Efficiency calculation of a thermoelectric generator for investigating the applicability of various thermoelectric materials

Accurate measurement of efficiency for a thermoelectric generator (TEG) is of great importance for materials research and development. Approximately all the parameters of a thermoelectric material (TEM) are temperature dependent, and so we cannot directly apply the ηmax formula for efficiency calculation in the large temperature range. In this work, we have calculated TEG efficiency, and we study the suitability of different TEMs like Bi2Te3, Sb2Te3, PbTe, TAGS ((AgSbTe2)0.15(GeTe)0.85), CeFe4Sb12, SiGe, and TiO1.1 in the estimation of TEG efficiency. The efficiency of TEG made up of Bi2Te3 or Sb2Te3 gives ∼7% in the temperature range of 310 K–500 K. PbTe or TAGS or CeFe4Sb12 generates ∼6% in the temperature range of 500 K–900 K and SiGe or TiO1.1 also have remarkable efficiency in the higher temperature range, i.e., ∼1200 K. The calculated efficiency obtained is close to experimental results. Here, we report the enhancement of efficiency by using the segmented technique for different combinations of the above-mentioned materials. To this end, the proposed values of overall efficiency of TEG by segmenting Bi2Te3 and PbTe; Bi2Te3 and TAGS; Bi2Te3 and CeFe4Sb12 are 12%, 14%, and 11.88%, respectively, for the temperature range of 310 K–900 K. For automobiles, the efficiency of TEG having fixed exhaust temperature with varying sink temperature is also discussed. For the steel industry and spacecraft applications (up to 1200 K), either segmentation is done by comprising Bi2Te3, PbTe and SiGe, or Bi2Te3 and TiO1.1, which yields an efficiency of ∼15.2% and ∼17.2%, respectively. The relative change in efficiency by considering loss at the interface surface is found to be 10.5%. The proposed methodology and results can be treated as a viable option for engineers who are looking to fabricate TEG in real life by using the temperature dependent material's parameters such as thermal conductivity, electrical conductivity, and Seebeck coefficient on which zT¯ depends.