One of the most appropriate approaches for enhancing the performance of the energy systems is integrating different subsystems for producing various beneficial products simultaneously. In the present study, a polygeneration system including a Kalina cycle, a reverse osmosis unit, a PEM electrolyzer, and a thermoelectric module that can generate power, fresh water, hot water, and hydrogen is examined. A thermodynamic simulation code in Engineering Equation Solver (EES) is prepared to predict the behavior of system. Using the exergy analysis different location of system with high irreversibility is determined. As the results show in the base case, the geothermal cycle condenser with 89.29 kW, reverse osmosis (RO) unit with 68.97 kW, heat exchanger 2 with 37.68 kW, and steam turbine with 22.52 kW have the highest exergy destruction rate respectively. The parametric analysis for identifying the influence of five decision variables namely steam turbine inlet pressure (P2), steam turbine back pressure (P4), vapor generator outlet pressure (P10), Kalina turbine backpressure (P13), and temperature difference of the heat exchanger (TD) is conducted. Additionally four major outputs consisting of exergy destruction rate (kW), exergy destruction cost rate ($/h), and electricity cost rate ($/h) are determined for implementing multi-criteria optimization. A tri-objective optimization to find the optimum states of the suggested system is conducted. With employing a selection method, the system arrangement with 328.2 kW of exergy destruction rate, 18.4 $/h of exergy destruction cost rate, and 12.83 $/h of electricity cost rate with determined value of decision variables is selected as final optimum state.
