2023ICERD8-C08 -- Analysis of Highly-Efficient Multi-Fuel Micro-Cogeneration Based on Solid Oxide Fuel Cells

The paper focuses on micro-cogeneration based on solid oxide fuel cells. Such systems can achieve outstandingly high electrical efficiency, in excess of 50%, already in the scale of single kilowatts. Moreover, application of high temperature fuel cells makes it possible to directly use numerous fuels such as natural gas, hydrogen, ammonia, dimethyl ether, biogas and others. Additionally, fuel flexibility is among the advantages which position solid oxide fuel cells at the forefront of new class of systems for simultaneous generation of electricity and heat. Despite that, there are several measures which can be introduced for further boosting the performance of such systems. In this paper, recirculation of anodic gas in a 10 kW SOFC system was studied using a numerical model. Several configurations of the system with SOFCs were under consideration. The model of a system with blower-driven anodic off-gas recirculation was developed and implemented in Aspen HYSYS modeling software. Three alternative fuels natural gas (NG), hydrogen and ammonia were considered for the stack with anode supported SOFCs. Main system parameters including net power and electrical efficiency are presented for multiple operation points with different recirculation ratio and fuel utilization factors. Operating conditions were defined based on experimental investigation of SOFC stacks carried out at the Institute of Power Engineering. A comparison with a reference system without recirculation is shown.