Performance comparison of thermoelectric generators using different materials

Thermoelectric generators (TEGs) are a promising device to harvest waste heat for power generation. Three material properties of TEGs, including the Seebeck coefficient, electrical resistivity, and thermal conductivity, are often considered as constants in the simulation. However, the performance of TEGs changes with different temperature. In this study, the performances, such as output power and efficiency of one constant property material and three temperature-dependent property materials are investigated numerically. The influences of the temperature difference, the temperature at the cold side surface, and current on the performance of the TEGs are analyzed. The predictions indicate that the output power of the TEGs deviate from the formula when their properties are temperature-dependent. In other words, the output power of the TEGs is not directly proportional to the temperature difference squared. The simulations also satisfy the result of self-consistency. In the case of the fixed temperature difference of 100 degrees C, when the temperature at cold side surface is lower, different performances of TEG are followed by different materials. The results also tell that one material whose ZT value increases with the rise in temperature has a similar trend in output power and efficiency to the constant-property material. However, another material that has the maximum value in the ZT curve has different trend in output power and efficiency from those of the constant-property material. (C) 2019 The Authors. Published by Elsevier Ltd.