A Constant Properties Model for the Performance Estimation in Segmented Thermoelectric Generator Elements and Its Experimental Validation Using an n-Type Mg₂Si_0.3Sn_0.7-Bi₂Te_{2.7< /sub>Se0.3 Segmented Leg}

Segmenting multiple compatible thermoelectric (TE) materialscanimprove the conversion efficiency in thermoelectric generators (TEGs)compared to single-material TEGs. A model to accurately estimate theperformance in segmented TEGs is essential for optimizing the geometricparameters. Constant properties models (CPMs) help in the quick estimationof the performance of TEGs working under large temperature differencesusing averaged material properties. This work discusses a CPM to predictthe performance of single and segmented TEG elements using a combinationof temperature-averaged and spatially-averaged TE properties. Spatialaveraging requires the knowledge of the temperature profile acrossthe TEG element length, which was obtained by solving the heat balanceequation with a numerical integration approach as suggested by Ponnusamyet al. In this work, we develop the CPM for the segmented TEG elements(CPMS). The model predictions were validated experimentally from theperformance evaluation of single Mg-2(Si0.3Sn0.7)(0.98)Bi-0.02 and segmented Mg-2(Si0.3Sn0.7)(0.98)Bi-0.02-Bi-2(Te2.7Se0.3)(0.98)(CuI)(0.02) TEG elements. Single and segmented TEG elementswith Cu contacts were prepared by a hot-pressing technique. Both Mg-2(Si0.3Sn0.7)(0.98)Bi-0.02 and Bi-2(Te2.7Se0.3)(0.98)(CuI)(0.02) TE materials show peak zT >1 in their measurement range. The experimental results show a maximumefficiency (eta(max)) of similar to 8.25% with 18% improvementfor the segmented structure at Delta T approximate to 302 K. The improvement mainly originated from lower heat input (Q(in)) even though the maximum power output (P (max)) became lower by similar to 30%. The performance predictionusing the CPM matches well with P (max) and eta(max) for the single TEG element,and using the CPMS, the predictions were P (max) and <25% error for eta(max) for the segmented TEG element experimental results. This work demonstrateshow CPMS can be used to predict device performance characteristicsin segmented TEGs.