Greenhouse Gas Emission and Thermodynamic Assessments of an Integrated Trigeneration System Based on a SOFC Driving a GAX Absorption Refrigeration System as a Subsystem

Exergy and greenhouse gas emission analyses are performed on a novel trigeneration system driven by a solid oxide fuel cell (SOFC). The trigeneration system also consists of a generator-absorber heat exchanger (GAX) absorption refrigeration system and a heat exchanger to produce electrical energy, cooling and heating, respectively. Four operating cases are considered: electrical power generation, electrical power and cooling cogeneration, electrical power and heating cogeneration, and trigeneration. Attention is paid to numerous system and environmental performance parameters, namely, exergy efficiency, exergy destruction rate, and greenhouse gas emissions. A maximum enhancement of 46% is achieved in the exergy efficiency when the SOFC is used as the primary mover for the trigeneration system compared to the case when the SOFC is used as a stand-alone unit. The main sources of irreversibility are observed to be the air heat exchanger, the SOFC, and the afterburner. The unit CO₂ emission (in kg/MWh) is considerably higher for the case in which only electrical power is generated. This parameter is reduced by half when the system is operated in a trigeneration mode.