Energy, exergy and exergoeconomic analysis of a trans-critical CO2 cycle powered by a single flash geothermal cycle in with/without economizer working modes

Abstract

The global utilization of renewable energy sources, particularly geothermal energy, is rising and the inefficient nature of geothermal cycles necessitates recovering lost heat. This research proposes a combined power generation cycle that simulates integrating a trans-critical carbon dioxide cycle with a single flash geothermal cycle, utilizing the EES. The study contrasts the system's performance between two operating states: "Without Economizer" and "With Economizer". The investigation analyzes the impact of an economizer on key output parameters, including energy efficiency, exergy efficiency, and net power output. In the "With Economizer" operating state, the net power output experiences a noticeable increase from 201.5 kW to 204.7 kW, resulting in a 1.58% enhancement in the performance of the "With Economizer" system. The energy efficiency metric demonstrates a corresponding improvement, rising by 1.55% from 3.28% in the "Without Economizer" system to 3.331% in the "With Economizer" system, aligning with the principles of the first law of thermodynamics. Furthermore, the energy efficiency, expressed as a percentage of energy units, shows an increase from 16.3% in the "Without Economizer" system to 16.56% in the "With Economizer" system, representing a 1.595% improvement based on the second law of thermodynamics or exergy. Regarding cost analysis, the study identifies the optimal separator pressure value for the system without an economizer, equivalent to 23. This configuration achieves a total cost rate of 01 $/GJ. Conversely, in the system with an economizer, the optimal pressure value for the production cost rate is 322.4 kPa, resulting in a cost rate of 23.57 $/GJ.