Sensitivity analysis of anode overpotential during start-up process of a high temperature proton exchange membrane fuel cell

Abstract

This paper investigates the sensitivity of start-up parameters during the start-up or warm-up process of a high temperature proton exchange membrane fuel cell (HT-PEMFC), where carbon monoxide (CO) contaminated hydrogen is used as fuel. The heating strategy considered in this study involves external heating of the HT-PEMFC to an initial start-up temperature (above 100°C), after which current is extracted, where the external heating still remains. A transient three-dimensional isothermal anode model is developed to determine the sensitivity of operational start-up parameters such as temperature increase rate, initial start-up temperature, CO volume fraction and extracted current density, on the anode overpotential during the start-up process. The results indicate that having a low initial start-up temperature is the key reason that makes the other parameters such as the current density, CO mole fraction and temperature increase rate, sensitive, especially at 108°C. In addition, temperature range of 130±5°C is most critical as the sensitivity reaches a peak for all parameters at the three considered initial start-up temperatures. In addition, a system-level energy analysis considered for the start-up process of a 1-kW stack, suggests that having low initial start-up temperature can reduce warm-up time and energy consumption.