The Design and Performance of a PEFC at a Temperature Below Freezing

At temperatures below freezing, air humidity becomes lower and produced water at the cathode freezes on the surface of catalyst, and it is difficult to start a PEFC (Polymer Electrolyte Fuel Cell) at a cold district. The object of the work is to study the performance of the fuel cell below the freezing point by experiments and simulation. To investigate the characteristics of the starting of a temperature below freezing the performance of a single cell was measured at temperatures from -3 to -25°C and pressures from 1 to 2 atm. The results of the experiments and simulation indicate that the performance of a PEFC decreases at higher current densities and pressures, and lower cell temperatures because of ice more produced on the reactive area of the cathode. To maintain the cell performance below freezing point, it is effective to adjust the current densities and gas flow rate to balance the produced and removed water. However at -5°C, heat generated in the fuel cell is effective to warm the cell and make self-starting possible. These results shows that it is necessary to heat the cell with an additional heat source in order to start the fuel cell below -5°C.