Effects of bipolar plate flow channel configuration on thermal-electric performance of direct ammonia solid oxide fuel cell: Part Ⅱ- Promoting in-cell ammonia endothermic decomposition via a novel parallel S-type channel arrangement

Abstract

This study explores impact of novel parallel S-type flow channels on ammonia decomposition and thermal-electric performance of direct ammonia solid oxide fuel cells (DA-SOFC). Four channel arrangements were numerically studied using single cell models: conventional unbent channels (UC–SOFC) and proposed single S-type channels (SSC–SOFC), double S-type channels (DSC-SOFC), triple S-type channels (TSC-SOFC). Cells with parallel S-type channel configurations outperformed unbent channel. Particularly, TSC-SOFC demonstrated the highest electrical performance, followed by DSC-SOFC, SSC-SOFC, and UC-SOFC, with power density improvements of 33.6%, 28.9%, and 28.9%, respectively, compared to UC-SOFC. Further results show that S-type channels exhibit self-heating effects, namely heat released from electrochemical reactions in the rear supplies ammonia decomposition in the front part of channel, enhancing H2 concentration and electrochemical reactions. Quantitatively, back-heat supplied to primary ammonia decomposition region increases by 33.3% in TSC-SOFC compared to UC-SOFC. Moreover, higher velocities in S-type channels enhance species diffusion towards rib underside, finally reducing concentration polarization and, improving power density. Besides of electrical performance, recycling waste heat from exhaust gases also improve the temperature uniformity cell, potentially benefiting the stability and lifetime of cell.