Efficiency of electrochemical systems

Rao, Ashok; Maclay, James D.; Samuelsen, Scott

doi:10.1016/j.jpowsour.2004.02.028

Cited by 36 publications

(15 citation statements)

References 5 publications

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“…There are many discussions in the literature on the efficiency analysis of fuel cells [1, [19][20][21]. The efficiency of a cell is usually expressed in terms of cell voltage, fuel utilization, and the thermoneutral voltage [22] …”

Section: Efficiency Modelmentioning

confidence: 99%

Performance analysis of a SOFC under direct internal reforming conditions

Janardhanan

Heuveline²,

Deutschmann

2007

Journal of Power Sources

116

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Section: Efficiency Modelmentioning

confidence: 99%

Performance analysis of a SOFC under direct internal reforming conditions

Janardhanan

Heuveline²,

Deutschmann

2007

Journal of Power Sources

116

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“…However, precise definitions of efficiency can vary widely [1][2][3]. In a narrow sense, an efficiency can be defined for the fuel cell alone.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of SOFC efficiency and fuel utilization as functions of fuel mixtures and operating conditions

Zhu

Kee

2006

Journal of Power Sources

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“…Efficiencies based on the first law (often found in the literature) can generate efficiency values greater than 100% for certain systems depending on whether the change in entropy for the overall chemical reaction involved in the process is positive or negative. See, for example, paper [28] on various definitions of FC efficiencies.…”

Section: Power Limits In Fuel Cellsmentioning

confidence: 99%

An Unified Approach to Limits on Power Generation and Power Consumption in Thermo-Electro-Chemical Systems

Sieniutycz

2013

Entropy

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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,  While bulk temperatures T i 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  k . 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 OPEN ACCESSEntropy 2013, 15 651 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. Keywords

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Efficiency of electrochemical systems

Cited by 36 publications

References 5 publications

Performance analysis of a SOFC under direct internal reforming conditions

Performance analysis of a SOFC under direct internal reforming conditions

Thermodynamics of SOFC efficiency and fuel utilization as functions of fuel mixtures and operating conditions

An Unified Approach to Limits on Power Generation and Power Consumption in Thermo-Electro-Chemical Systems

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