Abstract:

In the current study, a new configuration of power tri-generation cycle was suggested. In this cycle, the energy of hot gases output from the gas cycle in the heat recovery steam generator (HRSG), and the waste energy of the condenser in the steam cycle were recovered in the Organic Rankine Cycle (ORC). After the energy, exergy, and economic modeling of the cycle, the optimization of this cycle by the use of multipurpose genetic algorithm was performed. The objective functions were the electricity cost and the second law efficiency of thermodynamics. The variables chosen for optimization were the air to fuel molar ratio, the compression, and expansion ratio of the compressor and turbine of the gas cycle, the mass flow rate of water steam and refrigerant in steam cycles and ORC, the Pinch points between the gas cycle and steam, and steam cycles and ORC, and the maximum temperatures of the steam and ORC cycles. The optimization results showed that by choosing the optimal values of variables, the efficiency of the first and second thermodynamic laws, and the produced entropy would be 67.3%, 68.9%, and 3342.5 kW/K. Also, the generated electricity cost was reduced to 0.049 US$/kWh.

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