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Research on Fluid Mechanics and Heat Transfer

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "J: Thermal Management".

Deadline for manuscript submissions: closed (2 June 2024) | Viewed by 12400

Special Issue Editors


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Guest Editor
Department of Industrial Engineering, Alma Mater Studiorum Università di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy
Interests: stability analysis of convection flows in porous media; convection and instability of dissipative and non-Newtonian fluid flows; new features for the instability of shear flows.
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Guest Editor
Department of Industrial Engineering, Alma Mater Studiorum Università di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy
Interests: convection and heat transfer in porous media; thermal instability in dissipative flows; convection heat transfer in non-Newtonian fluids
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The study of thermal effects in fluid mechanics is a cornerstone of contemporary applied physics and engineering. There are many devices in daily life based on the phenomenon of convection heat transfer. Among these are the heat exchangers commonly employed in air conditioning and heating devices or the finned surfaces used, for instance, in the air cooling of electronic devices. There are design challenges that are mainly related to the mass and volume optimization of such devices. These engineering challenges are met by employing innovative fluid systems, such as nanofluids and solid materials such as metal foams or microchannels. Behind the design opportunities, there is ongoing fundamental research into the thermal fluid mechanics, with a focus on convection heat transfer in fluids and in fluid saturated porous media. Typical topics are related to the evaluation/enhancement of the heat transfer rate in a given system, or the exploration of the initiation conditions for convective flows. The latter topic mainly deals with the investigation of the onset of convective instability in a given basic state of the fluid. All these topics and the many more currently explored by the heat transfer community are the focus of this Special Issue.

Prof. Antonio Barletta
Dr. Michele Celli
Guest Editors

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Keywords

  • convection heat transfer
  • flow instability
  • convection in porous media
  • natural and mixed convection

Published Papers (12 papers)

