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Thermodynamic Optimization of Heat Devices, Stability and Control

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

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 3212

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Guest Editor
Department of Applied Physics, Faculty of Science, University of Salamanca, 37008 Salamanca, Spain
Interests: thermodynamics; statistical physics; heat engines
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The optimal design and operation of heat devices, irrespective of their macroscopic, mesoscopic, or microscopic nature, is associated with the estimation and control of specific parameters that lead to desirable high performance, usually settled by a compromise between fast production and reduced loss. In this context, the formalization of the study of non-equilibrium processes and the proposal, study, and optimization of non-equilibrium heat devices are issues in constant evolution.

An important point in the optimization realm is the proposal of unified figures of merit for any kind of energy converter, for which the trade-off between power and efficiency has been conventionally assumed. The universality of this trade-off has been a focus of research during the last few years and, as a result, the role of stability and the entropy production in the election of the figure of merit has been revealed as an emergent issue.

Consequently, the influence of control on the parameters and the device layout, the role of fluctuations in the energetic output records, and the stability of optimal operation regimes have become issues of special interest for the optimal design of heat devices, especially when control involves an energetic cost. With the purpose of providing a common space within which to present the latest advances in these areas, we launch the present Special Issue, in which contributions dealing with different kinds of energy converters, from quantum or micrometric to macroscopic, including models and natural heat devices, are welcome.

Prof. Dr. José Miguel Mateos Roco
Guest Editor

Manuscript Submission Information

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Keywords

  • heat devices
  • fluctuations
  • stability
  • control parameters
  • thermodynamic optimization

Published Papers (2 papers)

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Research

12 pages, 2797 KiB  
Article
Using a Partially Evaporating Cycle to Improve the Volume Ratio Problem of the Trilateral Flash Cycle for Low-Grade Heat Recovery
by Kai-Yuan Lai, Yu-Tang Lee, Ta-Hua Lai and Yao-Hsien Liu
Entropy 2021, 23(5), 515; https://doi.org/10.3390/e23050515 - 23 Apr 2021
Cited by 10 | Viewed by 1447
Abstract
This study examined the trilateral flash cycle characteristics (TFC) and partially evaporating cycle (PEC) using a low-grade heat source at 80 °C. The evaporation temperature and mass flow rate of the working fluids and the expander inlet’s quality were optimized through pinch point [...] Read more.
This study examined the trilateral flash cycle characteristics (TFC) and partially evaporating cycle (PEC) using a low-grade heat source at 80 °C. The evaporation temperature and mass flow rate of the working fluids and the expander inlet’s quality were optimized through pinch point observation. This can help advance methods in determining the best design points and their operating conditions. The results indicated the partially evaporating cycle could solve the high-volume ratio problem without sacrificing the net power and thermal efficiency performance. When the system operation’s saturation temperature decreased by 10 °C, the net power, thermal efficiency, and volume ratio of the trilateral flash cycle system decreased by approximately 20%. Conversely, with the same operational conditions, the net power and thermal efficiency of the partially evaporating cycle system decreased by only approximately 3%; however, the volume ratio decreased by more than 50%. When the system operating temperature was under 63 °C, each fluid’s volume ratio could decrease to approximately 5. The problem of high excessive expansion would be solved from the features of the partially evaporating cycle, and it will keep the ideal power generation efficiency and improve expander manufacturing. Full article
(This article belongs to the Special Issue Thermodynamic Optimization of Heat Devices, Stability and Control)
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21 pages, 6798 KiB  
Article
Comparative Assessment of Various Low-Dissipation Combined Models for Three-Terminal Heat Pump Systems
by Zhexu Li, Haibo Cao, Hanxin Yang and Juncheng Guo
Entropy 2021, 23(5), 513; https://doi.org/10.3390/e23050513 - 23 Apr 2021
Cited by 8 | Viewed by 1176
Abstract
Thermally driven heat pump systems play important roles in the utilization of low-grade thermal energy. In order to evaluate and compare the performances of three different constructions of thermally driven heat pump and heat transformer, the low-dissipation assumption has been adopted to establish [...] Read more.
Thermally driven heat pump systems play important roles in the utilization of low-grade thermal energy. In order to evaluate and compare the performances of three different constructions of thermally driven heat pump and heat transformer, the low-dissipation assumption has been adopted to establish the irreversible thermodynamic models of them in the present paper. By means of the proposed models, the heating loads, the coefficients of performance (COPs) and the optimal relations between them for various constructions are derived and discussed. The performances of different constructions are numerically assessed. More importantly, according to the results obtained, the upper and lower bounds of the COP at maximum heating load for different constructions are generated and compared by the introduction of a parameter measuring the deviation from the reversible limit of the system. Accordingly, the optimal constructions for the low-dissipation three-terminal heat pump and heat transformer are determined within the frame of low-dissipation assumption, respectively. The optimal constructions in accord with previous research and engineering practices for various three-terminal devices are obtained, which confirms the compatibility between the low-dissipation model and endoreversible model and highlights the validity of the application of low-dissipation model for multi-terminal thermodynamic devices. The proposed models and the significant results obtained enrich the theoretical thermodynamic model of thermally driven heat pump systems and may provide some useful guidelines for the design and operation of realistic thermally driven heat pump systems. Full article
(This article belongs to the Special Issue Thermodynamic Optimization of Heat Devices, Stability and Control)
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