Thermal management of solid oxide fuel cells with liquid metal

Effective thermal management of SOFCs is necessary for their long life and highly efficient operation, while the conventional method through excess air cooling is limited due to the inherently low thermal conductivity and capacity of air. In this study, a novel temperature control strategy is proposed by using liquid metal as a new kind of coolant that can work in both the stable operation stage and start-stop stage of an SOFC stack. A three-dimensional model is developed considering chemical/electrochemical reactions, mass, momentum and heat transfer processes to assess the effect of liquid metal cooling. The simulation results show that liquid metal has an excellent ability to improve the temperature uniformity and electric performance of the cell unit. The temperature difference of the cell unit cooled by air cooling is 60 K, which can be decreased to 15 K with liquid tin cooling. Furthermore, inlet air has little effect on the performance of the cell unit when liquid metal is chosen as coolant. The pumping powers of the air and liquid metal are compared at different excess air ratios and inlet velocities of liquid metal. The total pumping power consumption could be dramatically decreased when liquid metal is utilized as the coolant. Furthermore, the variations in the conductivity, heat capacity and convective resistance at different liquid metal inlet velocities are discussed.