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Engineering Modeling of Advanced Heat Transfer Problems

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

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 12331

Special Issue Editors

Department of Energy "Galileo Ferraris", Politecnico di Torino, 10129 Turin, Italy
Interests: advanced heat transfer; nuclear fusion engineering; high heat flux components; superconducting cables and magnets; concentrated solar power; cryogenics; models and scenarios for energy planning
Special Issues, Collections and Topics in MDPI journals
Laboratory of Thermal Engineering, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
Interests: transient and conjugate heat transfer; Stirling solar power systems; cryogenics; combustion dynamics and acoustics; machine learning

Special Issue Information

Dear Colleagues,

In the worldwide attempt to contribute to the energy transition, the solution of advanced heat transfer problems is of concern for several branches of power and energy engineering, and often becomes a key point in enabling new technologies or increasing the efficiency of the well-established technologies. If we remain within single-phase fluids, heat transfer modeling is related to issues in, e.g., conjugate heat transfer, radiation, and turbulent convection. In the applications, challenging problems can range from the removal of local high heat fluxes to the cooling/heating of devices with complex geometries or the need for the use-specific fluids as thermal vectors. The situations where more phases are involved could be even more complicated by the simultaneous occurrence of boiling heat transfer and two-phase phenomena. Heat transfer without the use of any fluids is also very fascinating and could be potentially ground-breaking in several applications.

The Special Issue we are launching presents issues encountered and solved in the modeling of advanced heat transfer problems in disparate engineering fields. The Special Issue will serve as a platform where ideas and methods can be shared and result in cross-fertilization between the different fields. We welcome papers where, apart from specific applications, the main achievements by the authors could be clearly understood, out of the peculiarities of the specific cases, and offered as lessons for readers. We look forward to reading your latest achievements in any of the directions highlighted above.

Prof. Dr. Laura Savoldi
Prof. Dr. Jim B.W. Kok
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Conjugate heat transfer
  • Turbulent convection
  • High heat flux removal
  • Boiling and condensation
  • Critical heat flux
  • Thermal radiation
  • Thermal absorption in gases and surfaces
  • Heat transfer in supercritical media
  • Cryogenic heat transfer

Published Papers (6 papers)

