Study on the Constant Voltage, Current and Current Ramping Cold Start Modes of Proton Exchange Membrane Fuel Cell 2021-01-0746
The cold-start of proton exchange membrane fuel cell (PEMFC) has been one of the technical challenges for fuel cell vehicle table ommercialization. In this study, a one-dimensional cold start transient model of PEMFC was developed for the transfer of water, heat, electrons and protons during the cold start process. Different loading modes, including constant voltage, constant current, and current ramping, were adopted for fuel cell cold starting analysis, respectively. The internal water-heat transfer within fuel cell was investigated under different loading modes. The results show that in the constant current mode, for the high current, the cold start process can produce more heat than other modes, which can increase fuel cell temperature rapidly. However, this process may easily fail before the ice fully covers the cathode catalyst layers (CL). Comparing with the constant current mode, the cold start with a constant voltage shows superior performance due to the highest possible current density at every time situation. During the constant voltage cold start, the current decreases gradually with the ice saturation increase, which is more likely to produce more heat and achieve a successful cold start. Nevertheless, the constant voltage mode is much harder to control than the constant current. As for the current ramping mode, especially a relatively large initial current density in combination with an appropriate ramping rate, which can generate more heat lead to a higher temperature before the fuel cell clod start failed. Therefore, the cold start mode of current ramping is easier to realize the successful cold start than constant voltage and constant current methods.