Ping Li and Junfeng Zhang
J. Heat Transfer   doi: 10.1115/1.4040257
To simulate heat transfer processes through periodic devices with non-uniform wall temperature distributions, we propose to decompose the regular temperature into two parts: namely the transient part and the equilibrium part. These two parts can be solved independently under their individual wall and inlet/outlet conditions. By calculating the flow field and the two component functions in one periodic module, one can easily generate the distributions of regular temperature in one or multiple modules. The algorithm and implementation are described in details, and the method is discussed thoroughly from mathematical, physical, and numerical aspects. Sample simulations are also presented to demonstrate the capacity and usefulness of this method for future simulations of thermal periodic flows using various numerical schemes.
TOPICS: Temperature, Heat transfer, Periodic structures, Wall temperature, Flow (Dynamics), Engineering simulation, Simulation, Equilibrium (Physics), Transients (Dynamics), Algorithms
research-article  
Wei Li, Yang Luo, Jing-zhi Zhang and W. J. Minkowycz
J. Heat Transfer   doi: 10.1115/1.4040147
This paper presents a fundamental research on hydrodynamics and heat transfer about an elongated bubble flow boiling in a circular microchannel. In present study, continuum Surface Force (CSF) model based on Volume of Fluid (VOF) methodis combined withthermocapillaryforce to explore the effects of thermocapillarity for flow boiling in microchannels. To validate the self-defined codes, a two-phase thermocapillary-driven flow and a Taylor bubble growing in a capillary tube are performed. Results of both test cases show good convergence and are in good agreement with data from other literatures. Bubble motion and local heat transfer coefficient (HTC) on the heated wall with respect to time are discussed in present study. It is found that for large Marangoni number (case 3), variation of surface tension has an influenceon bubble shape and temperature profile. Thermocapillary effect induces convection in liquid film region, which augments the HTCs at specified positions. The numerical investigation also shows that average HTC has increased by 6.7% in case 3 when compared with case 1. Thus, it is very significative to further study the influence of themocapillarity and Marangoni effect on bubble growth in microchannels.
TOPICS: Simulation, Bubbles, Evaporation, Gravity (Force), Microchannels, Boiling, Flow (Dynamics), Hydrodynamics, Heat transfer, Fluids, Bubbly flow, Convection, Heat transfer coefficients, Surface tension, Liquid films, Shapes, Temperature profiles
research-article  
Jiannan Chen, Rui-Na Xu, Zhen Zhang, Xue Chen, Xiaolong Ouyang, Gaoyuan Wang and Peixue Jiang
J. Heat Transfer   doi: 10.1115/1.4039903
Enhancing spray cooling with surface structures is a common, effective approach for high heat flux thermal management to guarantee the reliability of the many high power, high speed electronics and to improve the efficiency of new energy systems. However, the fundamental heat transfer enhancement mechanisms are not well understood especially for nanostructures. Here, we fabricated six groups of nanowire arrayed surfaces with various structures and sizes that show for the first time how these nanostructures enhance the spray cooling by improving the surface wettability and the liquid transport to quickly rewet the surface and avoid dry out. These insights into the nanostructure spray cooling heat transfer enhancement mechanisms are combined with microstructure heat transfer mechanism in integrated microstructure and nanostructure hybrid surface that further enhances the spray cooling heat transfer.
TOPICS: Cooling, Sprays, Nanowires, Heat transfer, Nanostructures , Reliability, Energy / power systems, Thermal management, Electronics, Heat flux
research-article  
Marcelo J.S. de Lemos and Paulo Carvalho
J. Heat Transfer   doi: 10.1115/1.4039915
This work presents a study of double-diffusive free convection in a porous square cavity under turbulent flow regime and with aiding drive. The thermal non-equilibrium model was employed to analyze the energy and mass transport across the enclosure. Governing equations were time- and volume averaged according to the double-decomposition concept. Analysis of a modified Lewis number, Lem, showed that for porous media this parameter presents opposite behavior when varying the thermal conductivity ratio or the Schmidt number, while maintaining the same value for Lem. Differently form free flow, the existence of the porous matrix contributes to the overall thermal diffusivity of the medium, whereas mass diffusivity is only effective within the fluid phase for an inert medium. Results indicated that increasing Lem through an increase in Sc reduces flow circulation inside porous cavities, reducing Nuw and increasing Shw. Results further indicate that increasing the buoyancy ratio N promotes circulation within the porous cavity, leading to an increase in turbulence levels within the boundary layers. Partial contributions of each phase of the porous cavity (solid and fluid) to the overall average Nusselt number becomes independent of N for higher values of the thermal conductivity ratio, ks/kf. Further, for high values of ks/kf, the average Nusselt number drops as N increases.
