MCFC performance diagnosis by using the current-pulse method

Several problems prevent molten carbonate fuel cells (MCFC) operation for an extended period. However, if the degradation factors can be identified and resolved in a timely manner, MCFC could become a valuable technology. Therefore, a performance diagnosis should be developed which enables the simple and instantaneous determination of MCFC degradation factors. A suitable six parameter equation obtained by a current-pulse method, obtainable from MCFCʹs transient response in 100 ms, is expressible in an equivalent circuit composed of three sub-circuits. The relationship between these parameters and each degradation factor is evaluated by a single MCFC cell, the electrode area of which is 16 cm2. Degradation factors include cross-leakage, electrolytic loss, cell temperature distribution and gas composition/flow rate. As a result, each of six parameters in the MCFC transient response corresponds to an ohmic potential drop, anode/cathode gas diffusion resistance, reactive resistance, three-phase interfacial resistance and electrolyte properties, respectively. The proposed performance diagnosis specifies the degradation factors by combining the six parameters. Performance diagnosis was applied to a single MCFC cell of an electrode area of 81 cm in extended operations, and the degradation factor diagnosed. As a result, the diagnosis was able to specify the cell degradation factors from the degradation factor ratio, corresponding to cell voltage, cell resistance and the N2 concentration of MCFC single cell performance. Therefore, the proposed performance diagnosis is able to easily specify the driven MCFC degradation factors in a timely manner.