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Research

17 pages, 16972 KiB  
Article
Numerical Simulations of Heat Loss Effect on Premixed Jet Flame Using Flamelet Generated Manifold Combustion Model
Energies 2022, 15(3), 730; https://doi.org/10.3390/en15030730 - 19 Jan 2022
Cited by 3 | Viewed by 1385
Abstract
Numerical simulations are performed on a combustor setup which represents the recirculating behaviour of a combustor in the flameless combustion regime. Previous experimental and numerical studies showed that heat loss is prominent for this setup. Here, the amount of heat loss through the [...] Read more.
Numerical simulations are performed on a combustor setup which represents the recirculating behaviour of a combustor in the flameless combustion regime. Previous experimental and numerical studies showed that heat loss is prominent for this setup. Here, the amount of heat loss through the combustor walls is quantified and its effect analysed. For this a non-adiabatic Flamelet Generated Manifold (FGM) model is employed. This model uses tabulated chemistry in combination with governing equations for a small set of control variables to accurately describe a turbulent flame. In the current implementation, equations for enthalpy and the mean and variance of the reaction progress variable are solved. Turbulence-chemistry interactions are incorporated through a presumed-PDF approach. In contrast to earlier work, the model is applied in the commercial solver Ansys CFX, coupled to a low-mach, compressible, steady-state Reynolds-Averaged Navier-Stokes (RANS) turbulence model. Results from the simulations show that heat loss consumes over 30% of the combustor’s thermal power. Despite this large heat loss, its effect on the combustion chemistry is small. The inclusion of heat loss in the chemistry tabulation does improve the prediction of the velocity and temperature field in the primary reaction zone. However, the effect of including heat loss is limited in the prediction of species concentrations. Full article
(This article belongs to the Special Issue Engineering Modeling of Advanced Heat Transfer Problems)
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17 pages, 34607 KiB  
Article
A New Lumped Approach for the Simulation of the Magnetron Injection Gun for MegaWatt-Class EU Gyrotrons
Energies 2021, 14(8), 2068; https://doi.org/10.3390/en14082068 - 08 Apr 2021
Cited by 1 | Viewed by 1506
Abstract
In the framework of the ITER (International Thermonuclear Experimental Reactor) project, one of the key components of the reactor is the ECRH (Electron Cyclotron Resonance Heating). This system has the duty to heat the plasma inside the tokamak, using high frequency and power [...] Read more.
In the framework of the ITER (International Thermonuclear Experimental Reactor) project, one of the key components of the reactor is the ECRH (Electron Cyclotron Resonance Heating). This system has the duty to heat the plasma inside the tokamak, using high frequency and power radio waves, produced by sets of 1MW gyrotrons. One of the main issues related to the gyrotron operation is the output power drop that happens right after the beginning of a pulse. In this work, we study the underlying phenomena that cause the power drop, focusing on the gyrotron’s MIG (Magnetron Injection Gun) of the 1MW, 170 GHz European Gyrotron prototype for ITER. It is shown how the current emission and the temperature of the emitter are tightly bound, and how their interaction causes the power drop, observed experimentally. Furthermore, a simple yet effective lumped-parameter model to describe the MIG’s cathode thermal dynamics is developed, which is able to predict the power output of the gyrotron by simulating the propagation of the heat inside this component. The model is validated against test results, showing a good capability to reproduce the measured behavior of the system, while still being open to further improvements. Full article
(This article belongs to the Special Issue Engineering Modeling of Advanced Heat Transfer Problems)
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21 pages, 8449 KiB  
Article
Experimental Investigation on CIRCE-HERO for the EU DEMO PbLi/Water Heat Exchanger Development
Energies 2021, 14(3), 628; https://doi.org/10.3390/en14030628 - 26 Jan 2021
Cited by 4 | Viewed by 1720
Abstract
The present paper describes the experimental campaign executed at the ENEA Brasimone Research Centre aiming at supporting the development of a PbLi/water heat exchanger suitable for the lithium–lead loops of the dual coolant lithium lead and the water cooled lithium lead breeding blankets [...] Read more.
The present paper describes the experimental campaign executed at the ENEA Brasimone Research Centre aiming at supporting the development of a PbLi/water heat exchanger suitable for the lithium–lead loops of the dual coolant lithium lead and the water cooled lithium lead breeding blankets of the EU DEMO fusion reactor. The experiments were performed in a test section named HERO, installed inside the main vessel of the lead–bismuth eutectic-cooled pool-type facility CIRCE. The test section hosts a steam generator bayonet tube mock-up in relevant scale, which was selected as a promising configuration for DEMO purposes. For the thermal-hydraulic characterization of the component, five tests were executed at different water pressures (6, 8, 12 MPa, two tests at 10 MPa), and liquid metal flow rates (40, 33, 27, 20, 10 kg/s). The experimental outcomes proved the technological feasibility of this novel steam generator and its suitability for the DEMO PbLi loops. The activity was completed with a post-test analysis using two versions of the system code RELAP5. Because the experiments were executed with lead–bismuth eutectic, a scaling analysis is proposed to find the equivalence with PbLi. RELAP5 code was applied to recalculate the experimental data using PbLi as working fluid. Full article
(This article belongs to the Special Issue Engineering Modeling of Advanced Heat Transfer Problems)
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19 pages, 3847 KiB  
Article
Numerical Assessment of Heat Transfer and Entropy Generation of a Porous Metal Heat Sink for Electronic Cooling Applications
Energies 2020, 13(15), 3851; https://doi.org/10.3390/en13153851 - 28 Jul 2020
Cited by 6 | Viewed by 2154
Abstract
