Identification and selection of unconstrained controls in power systems propelled by heat and mass transfer

Sieniutycz, Stanisław

doi:10.1016/j.ijheatmasstransfer.2010.10.009

Cited by 14 publications

(8 citation statements)

References 12 publications

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“…Whenever fuel cell can be regarded as a linear system (the case of constant, current independent resistances), an important theoretical estimate of FC power limits can be obtained (Sieniutycz 2011). Yet, before making this estimate, we shall point out a link between the mathematics of thermal or chemical engines and fuel cells.…”

Section: Some Recent Theoretical Results On Power Limitsmentioning

confidence: 99%

Thermodynamic aspects of power generation in imperfect fuel cells: part II

Sieniutycz

2011

International Journal of Ambient Energy

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This research continues the thermodynamic analysis of steady-state solid oxide fuel cells initiated in Sieniutycz (Sieniutycz, S., 2010, Thermodynamic aspects of power generation in imperfect fuel cells: part I. International Journal of Ambient Energy, 31 (4), [195][196][197][198][199][200][201][202]. This analysis focuses on the effect of incomplete conversions in chemical reactions. A general approach is developed that attributes lowering of the cell voltage below its reversible value to polarisations and imperfect chemical conversions. Relevant model, appropriate for systems with complete conversions, is extended to imperfect cases. The performance curves of a fuel cell and the effect of typical design and operating parameters on the cell behaviour are analysed. A general result is obtained for power limits of fuel cells propelled by linear transport phenomena.

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Section: Some Recent Theoretical Results On Power Limitsmentioning

confidence: 99%

Thermodynamic aspects of power generation in imperfect fuel cells: part II

Sieniutycz

2011

International Journal of Ambient Energy

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“…The volume limitation of the present paper does not allow for inclusion of all derivations to make the paper selfcontained, thus the reader may need to turn to some previous works [2,4,11,12,15,34]. In particular, we refer to the derivations and theory of special while useful control variables (Carnot controls; [2,4,43]). …”

Section: Concluding Remarks and Discussionmentioning

confidence: 99%

“…Active (power producing) driving forces corresponding with Eqs. (43) and (44) are the temperature difference T 10 À T 20 and chemical affinity m 10 À m 20 . The chemical power yield is p ¼ ðT 10 À T 20 ÞI s þ ðm 10 À m 20 ÞI n…”

Section: Influence Of Transport Phenomena On Power Yieldmentioning

confidence: 99%

Synthesizing modeling of power generation and power limits in energy systems

Sieniutycz

2015

Energy

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“…There is also a novelty in the mathematical structure of Hamiltonians applied here, which admit discrete process rates as entities explicitly dependent on time intervals, . Until now Hamiltonians were used in power systems quite seldom, and were limited to models with  -independent discrete rates, the models which sometimes prove to be oversimplified [10,38,39]. This expression contains classical heat fluxes q 1 and q 2 identified with the so-called senstive heat (the heat attributed to thermal agitations in the continuum medium).…”

Section: Final Remarksmentioning

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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Identification and selection of unconstrained controls in power systems propelled by heat and mass transfer

Cited by 14 publications

References 12 publications

Thermodynamic aspects of power generation in imperfect fuel cells: part II

Thermodynamic aspects of power generation in imperfect fuel cells: part II

Synthesizing modeling of power generation and power limits in energy systems

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

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