Maximum Power and The Corresponding Efficiency for A Carnot-like Thermoelectric Cycle Based on Fluctuation Theorem

Abstract

Here, we investigate the maximum power and corresponding efficiency of thermoelectric generators through devising a set of protocols for the isothermal and adiabatic processes of thermoelectricity to build a Carnot-like thermoelectric cycle, with the analysis based on fluctuation theorem (FT). First of all, the Carnot efficiency can be readily obtained for the quasi-static thermoelectric cycle, with the vanishing power. Moreover, the maximum power-efficiency pair of the finite-time thermoelectric cycle is derived, which is found to have the identical form to that of Brownian motors characterized by the stochastic thermodynamics. However, it is of significant discrepancy compared to the linear-irreversible and endoreversible-thermodynamics-based formulations. The distinction compared to the linear-irreversible-thermodynamics case could result from the difference in the definitions of Peltier and Seebeck coefficients in the thermoelectric cycle. As for the endoreversible thermodynamics, we argue the applicability of endoreversibility could be questionable for analyzing the thermoelectric cycle here, due to the incompatibility of the endoreversible hypothesis that attributes the irreversibility to finite heat transfer with thermal reservoirs, though the distinction of the mathematical expressions can vanish with the assumption that the ratio of thermoelectric power factors at the high and low temperatures is equal to the square root of the temperature ratio (this condition could significantly deviate from the practical case).