A gradient channel-width flow field for temperature uniformity enhancement in ammonia fueled solid oxide fuel cell

A novel gradient channel-width flow field for ammonia fueled solid oxide fuel cell anode is designed. The design divides straight channels into three segments, each featuring distinct channel widths to enhance the chemical/electrochemical reaction and temperature uniformity along the fuel flow direction. A rib-free region is introduced at the junction of each segment, which enhances the in-plane convection transport and improves gas distribution uniformity across adjacent channels. Three-dimensional single cell model is developed combining the decomposition of ammonia, multi-component diffusion processes, and electrochemical reactions to numerically investigate its characteristics. The novel design, and its combination with baffles are thoroughly compared with traditional flow fields (the parallel and serpentine) in output performance, internal transport process, reaction and temperature distribution. Results demonstrate that this novel design achieves a more uniform distribution of temperature, gas and reactions. Under the optimal output performance condition, the gradient channel-width with baffles flow field reduces the maximum temperature difference to 22.0 K whereas the parallel and serpentine flow fields are 38.3 K and 51.2 K, respectively, and it achieves higher ammonia conversion rate and more uniform current density distribution at the expense of slight decrease in power density. Moreover, the effects of various operating conditions on ammonia fueled solid oxide fuel cells with the gradient channel-width with baffles flow field are investigated, which unveils the comprehensive advantages of the gradient channel-width with baffles flow field in terms of the uniformity of temperature and current density.