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Research

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16 pages, 6893 KiB  
Article
Tilt Angle Effect on Natural Convection Heat Transfer from an Inclined Array of Square Cylinders
by Zeyad Al-Suhaibani, Mohamed Ali and Redhwan Almuzaiqer
Energies 2024, 17(7), 1516; https://doi.org/10.3390/en17071516 - 22 Mar 2024
Viewed by 689
Abstract
Natural convection heat transfer from an inclined array of square cross-section cylinders is experimentally studied. Three cylinders of side length D = 0.02 m and 1 m length are used to form the inclined array. Three-cylinder axis inclination angles to the horizontal of [...] Read more.
Natural convection heat transfer from an inclined array of square cross-section cylinders is experimentally studied. Three cylinders of side length D = 0.02 m and 1 m length are used to form the inclined array. Three-cylinder axis inclination angles to the horizontal of 30°, 45°, and 60° are considered. The cylinders are heated using an internal heating element of constant heat flux. Surface temperatures are measured along the three surfaces of each cylinder; upper, lower, and the front side at nine points spaced evenly by 10 cm. The local circumference average temperature is obtained at each point. Four center-to-center distances to side length S/D = 1.25, 1.75, 2.25, and 2.75 are used. Local Nusselt numbers and the modified Rayleigh numbers are obtained for each cylinder at each circumference averaged temperature point. Results show that the lower cylinder heat transfer is least affected by the array compared to that of its single one followed by the middle and the upper cylinder for all S/D and the inclination angles used. The Nusselt number is degraded from that of the single cylinder at a small S/D and that degradation decreases as the S/D increases for all angles. It is observed that the Nusselt number enhances at the small cylinder axis tilt angle of 30°, followed by 45°, and 60°, especially at high modified Rayleigh numbers. New novel general empirical correlations for Nusselt numbers are obtained for each S/D using the cylinder axis tilt angle, the modified Rayleigh numbers, and the cylinder number in the array as parameters. A new general correlation is obtained for the array using the modified Rayleigh number, S/D, the cylinder axis tilt angle, and the cylinder sequential order number as parameters. These new correlations will help any engineering applications using such a configuration of the array. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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23 pages, 5873 KiB  
Article
A Minimum Entropy Production Approach to Optimization of Tubular Chemical Reactors with Nature-Inspired Design
by Natalya Kizilova, Akash Shankar and Signe Kjelstrup
Energies 2024, 17(2), 432; https://doi.org/10.3390/en17020432 - 16 Jan 2024
Viewed by 779
Abstract
The problem of the shape optimization of tubular-type plug-flow chemical reactors equipped with a fluid flow-based cooling system is considered in this work. The hydraulic radius Rh(z) = 2A(z)/P(z) and an equivalent [...] Read more.
The problem of the shape optimization of tubular-type plug-flow chemical reactors equipped with a fluid flow-based cooling system is considered in this work. The hydraulic radius Rh(z) = 2A(z)/P(z) and an equivalent surface area-based radius Rs = P(z)/() were computed from the cross-sectional area A(z) and perimeter P(z) measured along the nasal duct of Northern reindeer and used for shape optimization as nature-inspired design. The laminar flow in the cooling system was modeled using the Navier–Stokes equations for an incompressible liquid. In the central tube, a set of chemical reactions with temperature-dependent rates was considered. The temperature and flow velocity fields, pumping pressure, mass flow rate, and total heat flux Jth were obtained by numerical methods. Comparative analyses of the efficiency of different geometries were conducted on Pareto frontiers for hydraulic resistivity Zh, thermal resistivity Zth, thermal inlet length Lth, and entropy production Sirr as a sum of contributions from chemical reactions, thermal, and viscous dissipation. It was shown that the tube with Rs(z) as an interface between the reactor and cooler has the best Pareto efficiency using the (Zh,Zth,Lth) objective functions. Surprisingly, this design also exhibits the lowest Sirr and a more uniform distribution Sirr(z) (i.e., equipartition) among other designs. This geometry is suggested for densely packed tubular reactors. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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14 pages, 1587 KiB  
Article
Slip Backflow of Polymers in Elastic Fractures for Subsurface Heat Recovery
by Alessandro Lenci, Farhad Zeighami, Irene Daprà and Vittorio Di Federico
Energies 2023, 16(24), 7999; https://doi.org/10.3390/en16247999 - 10 Dec 2023
Viewed by 803
Abstract
This research delves into the complexities of backflow phenomena in finite-length and flat-walled fractures with elastic walls, specifically focusing on power-law fluids, whose shear-thinning behavior distinguishes them from Newtonian fluids. We model the backflow process under the lubrication approximation and by incorporating the [...] Read more.
