Long-term testing of PEM Fuel Cell Stack with the application of air-independent propulsion systems for submarine

The quest for technology to build submarines equipped with an air-independent propulsion system is increasing. PEM fuel is one of the best options for a submarine power supply system. Durability is one of the main competition factor of polymer fuel cell technology with other power generation technologies. Regarding the importance of polymer fuel cell stack stability tests, for the first time in Iran, performance of polymer fuel cell stack was evaluated over a period of 200 hours. Durability test condition was determined based on universal well-known protocols and according to the intended use, in three sections: assessment of polarization curve, electrochemical impedance spectroscopy and fluoride ions (Fenton test), pH, and electrical conductivity of the anode and cathode side discharge water changes in the intervals of 25 hours. Based on the results, it was found that oxidant shortage, accumulation of water particles in the third cell, and the formation of droplets of water in needles, caused by the design of gas manifolds as well as the applied operation conditions, act as reversible factors for the performance loss of the fuel cell stack. Analyzing the electrochemical impedance spectrum, it was determined that the ohmic resistivity remained almost constant over the 200 hour test (1500mΩ/cm2). The higher charge transfer resistance in the third cell than the others can be attributed to the accumulation of water in the last cell. Investigating the fluoride ions, pH and conductivity of the outlet water from the anode and cathode side of fuel cell stack, it was revealed that performance during 200 hours does not have an effect on the membrane chemical structure, and the chemical degradation of its structure will take place at longer times.