Performance analyzes of an integrated phosphoric acid fuel cell and thermoelectric device system for power and cooling cogeneration

In addition to electricity generation, phosphoric acid fuel cell (PAFC) produces a significant amount of waste heat. In this study, a hybrid system mainly consisting of a PAFC, a thermoelectric generator, and a thermoelectric cooler is proposed to recover the produced waste heat aiming for performance enhancement. Considering thermodynamic and electrochemical irreversible losses within the system, an analytical relationship between the dimensionless electric current of the thermoelectric element and the current density of the PAFC is derived. Analytical formulas for power density and efficiency of the hybrid system are derived. The characteristics and the optimum criteria evaluating the performance parameters are revealed for the studied system. Numerical solutions show that the power density and efficiency of the hybrid system allow 2.3% and 2.8% larger than that of a stand-alone PAFC, respectively. The present hybrid system is found to be feasible and effective. Comprehensive parametric studies are conducted to analyze the effects of operating conditions and design parameters on the proposed system. The conclusions drawn can provide theoretical guidance for PAFC performance enhancements and system designs.