Study on the startup-shutdown performance of gas foil bearings-rotor system in proton exchange membrane fuel cells

The startup-shutdown behavior of the gas foil bearings-rotor system is vital for proton exchange membrane fuel cells due to the inherently frequent start-stop of hydrogen fuel cell vehicles, which significantly affects the sustainable power generation and efficiency of the fuel cells. In this paper, the effects of three systematic factors including bump foil structure, nominal clearance, and coating on the dynamic response of the bearings-rotor system are first investigated based on startup-shutdown experiments. The mathematical model considering both gas film and thermo-hydrodynamic characteristics is presented to investigate the startup-shutdown behavior further. The influencing mechanisms of the factors on performance are analyzed. The energetic results demonstrate that the bearing structure parameters have a significant influence on the startup-shutdown performance and energy consumption. Considering optimal startup-shutdown performance, a better bearingsrotor system is proposed. Compared to the average values in all cases, the take-off speed, temperature rise, and average energy consumption of the system are decreased by 51.3%, 16.2%, and 60.7%, respectively. This indicates that the startup-shutdown improvement of the bearing-rotor system has great significance for enhancing the energy efficiency of the fuel cell.