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Heat and Mass Transfer: Thermophysical Characteristics of Composite Materials

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "J1: Heat and Mass Transfer".

Deadline for manuscript submissions: 30 November 2024 | Viewed by 2329

Special Issue Editors


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Guest Editor
Department of Mechanical Engineering, Universitatea Transilvania din Brasov, Brasov, Romania
Interests: heat and mass transfer in wood drying; thermal properties of composites; wood biomass;

E-Mail Website
Guest Editor
Department of Mechanical Engineering, Transilvania University of Brasov, 500036 Brasov, Romania
Interests: heat transfer; heat exchangers; heat pipes; nanofluids for heat transfer applications
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Wood Engineering, Transilvania University of Brasov, 500036 Brasov, Romania
Interests: wood composite material; lighter wood particles; the physics of wood; the quality of composites
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Composites are highly effective alternatives to classical materials owing to their increased properties. They are an exceptionally topical issue for researchers and practitioners in various fields. Indeed, the development of new composites and the study of their benefits holds central stage within the international research community today.

This Special Issue aims to disseminate advanced research on the physical and thermal properties of composites when subjected to heat and mass transfer processes. Fundamental research and applications, i.e. theoretical, experimental and numerical studies are welcome. Potential topics include, but are not limited to, the physical and thermal properties of advanced composites, microcomposites and macrocomposites, high thermal conductivity and thermal insulating composites, eco-friendly composites, bio-based composites, and natural composites (wood and biological materials).  

We are confident that our joint efforts, when publicized in this issue, will make a  real contribution to the advancement of this expanding and fascinating field while also allowing specialists to keep abreast with the latest research in the area.

Dr. Daniela Sova
Dr. Gabriela Huminic
Prof. Dr. Aurel Lunguleasa
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

  • structure
  • density
  • porosity
  • anisotropy and anisotropic effects
  • surface properties
  • thermal conductivity
  • thermal diffusivity
  • specific heat
  • thermal expansion
  • thermal interface conductance
  • permeability
  • diffusion coefficient

Published Papers (3 papers)