In the present study, the thermal performance of an electronic equipment cooling system is investigated. The heat sink used in the current cooling system consists of a porous channel with a rectangular cross-section that is assumed to be connected directly to the hot [...] Read more.
In the present study, the thermal performance of an electronic equipment cooling system is investigated. The heat sink used in the current cooling system consists of a porous channel with a rectangular cross-section that is assumed to be connected directly to the hot surface of an electronic device. In this modeling, a fully developed flow assumption is used. The Darcy–Brinkman model was used to determine the fluid flow field. Since using the local thermal equilibrium (LTE) model may provide results affected by the error in metal foams, in the present research, an attempt has first been made to examine the validity range of this model. The local thermal non-equilibrium (LTNE) model taking into account the viscous dissipation effect was then used to determine the temperature field. To validate the numerical solution, the computed results were compared with other studies, and an acceptable agreement was observed. Analysis of the temperature field shows that if the fluid–solid-phase thermal conductivity ratio is 1 or the Biot number has a large value, the difference between the temperature of the solid phase and the fluid phase decreases. Moreover, the effect of important hydrodynamic parameters and the porous medium characteristics on the field of hydrodynamic, heat, and entropy generation was studied. Velocity field analysis shows that increasing the pore density and reducing the porosity cause an increase in the shear stress on the walls. By analyzing the entropy generation, it can be found that the irreversibility of heat transfer has a significant contribution to the total irreversibility, leading to a Bejan number close to 1. As a guideline for the design of a porous metal heat sink for electronic equipment, the use of porous media with low porosity reduces the total thermal resistance and improves heat transfer, reducing the total irreversibility and the Bejan number. Moreover, the increasing of pore density increases the specific porous surface; consequently, it reduces the total irreversibility and Bejan number and improves the heat transfer. Full article
(This article belongs to the Special Issue Engineering Modeling of Advanced Heat Transfer Problems)
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23 pages, 7385 KiB  
Article
Hybrid 1D + 2D Modelling for the Assessment of the Heat Transfer in the EU DEMO Water-Cooled Lithium-Lead Manifolds
Energies 2020, 13(14), 3525; https://doi.org/10.3390/en13143525 - 08 Jul 2020
Cited by 3 | Viewed by 2178
Abstract
The European demonstration fusion power reactor (EU DEMO) tokamak will be the first European fusion device to produce electricity and to include a breeding blanket (BB). In the framework of the design of the EU DEMO BB, the analysis of the heat transfer [...] Read more.
The European demonstration fusion power reactor (EU DEMO) tokamak will be the first European fusion device to produce electricity and to include a breeding blanket (BB). In the framework of the design of the EU DEMO BB, the analysis of the heat transfer between the inlet and outlet manifold of the coolant is needed, to assess the actual cooling capability of the water entering the cooling channels, as well as the actual coolant outlet temperature from the machine. The complex, fully three-dimensional conjugate heat transfer problem is reduced here with a novel approach to a simpler one, decoupling the longitudinal and transverse scales for the heat transport by developing correlations for a conductive heat-transfer problem. While in the longitudinal direction a standard 1D model for the heat transport by fluid advection is adopted, a set of 2D finite elements analyses are run in the transverse direction, in order to lump the 2D heat conduction effects in suitable correlations. Such correlations are implemented in a 1D finite volume model with the 1D GEneral Tokamak THErmal-hydraulic Model (GETTHEM) code (Politecnico di Torino, Torino, Italy); the proposed approach thus reduces the 3D problem to a 1D one, allowing a parametric evaluation of the heat transfer in the entire blanket with a reduced computational cost. The deviation from nominal inlet and outlet temperature values, for the case of the Water-Cooled Lithium-Lead BB concept, is found to be always below 1.4 K and, in some cases, even to be beneficial. Consequently, the heat transfer among the manifolds at different temperatures can be safely (and conservatively) neglected. Full article
(This article belongs to the Special Issue Engineering Modeling of Advanced Heat Transfer Problems)
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21 pages, 12320 KiB  
Article
Flow Boiling of Low-Pressure Water in Microchannels of Large Aspect Ratio
Energies 2020, 13(11), 2689; https://doi.org/10.3390/en13112689 - 27 May 2020
Cited by 4 | Viewed by 2313
Abstract
Flow boiling heat transfer in microchannels can provide a high cooling rate, while maintaining a uniform wall temperature, which has been extensively studied as an attractive solution for the thermal management of high-power electronics. The depth-to-width ratio of the microchannel is an important [...] Read more.
Flow boiling heat transfer in microchannels can provide a high cooling rate, while maintaining a uniform wall temperature, which has been extensively studied as an attractive solution for the thermal management of high-power electronics. The depth-to-width ratio of the microchannel is an important parameter, which not only determines the heat transfer area but also has dominant effect on the heat transfer mechanisms. In the present study, numerical simulations based on the volume of fraction models are performed on the flow boiling in very deep microchannels. The effects of the depth-to-width ratio on the heat transfer coefficient and pressure drop are discussed. The bubble behavior and heat transfer characteristics are analyzed to explain the mechanism of heat transfer enhancement. The results show the very deep microchannels can effectively enhance the heat transfer, lower the temperature rise and show promising applications in the thermal management of high-power electronics. Full article
(This article belongs to the Special Issue Engineering Modeling of Advanced Heat Transfer Problems)
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