Abstract
In this study, segmented thermoelectric generators (TEGs) have been simulated with various state-of-the-art TE materials spanning a wide temperature range, from 300 K up to 1000 K. The results reveal that by combining the current best p-type TE materials, BiSbTe, MgAgSb, K-doped PbTeS and SnSe with the strongest n-type TE materials, Cu-Doped BiTeSe, AgPbSbTe and SiGe to build segmented legs, TE modules could achieve efficiencies of up to 17.0% and 20.9% at ΔT = 500 K and ΔT = 700 K, respectively, and a high output power densities of over 2.1 Watt cm−2 at the temperature difference of 700 K. Moreover, we demonstrate that successful segmentation requires a smooth change of compatibility factor s from one end of the TEG leg to the other, even if s values of two ends differ by more than a factor of 2. The influence of the thermal radiation, electrical and thermal contact effects have also been studied. Although considered potentially detrimental to the TEG performance, these effects, if well-regulated, do not prevent segmentation of the current best TE materials from being a prospective way to construct high performance TEGs with greatly enhanced efficiency and output power density.
Highlights
One question arises naturally: is it possible to build segmented Thermoelectric generators (TEGs) with various TE materials and make them cooperate with each other to result in an overall high performance? A few researchers have done some work in this respect, for example, Snyder et al introduced a function called compatibility factor that characterizes the feasibility of combining two or more TE materials without having them adversely interacting with each other[30,31]
The third and fourth layers of TE materials are added to TEGs for ΔT = 500 K and 700 K
It is found that the TEG modules with the current best p-type TE materials teamed up with the strongest n-type TE materials could yield efficiencies of up to 17.0% and
Summary
One-unicouple models with various footprints were utilized by Rezania et al to study the optimization of power generation based on p-type Zn4Sb3 and n-type Mg2Si1−xSnx[37] These 3D models are simple in geometry with less number of TE unicoulples, and use out-of-date materials. One is that segmentation introduces new interfaces between TE materials in addition to leg-electrode interfaces These interfaces host electrical and thermal contact resistances, which incur net losses, for example, extra Joule heat, but can cause temperature redistribution in the TEG leg, offsetting the optimal temperature range for each TE materials, thereby reducing the overall efficiency and output power. On the basis of TEG model with the optimized p-n leg ratio, thermal radiation and contact resistances have been taken into account Both the electrical and thermal contact resistances at segment-segment and segment-electrode interfaces are examined. All the simulations in this study are implemented by using the 3D finite element analysis (FEA) solver Ansys
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