Thermodynamic and optimization analysis of a fuel cell-based combined cooling, heating, and power system integrated with LNG-fueled chemical looping hydrogen generation

Abstract

Chemical looping combustion technology is essential to achieve efficient decarbonized electricity generation for fossil-fueled power plants. However, the existing chemical looping hydrogen generation (CLHG)-driven cogeneration systems have complex refrigeration units and energy-consuming carbon capture. This study proposes a novel solid oxide fuel cell (SOFC)-based combined cooling, heating, and power (CCHP) system, which is integrated with the CLHG and fueled by a liquid natural gas (LNG) regasification process. The system is designed to enhance the overall performance by directly recovering LNG cold energy for cooling and liquefying the resulting CO2. The energy and exergy performance of the system under the baseline design case are evaluated. Subsequently, we discuss the impact of key design parameters on system performance and weigh between cooling/heating power and net power generation for the system dominated by the combined heat and power (CHP)/combined cooling and power (CCP) mode. Our findings reveal that the proposed system exhibits an electrical efficiency of 66.92 % and an exergy efficiency of 53.94 % under the baseline design case. The exergy loss ratio for condenser1 is identified as the highest among all components, accounting for 29.50 %. The constituent unit with the largest exergy loss contribution is the LNG regasification unit, followed by the SOFC unit, CLHG unit, transcritical CO2 cycle unit, and heating unit. More hydrogen needs to be replenished when fuel flow in the CLHG and fuel utilization in the SOFC are used to improve system performance. The optimal electrical and exergy efficiencies of the system predominantly designed in CCP mode surpass those in CHP mode by 4.27 % and 0.57 %, respectively. The results can guide potential applications of CLHG-based cogeneration systems.