Probabilistic Finite Time Thermodynamics: A Chemically Driven Engine

Bădescu, Viorel; Andresen, Bjarne

doi:10.1515/jnet.1996.21.4.291

Cited by 16 publications

(14 citation statements)

References 12 publications

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“…The probabilistic approach allows defining some statistical measures for the variation in size. Therefore, it can be superior to the deterministic empirical models [136]. The statistical modeling of the evolution of volatile matter with respect to particle size and temperature will increase the accuracy of the model.…”

Section: Discussionmentioning

confidence: 99%

A review on devolatilization of coal in fluidized bed

Borah

Ghosh

Rao

2011

Int. J. Energy Res.

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SUMMARYDevolatilization is an important step in fluidized bed combustion and gasification of coal. 'Devolatilization' is a general term that signifies the removal of volatile matters from the coal matrix. It is an extremely important step because the combustion of volatile matter can account for 50% of the specific energy of fluidized bed combustion of a high-volatile coal. Significant insights into the complex physicochemical phenomena that occur during devolatilization have been obtained in the recent years. This review focuses on the devolatilization of coal in an inert gas, air, and oxygen-enriched air, with emphasis on the effects of the operating parameters (e.g. temperature, heating rate, pressure, and gas velocity) on the yield of volatile matter. Particle size, oxygen content of the fluidizing gas, volatile content of coal and specific heat are some of the other important parameters for the devolatilization of coal. This review also explains the development and application of structural and empirical models. The structural models (e.g. FG-DVC and CPD models) are fairly complex. However, they can accurately predict the yields of gas and tar. It is observed from the review of the literature that the mechanism of coal devolatilization needs further study. Although the shrinking-core model can describe the devolatilization in the beginning and toward the end of the process, major deviations are often observed. The economic studies reveal that the capital cost of fluidized bed combustion reduces upon doubling the capacity. Some problems associated with bubbling fluidized bed combustion (e.g. the increase in freeboard temperature) have been explained with the present knowledge of devolatilization.

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Section: Discussionmentioning

confidence: 99%

A review on devolatilization of coal in fluidized bed

Borah

Ghosh

Rao

2011

Int. J. Energy Res.

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“…[106] Aus den Gleichungen (15) und (16) für die thermodynamische Länge bzw. die Dissipation, wobei M die Matrix in Gleichung (10) ist und X alle extensiven Variablen des Systems beinhaltet, folgt die generelle Ungleichung (17).…”

Section: Mesoskopische Systemeunclassified

“…Ein Bericht über eine statische mechanische Version erschien 1996. [17] Mironova wendete die optimierte Regelung auf chemische Reaktionen an. [18,61,62] Der optimale Temperaturverlauf für die industriell wichtige Reaktion der Ammoniaksynthese, N 2 + 3 H 2 Q2 NH 3 , wurde mit einer Geschwindigkeitsgleichung nach Temkin-Pyzhev ermittelt.…”

Section: Chemische Reaktionenunclassified

“…Zeit zur Analyse von chemischen Reaktionen und Trennungsprozessen eingesetzt wurde. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] Grundlagenforschung und Anlagentechnik leben weitgehend in getrennten Welten mit eigenen Zeitschriften und Konferenzen. Es hat daher etliche Jahre gedauert, bis die Thermodynamik in endlicher Zeit Eingang in die Ingenieurwissenschaften fand.…”

Section: Introductionunclassified

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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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“…In 1996, Badescu and Andresen [30] proposed that finite-time thermodynamics can be complemented with some probabilistic concepts allowing a more accurate description of the performance indicators of a power system. These authors studied a continuous flow tube reactor which supplies heat to an engine arising from a chemical reaction with linear kinetics.…”

Section: Otto Engine With Fluctuant Heat Reactionmentioning

confidence: 99%

A simplified irreversible Otto engine model with fluctuations in the combustion heat

Rocha-Martínez¹,

Navarrete-González²,

Pavía-Miller³

et al. 2006

International Journal of Ambient Energy

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SYNOPSISIn this work we present a simplified irreversible Otto engine model which includes power losses and a chemical combustion reaction at the end of the adiabatic compression. The heat released in the combustion reaction is taken as a fluctuant quantity around its mean value. The fluctuations are simulated by means of a Gaussian stochastic process for a rich-air intake mixture and by two non-linear deterministic noisy maps in the case of poor-air mixtures. The fluctuant combustion heat drives the Otto engine model producing in turn fluctuant power output and fluctuant cycle efficiency. We analyse the size of the fluctuant outputs in terms of the fluctuant input.

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Probabilistic Finite Time Thermodynamics: A Chemically Driven Engine

Cited by 16 publications

References 12 publications

A review on devolatilization of coal in fluidized bed

A review on devolatilization of coal in fluidized bed

Aktuelle Trends in der Thermodynamik in endlicher Zeit

A simplified irreversible Otto engine model with fluctuations in the combustion heat

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