Predicting Local Temperature, Utilization, and Voltage Gradients in rSOC Stacks under Dynamic Operation

Zenodo (CERN European Organization for Nuclear Research)

Abstract

As highly efficient and fuel-flexible devices capable of switching between power generation and electrolysis, reversible solid oxide cells (rSOCs) offer a promising pathway for integrating fluctuating renewable energy into future energy systems. rSOCs operating in dynamic environments must withstand rapid variations in electrical load, fuel composition, and operating mode while remaining within strict thermal and electrochemical limits. Existing models often lack the spatial fidelity needed to capture these constraints or the computational tractability required for large-scale and system-level studies. This work presents a dynamic, one-dimensional rSOC stack model implemented in Modelica, constructed by coupling a mechanistic single-cell unit into an array-based stack representation. The model captures the essential multi-physics of rSOC operation—including electrochemistry, gas transport, heat transfer, and fuel conversion—and inherently supports reversible SOFC/SOEC operation and fuel-flexible behavior.The discretization along the stack direction enables per-cell prediction of temperature, fuel utilization, and cell voltage, thereby resolving spatial non-uniformities that critically shape safe operating limits. As illustrated in the accompanying figure, simulations across global fuel utilizations of 0.70–0.95 reveal the migration of thermal hot zones, the emergence of fuel-starvation regions, and the amplification of local voltage gradients. These insights enable the derivation of operating envelopes that couple current density, utilization, and fuel composition for safe and efficient operation.Owing to its computational efficiency and physical consistency, the model serves as a high-fidelity yet tractable tool for a broad range of analyses—from fuel-flexible stack operation and control strategy development to grid-interactive rSOC system assessment, where fluctuating renewable power, load-following operation, and mode switching impose demanding transient conditions on the stack. This framework therefore provides a rigorous and scalable basis for advancing next-generation, fuel-flexible, and grid-integrated rSOC technologies.

Authors 8

1. Sreejoe Kaniyamparambil Aachen Chair of Thermodynamics of Mobile Energy Conversion Systems (TME)

   RWTH Aachen University

   Affiliation as printed

   Chair of Thermodynamics of Mobile Energy Conversion Systems, RWTH Aachen University, Aachen, Germany

2. Marvin Schmidt Aachen Chair of Thermodynamics of Mobile Energy Conversion Systems (TME)

   RWTH Aachen University

   Affiliation as printed

   Chair of Thermodynamics of Mobile Energy Conversion Systems, RWTH Aachen University, Aachen, Germany

3. Felix Kunert Aachen Chair of Thermodynamics of Mobile Energy Conversion Systems (TME)

   RWTH Aachen University

   Affiliation as printed

   Chair of Thermodynamics of Mobile Energy Conversion Systems, RWTH Aachen University, Aachen, Germany

4. Stefan Sterlepper Aachen Chair of Thermodynamics of Mobile Energy Conversion Systems (TME)

   RWTH Aachen University

   Affiliation as printed

   Chair of Thermodynamics of Mobile Energy Conversion Systems, RWTH Aachen University, Aachen, Germany

5. Adrian Schloßhauer Aachen FEV Europe GmbH

   FEV (Germany)

   Affiliation as printed

   FEV Europe GmbH, Aachen, Germany

6. Simon Mertes Aachen Chair of Thermodynamics of Mobile Energy Conversion Systems (TME)

   RWTH Aachen University

   Affiliation as printed

   Chair of Thermodynamics of Mobile Energy Conversion Systems, RWTH Aachen University, Aachen, Germany

7. Jannik Kexel Aachen FEV Europe GmbH

   FEV (Germany)

   Affiliation as printed

   FEV Europe GmbH, Aachen, Germany

8. Stefan Pischinger Aachen Chair of Thermodynamics of Mobile Energy Conversion Systems (TME)

   RWTH Aachen University

   Affiliation as printed

   Chair of Thermodynamics of Mobile Energy Conversion Systems, RWTH Aachen University, Aachen, Germany