Performance of a composite thermoelectric generator with different arrangements of SiGe, BiTe and PbTe under different configurations

In this study, we analyze the role of the thermoelectric (TE) properties, namely Seebeck coefficient , thermal conductivity and electrical resistivity , of three different materials in a composite thermoelectric generator (CTEG) under different configurations. The CTEG is composed of three thermoelectric modules (TEMs): (1) two TEMs thermally and electrically connected in series (SC); (2) two branches of TEMs thermally and electrically connected in parallel (PSC); and (3) three TEMs thermally and electrically connected in parallel (TEP). In general, each of the TEMs have different thermoelectric parameters, namely a Seebeck coefficient α, a thermal conductance K and an electrical resistance R. Following the framework proposed recently, we show the effect of: (1) the configuration; and (2) the arrangements of TE materials on the corresponding equivalent figure of merit Z_eq and consequently on the maximum power P_max and efficiency η of the CTEG. Firstly, we consider that the whole system is formed of the same thermoelectric material (α₁, K₁, R₁ = α₂, K₂, R₂ = α₃, K₃, R₃) and, secondly, that the whole system is constituted by only two different thermoelectric materials (α_i, K_i, R_i = α_j, K_j, R_j ≠ α_l, K_l, R_l, where i; j; l can be 1, 2 or 3). In this work, we propose arrangements of TEMs, which clearly have the advantage of a higher thermoelectric figure of merit value compared to a conventional thermoelectric module. A corollary about the Z_{eq max} for CTEG is obtained as a result of these considerations. We suggest an optimum configuration.