Performance evaluation of a geothermal-driven ejector power-cooling system: A comparative study of different refrigerants

The growing need for sustainable energy systems has increased research interest in energy systems capable of providing power and cooling from renewable energy resources. In this regard, a geothermal-assisted ejector refrigeration cycle (PERC) is developed and thermodynamically analyzed using five different working fluids, namely R134a, R1234yf, R600a, R1234ze(E), and R717. The performance characteristics are studied by conducting both energy analysis and exergy analysis on Engineering Equation Solver (EES). The impacts of various types of working fluids and geothermal source temperatures on net power production, cooling capacity, energetic efficiency, exergetic efficiency, and exergy irreversibility are carefully assessed in detail. Under the base operating condition of this novel power cycle, R600a produces the maximum net power output and exergy efficiency of 324.5 kW and 32.98%, respectively, while exhibiting the minimum exergy destruction of 660.8 kW. In contrast, R717 offers the maximum cooling capacity and energy efficiency of 344.7 kW and 22.81%, respectively. It can be observed from the parametric study that increasing the geothermal source temperature from 160 °C to 200 °C increases both the power and cooling output for all the working fluids. Higher source temperatures cause higher exergy destruction and lower exergy efficiencies because of greater irreversibilities within the system. It is thus concluded that the choice of working fluid plays an important role in determining the thermodynamic performance of the system. R600a has shown the highest exergy efficiency, while R717 has emerged as a better choice for cooling applications.