Thermodynamic Performance Assessment of Gas Turbine Trigeneration System for Combined Heat Cold and Power Production

The thermodynamic performance of the combustion gas turbine trigeneration system has been studied based on first law as well as second law analysis. The effects of overall pressure ratio and process heat pressure on fuel utilization efficiency, electrical to thermal energy ratio, second law efficiency, and exergy destruction in each component are examined. Results for gas turbine cycle, cogeneration cycle, and trigeneration cycle are compared. Thermodynamic analysis indicates that maximum exergy is destroyed during the combustion and steam generation process, which represents over 80% of the total exergy destruction in the overall system. The first law efficiency, electrical to thermal energy ratio, and second law efficiency of trigeneration system, cogeneration system, and gas turbine cycle significantly varies with the change in overall pressure ratio but the change in process heat pressure shows small variations in these parameters. Results clearly show that performance evaluation of the trigeneration system based on first law analysis alone is not adequate and hence more meaningful evaluation must include second law analysis.