Optimization of thermal systems based on finite-time thermodynamics and thermoeconomics

Durmayaz, Ahmet; Söğüt, Oğuz Salim; Şahi̇n, Bahri̇; Yavuz, Hasbi̇

doi:10.1016/j.pecs.2003.10.003

Cited by 318 publications

(129 citation statements)

References 272 publications

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“…Besides the criterion of maximum conversion efficiency [16], other optimization criteria have been proposed: maximum power [17,18], maximum of power density [19], thermo-economic optimization [20,21] or ecological optimization [22,23].…”

Section: Endoreversible Heat Enginementioning

confidence: 99%

“…Finally, we obtain in a new way all the classical results and in particular the associated energy conversion efficiency at the optimal point hs cs CNCA T T Ș 1 which depends only on the temperatures of heat source and heat sink [18]. The characteristics of this optimal point (O) can be determined through other ways.…”

Section: Determination Of the Maximum Mechanical Power And The Associmentioning

confidence: 99%

“…The drawback of this method is that one can't directly control the temperature h T . Other authors [18] used a more general method of Lagrange paradoxical character of the Carnot engine which gives the best energy conversion efficiency with zero production of mechanical power! …”

Section: Determination Of the Maximum Mechanical Power And The Associmentioning

confidence: 99%

See 2 more Smart Citations

Association of Finite-Time Thermodynamics and a Bond-Graph Approach for Modeling an Endoreversible Heat Engine

Dong

El-Bakkali

Descombes³

et al. 2012

Entropy

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Abstract:In recent decades, the approach known as Finite-Time Thermodynamics has provided a fruitful theoretical framework for the optimization of heat engines operating between a heat source (at temperature hs T ) and a heat sink (at temperature cs T ). The aim of this paper is to propose a more complete approach based on the association of Finite-Time Thermodynamics and the Bond-Graph approach for modeling endoreversible heat engines. This approach makes it possible for example to find in a simple way the characteristics of the optimal operating point at which the maximum mechanical power of the endoreversible heat engine is obtained with entropy flow rate as control variable. Furthermore it provides the analytical expressions of the optimal operating point of an irreversible heat engine where the energy conversion is accompanied by irreversibilities related to internal heat transfer and heat dissipation phenomena. This original approach, applied to an analysis of the performance of a thermoelectric generator, will be the object of a future publication.

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Section: Endoreversible Heat Enginementioning

confidence: 99%

Section: Determination Of the Maximum Mechanical Power And The Associmentioning

confidence: 99%

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Association of Finite-Time Thermodynamics and a Bond-Graph Approach for Modeling an Endoreversible Heat Engine

Dong

El-Bakkali

Descombes³

et al. 2012

Entropy

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“…The work output increases, reaches maximum and decreases with the increase of pressure ratio. It happens for each of the given values of temperature 3 ϑ . The pressure ratio in which the function reaches maximum moves to the higher value with the increase of temperature 3 ϑ .…”

Section: Exergy Destruction In a Combustion Chamber Compressor And Gmentioning

confidence: 99%

“…Criterion of maximum efficiency is used most frequently in power plants, in which the fuel consumption is important, while the criterion of maximum work output is significant in aircrafts in which the propulsion is of great importance. Both fuel consumption and thrust gain may be equally important, for example, for ship propulsion systems, therefore, in this case, both the maximum power and the maximum thermal efficiency criteria have to be considered in the design [3]. In detailed analysis [4], for thermodynamic optimization of a Brayton cycle, authors proposed two goal functions.…”

Section: Introductionmentioning

confidence: 99%

Exergy analysis of a Brayton cycle with variable physical properties and variable composition of working substance

et al. 2016

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Original scientific paperThe exergy analysis of a Brayton cycle is performed in the paper. The four input variables: the ratio of the compressor exit and inlet pressures, the ratio of inlet temperature of gases in turbine and inlet temperature of air in compressor and the isentropic efficiencies of the compressor and turbine are analysed. The temperature ratio is varied in a way that the compressor inlet temperature of air is maintained constant, while the turbine inlet temperature of flue gases is varied from 900 to 1200°C. In the combustion chamber methane is completely combusted with excess air ratio which is determined by the temperature of flue gases at the turbine inlet. The analysis further includes variability of the molar heat capacities of air and flue gases with temperature and variability of their heat capacity ratios. The exergy destruction in turbine, compressor and combustion chamber and also total exergy efficiency of the cycle are considered in the analysis. Keywords: Brayton cycle, variable physical properties, variable composition of working substance, maximum work output, maximum thermal efficiency Eksergijska analiza Braytonovog ciklusa s promjenjivim fizikalnim svojstvima i promjenjivim sastavom radne tvariIzvorni znanstveni članak U radu je provedena eksergijska analiza Braytonovog ciklusa. Četiri ulazne varijable, omjer tlakova na izlazu i ulazu u kompresor, omjer temperature na ulazu u turbinu i temperature na ulazu u kompresor, te izentropski stupnjevi djelovanja kompresora i turbine su uzeti u analizu. Omjer temperatura je variran tako da je temperatura zraka na ulazu u kompresor držana konstantnom, a temperatura dimnih plinova na ulazu u turbinu je varirana od 900 °C do 1200 °C. U komori za izgaranje potpuno izgara metan s pretičkom zraka koji je određen temperaturom dimnih plinova na ulazu u turbinu. Analiza nadalje uključuje promjenjivost molarnih toplinskih kapaciteta zraka i dimnih plinova s temperaturom i promjenjivost njihovih izentropskih eksponenata. Eksergijska destrukcija u komori za izgaranje, turbini i kompresoru kao i ukupna eksergijska efikasnost su uzete u analizu.Ključne riječi: Braytonov ciklus, promjenjiva fizikalna svojstva, promjenjiv sastav radne tvari, maksimalni neto rad, maksimalni stupanj djelovanja

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Aktuelle Trends in der Thermodynamik in endlicher Zeit

Andresen

2011

Angewandte Chemie

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Das Leitmotiv der Thermodynamik in endlicher Zeit (“finite‐time thermodynamics”) ist der Preis der Ungeduld und seine Minimierung. Reversible Prozesse können vollständig effizient sein, laufen jedoch meist unverhältnismäßig langsam ab. In allen Situationen – chemisch, mechanisch oder ökonomisch – sind wir bereit, mehr zu zahlen, damit eine Aufgabe schneller erledigt wird. Die Thermodynamik in endlicher Zeit befasst sich mit der Entwicklung von Methoden, diese Zusatzkosten zu begrenzen, wobei diese nicht zwingend monetär sein müssen, sondern sich auch auf Energieaufwand, Entropieproduktion oder dergleichen beziehen können. Die Thermodynamik in endlicher Zeit bietet Verfahren, den optimalen Pfad oder Betriebsmodus bei minimalem Zusatzaufwand zu berechnen. Ausgangspunkt ist es dabei, das System durch den Einfluss einer zeitlich variierenden Umgebung auf den optimalen Weg zu bringen; dies ist wie das Lenken eines Pferdes, das man einer Karotte an einem Stock nachlaufen lässt.

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Optimization of thermal systems based on finite-time thermodynamics and thermoeconomics

Cited by 318 publications

References 272 publications

Association of Finite-Time Thermodynamics and a Bond-Graph Approach for Modeling an Endoreversible Heat Engine

Association of Finite-Time Thermodynamics and a Bond-Graph Approach for Modeling an Endoreversible Heat Engine

Exergy analysis of a Brayton cycle with variable physical properties and variable composition of working substance

Aktuelle Trends in der Thermodynamik in endlicher Zeit

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