Design and comparative exergy and exergo-economic analyses of a novel integrated Kalina cycle improved with fuel cell and thermoelectric module

Combined cooling, heating, and power systems (CCHP) have attracted a lot of attention due to their distinctive advantages of high system and economic efficiencies in addition to less greenhouse gas emissions. The current study investigates the performance of a Kalina cycle-based CCHP system in which geothermal energy is utilized as the low temperature source of prime energy. A thermoelectric generator is used in the system for retrieving wasted heat and producing extra amount of electricity thereby leading to higher overall efficiency. Two types of fluids, i.e. geothermal water and mixture of water-ammonia, are employed for the steam cycle and Kalina cycle, respectively. A comparative performance analysis is carried out on three system configurations, namely; basic Kalina cycle system, Kalina cycle with a thermoelectric generator (TEG), and Kalina cycle integrated with TEG and a Proton Exchange Membrane Fuel Cell (PEMFC). The results demonstrated that employing TEG increases the output power by 25.1 kW and improves cycle efficiency by 1.7%. Moreover, integrating both TEG and PEMFC increases the net output power of the proposed system to 1101 kW, which is 993.2 kW and 971.7 kW higher than the basic Kalina cycle system and the Kalina cycle system coupled with the TEG respectively. In addition, the exergy analysis of each component in the system showed that the condenser has the most exergy destruction. Multi-criteria optimization is applied to seek the optimum operation condition of the proposed system. The net output power and electricity cost were used as two critical optimization targets. An optimum condition of the system is suggested using the concept of ideal point on the Pareto front plot.