This research delves into the complexities of backflow phenomena in finite-length and flat-walled fractures with elastic walls, specifically focusing on power-law fluids, whose shear-thinning behavior distinguishes them from Newtonian fluids. We model the backflow process under the lubrication approximation and by incorporating the linear Navier slip law. We numerically examine the influence of parameters such as slip length, fluid rheology, and external pressure on the backflow propagation of the carrier fluid. Our findings underscore the significant role played by the rheological index in determining the fracture closure rate. Additionally, our investigations highlight the marked effect of external pressure variations on pressure distribution within the fracture. Notably, the friction coefficient at the fracture walls, as denoted by a dimensionless slip number, exhibits limited influence on the fundamental dynamics of the problem. These insights advance our understanding of power-law fluid backflow and have wide-ranging applications across various engineering disciplines. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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22 pages, 8252 KiB  
Article
Cyclic Appearance and Disappearance of Aerosol Nucleation in the Boundary Layer of Drops of Volatile Liquid
by Patrick Scheunemann, Mark Jermy and Paul Stephenson
Energies 2023, 16(22), 7491; https://doi.org/10.3390/en16227491 - 8 Nov 2023
Viewed by 681
Abstract
The cyclic appearance and disappearance of nucleation was observed in the boundary layer of drops of 1,3-propanediol, 1,2-propanediol, and glycerol, close to the boiling point and exposed to a cooler airflow. Although continuous nucleation has previously been widely observed, the cyclic nature of [...] Read more.
The cyclic appearance and disappearance of nucleation was observed in the boundary layer of drops of 1,3-propanediol, 1,2-propanediol, and glycerol, close to the boiling point and exposed to a cooler airflow. Although continuous nucleation has previously been widely observed, the cyclic nature of the phenomenon observed here is unusual. It was observed in experiments with free-falling drops and fixed drops in an upflow of air. To investigate this unexpected phenomenon further, the phenomenon was reproduced in two finite volume models. The first model used 1D potential flow solutions to approximate the airflow around the spherical windward face of the droplet. The second model used CFD to model the airflow. Both models used classical nucleation theory, the Stefan–Fuchs model of droplet growth by condensation, mass transfer by evaporation, diffusion, convection, and heat transfer by diffusion and convection. Despite several simplifications, the most important being the assumption that the drop has a uniform temperature, both models predict the frequency of nucleation to be better than the order of magnitude. These models also predict the experimentally observed power law dependence of nucleation frequency on air speed. It is proposed that the cyclic nature of the phenomenon is caused by the following process: the depletion of condensable vapour around the freshly nucleated aerosol due to condensation onto the aerosol results in reduced supersaturation, which stops further nucleation, and then the replenishment of this vapour by diffusion and convection from the parent drop, with nucleation of aerosol recommencing when the supersaturation has recovered sufficiently—then, the repetition of these steps in a cycle. It is proposed that the process depends mostly on the maximum saturation ratio in the boundary layer, which itself is determined by four key dimensionless numbers: the Lewis number, the Peclet number, the Reynolds number, and the ratio of the vapour pressure of the condensable compound at drop surface temperature to the vapour pressure of the same species at ambient temperature. A practical application of the phenomenon may be as a means of validation of thermo-fluid models, which include nucleation. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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27 pages, 9667 KiB  
Article
On the Measure of the Heat Transfer Performance of RANS Turbulence Models in Single Round Jet Impingement
by Sebastian Gurgul and Elzbieta Fornalik-Wajs
Energies 2023, 16(21), 7236; https://doi.org/10.3390/en16217236 - 24 Oct 2023
Cited by 3 | Viewed by 907
Abstract
The jet impingement phenomenon is one of the processes which can enhance heat transfer. Due to its complex nature, it has been the subject of many experimental and numerical analyses in which researchers have tried to quantify and qualitatively describe it. However, the [...] Read more.
