Multi-Scale Assessment of Cr Contamination Levels in SOFC Cathode Environment

Abstract

This study aims to quantify in a holistic approach chromium (Cr) contamination in solid oxide fuel cell (SOFC) stack testing using adapted tools: i) a hot gas sampling method to analyze volatile Cr species in the air flux at the cathode inlet location; and ii) a rapid quantification method for Cr as condensed matter in cathode material of post-test samples. The hot air sampling method reveals itself as a reproducible and time-resolved quantification technique for Cr trace amounts in a gas flow; this technique is seen as a promising evaluation tool for Cr contamination issues in SOFC systems. The quantification method reveals severe Cr-poisoning in a cell. The combined findings indicate that Cr contamination generated by system components located upstream the cell must be suppressed by hindering the access of Cr pollutants to the cathode compartment.

The Effects of Dynamic Dispatch on the Degradation and Lifetime of Solid Oxide Fuel Cell Systems

“…Model predictions are also in line with chromium detection post-test analyses. 48 Care is however required when using this model for lifetime predictions, as the dominant degradation processes may change depending on the materials, stack design and operating strategy. In the conditions studied here, degradation of the electrolyte and anode dominates from approximately 0 h to 2000 h. Degradation mechanisms for the electrolyte and anode reach a plateau after 500-2500 h, and 1000-10000 h, respectively.…”

The Effects of Dynamic Dispatch on the Degradation and Lifetime of Solid Oxide Fuel Cell Systems

“…Model predictions are also in line with chromium detection post-test analyses. 48 Care is however required when using this model for lifetime predictions, as the dominant degradation Figure 5. Typical evolution during operation at constant system power of the SRU potential (left), air ratio (left) and current density (right).…”

Addressing planar solid oxide cell degradation mechanisms: A critical review of selected components

“…The parabolic rate constant relating the weight gain due to the scale growth to the oxidation time, provides an estimate of the high‐temperature oxidation resistance of the material under investigation. For FSSs, Kp values are commonly in the range of 10 −10 to 10 −14 g 2 cm −4 s −1 and are strongly related to the operating temperature and chromium amount in the steel composition 42,240,241 . There is also a report that the estimation of the Kp value is more complicated.…”

“…For FSSs, Kp values are commonly in the range of 10 −10 to 10 −14 g 2 cm −4 s −1 and are strongly related to the operating temperature and chromium amount in the steel composition. 42,240,241 There is also a report that the estimation of the Kp value is more complicated. The oxidation experiment of FSSs for longer times up to 500 h in ref.…”

“…The development of sophisticated algorithms and tools for multi‐scale assessment of performance from cell to system level – as in ref. 42 – cannot avoid long‐term tests (several years) to mimic real operation. The results of the NEDO project described above 11–38 arise from evaluation under conditions in which heat or flow distribution is well controlled, in optimized stack design and under rated operation conditions.…”