Proposal and analysis of a novel CCHP system based on SOFC for coalbed methane recovery

Abstract

To utilize the waste heat from coalbed methane, this study presents a novel solid oxide fuel cell (SOFC) system combined with a transcritical carbon dioxide cycle, lithium bromide absorption refrigeration cycle, ammonia vapor compression refrigeration cycle, and water heating cycle to provide power, cooling, and heating. An Aspen Plus model is developed to perform thermodynamic and exergy analyses, assessing system performance. The results indicate that critical parameters such as current density and operating temperature of the SOFC have a significant influence on the overall system. Increasing current density and air preheating temperature enhance thermal efficiency while raising the SOFC operating temperature reduces it. For the specified coalbed methane flow, the system achieves electrical efficiency, thermal efficiency, and exergy efficiency of 52.46%, 86.30%, and 75.58%, respectively. Additionally, the cooling capacity, power generation, and heat production are obtained as 1567.72 kW, 4879.1 kW, and 2476.43 kW, respectively. The SOFC system has the largest exergy destruction, accounting for 48.8% of the total exergy destruction, but the overall exergy efficiency remains at around 75%. The results illustrate that the proposed integrated system provides a high level of efficiency and reliability, thereby offering a new avenue for the efficient and rational utilization of CBM.