Details
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 5-13 |
| Seitenumfang | 9 |
| Fachzeitschrift | Energy Harvesting and Systems |
| Jahrgang | 2 |
| Ausgabenummer | 1 |
| Publikationsstatus | Veröffentlicht - 12 März 2015 |
Abstract
thermoelectricity in the framework of the thermodynamics
of irreversible processes, which uses rather abstract kinetic
matrix and generalized forces to describe the flux of the
substance-like quantities electric charge and thermal energy
(“heat”). A brief review of the derivation of the basic equations
according to this model is given. Primarily, this model
relies on the total differential of energy as in Gibb’s thermodynamics,
but it then removes entropy to capture the energy
production rate as ameasure of irreversibility. Depending on
the fluxes of interest, “proper” generalized forces are identified.
The use of Onsager’s reciprocal relations helps to determine
the coefficients of a kinetic matrix to link the
generalized forces with the generalized potentials. The present
article places entropy back into the as-obtained basic
equations. The equations are then transformed such that the
flux densities of electric charge and entropy appear with
equal ranks. The respective conjugated intensive variables
electrochemical potential and temperature then appear as
the thermodynamic potentials. Moreover, the thermoelectric
material is described by a material-specific tensor, which is
composed only of the isothermal electric conductivity, the
Seebeck coefficient and the entropy conductivity. The result
is identical to that recently obtained by Fuchs using a direct
entropic approach,which does not require Onsager’s reciprocal
relations as a prerequisite. The benefit of this approach is
the appearance of a material-specific thermoelectric tensor
rather than a so-called kineticmatrix,which not only provides
a new quality to the discussion but also facilitates descriptions
of the thermoelectric phenomenon and the underlying
energy conversion process. The latter can easily be understood
as the transfer of energy from thermal to electric phenomenon
or vice versa when fluxes of entropy and electric
charge, as well as the local thermodynamic potentials temperature
and electrochemical potential, are known.
Schlagwörter
- Thermodynamische Potenziale, Güteparameter, Energietransfer, Thermoelektrizität
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in: Energy Harvesting and Systems, Jahrgang 2, Nr. 1, 12.03.2015, S. 5-13.
Publikation: Beitrag in Fachzeitschrift › Übersichtsarbeit › Forschung › Peer-Review
}
TY - JOUR
T1 - Thermoelectric Material Tensor Derived from the Onsager–de Groot–Callen Model
AU - Feldhoff, Armin
PY - 2015/3/12
Y1 - 2015/3/12
N2 - The Onsager–de Groot–Callen model describesthermoelectricity in the framework of the thermodynamicsof irreversible processes, which uses rather abstract kineticmatrix and generalized forces to describe the flux of thesubstance-like quantities electric charge and thermal energy(“heat”). A brief review of the derivation of the basic equationsaccording to this model is given. Primarily, this modelrelies on the total differential of energy as in Gibb’s thermodynamics,but it then removes entropy to capture the energyproduction rate as ameasure of irreversibility. Depending onthe fluxes of interest, “proper” generalized forces are identified.The use of Onsager’s reciprocal relations helps to determinethe coefficients of a kinetic matrix to link thegeneralized forces with the generalized potentials. The presentarticle places entropy back into the as-obtained basicequations. The equations are then transformed such that theflux densities of electric charge and entropy appear withequal ranks. The respective conjugated intensive variableselectrochemical potential and temperature then appear asthe thermodynamic potentials. Moreover, the thermoelectricmaterial is described by a material-specific tensor, which iscomposed only of the isothermal electric conductivity, theSeebeck coefficient and the entropy conductivity. The resultis identical to that recently obtained by Fuchs using a directentropic approach,which does not require Onsager’s reciprocalrelations as a prerequisite. The benefit of this approach isthe appearance of a material-specific thermoelectric tensorrather than a so-called kineticmatrix,which not only providesa new quality to the discussion but also facilitates descriptionsof the thermoelectric phenomenon and the underlyingenergy conversion process. The latter can easily be understoodas the transfer of energy from thermal to electric phenomenonor vice versa when fluxes of entropy and electriccharge, as well as the local thermodynamic potentials temperatureand electrochemical potential, are known.
AB - The Onsager–de Groot–Callen model describesthermoelectricity in the framework of the thermodynamicsof irreversible processes, which uses rather abstract kineticmatrix and generalized forces to describe the flux of thesubstance-like quantities electric charge and thermal energy(“heat”). A brief review of the derivation of the basic equationsaccording to this model is given. Primarily, this modelrelies on the total differential of energy as in Gibb’s thermodynamics,but it then removes entropy to capture the energyproduction rate as ameasure of irreversibility. Depending onthe fluxes of interest, “proper” generalized forces are identified.The use of Onsager’s reciprocal relations helps to determinethe coefficients of a kinetic matrix to link thegeneralized forces with the generalized potentials. The presentarticle places entropy back into the as-obtained basicequations. The equations are then transformed such that theflux densities of electric charge and entropy appear withequal ranks. The respective conjugated intensive variableselectrochemical potential and temperature then appear asthe thermodynamic potentials. Moreover, the thermoelectricmaterial is described by a material-specific tensor, which iscomposed only of the isothermal electric conductivity, theSeebeck coefficient and the entropy conductivity. The resultis identical to that recently obtained by Fuchs using a directentropic approach,which does not require Onsager’s reciprocalrelations as a prerequisite. The benefit of this approach isthe appearance of a material-specific thermoelectric tensorrather than a so-called kineticmatrix,which not only providesa new quality to the discussion but also facilitates descriptionsof the thermoelectric phenomenon and the underlyingenergy conversion process. The latter can easily be understoodas the transfer of energy from thermal to electric phenomenonor vice versa when fluxes of entropy and electriccharge, as well as the local thermodynamic potentials temperatureand electrochemical potential, are known.
KW - Thermodynamic potentials
KW - Figure of merit
KW - Energy transfer
KW - Thermoelectricity
KW - Thermodynamische Potenziale
KW - Güteparameter
KW - Energietransfer
KW - Thermoelektrizität
U2 - 10.1515/ehs-2014-0040
DO - 10.1515/ehs-2014-0040
M3 - Review article
VL - 2
SP - 5
EP - 13
JO - Energy Harvesting and Systems
JF - Energy Harvesting and Systems
SN - 2329-8774
IS - 1
ER -