TOPICS: Porous materials, Turbulence, Equilibrium (Physics), Buoyancy, Convection, Cavities, Flow (Dynamics), Fluids, Thermal conductivity, Boundary layers, Thermal diffusivity, Natural convection
research-article  
Salam Hadi and Mustafa Rahomey
J. Heat Transfer   doi: 10.1115/1.4039642
Numerical simulations are carried out for fluid flow and natural convection heat transfer induced by a temperature difference between a hot inner cylinder with different geometries (i.e. circular; triangular; elliptic; rectangular; and rhombic) and a cold outer square enclosure filled with nanofluid superposed porous-nanofluid layers. The Darcy-Brinkman model is applied for the saturated porous layer with nanofluid. Moreover, the transport equations (mass, momentum, and energy) are solved numerically using the Galerkin weighted residual method by dividing the domain into two sets of equations for every layer with incorporating a non-uniform mesh size. The considered domains in this investigation are closely examined over a wide range of Rayleigh number (103 = Ra= 106), Darcy number (10-5 = Da = 10-1), the thickness of porous layer (0% = Xp = 100%), thermal conductivity ratio (1 = Rk = 20) and nanoparticle volume fraction (0 = ? = 0.1), respectively. The nanofluid is considered to be composed of Cu-nanoparticle and water as a base fluid. The results showed that the obtained total surfaces-averaged Nusselt numbers of the enclosure, in all cases, at the same operating conditions, the rate of heat transfer from the enclosure which the triangular cylinder is located inside is better. Also, as the thickness of the porous layer is increased from 20% to 80%, the free convection performance will decrease significantly (to about 50%) due to the hydrodynamic properties of the porous material.
TOPICS: Natural convection, Circular cylinders, Cylinders, Nanofluids, Heat transfer, Nanoparticles, Thermal conductivity, Momentum, Fluid dynamics, Temperature, Fluids, Porous materials, Computer simulation, Rayleigh number, Water
research-article  
Je-Chin Han
J. Heat Transfer   doi: 10.1115/1.4039644
Gas turbines have been extensively used for aircraft engine propulsion, land-based power generation, and industrial applications. Power output and thermal efficiency of gas turbines increase with increasing turbine rotor inlet temperatures (RIT). Currently, advanced gas turbines operate at turbine RIT around 1700°C far higher than the yielding point of the blade material temperature about 1200°C. Therefore, turbine rotor blades need to be cooled by 3-5% of high-pressure compressor air around 700°C. To design an efficient turbine blade cooling system, it is critical to have a thorough understanding of gas turbine heat transfer characteristics within complex 3-D unsteady high-turbulence flow conditions. Moreover, recent research trend focuses on aircraft gas turbines operate at even higher RIT up to 2000°C with a limited amount of cooling air, and land-based power generation gas turbines (including 300-400 MW combined cycles with 60% efficiency) burn alternative syngas fuels with higher heat load to turbine components. It is important to understand gas turbine heat transfer problems with efficient cooling strategies under new harsh working environments. Advanced cooling technology and durable thermal barrier coatings (TBCs) play most critical roles for developments of new-generation high-efficiency gas turbines with near-zero emissions for safe and long-life operation. This paper reviews basic gas turbine heat transfer issues with advanced cooling technologies and documents important relevant papers for future research references.
