National Natural Science Foundation [51076134]; Fundamental Research Fund for the Central Universities, People's Republic of China [201112G006]The model of a hybrid system composed of a molten carbonate fuel cell (MCFC) and a heat engine is presented, in which multi-irreversibilities such as overpotentials in the electrochemical reaction, heat leak from the MCFC to the environment, non-perfect regeneration in the regenerator, and finite-rate heat transfer in the heat engine are taken into account. Expressions for the efficiency and power output of the system are analytically derived, from which the general characteristics of the hybrid system are revealed and the optimum criteria of some main parameters such as the current density, efficiency and power output are determined. The influence of the irreversible losses on the performance of the hybrid system is discussed. Moreover, a multi-objective function including both the efficiency and the power output is put forward and used to further subdivide the optimally operating region of the hybrid system. The results obtained here are very general and may be directly used to derive the various interesting conclusions of the hybrid systems operated under different special cases
