Thomson Power in the Model of Constant Transport Coefficients for Thermoelectric Elements

Garrido, Javier; Casanovas, A.; Manzanares, José A.

doi:10.1007/s11664-019-07351-y

Cited by 6 publications

(1 citation statement)

References 37 publications

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“…Only occasionally, e.g., when

is close to linear, the

position works well for correction but fails for most materials as it does not take into account the asymmetry of heat sources and heat conduction. Similarly, models suggesting half of the Thomson heat on either side for correcting the CPM results [ 14 , 15 , 16 , 26 , 27 ] will mostly not work sufficiently. The correction employing the

peak position is close to the exact numerical correction for most materials as this position considers the asymmetry exactly.…”

Section: Methods Results and Discussionmentioning

confidence: 99%

Discrepancy between Constant Properties Model and Temperature-Dependent Material Properties for Performance Estimation of Thermoelectric Generators

Ponnusamy

Boor

Müller

2020

Entropy

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The efficiency of a thermoelectric (TE) generator for the conversion of thermal energy into electrical energy can be easily but roughly estimated using a constant properties model (CPM) developed by Ioffe. However, material properties are, in general, temperature (T)-dependent and the CPM yields meaningful estimates only if physically appropriate averages, i.e., spatial averages for thermal and electrical resistivities and the temperature average (TAv) for the Seebeck coefficient (α), are used. Even though the use of αTAv compensates for the absence of Thomson heat in the CPM in the overall heat balance, we find that the CPM still overestimates performance (e.g., by up to 6% for PbTe) for many materials. The deviation originates from an asymmetric distribution of internally released Joule heat to either side of the TE leg and the distribution of internally released Thomson heat between the hot and cold side. The Thomson heat distribution differs from a complete compensation of the corresponding Peltier heat balance in the CPM. Both effects are estimated quantitatively here, showing that both may reach the same order of magnitude, but which one dominates varies from case to case, depending on the specific temperature characteristics of the thermoelectric properties. The role of the Thomson heat distribution is illustrated by a discussion of the transport entropy flow based on the α(T) plot. The changes in the lateral distribution of the internal heat lead to a difference in the heat input, the optimum current and thus of the efficiency of the CPM compared to the real case, while the estimate of generated power at maximum efficiency remains less affected as it is bound to the deviation of the optimum current, which is mostly <1%. This deviation can be corrected to a large extent by estimating the lateral Thomson heat distribution and the asymmetry of the Joule heat distribution. A simple guiding rule for the former is found.

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“…Only occasionally, e.g., when

is close to linear, the

peak position is close to the exact numerical correction for most materials as this position considers the asymmetry exactly.…”

Section: Methods Results and Discussionmentioning

confidence: 99%