Abstract

Thermoelectric generator modules are solid-state semiconductor devices that convert heat directly to electricity. Because thermoelectric generators are small and free of moving parts, they are well suited to recovering waste heat from various processes, such as automotive exhaust, increasing the overall energy efficiency of the process. Waste heat recovery is becoming increasingly important as the global energy demand continues to rise. Recently, large improvements in thermoelectric materials have been realized as a consequence of better nanoscale materials science which show great promise, but accurate device-level characterization is needed in order to optimize device design. To date, a handful of different characterization methods have been developed for thermoelectric generator modules but these methods have not been rigorously compared.

Four characterization methods for thermoelectric modules, a steady state, rapid steady state, modified Harman, and Gao Min method were compared on equipment designed in the RIT Sustainable Energy Lab that has been thoroughly characterized and calibrated. Using a single thermoelectric module and the aforementioned well-characterized test stand, the four methods selected were compared side-by-side. The results obtained from each method were different despite being derived from the same model of thermoelectric modules. The four methods compared had never been directly compared using the same module, and our results indicate that one must know both parameter values and the method used to obtain them in order to apply the results.

Analytic modeling suggested that the main cause of the discrepancy was the thermal resistance of the thermoelectric module substrate and associated thermal contact resistances. Experiments confirmed that separating the effect of thermal contact resistance could explain the discrepancies between test methods, which implies that thermal contact resistance is an important thermoelectric module parameter that should be measured. This conclusion is supported by other recent publications. Based on the analytic model, we suggest multiple ways to measure thermal contact resistance by combining common testing techniques. If thermal contact resistance is measured and integrated into models of device performance, test results will be consistent between methods, thermoelectric module models will have higher fidelity, and the effect of different manufacturing techniques on the thermal contact resistance can be studied.

Library of Congress Subject Headings

Thermoelectric generators--Mathematical models

Publication Date

5-2015

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Robert J. Stevens

Advisor/Committee Member

Satish G. Kandlikar

Advisor/Committee Member

Steven W. Day

Comments

Physical copy available from RIT's Wallace Library at TK2950 .P54 2015

Campus

RIT – Main Campus

Plan Codes

MECE-MS

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