Performance evaluation of an alkaline fuel cell/thermoelectric generator hybrid system

• A new hybrid system consisting of an AFC and a multi-couple TEG is put forward.
• Thermodynamic-electrochemical irreversibilities in the system are characterized.
• The operating current density region that the TEG exerts its function is determined.
• The equivalent maximum power density of the AFC can be increased by up to 23%.
• The effects of some important operating parameters on the performance are revealed.

A hybrid system consisting of an AFC (Alkaline Fuel Cell), a TEG (Thermoelectric Generator) and a regenerator is put forward, where the AFC converts the chemical energy in the hydrogen into electrical energy and thermal energy, and the released thermal energy is subsequently converted into electrical energy through the bottoming TEG. The main irreversible losses in each element of the hybrid system are characterized, and numerical expressions for the efficiency and power output of the AFC, TEG and hybrid system are respectively derived. The fundamental relation between the operating current density of the AFC and the dimensionless current of the TEG is obtained, from which the region of the operating current density of the AFC that the TEG exerts its function is determined. By employing such a hybrid system, the equivalent maximum power density of the AFC can be increased by up to 23%. The effects of the operating current density, operating temperature, heat conductivity, and integrated parameter on the performance of the hybrid system are revealed. The results obtained in the present paper will provide some theoretical guidance for the performance improvement of the AFC.