Single Stage Arrangement

For the single stage arrangement of the thermoelectric module, the variation of stress along the selected centerline locations of various thermoelectric legs with different materials is shown in Figure 10d,e. Figure 10d shows the variations of stress in different p-type semiconductor materials of various legs geometries and Figure 10e shows the variations of stress in different n-type semiconductor materials of various legs geometries. For each geometry, same p-type and n-type semiconductor material showed similar behavior with small variations in values due to same thermal properties [1]. However, the same p-type and n-type semiconductor material had different electrical properties. The intensity of stress was high at the intersection of the thermoelectric legs and the hot plate (top of the thermoelectric legs) for the single stage arrangement of the thermoelectric module with materials and leg geometries, as shown in Figure 10d,e because the materials of the thermoelectric legs and hot plate were different, and the top of the legs was exposed to a higher temperature. The stress reduced from the hot side of the thermoelectric legs to the cold side of the thermoelectric legs with the minimum value at the bottom of the leg near the cold junction plate because of reduction in temperature [1,10,11]. The materials of the thermoelectric legs and the cold side plate were also different, but the temperature at this location was low to generate lower stress. For the SiGe material, the square and trapezoidal legs showed higher stress compared to the cylindrical legs. Similarly, for the Bi2Te<sup>3</sup> material, the cylindrical legs presented lower stress than the other leg geometries. The higher temperature difference showed higher thermal stress. Therefore, the Bi2Te<sup>3</sup> material showed lower stress than the SiGe material for all three leg geometries because stress variation along the selected locations was presented at a temperature difference of 480 ◦C for the Bi2Te<sup>3</sup> material and 980 ◦C for the SiGe material.
