A novel silicon carbide plate-fin heat exchanger and its thermal and hydraulic performance for SOFC cathode air preheater application

This paper focuses on a novel silicon carbide (SiC) plate-fin heat exchanger (PFHE) for the cathode air preheater application of Solid Oxide Fuel Cells (SOFCs). An innovative assembly method and a reliable connection structure with the system's metal pipelines were proposed, and then a prototype of the SiC PFHE with offset strip fins was developed. Additionally, a performance testing apparatus for the SOFC cathode air preheater was built. Based on this testing setup, experimental studies and application validation on the heat transfer and flow characteristics of the SiC PFHE were conducted. Finally, the application prospect of SiC PFHE in SOFC systems was further evaluated and compared with metallic plate heat exchangers. The results indicate that the assembly structure and test procedure of the SiC PFHE not only realize the reliable high temperature sealing, but also effectively reduce the thermal stress of SiC ceramic material. Essential parameters such as overall heat transfer coefficient, Colburn factor, and friction factor reveal consistent trends with existing literature under various operating conditions at average Reynolds number in the range from 84 to 361. The SiC PFHE has significant advantages in upper operating temperature limit and high temperature structural integrity and reliability.