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Entropy
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Entropy and Energy Extraction
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Entropy and Energy Extraction

A special issue of Entropy (ISSN 1099-4300). This special issue belongs to the section "Thermodynamics".

Deadline for manuscript submissions: closed (20 December 2013) | Viewed by 35051

Special Issue Editor

Dr. Fabio La Mantia

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Guest Editor
CES - Zentrum für Elektrochemie, Ruhr-Universität Bochum, Universitätsstr. 150, NC 4/73, D-44780 Bochum, Germany
Interests: semiconductor and energy conversion

Special Issue Information

Dear Colleagues,

The journal “Entropy” is planning to publish a special issue on “entropy and Energy extraction”, and we would like to invite you to contribute to this volume with your articles. 
The importance of entropy in the field of energy conversion and extraction is connected with the second principle of Thermodynamics: it is stated that the entropy of an isolated system is always increasing; it can also be interpreted as the fact that the extractable energy from a system is lower than the total internal energy of the system, because of the impossibility to extract energy from the configurational changes. In particular, the internal entropy production, correlated with the gradients of concentration, pressure and temperature generated inside the system, is of fundamental importance in the energy conversion and extraction. Several effects become important in this frame, between which the entropy of phase transitions in solid phases, the internal entropy production due to transport and diffusion, and the entropy production due to hysteretic phenomena. Moreover, entropy itself can be a source of energy, in the form of osmotic pressure: the gradient in salinity concentration can be used to extract mechanical or electric energy, or, vice versa, electric or mechanical energy can be used to produce gradient of concentration.
In this special issue of “Entropy” we seek contributions that shine light on the entropy production during energy conversion and extraction and how it contributes to the efficiency of energy extraction, and also on the extraction of energy through concentration gradients. Papers focused on the correlation between the entropy production and the physical variables (like Onsager reciprocal relations) are especially welcome.

Dr. Fabio La Mantia
Guest Editor

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. 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 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

  • internal entropy production
  • energy extraction
  • energy conversions
  • solar cells
  • batteries
  • fuel cells
  • super-capacitors
  • desalination
  • energy extraction from salinity gradient
  • thermodynamics of phase transitions
  • transport in solution
  • transport in solid phase
  • thermodynamics of hysteresis

Published Papers (4 papers)

