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以最小Gibbs自由能法计算固体氧化物燃料电池在不同组成碳基燃料气体组成下的理论积碳量,在此基础上讨论电池的理论开路电压(OCV),并测试在CO_2重整甲烷下Ni-YSZ‖YSZ‖LSM阳极支撑固体氧化物燃料电池的OCV.计算表明,理论积碳量从C-H-O相图的C角往积碳界线处以均匀速率减小.当积碳全部发生电化学氧化时,建议提高燃料气的碳氢比以获得较高OCV;反之则建议减小碳氢比.当燃气组分接近位于C-H-O相图中OCV界线(OCV=0 V)时,OCV会发生急剧下降.同样地,实验表明,当燃气中CO_2体积分数高于80%,会使得OCV大幅下降.综上可知,燃料气组分控制在积碳界线附近将有利于减少积碳并保证一定的电池发电性能.600℃时,在积碳界线的非积碳区侧,提高燃气中氢含量可提高OCV.而采用相同含量的CO_2稀释时,CH_4、H2和CO燃气下电池的OCV则依次降低.另外,实验表明升高外重整比例和降低温度,并不能显著提高OCV.
The theoretical Gibbs free energy of solid oxide fuel cells with different compositions of carbon-based fuel gas compositions was calculated by the Gibbs free energy method. Based on this, the theoretical open circuit voltage (OCV) of the batteries was discussed and the Ni -YSZ‖YSZ‖LSM anode supports the OCV of solid oxide fuel cells.The calculation shows that the theoretical amount of carbon deposition decreases from the C angle of the CHO phase diagram toward the carbon deposition boundary at a uniform rate.When all the carbon deposition occurs electrochemical oxidation, It is recommended to increase the hydrocarbon ratio of the fuel gas to obtain a higher OCV; conversely, a reduction of the hydrocarbon ratio is recommended. A drastic decrease in OCV occurs when the gas composition is near the OCV boundary (OCV = 0 V) in the CHO phase diagram. , The experiment shows that when the volume fraction of CO_2 in the gas is higher than 80%, the OCV will decrease drastically.Consequently, controlling the composition of the fuel gas near the boundary of carbon deposition will help to reduce the carbon deposition and ensure a certain battery power generation performance. At 600 ℃, increasing the hydrogen content in the gas increased the OCV at the non-carbon deposition side of the carbon deposition boundary, while the OCV of the CH_4, H2 and CO gas decreased in the same CO 2 dilution. Indicated increased external reforming ratio and lower temperature, and Can not significantly improve OCV.