Investigation of the Effects of Operating Parameters on the Thermodynamic Performance of an Integrated Multi- Generation System Based on Geothermal Energy and Liquefied Natural Gas (LNG) Cold Energy for Simultaneous Electricity, Hydrogen, and Freshwater Production

The integrated utilization of renewable energy resources and waste energy recovery has recently attracted considerable attention as an effective approach to improving energy efficiency and mitigating environmental impacts. In this study, the effects of key operating parameters on the performance of an integrated multi-generation system driven by geothermal energy and the cold energy of liquefied natural gas (LNG) are investigated for the simultaneous production of power, hydrogen, and freshwater. The proposed system consists of a geothermal power plant, an LNG cold energy recovery unit, a double-effect desalination unit, and a proton exchange membrane (PEM) electrolyzer. Energy and exergy analyses were conducted under steady-state conditions using Aspen HYSYS. To ensure the reliability of the developed model, the simulation results were validated against reference data, demonstrating good agreement. The results indicate that increasing the LNG pressure enhances the net power output, reaching ۲۱۷۰ kW at a pressure of ۶۰۰۰ kPa, corresponding to a ۱۰.۴% improvement compared with the baseline case. Moreover, the exergy efficiency increased from ۳۶.۵% to approximately ۳۹%, representing a ۶.۸% enhancement. The investigation of geothermal fluid pressure revealed that the total exergy destruction decreased to ۲۱۸۳ kW at ۱۲۰ kPa, corresponding to a ۵.۲% reduction relative to the initial operating condition. In addition, increasing the water feed rate to the PEM electrolyzer from ۰.۷ to ۱.۳ kg/h increased the hydrogen production rate from ۵.۵ to ۱۰.۳ kg/h, representing an approximately ۸۵% improvement. Overall, the findings demonstrate that appropriate selection of operating parameters significantly enhances power generation, improves exergy efficiency, reduces thermodynamic irreversibilities, and increases hydrogen production. Therefore, the proposed integrated system represents a promising solution for the sustainable co-production of clean electricity, hydrogen, and freshwater by effectively utilizing geothermal energy and LNG cold energy.

کلیدواژه ها:

Geothermal energy ، LNG cold energy ، Multi-generation system ، Hydrogen production ، Double-effect desalination