To investigate the effects of varying assisted heating methods on the proton exchange membrane fuel cell (PEMFC) stack in extremely low-temperature conditions, a quasi-two-dimensional dynamic model is developed. This model considers the effect of cooling channels on cold starts and has been verified by experimental data. The limited self-start ability of an adiabatic PEMFC is tested, and the result shows that the PEMFC cannot start successfully from −40°C. Then, the effects of resistance wire heating and recycled coolant heating methods on the PEMFC stack are analyzed at −40°C. For the resistance wire heating method, due to the limitation of thermal conductivity, higher heating power can hardly raise the temperature of the middle cells in the stack. Furthermore, only stacks with fewer than 6 cells can start successfully. For the recycled coolant heating method, the heat can be effectively transferred to the internal zone of the stack through the coolant. The maximum temperature difference in the stack is decreased (from 32.43°C to 7.64°C, 308.6 mW cm−2) with higher coolant flow rates. However, higher heating power is needed to achieve a successful cold start (205.8 mW cm−2 under 0.01 m s−1, 308.6 mW cm−2 under 0.05 m s−1). In summary, the recycled coolant heating method is more suitable for the cold start of the stack at −40°C.
