Endoreversible modeling of a PEM fuel cell

Wagner, Katharina; Hoffmann, Karl Heinz

doi:10.1515/jnet-2015-0061

Cited by 27 publications

(16 citation statements)

References 12 publications

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“…The chemical reactor, which is the third type of endoreversible subsystems and which was introduced by Wagner [48,49], is slightly different from the endoreversible engine. However, this subsystem type, as well as chemical reactions in principal are not considered and hence not explained in detail in this work.…”

Section: Subsystemsmentioning

confidence: 99%

Dissipative Endoreversible Engine with Given Efficiency

Masser

Hoffmann

2019

Entropy

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Endoreversible thermodynamics is a finite time thermodynamics ansatz based on the assumption that reversible or equilibrated subsystems of a system interact via reversible or irreversible energy transfers. This gives a framework where irreversibilities and thus entropy production only occur in interactions, while subsystems (engines, for instance) act as reversible. In order to give an opportunity to incorporate dissipative engines with given efficiencies into an endoreversible model, we build a new dissipative engine setup. To do this, in the first step, we introduce a more general interaction type where energy loss not only results from different intensive quantities between the connected subsystems, which has been the standard in endoreversible thermodynamics up to now, but is also caused by an actual loss of the extensive quantity that is transferred via this interaction. On the one hand, this allows the modeling of leakages and friction losses, for instance, which can be represented as leaky particle or torque transfers. On the other hand, we can use it to build an endoreversible engine setup that is suitable to model engines with given efficiencies or efficiency maps and, among other things, gives an expression for their entropy production rates. By way of example, the modeling of an AC motor and its loss fluxes and entropy production rates are shown.

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Section: Subsystemsmentioning

confidence: 99%

Dissipative Endoreversible Engine with Given Efficiency

Masser

Hoffmann

2019

Entropy

Self Cite

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“…The concept of endoreversible thermodynamics assumes that all irreversibilities may be treated as a transport of heat and/or mass from a source to a sink, as stated in [2,3,4,5,6] and references therein. The presented approach slightly differs from the endoreversibility concept and it is connected with the principle of minimum entropy production and with the attenuation of fluctuations of all thermodynamic quantities.…”

Section: Introductionmentioning

confidence: 99%

On the Efficiency of Electrochemical Devices from the Perspective of Endoreversible Thermodynamics

Maršík

Martı́n

Tucek

et al. 2019

Journal of Non-Equilibrium Thermodynamics

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The current work presents a concept that deals with the production of entropy generated by non-equilibrium processes in consequence of mass and energy transfer. The often used concept of endoreversible thermodynamics is based on the non-realistic conjecture that the entire entropy production is realized at the system boundary. In this contribution, an open system in a thermodynamically non-equilibrium state is assumed. Production of entropy is generated due to non-equilibrium processes accompanied by energy conversion. The steady state of the system is maintained by a negative entropy flux. The conclusions for expansion energy conversion, i. e., thermal machines, confirm the general outcomes of the endoreversible thermodynamics. However, the presented conclusions related to non-expansion energy conversion offer a new perspective on the principle of minimum entropy production and the corresponding stability conditions at steady state. The analysis of the energy conversion in closed cycles is presented for fuel cells, i. e., non-expansion energy conversion. The efficiency of the energy conversion is maximal at zero power output. Moreover, the efficiency of the fuel cells, and consequently the efficiency of all non-expansion energy conversion processes, depends on the load and then the maximal possible efficiency can be determined.

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“…FTT, also known as entropy generation minimization (EGM) [ 31 , 32 , 33 , 34 , 35 ] in engineering, can obtain the optimal performances and optimal configurations of various energy conversion devices and systems subjected to finite-time and/or finite-size, and the optimal results obtained are more powerful to guide thermal designs and optimizations of real-word devices. The wide applications of FTT in chemical reactions, heat and mass transfer processes have obtained many important theoretical achievements [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. Månson and Andresen [ 36 ] firstly applied FTT to obtain the optimal paths of ammonia reactor with the maximum production rate as the objective function.…”

Section: Introductionmentioning

confidence: 99%

“…Chen et al [ 40 ] obtained EGM analytical solutions of the combustion chemical reactions subjected to a given fuel conversion, which obey general rate equations. Wagner and Hoffmann [ 41 , 42 ] established endoreversible models of finite-rate chemical reactions [ 41 ] and used these extensions of endoreversible thermodynamics to investigate the maximum power output of a fuel cell [ 42 ]. Some scholars had studied the optimal configurations of the heat reservoir temperature profiles of the industrial reactors in depth by using the minimum EGR as an objective function, including the sulfur dioxide oxidation reactor [ 43 ], the tubular steam reformer [ 44 , 45 ] and the sulfuric acid decomposition reactor [ 46 ].…”

Section: Introductionmentioning

confidence: 99%

Entropy Generation Minimization for Reverse Water Gas Shift (RWGS) Reactors

Zhang

Chen

Xia

et al. 2018

Entropy

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Thermal design and optimization for reverse water gas shift (RWGS) reactors is particularly important to fuel synthesis in naval or commercial scenarios. The RWGS reactor with irreversibilities of heat transfer, chemical reaction and viscous flow is studied based on finite time thermodynamics or entropy generation minimization theory in this paper. The total entropy generation rate (EGR) in the RWGS reactor with different boundary conditions is minimized subject to specific feed compositions and chemical conversion using optimal control theory, and the optimal configurations obtained are compared with three reference reactors with linear, constant reservoir temperature and constant heat flux operations, which are commonly used in engineering. The results show that a drastic EGR reduction of up to 23% can be achieved by optimizing the reservoir temperature profile, the inlet temperature of feed gas and the reactor length simultaneously, compared to that of the reference reactor with the linear reservoir temperature. These optimization efforts are mainly achieved by reducing the irreversibility of heat transfer. Optimal paths have subsections of relatively constant thermal force, chemical force and local EGR. A conceptual optimal design of sandwich structure for the compact modular reactor is proposed, without elaborate control tools or excessive interstage equipment. The results can provide guidelines for designing industrial RWGS reactors in naval or commercial scenarios.

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Endoreversible modeling of a PEM fuel cell

Cited by 27 publications

References 12 publications

Dissipative Endoreversible Engine with Given Efficiency

Dissipative Endoreversible Engine with Given Efficiency

On the Efficiency of Electrochemical Devices from the Perspective of Endoreversible Thermodynamics

Entropy Generation Minimization for Reverse Water Gas Shift (RWGS) Reactors

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