The jet impingement phenomenon is one of the processes which can enhance heat transfer. Due to its complex nature, it has been the subject of many experimental and numerical analyses in which researchers have tried to quantify and qualitatively describe it. However, the lack of crucial information regarding procedures, accuracy, geometry settings, boundary conditions, etc. makes it challenging to compare the results, validate turbulence models, and reproduce data. In this publication, the authors show a consistent and systematic numerical analysis of round and turbulent jet impingement based on RANS turbulence models. The results have been calculated for various geometrical configurations, Reynolds number values, and turbulence models, and compared with experimental and numerical data available in the literature to show their similarities and differences. It led to unique data collection, which was used in the novel quantitative analysis and helped lead to proposing the measure of the heat transfer performance of a particular turbulence model. Such a measure has not been reported so far. The measure exhibited that no turbulence model is suitable for all analyzed parameters. Quantitative comparisons enable recommendations of turbulence models for analyzed cases which have the potential to accelerate the design process of devices and could be a source of suggestions for other researchers. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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38 pages, 3886 KiB  
Article
Multiple-Relaxation-Time Lattice Boltzmann Simulation of Soret and Dufour Effects on the Thermosolutal Natural Convection of a Nanofluid in a U-Shaped Porous Enclosure
by Md. Mahadul Islam, Md Farhad Hasan and Md. Mamun Molla
Energies 2023, 16(21), 7229; https://doi.org/10.3390/en16217229 - 24 Oct 2023
Cited by 4 | Viewed by 973
Abstract
This article reports an investigation of the Soret and Dufour effects on the double-diffusive natural convection of Al2O3-H2O nanofluids in a U-shaped porous enclosure. Numerical problems were resolved using the multiple-relaxation-time (MRT) lattice Boltzmann method [...] Read more.
This article reports an investigation of the Soret and Dufour effects on the double-diffusive natural convection of Al2O3-H2O nanofluids in a U-shaped porous enclosure. Numerical problems were resolved using the multiple-relaxation-time (MRT) lattice Boltzmann method (LBM). The indented part of the U-shape was cold, and the right and left walls were heated, while the bottom and upper walls were adiabatic. The experimental data-based temperature and nanoparticle size-dependent correlations for the Al2O3-water nanofluids are used here. The benchmark results thoroughly validate the graphics process unit (GPU) based in-house compute unified device architecture (CUDA) C/C++ code. Numeral simulations were performed for a variety of dimensionless variables, including the Rayleigh number, (Ra = 104,105,106), the Darcy number, (Da = 102,103,104), the Soret number, (Sr = 0.0,0.1,0.2), the Dufour number, (Df = 0.0,0.1,0.2), the buoyancy ratio, (2Br2), the Lewis number, (Le = 1,3,5), the volume fraction, (0ϕ0.04), and the porosity, ϵ = (0.20.8), and the Prandtl number, Pr = 6.2 (water) is fixed to represent the base fluid. The numerical results are presented in terms of streamlines, isotherms, isoconcentrations, temperature, velocity, mean Nusselt number, mean Sherwood number, entropy generation, and statistical analysis using a response surface methodology (RSM). The investigation found that fluid mobility was enhanced as the Ra number and buoyancy force increased. The isoconcentrations and isotherm density close to the heated wall increased when the buoyancy force shifted from a negative magnitude to a positive one. The local Nu increased as the Rayleigh number increased but reduced as the volume fraction augmented. Furthermore, the mean Nu (Nu¯) decreased by 3.12% and 6.81% and the Sh¯ increased by 83.17% and 117.91% with rising Lewis number for (Ra=105 and Da=103) and (Ra=106 and Da=104), respectively. Finally, the Br and Sr demonstrated positive sensitivity, and the Ra and ϕ showed negative sensitivity only for higher values of ϕ based on the RSM. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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18 pages, 4324 KiB  
Article
Exploring the Bioenergy Potential of Microfluidics: The Case of a T-Micromixer with Helical Elements for Sustainable Energy Solutions
by Abdelkader Mahammedi, Naas Toufik Tayeb, Kouider Rahmani, Awf Al-Kassir and Eduardo Manuel Cuerda-Correa
Energies 2023, 16(20), 7123; https://doi.org/10.3390/en16207123 - 17 Oct 2023
Viewed by 899
Abstract
This study explores the potential application of microfluidics in the field of bioenergy, with a particular focus on the energy potential of biogas derived from vine shoots, a locally abundant waste material. The enhanced mixing capability of a micromixer has been analyzed to [...] Read more.
This study explores the potential application of microfluidics in the field of bioenergy, with a particular focus on the energy potential of biogas derived from vine shoots, a locally abundant waste material. The enhanced mixing capability of a micromixer has been analyzed to make it suitable for microfluidic energy applications. Mixing index, pressure drop, and kinematic measurements within the T-micromixer with helical elements and their related mixing performances have been studied and validated using CFD for different values of Reynolds number (0.1–60) for laminar Newtonian miscible fluid. Geometrical characteristics were further examined to improve the mixing performance. Various values of twisted angles were evaluated and compared to choose the optimal angle. A new parameter, Q, was introduced to represent the ratio of vorticity square over the sum of vorticity square and deformation square intensities. Furthermore, the results of the numerical simulation were compared with the given data in the literature, showing a significant agreement, in addition to the fact that a high-quality mixture can be created with a geometry angle of 90°, and a mixing index above 0.99 can be obtained at low Reynolds numbers. The numerical investigation of the flow regimes of miscible fluid in the T-microkenics with the proposed angle can be utilized to develop the mixing performance of the micromixers in a wide variety of processes. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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18 pages, 10460 KiB  
