| High temperature proton exchange fuel cell(HT-PEMFC)usually means the fuel cell which works above 100 °C.Due to its higher operating temperature,it shows several technological and commercial advantages compared with traditional PEMFC,including faster electrochemical kinetics,simpler water management and cooling,easier useful waste heat recovery,and higher tolerance to CO poisoning.In recent years,HT-PEMFC has become a popular topic in the field of fuel cell research.However,with the higher operating temperature,there will be a longer start-up process.The start-up process has great influence on the cell performance.It is significant to HT-PEMFC working cycle which requires comprehensive understanding of the heat and mass transfer mechanism of HT-PEMFC.So the study about HE-PEMFC start-up process is quite necessary.After the preparation of membrane electrolyte assemblies,HT-PEMFC is designed and connected to the testing system.Experimental results show that the HT-PEMFC has a great cell performance under high temperature.Further,a three-dimensional dynamic multi-phase model is developed for HT-PEMFC and validated with the experimental results.It is found that the constant voltage mode can make HT-PEMFC reach its normal operating temperature faster than the constant current density.During the start-up process,there is liquid water produced.The effects of surrounding environment are also analyzed and investigated.It is found that the heat convection coefficient and surrounding temperature have an important influence on the HT-PEMFC start-up process.To shorten the start-up time,a new non-heating method,variable voltage start-up strategy,is proposed and compared with the traditional assisting heating method.It turns out that the HT-PEMFC start-up performance can be improved significantly both with assistant heating method and variable voltage start-up strategy.But the latter not only saves the start-up time but also more convenient and energy saving. |
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