Modelling and experimental investigation of high temperature proton exchange membrane fuel cells
Raj Kamal Abdul Rasheed
Date of Issue2017-07-05
School of Mechanical and Aerospace Engineering
Although high-temperature proton exchange membrane fuel cells (HT -PEMFC) have many attractive features, they are not yet at the same level of development or performance as compared to the low-temperature proton exchange membrane fuel cells (LT -PEMFCs). There are several technical challenges that contribute to the delay for commercialization of HT-PEMFCs. One of these challenges includes suitable warm-up strategy during start-up of the device and obviously, reducing time and energy consumption is critical. Thus, the research is aimed towards the investigation of novel dynamics of start-up with key interests in time and energy management. Firstly, an analytical model was developed to explore novel concept and extend the existing boundaries that defined start-up. Start-up with current extraction from room temperature was conceptualized and investigated with a transient analytical model that inherently included the boiling phase change. Secondly, an existing start-up process by current extraction at an intermediate temperature (e.g. 120°C) was further investigated. This effort accounts for a substantial portion of the thesis, where carbon monoxide (CO) poisoning is investigated under transient temperature conditions during start-up. A numerical three dimensional model was developed and validated experimentally. The model was further used for sensitivity analysis to assess the critical importance of start-up parameters. The key novelty of this effort relates to the generation of transient adsorption kinetics behavior and the resulting anode overpotential, with a key emphasis on assessing whether a start-up process, in the presence of CO, can be performed successfully. Next, an experimental investigation of the open circuit voltage (OCV) was also done in the presence of an external heating input, which mimics the typical scenario experienced during the start-up of a HT-PEMFC. A comparison between the OCV under a temperature increase rate with respect to time, and the existing Nernst equation was done.