Article
Free Surface Motion of a Liquid Pool with Isothermal Sidewalls as a Benchmark for Marangoni Convection Problems
by Bruce E. Ciccotosto and Caleb S. Brooks
Energies 2023, 16(19), 6824; https://doi.org/10.3390/en16196824 - 26 Sep 2023
Viewed by 887
Abstract
In single phase flows, benchmarks like the lid driven cavity have become recognized as fundamental tests for newly developed computational fluid dynamics, CFD, codes. For multiphase free surface flows with variable surface tension, the presently studied pool with isothermal sidewalls is suggested as [...] Read more.
In single phase flows, benchmarks like the lid driven cavity have become recognized as fundamental tests for newly developed computational fluid dynamics, CFD, codes. For multiphase free surface flows with variable surface tension, the presently studied pool with isothermal sidewalls is suggested as it is the simplest domain where Marangoni effects can dominate. It was also chosen due to its strange sensitivity to the initial setup which is discussed at length from a chosen number of ‘scenarios’. It was found that the fluid interface can reverse deformation by a change in the top boundary condition, the liquid equation of state, and the gravity level. For the top boundary condition, this reversal is due to vapor expansion within the closed volume, creating an additional convection mechanism. Not only does the interface reverse, but the peak height changes by more than an order of magnitude at the same Marangoni number. When including gravity, the peak velocity can increase significantly, but it can also cause a decrease when done in combination with a change in the top wall boundary condition. Finally, thermal expansion of the liquid phase causes the peak velocity to be reduced, with additional reductions from the gravity and top wall condition. The differences in each scenario could lead to significant errors in analyzing a practical application of Marangoni flows. Therefore, it is important to demonstrate that a new CFD code can not only resolve Marangoni convection, but also has the capability to resolve the scenario most relevant to the application at hand. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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10 pages, 2265 KiB  
Article
Unstable Convection in a Vertical Double–Layer Porous Slab
by Stefano Lazzari, Michele Celli, Antonio Barletta and Pedro Vayssière Brandão
Energies 2023, 16(13), 4938; https://doi.org/10.3390/en16134938 - 25 Jun 2023
Viewed by 784
Abstract
A convective stability analysis of the flow in a vertical fluid-saturated porous slab made of two layers with different thermophysical properties is presented. The external boundaries are isothermal with one of them impermeable while the other is open to an external fluid reservoir. [...] Read more.
A convective stability analysis of the flow in a vertical fluid-saturated porous slab made of two layers with different thermophysical properties is presented. The external boundaries are isothermal with one of them impermeable while the other is open to an external fluid reservoir. This study is a development of previous investigations on the onset of thermal instability in a vertical heterogeneous porous slab where the heterogeneity may be either continuous or piecewise as determined by a multilayer structure. The aim of this paper is investigating whether a two-layer structure of the porous slab may lead to the onset of cellular convection patterns. The linear stability analysis is carried out under the assumption that one porous layer has a thermal conductivity much higher than the other layer. This assumption may be justified for the model of a heat transfer enhancement system involving a saturated metal foam. A flow model for the natural convection based on Darcy’s momentum transfer in a porous medium is adopted. The buoyancy-induced basic flow state is evaluated analytically. Small-amplitude two-dimensional perturbations of the basic state are introduced, thus leading to a linear set of governing equations for the disturbances. A normal mode analysis allows one to formulate the stability eigenvalue problem. The numerical solution of the stability eigenvalue problem provides the onset conditions for the thermal instability. Moreover, the results evidence that the permeability ratio of the two layers is a key parameter for the critical conditions of the instability. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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19 pages, 849 KiB  
