Optimal working conditions for thermoelectric generators with realistic thermal coupling

Abstract

We study how maximum output power can be obtained from a thermoelectric\ngenerator(TEG) with nonideal heat exchangers. We demonstrate with an analytic\napproach based on a force-flux formalism that the sole improvement of the\nintrinsic characteristics of thermoelectric modules including the enhancement\nof the figure of merit is of limited interest: the constraints imposed by the\nworking conditions of the TEG must be considered on the same footing.\nIntroducing an effective thermal conductance we derive the conditions which\npermit maximization of both efficiency and power production of the TEG\ndissipatively coupled to heat reservoirs. Thermal impedance matching must be\naccounted for as well as electrical impedance matching in order to maximize the\noutput power. Our calculations also show that the thermal impedance does not\nonly depend on the thermal conductivity at zero electrical current: it also\ndepends on the TEG figure of merit. Our analysis thus yields both electrical\nand thermal conditions permitting optimal use of a thermoelectric generator.\n