Study on the temperature distribution and its effect on self-start of large-area proton exchange membrane fuel cells at subzero temperatures

Abstract

A rapid and safe cold start is essential for the commercialisation of proton exchange membrane fuel cell (PEMFC) vehicles, and self-start is considered as the optimal way to fulfil this expectation. In this study, the self-start of large-area PEMFCs is investigated. It is found that there exists a severe temperature distribution nonuniformity along the flow direction during one-way air-supply self-start, and the cold-start capability is limited by the fact that most of the heat is concentrated in the inlet area, while less heat is in the outlet area, which makes it difficult to start at −15 °C. To solve this issue, an alternating air-supply strategy is suggested. By applying this strategy, temperature distribution uniformity and cold-start performance are significantly improved. Self-start from −15 °C and −20 °C can be achieved in 165 s and 142 s with starting voltages of 0.8 V and 0.6 V, respectively. The alternating interval has a negligible impact on start-up time but will affect the temperature distribution and fluctuation. The advantages of alternate air supply are analyzed based on the calculation of heat generation and water production. A performance degradation test indicates that cell performance is well preserved after 20 cold starts