Article
Onset of Viscous Dissipation Instability in Plane Couette Flow with Temperature-Dependent Viscosity
by Alioune Sene, Sara Ben Sadek, Silvia C. Hirata and Mohamed Najib Ouarzazi
Energies 2023, 16(10), 4172; https://doi.org/10.3390/en16104172 - 18 May 2023
Cited by 2 | Viewed by 1174
Abstract
The conditions for the onset of dissipation thermal instability with temperature-dependent viscosity in the plane Couette flow of a Newtonian fluid are analyzed. The studied system consists of a horizontal fluid layer confined between an adiabatic (fixed) lower wall and an isothermal (moving) [...] Read more.
The conditions for the onset of dissipation thermal instability with temperature-dependent viscosity in the plane Couette flow of a Newtonian fluid are analyzed. The studied system consists of a horizontal fluid layer confined between an adiabatic (fixed) lower wall and an isothermal (moving) upper wall. Both the exponential and the linear fluidity models are considered in order to account for the thermodependency of the fluid’s viscosity. The linear stability analysis of the base solution with respect to arbitrarily oriented normal modes is carried out numerically by employing a shooting method. The most unstable disturbances are proven to be stationary longitudinal rolls, and their stability is governed by three dimensionless parameters: the viscous dissipation Rayleigh number, Prandtl number and a parameter that represents the variability of the viscosity with temperature. It is shown that the effect of the variation of the viscosity is to promote the stability of the base flow. As expected, the two viscosity models’ results diverge as the variability of the viscosity increases, and the exponential model is found to be more stable than the linear fluidity one. By considering the thermophysical properties of real fluids, it is shown that viscous dissipation thermal instability precedes hydrodynamic instability. An energy budget analysis is proposed to better understand both the stabilization effect of the thermal variability of the viscosity and differences with viscous dissipation hydrodynamic instability. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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15 pages, 2824 KiB  
Article
Prediction of Friction Factor and Heat Transfer Coefficient for Single-Phase Forced Convection Inside Microfin Tubes
by Luisa Rossetto and Andrea Diani
Energies 2023, 16(10), 4053; https://doi.org/10.3390/en16104053 - 12 May 2023
Cited by 4 | Viewed by 1203
Abstract
Microfin tubes are widely used to enhance heat transfer in heat exchangers in order to reduce volumes, costs and refrigerant charge. Much experimental work has been published for the flow of liquids, while some experimental work is available for the flow of gases [...] Read more.
Microfin tubes are widely used to enhance heat transfer in heat exchangers in order to reduce volumes, costs and refrigerant charge. Much experimental work has been published for the flow of liquids, while some experimental work is available for the flow of gases for the chemical, refrigeration and air conditioning industry. This work reviews the literature and presents new experimental friction factors for the flow of the superheated vapor of R1234ze(E) in a 5 mm outside diameter microfin tube. The authors have also collected an extensive data bank of heat transfer coefficients (around 648 points from different research laboratories) and friction factors (around 536 points), covering 45 different geometries of inner finned tubes. After comparing the predictions from available correlations with experimental data, the present paper suggests the best performing equations for the calculation of the friction factor and of the Nusselt number during forced convection flow of liquids and gases. The suggested model for friction factor estimates the experimental values with a relative and absolute deviation of −0.3% and 7.9%, respectively, whereas the suggested model for the heat transfer coefficient predicts the experimental data bank with a relative and absolute deviation of −3.3% and 13.9%, respectively. The validity range of the two correlations is extremely wide, covering microfin tubes with diameters from 2.6 mm to 24.4 mm, and Reynolds number from about approximately 1000 to 300,000 for the friction factor, and from 3000 to 1,000,000 for the heat transfer coefficient. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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Review

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24 pages, 7500 KiB  
Review
Heat Transfer and Thermal Energy Storage Enhancement by Foams and Nanoparticles
by Assunta Andreozzi, Pietro Asinari, Antonio Barletta, Vincenzo Bianco, Johan Augusto Bocanegra, Pedro Vayssière Brandão, Bernardo Buonomo, Roberta Cappabianca, Michele Celli, Eliodoro Chiavazzo, Paolo De Angelis, Andrea Diani, Sauro Filippeschi, Marcello Iasiello, Oronzio Manca, Sergio Nardini, Carlo Nonino and Luisa Rossetto
Energies 2023, 16(21), 7421; https://doi.org/10.3390/en16217421 - 3 Nov 2023
Cited by 2 | Viewed by 1041
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Research on Fluid Mechanics and Heat Transfer)
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