Multi-aspect optimization of a geothermal-based integrated Kalina-proton exchange membrane fuel cell with ejector cooling and desalination systems

Abstract

In order to use geothermal energy efficiently, a novel poly-generation system is introduced in the present study. In this configuration, the topping system is comprised of the combined modified Kalina cycle and proton exchange membrane fuel cell for power generation. Moreover, the bottoming configuration is composed of an ejector cooling system and a humidification-dehumidification desalination unit for cooling and freshwater production. Furthermore, the output heating is get from the heat rejection stage in the Kalina cycle. The proposed system is examined from energy, exergy, and exergy-economic perspectives through parametric analysis and multi-objective optimization. The effect of changes in geothermal water temperature, the upper pressure of the Kalina cycle, the flash temperature of the Kalina cycle, the outlet temperature of the fuel cell, and the current density of the fuel cell are assessed on the output parameters. Considering exergy efficiency and payback period as the target functions, they are calculated as 43.94 % and 0.859 years. In this case, the considered system can produce 549.1 kW of power, 140.2 kW of cooling, 46.29 kW of heating, and 0.0326 kg/s of freshwater.