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Research

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1156 KiB  
Article
Thermoelectric System in Different Thermal and Electrical Configurations: Its Impact in the Figure of Merit
by Alexander Vargas-Almeida, Miguel Angel Olivares-Robles and Pablo Camacho-Medina
Entropy 2013, 15(6), 2162-2180; https://doi.org/10.3390/e15062162 - 31 May 2013
Cited by 17 | Viewed by 10467
Abstract
In this work, we analyze different configurations of a thermoelectric system (TES) composed of three thermoelectric generators (TEGs). We present the following considerations: (a) TES thermally and electrically connected in series (SC); (b) TES thermally and electrically connected in parallel (PSC); and (c) [...] Read more.
In this work, we analyze different configurations of a thermoelectric system (TES) composed of three thermoelectric generators (TEGs). We present the following considerations: (a) TES thermally and electrically connected in series (SC); (b) TES thermally and electrically connected in parallel (PSC); and (c) parallel thermally and series electrical connection (SSC). We assume that the parameters of the TEGs are temperature-independent. The systems are characterized by three parameters, as it has been showed in recent investigations, namely, its internal electrical resistance, R, thermal conductance under open electrical circuit condition, K, and Seebeck coefficient α. We derive the equivalent parameters for each of the configurations considered here and calculate the Figure of Merit Z for the equivalent system. We show the impact of the configuration of the system on Z, and we suggest optimum configuration. In order to justify the effectiveness of the equivalent Figure of Merit, the corresponding efficiency has been calculated for each configuration. Full article
(This article belongs to the Special Issue Entropy and Energy Extraction)
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550 KiB  
Article
Analysis of an Air Powered Engine System Using a Multi-Stage Radial Turbine
by Xuehui Zhang, Haisheng Chen, Xiaohui Yan, Xinjing Zhang and Chunqing Tan
Entropy 2013, 15(4), 1186-1201; https://doi.org/10.3390/e15041186 - 28 Mar 2013
Cited by 7 | Viewed by 6515
Abstract
The performance and design criteria of air powered multistage turbines are studied thermodynamically in this paper. In-house code is developed in the C++ environment and the characteristics of four-stage turbines with inter-heating are analyzed in terms of maximum thermal efficiency, maximum exergy efficiency [...] Read more.
The performance and design criteria of air powered multistage turbines are studied thermodynamically in this paper. In-house code is developed in the C++ environment and the characteristics of four-stage turbines with inter-heating are analyzed in terms of maximum thermal efficiency, maximum exergy efficiency and maximum work output over the inlet temperature range of 293 K–793 K with inlet pressure of 70 bar. It is found that the maximum thermal efficiency, maximum exergy efficiency and maximum work output are 62.6%, 91.9%, 763.2 kJ/s, respectively. However, the thermal efficiency, exergy efficiency and work output are not equivalent for the four-stage radial turbine. It is suggested that at low working temperatures both maximum exergy efficiency and maximum work output can be used as the design objective, however, only maximum work output can be used as the design objective for the four-stage radial turbine over the working temperature range in this work. Full article
(This article belongs to the Special Issue Entropy and Energy Extraction)
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370 KiB  
Article
An Unified Approach to Limits on Power Generation and Power Consumption in Thermo-Electro-Chemical Systems
by Stanisław Sieniutycz
Entropy 2013, 15(2), 650-677; https://doi.org/10.3390/e15020650 - 11 Feb 2013
Cited by 3 | Viewed by 5421
Abstract
This research presents a unified approach to power limits in power producing and power consuming systems, in particular those using renewable resources. As a benchmark system which generates or consumes power, a well-known standardized arrangement is considered, in which two different reservoirs are [...] Read more.
This research presents a unified approach to power limits in power producing and power consuming systems, in particular those using renewable resources. As a benchmark system which generates or consumes power, a well-known standardized arrangement is considered, in which two different reservoirs are separated by an engine or a heat pump. Either of these units is located between a resource fluid (‘upper’ fluid 1) and the environmental fluid (‘lower’ fluid, 2). Power yield or power consumption is determined in terms of conductivities, reservoir temperatures and internal irreversibility coefficient, F. While bulk temperatures Ti of reservoirs’ are the only necessary state coordinates describing purely thermal units, in chemical (electrochemical) engines, heat pumps or separators it is necessary to use both temperatures and chemical potentials mk. Methods of mathematical programming and dynamic optimization are applied to determine limits on power yield or power consumption in various energy systems, such as thermal engines, heat pumps, solar dryers, electrolysers, fuel cells, etc. Methodological similarities when treating power limits in engines, separators, and heat pumps are shown. Numerical approaches to multistage systems are based on methods of dynamic programming (DP) or on Pontryagin’s maximum principle. The first method searches for properties of optimal work and is limited to systems with low dimensionality of state vector, whereas the second investigates properties of differential (canonical) equations derived from the process Hamiltonian. A relatively unknown symmetry in behaviour of power producers (engines) and power consumers is enunciated in this paper. An approximate evaluation shows that, at least ¼ of power dissipated in the natural transfer process must be added to a separator or a heat pump in order to assure a required process rate. Applications focus on drying systems which, by nature, require a large amount of thermal or solar energy. We search for minimum power consumed in one-stage and multi-stage operation of fluidized drying. This multi-stage system is supported by heat pumps. We outline the related dynamic programming procedure, and also point out a link between the present irreversible approach and the classical problem of minimum reversible work driving the system. Full article
(This article belongs to the Special Issue Entropy and Energy Extraction)
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Review

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717 KiB  
Review
Capacitive Mixing for Harvesting the Free Energy of Solutions at Different Concentrations
by Raúl A. Rica, Roberto Ziano, Domenico Salerno, Francesco Mantegazza, Renéa Van Roij and Doriano Brogioli
Entropy 2013, 15(4), 1388-1407; https://doi.org/10.3390/e15041388 - 17 Apr 2013
Cited by 113 | Viewed by 12217
Abstract
An enormous dissipation of the order of 2 kJ/L takes place during the natural mixing process of fresh river water entering the salty sea. “Capacitive mixing” is a promising technique to efficiently harvest this energy in an environmentally clean and sustainable fashion. This [...] Read more.
An enormous dissipation of the order of 2 kJ/L takes place during the natural mixing process of fresh river water entering the salty sea. “Capacitive mixing” is a promising technique to efficiently harvest this energy in an environmentally clean and sustainable fashion. This method has its roots in the ability to store a very large amount of electric charge inside supercapacitor or battery electrodes dipped in a saline solution. Three different schemes have been studied so far, namely, Capacitive Double Layer Expansion (CDLE), Capacitive Donnan Potential (CDP) and Mixing Entropy Battery (MEB), respectively based on the variation upon salinity change of the electric double layer capacity, on the Donnan membrane potential, and on the electrochemical energy of intercalated ions. Full article
(This article belongs to the Special Issue Entropy and Energy Extraction)
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