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Research

19 pages, 10341 KiB  
Article
Equivalent Thermal Conductivity of Topology-Optimized Composite Structure for Three Typical Conductive Heat Transfer Models
by Biwang Lu and Jing He
Energies 2024, 17(11), 2558; https://doi.org/10.3390/en17112558 - 24 May 2024
Viewed by 344
Abstract
Composite materials and structural optimization are important research topics in heat transfer enhancement. The current evaluation parameter for the conductive heat transfer capability of composites is effective thermal conductivity (ETC); however, this parameter has not been studied or analyzed for its applicability to [...] Read more.
Composite materials and structural optimization are important research topics in heat transfer enhancement. The current evaluation parameter for the conductive heat transfer capability of composites is effective thermal conductivity (ETC); however, this parameter has not been studied or analyzed for its applicability to different heat transfer models and composite structures. In addition, the optimized composite structures of a specific object will vary when different optimization methods and criteria are employed. Therefore, it is necessary to investigate a suitable method and parameter for evaluating the heat transfer capability of optimized composites under different heat transfer models. Therefore, this study analyzes and summarizes three typical conductive heat transfer models: surface-to-surface (S-to-S), volume-to-surface (V-to-S), and volume-to-volume (V-to-V) models. The equivalent thermal conductivity (keq) is proposed to evaluate the conductive heat transfer capability of topology-optimized composite structures under the three models. A validated simulation method is used to obtain the key parameters for calculating keq. The influences of the interfacial thermal resistance and size effect on keq are considered. The results show that the composite structure optimized for the V-to-S and V-to-V models has a keq value of only 79.4 W m−1 K−1 under the S-to-S model. However, the keq values are 233.4 W m−1 K−1 and 240.3 W m−1 K−1 under the V-to-S and V-to-V models, respectively, which are approximately 41% greater than those of the in-parallel structure. It can be demonstrated that keq is more suitable than the ETC for evaluating the V-to-S and V-to-V heat transfer capabilities of composite structures. The proposed keq can serve as a characteristic parameter that is beneficial for heat transfer analysis and composite structural optimization. Full article
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12 pages, 1930 KiB  
Article
Analysis of the Cooling Modes of the Lining of a Ferroalloy-Casting Ladle
by Evgeniy Prikhodko, Alexandr Nikiforov, Akmaral Kinzhibekova, Nazgul Aripova, Amangeldy Karmanov and Vladimir Ryndin
Energies 2024, 17(5), 1229; https://doi.org/10.3390/en17051229 - 4 Mar 2024
Viewed by 574
Abstract
An important element of the operation of high-temperature aggregates are modes that change over time. During these modes, maximum temperature changes are recorded in the cross-section of the lining of the aggregate. The difference in temperature leads to the formation of thermal stresses, [...] Read more.
An important element of the operation of high-temperature aggregates are modes that change over time. During these modes, maximum temperature changes are recorded in the cross-section of the lining of the aggregate. The difference in temperature leads to the formation of thermal stresses, which are the main reason for the repair of aggregates. During rapid heating, the inner layers of the lining are subjected to compressive stresses, while during rapid cooling, these layers experience tensile stresses. Under the same conditions, rapid cooling of the lining is more critical, since refractories have poor resistance to tension. The purpose of the study is to calculate and analyze the thermal stresses that arise during cooling of the casting ladle lining. The stresses are determined based on the calculation of the unsteady temperature field of the lining. Thermal stress values are necessary for analysis of the current cooling rates of casting ladles and subsequent development of optimal cooling modes for the lining. To solve the heat conductivity equation, a numerical method was chosen using an implicit four-point difference scheme. To study the cooling process of the casting ladle lining, temperature measurements were carried out in the zone of the greatest wear of the lining. Under conditions of natural convection, cooling of the casting ladle lining occurs unevenly. Cooling schedules during natural convection are characterized by significant unevenness and high rates of temperature decrease. The cooling rates of the inner surface of the lining at the initial stage of cooling significantly exceed the values recommended in the technical literature. Such cooling rates lead to the appearance of significant thermal stresses in the lining. For a refractory that has not been in service, the maximum thermal compressive stresses exceed the ultimate compressive strength by 1.27 times, and the tensile stresses exceed the corresponding limit values by 4.4 times. For refractories that have worked three fuses in the ladle lining, the maximum thermal compressive stresses exceed the ultimate compressive strength by 1.28 times, and the tensile stresses exceed the corresponding limit values by 3.19 times. The studied cooling modes for the casting ladle lining are unacceptable for operation. Cooling, taking into account the indicated rates, leads to the destruction of the lining material. To increase the resistance and duration of the working campaign of casting ladle linings, it is necessary to develop cooling modes for the lining at speeds at which the resulting thermal stresses do not exceed the strength of the refractory materials. Full article
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12 pages, 2327 KiB  
Article
Analysis of the Effect of Temperature on the Ultimate Strength of Refractory Materials
by Evgeniy Prikhodko, Alexandr Nikiforov, Akmaral Kinzhibekova, Alexandr Paramonov, Nazgul Aripova and Amangeldy Karmanov
Energies 2023, 16(18), 6732; https://doi.org/10.3390/en16186732 - 21 Sep 2023
Cited by 1 | Viewed by 986
Abstract
The energy efficiency of high-temperature batch aggregates largely depends on the modes of their heating and cooling. The modes of heating and cooling of aggregates in which thermal stress does not exceed the critical values of the ultimate strength of the refractories make [...] Read more.
The energy efficiency of high-temperature batch aggregates largely depends on the modes of their heating and cooling. The modes of heating and cooling of aggregates in which thermal stress does not exceed the critical values of the ultimate strength of the refractories make it possible to increase their service life. The increase in the service life of refractories will lead to a reduction in the number of lining repairs and a decrease in the specific consumption of refractory materials per ton of technological product. Shorter warm-up and cool-down times result in lower energy consumption. Reducing the time for variable modes for casting ladles increases their turnover (the number of melt discharges into the ladle per day). Increasing ladle turnover not only reduces the number of ladles but also improves the economic performance of the enterprise. The ultimate strength of the refractory material significantly affects the rate of temperature change during heating and cooling of the refractory masonry. The purpose of this research is to study the dependence of the ultimate compression and tensile strengths of chamotte materials of the ShKU brand on temperature. The determination of the compression and tensile strengths was carried out on new samples of refractory materials as well as on samples of refractories that were in operation until the intermediate repair. To determine the ultimate compression strength of chamotte refractories, the standard technique for axial compression of the test specimen until its destruction was used. To determine the ultimate tensile strength, a three-point bending test was used with additional control of the surface temperature of the test sample during the test. The ultimate compression strength of chamotte refractories of the ShKU-32 brand increased for the new refractories by a maximum of 44%. For refractories that were in operation until the intermediate repair, the ultimate compression strength increased by a maximum of 56%. The value of the ultimate tensile strength at elevated temperatures turned out to be higher than the value at a temperature of 20 °C. For new refractories, the maximum ultimate tensile strength is 25% higher than the ultimate tensile strength under normal conditions. For refractories that were in operation until the intermediate repair, the maximum ultimate tensile strength increased by 24%. The obtained results can be used to increase the rate of heating or cooling of linings. Full article
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