Identification of the cold start boundaries of proton exchange membrane fuel cells based on one dimensional multi-phase model

The cold start performance of fuel cells is crucial for enhancing their durability and promoting their commercialization. However, understanding the impact of various temperatures and membrane water content during the start-up process is a prerequisite for improving the success rate. This study establishes a one-dimensional multi-phase cold start model of a fuel cell stack, which is experimentally validated. Based on this model, the effects of varying loading rates, temperatures, and membrane water content on the initial freezing temperature at the end plate, the initial freezing temperature at the center cell, the minimum temperature for successful cold start, and the maximum membrane water content during successful start-up are investigated. Results indicate that as temperature decreases, cold start performance progressively deteriorates. With increasing loading rates, the initial freezing temperature at the end plate and the minimum temperature for successful cold start decrease, although the rate of decline gradually slows. Specifically, as the loading rate increases from 0.004 to 0.040 A cm−2, the initial freezing temperature at the end plate decreases from −5.5 °C to −6.8 °C, and the minimum temperature for successful cold start-up drops from −8.5 °C to −13.5 °C. The initial freezing temperature at the center cell shows minor fluctuations, ranging between −8.3 °C and −8.8 °C. Additionally, as the loading rate increases, the maximum membrane water content during successful start-up also increases, and the boundary range for successful start-up expands. This research provides a reliable theoretical basis for formulating loading strategies and setting initial conditions for cold start.