Start-Stop Cycle-Induced Failure-Mode Transition in SOFC-Powered Northern Sea Route Shipping: A Hierarchical Bayesian Competing-Risk Analysis

초록

Solid oxide fuel cells (SOFCs) are a promising near-zero-emission propulsion source for Northern Sea Route (NSR) vessels, but their yttria-stabilized zirconia (YSZ) electrolyte and Ni-cermet anode are susceptible to thermomechanical degradation under repetitive start-stop thermal cycling. We develop a hierarchical Bayesian competing-risk framework built on a dual degradation model that decomposes area-specific resistance (ASR) growth into cycle-induced fatigue and time-dependent electrochemical aging and apply it across six NSR duty-cycle scenarios spanning f = 1-27 cycles/month. Posterior inference via the No-U-Turn Sampler (NUTS) yields 17 estimated parameters meeting standard convergence criteria (R<^> <= 1.01, ESSbulk >= 479, zero divergent transitions). The analysis identifies a failure-mode transition at f approximate to 3-6 cycles/month: high-frequency routes are crack-dominated (S1a: 10/15 cells fail by crack within the 600-cycle window with 5/15 right-censored), whereas low-frequency routes are ASR-dominated (S3b: 100% ASR). Global sensitivity analysis indicates the time-dependent rate coefficient k(time) as the primary remaining-useful-life driver (S-T = 0.37-0.46). Cycle-based maintenance thresholds span 160 cycles (S3b) to >= 600 cycles (S2b), bracketed by S1a (270 cycles, 10.0 months, crack-dominant) and S3a (480 cycles, 160 months, transition regime); qualitative consistency with published experimental data supports physical plausibility.

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