Elucidation of Degradation Factor Distribution by the Improved Diagnostics

Our diagnostics evaluates the PEFC’s transient response with a resistance polarization, an activation polarization and a diffusion polarization, and derives diagnostics parameters by analyzing this transient response. We have clarified the degradation factors (the three polarizations) and distribution by applying this diagnostics system to PEFC short stack or PEFC single cell with a quadrisection separator. Finally, Tsuruga Electric Corporation has sold maintenance equipment as PEFC Performance Diagnostics System (PPSD) "356 TD" using this diagnostic method. Conventional diagnostics equipment is too expensive, and an analyzing time is too long. However, our equipment, the 356TD is able to diagnose deterioration factors as well as impedance analysis by measuring the transient response for about one minute and is dramatically cheaper than conventional one. However, because the reflection of each deterioration factor in each pa ra m eter is small, it is necessary to diagnose the parameters strictly. Therefore, as there is a possibility of causing the diagnostic error, it should be improved. We have developed a new algorithm for PEFC performance diagnostics that solves the transient response by the third differential equation directly to satisfy the demand mentioned above last year. A new diagnostic approximates the transient response of PEFC directly using the on-line algorithm of the method of least squares and obtains three diagnostic parameters sequentially. The adequacy of a new algorithm was verified by evaluating the cell inner heat flux distribution using a special separator that can measure heat flux distribution and a 25cm2 PEFC single cell. As a result, the special separator was able to obtain a corresponding heat flux distribution to a past temperature distributed data. Moreover, our new algorithm was able to derive corresponding three parameters to previous diagnostics parameters though it has to be verified further.