TOPICS: Cooling, Gas turbines, Turbines, Heat transfer, Temperature, Rotors, Blades, Energy generation, Thermal barrier coatings, Aircraft engines, Emissions, Combined cycles, Thermal efficiency, Turbine components, Syngas, Aircraft, Flow (Dynamics), Heat, Cooling systems, Fuels, Turbulence, Compressors, Stress, Propulsion, Turbine blades, High pressure (Physics), Design
research-article  
Francisco Valentin, Narbeh Artoun, Masahiro Kawaji and Donald McEligot
J. Heat Transfer   doi: 10.1115/1.4039585
High pressure/high temperature forced and mixed convection experiments have been performed with helium and nitrogen at temperatures and pressures up to 893K and 64 bar, respectively. The test section had a 16.8-mm ID flow channel in a 108-mm OD graphite column. Flow regimes included turbulent, transitional and laminar flows with the inlet Reynolds numbers ranging from 1,500 to 15,000. Due to strong heating, the local Reynolds number decreased by up to 50% over the 2.7-m test section. In addition, heat transfer degradation and flow laminarization caused by intense heating led to Nusselt numbers 20~50% lower than the values given by the modified Dittus-Boelter and modified Gnielinski correlations. Flow laminarization criteria were considered based on a dimensionless acceleration parameter (Kv) and buoyancy parameter (Bo*). Upward turbulent flows displayed higher wall temperatures than downward flows, due to the impact of flow laminarization which is not expected to affect buoyancy-opposed flows. Laminar Reynolds number flows presented an opposite behavior due to the enhancement of heat transfer for buoyancy-aided flows. At low Reynolds numbers, downward flows displayed higher and lower wall temperatures in the upstream and downstream regions, respectively, than the upward flow cases. In the entrance region of downward flows, convection heat transfer was reduced due to buoyancy leading to higher wall temperatures, while in the downstream region, buoyancy-induced mixing caused higher convection heat transfer and lower wall temperatures.
TOPICS: Flow (Dynamics), High pressure (Physics), Graphite, High temperature, Buoyancy, Reynolds number, Wall temperature, Heating, Heat transfer, Turbulence, Convection, Mixed convection, Entrance region, Laminar flow, Temperature, Helium, Nitrogen
research-article  
James Grisham, Ashkan Akbariyeh, Weiya Jin, Dr. Brian H. Dennis and Bo P. Wang
J. Heat Transfer   doi: 10.1115/1.4039541
Sensitivity information is often of interest in engineering applications (e.g., gradient-based optimization). Heat transfer problems frequently involve complicated geometries for which exact solutions cannot be easily derived. As such, it is common to resort to numerical solution methods such as the finite element method. The semi-analytic complex variable method is an accurate and efficient approach to computing sensitivities within a finite element framework. The method is introduced and a derivation is provided along with a detailed description of the algorithm which requires very minor changes to the analysis code. Three benchmark problems in steady-state heat transfer are studied including a nonlinear problem, an inverse shape determination problem and a reliability analysis problem. It is shown that the semi-analytic complex variable method is superior to the other methods considered in terms of computation time and sensitivity to perturbation size.
TOPICS: Heat transfer, Event history analysis, Finite element methods, Algorithms, Engineering systems and industry applications, Finite element analysis, Optimization, Computation, Shapes, Steady state
research-article  
Fatma Habbachi, Fakhreddine Segni Oueslati, Rachid Bennacer and Afif Elcafsi
J. Heat Transfer   doi: 10.1115/1.4038828
This paper is a numerical study was conducted to investigate the conjugate of the flow and heat transfer from the three-dimensional natural convection, in a cubic enclosure partially filled with a central cubic porous block which is in out thermal equilibrium with the fluid media. The physical model considered here assumes the existence of a temperature difference across the enclosure between the left and the right wall, the other walls are adiabatic. Under these conditions, flow from inside the enclosure is generated by the temperature difference across the enclosure and the interaction between the solid matrix and the fluid. Variations of Nusselt number on the hot and cold walls are also presented to show the overall characteristics of heat transfer to the interior of the enclosure. The study found that the fluid flow and heat transfer are governed by the dimensionless thickness of the porous layer , and the thermal conductivity ratio of the solid matrix of the porous media to that of the fluid . The complex obtained flow structure and corresponding heat transfer (velocity, temperature profiles) are discussed at a steady state. The numerical results are reported in terms of isotherms, velocity field, streamlines, and averaged Nusselt number. Thus, the results of this work can help develop new tools and means to optimize the overall heat transfer rate, which is important in many electronic energy components and other systems.
TOPICS: Heat transfer, Energy / power systems, Optimization, Cavities, Flow (Dynamics), Fluids, Temperature, Natural convection, Porous materials, Thermal conductivity, Thermal equilibrium, Steady state, Temperature profiles, Fluid dynamics

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