Masterarbeit

In fuel cell systems, an excess of hydrogen is always supplied to the fuel cell stack to enable an electrochemical reaction to take place efficiently. The unconverted hydrogen is usually returned to the inlet channel, i.e. recirculated, to reduce hydrogen consumption and increase efficiency.

Recirculation can be either active with a hydrogen blower or passive with a jet pump based on the venturi principle. Passive recirculation is more energy-efficient, but the hydrogen recirculation rate is tied to the geometry of the venturi nozzle and therefore cannot be adjusted to different power points of the fuel cell. A variable passive hydrogen recirculation system can make this possible and thus increase the efficiency of the fuel cell system.

Task:

In this Master's thesis, a concept for a variable venturi nozzle for fuel cell systems is to be developed that enables adjustable hydrogen recirculation rates. By combining flow simulations and fuel cell system simulations, a suitable design with an adjustable flow geometry can be determined. Based on typical load cases, an operation management concept and the constructive implementation for the application can be developed.