Performance analysis of the system integrating a molten carbonate fuel cell and a thermoelectric generator with inhomogeneous heat conduction

Abstract

• TEG with inhomogeneous thermoelectric materials is integrated to MCFC. • Major irreversible losses of the proposed hybrid system are considered. • The influence of materials inhomogeneity on the system properties is analyzed. • Performance enhancement is achieved with inhomogeneous thermoelectric materials. • The influences of main parameters on the system performance are obtained. To evaluate the potential of inhomogeneous thermoelectric materials, the hybrid system model comprised of a molten carbonate fuel cell, a thermoelectric generator with inhomogeneous heat conduction and a regenerator is established. In particular, thermal conductivity of thermoelectric materials is regarded as a spatial dependence coefficient. Taking electrochemical and thermodynamic irreversible losses into account, the expressions of hybrid system’s equivalent output power and efficiency are deduced and optimal operating current density interval of proposed system is determined. The maximum output power density and efficiency of the hybrid system is 35.4% and 6.9% higher than stand-alone molten carbonate fuel cell, respectively. It is proved that inhomogeneous thermoelectric materials are capable of significantly enhancing the hybrid system performance, since the efficiency can be improved by 25.4% and the optimal operating interval is shifted to a lower current density direction compared with that with homogeneous materials. Finally, several critical parameters on the system performance are analyzed through further discussions of the established model. The results obtained can sever as a theoretical guidance for the optimization of thermoelectric integrated system.