Special Issue "Entropy Generation Minimization II"

A special issue of Entropy (ISSN 1099-4300).

Deadline for manuscript submissions: closed (31 August 2019).

Special Issue Editors

Prof. Dr. Sergio Nardini
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Guest Editor
Dipartimento di Ingegneria, Università degli Studi della Campania “Luigi Vanvitelli”, Via Roma 29, 81031 Aversa (CE), Italy
Interests: thermal systems; active solar systems; passive solar systems; heat transfer with nanofluids and porous media; forecast of energy consumption
Special Issues and Collections in MDPI journals
Ass. Prof. Bernardo Buonomo

Guest Editor
Dipartimento di Ingegneria Industriale e dell'Informazione. Università degli Studi della Campania "Luigi Vanvitelli", Via Roma 29, Aversa (CE) 81031, Italy
Interests: entropy generation; convective heat transfer; heat transfer by nanofluids; thermal storage; heat transfer in porous media; heat transfer in microchannel
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Due to growing worldwide competition and the need to increase efficiency, it has become essential to optimize processes and systems. Optimization models are widely used in research and practice in order to minimize or maximize one or more variables. Entropy is used extensively in analyzing thermal processes and systems and in defining ideal processes that are isentropic. Many papers have recently carried out investigations by using the second law of thermodynamics for the optimization of thermal systems. The second law aspects can also be included in the analysis and design of thermal systems by considering irreversibilities that arise due to heat transfer and friction, which lead generation entropy.

A minimization of the generated entropy leads to an optimum system based on thermal aspects alone. These considerations may be linked with other aspects, such as economic considerations, to obtain an optimal design.

The aim of this Special Issue is to collect original research articles, as well as review articles, on the most recent developments and research efforts in this field, with the purpose of providing guidelines for future research directions.

Prof. Dr. Sergio Nardini
Dr. Bernardo Buonomo
Guest Editors

Manuscript Submission Information

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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. Entropy is an international peer-reviewed open access monthly 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 1600 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

Entropy generation minimization, Irreversible processes, exergy, Finite Time Thermodynamics, Heat Transfer, Heat-work conversion, Viscous dissipation, heat transfer in porous media, nanofluids, convection heat transfer, turbulent flow applications

Published Papers (4 papers)

