Discrepancy between Constant Properties Model and Temperature-Dependent Material Properties for Performance...

Area of Science:

• Materials Science
• Thermodynamics
• Energy Conversion

Background:

• The constant properties model (CPM) provides a basic estimate for thermoelectric (TE) generator efficiency.
• Material properties like resistivity and the Seebeck coefficient are generally temperature-dependent, complicating accurate modeling.
• Existing models often use averaged properties, which can lead to inaccuracies.

Purpose of the Study:

• To investigate the overestimation of thermoelectric generator efficiency by the constant properties model.
• To quantify the impact of asymmetric Joule heat and Thomson heat distribution on TE performance.
• To develop methods for correcting CPM predictions for improved accuracy.

Main Methods:

• Analysis of heat transfer within thermoelectric legs, considering temperature-dependent properties.
• Quantitative estimation of Joule and Thomson heat distribution effects.
• Comparison of CPM predictions with corrected models for various materials.

Main Results:

• The CPM overestimates TE generator efficiency, with deviations up to 6% for materials like PbTe.
• Asymmetric Joule heat distribution and Thomson heat distribution significantly impact efficiency.
• The relative importance of these effects varies with the specific temperature characteristics of thermoelectric properties.

Conclusions:

• The constant properties model requires corrections for Joule and Thomson heat distribution to accurately predict thermoelectric generator efficiency.
• Understanding heat distribution is crucial for optimizing TE device performance.
• A simple guideline for estimating Thomson heat distribution has been identified.