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Research

Open AccessArticle
Entropy Generation in Cu-Al2O3-H2O Hybrid Nanofluid Flow over a Curved Surface with Thermal Dissipation
Entropy 2019, 21(10), 941; https://doi.org/10.3390/e21100941 - 26 Sep 2019
Cited by 3
Abstract
Heat transfer and entropy generation in a hybrid nanoliquid flow caused by an elastic curved surface is investigated in the present article. To examine the effects of frictional heating on entropy generation, the energy dissipation function is included in the energy equation. The [...] Read more.
Heat transfer and entropy generation in a hybrid nanoliquid flow caused by an elastic curved surface is investigated in the present article. To examine the effects of frictional heating on entropy generation, the energy dissipation function is included in the energy equation. The Tiwari and Dass model for nanofluid is used by taking water as a base fluid. A new class of nanofluid (hybrid nanofluid) with two kinds of nanoparticles, Copper (Cu) and Aluminum oxide (Al2O3), is considered. Curvilinear coordinates are used in the mathematical formulation due to the curved nature of the solid boundary. By utilizing similarity transformations, the modelled partial differential equations are converted into ordinary differential equations. Shooting and the Runge-Kutta-Fehlberg method (FRKM) have been used to solve the transformed set of non-linear differential equations. The expression for entropy generation is derived in curvilinear coordinates and computed by using the numerical results obtained from dimensionless momentum and energy equations. Comparisons of our numerical results and those published in the previous literature demonstrate excellent agreements, validating our numerical simulation. In addition, we have also conducted parametric studies and find that entropy generation and temperature suppress with increasing values of dimensionless radius of curvature. Furthermore, it is found that less entropy is generated in regular nanofluid as compare to hybrid nanofluid. To examine the influences of a set of embedding physical parameters on quantities of interest, different graphs are plotted and discussed. Full article
(This article belongs to the Special Issue Entropy Generation Minimization II)
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Open AccessArticle
Generalized Entropy Generation Expressions in Gases
Entropy 2019, 21(4), 330; https://doi.org/10.3390/e21040330 - 27 Mar 2019
Cited by 2
Abstract
In this study, we generalize our previous methods for obtaining entropy generation in gases without the need to carry through a specific expansion method, such as the Chapman–Enskog method. The generalization, which is based on a scaling analysis, allows for the study of [...] Read more.
In this study, we generalize our previous methods for obtaining entropy generation in gases without the need to carry through a specific expansion method, such as the Chapman–Enskog method. The generalization, which is based on a scaling analysis, allows for the study of entropy generation in gases for any arbitrary state of the gas and consistently across the conservation equations of mass, momentum, energy, and entropy. Thus, it is shown that it is theoretically possible to alter specific expressions and associated physical outcomes for entropy generation by changing the operating process gas state to regions significantly different than the perturbed, local equilibrium or Chapman–Enskog type state. Such flows could include, for example, hypersonic flows or flows that may be generally called hyper-equilibrium state flows. Our formal scaling analysis also provides partial insight into the nature of entropy generation from an informatics perspective, where we specifically demonstrate the association of entropy generation in gases with uncertainty generated by the approximation error associated with density function expansions. Full article
(This article belongs to the Special Issue Entropy Generation Minimization II)
Open AccessArticle
Entropy Generation Rate Minimization for Methanol Synthesis via a CO2 Hydrogenation Reactor
Entropy 2019, 21(2), 174; https://doi.org/10.3390/e21020174 - 13 Feb 2019
Cited by 15
Abstract
The methanol synthesis via CO2 hydrogenation (MSCH) reaction is a useful CO2 utilization strategy, and this synthesis path has also been widely applied commercially for many years. In this work the performance of a MSCH reactor with the minimum entropy generation [...] Read more.
The methanol synthesis via CO2 hydrogenation (MSCH) reaction is a useful CO2 utilization strategy, and this synthesis path has also been widely applied commercially for many years. In this work the performance of a MSCH reactor with the minimum entropy generation rate (EGR) as the objective function is optimized by using finite time thermodynamic and optimal control theory. The exterior wall temperature (EWR) is taken as the control variable, and the fixed methanol yield and conservation equations are taken as the constraints in the optimization problem. Compared with the reference reactor with a constant EWR, the total EGR of the optimal reactor decreases by 20.5%, and the EGR caused by the heat transfer decreases by 68.8%. In the optimal reactor, the total EGRs mainly distribute in the first 30% reactor length, and the EGRs caused by the chemical reaction accounts for more than 84% of the total EGRs. The selectivity of CH3OH can be enhanced by increasing the inlet molar flow rate of CO, and the CO2 conversion rate can be enhanced by removing H2O from the reaction system. The results obtained herein are in favor of optimal designs of practical tubular MSCH reactors. Full article
(This article belongs to the Special Issue Entropy Generation Minimization II)
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Open AccessArticle
Thermodynamic Analysis of Entropy Generation Minimization in Thermally Dissipating Flow Over a Thin Needle Moving in a Parallel Free Stream of Two Newtonian Fluids
Entropy 2019, 21(1), 74; https://doi.org/10.3390/e21010074 - 16 Jan 2019
Cited by 2
Abstract
This article is devoted to study sustainability of entropy generation in an incompressible thermal flow of Newtonian fluids over a thin needle that is moving in a parallel stream. Two types of Newtonian fluids (water and air) are considered in this work. The [...] Read more.
This article is devoted to study sustainability of entropy generation in an incompressible thermal flow of Newtonian fluids over a thin needle that is moving in a parallel stream. Two types of Newtonian fluids (water and air) are considered in this work. The energy dissipation term is included in the energy equation. Here, it is presumed that u (the free stream velocity) is in the positive axial direction (x-axis) and the motion of the thin needle is in the opposite or similar direction as the free stream velocity. The reduced self-similar governing equations are solved numerically with the aid of the shooting technique with the fourth-order-Runge-Kutta method. Using similarity transformations, it is possible to obtain the expression for dimensionless form of the volumetric entropy generation rate and the Bejan number. The effects of Prandtl number, Eckert number and dimensionless temperature parameter are discussed graphically in details for water and air taken as Newtonian fluids. Full article
(This article belongs to the Special Issue Entropy Generation Minimization II)
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