Numerical simulation and energy, exergy, economic and environmental (4E) analyses of a geothermal heat exchanger equipped with special conical turbulator containing hybrid nanofluid

چکیده مقاله

Renewable energy sources are crucial for combating climate change and ensuring sustainable development. Geothermal energy, in particular, offers a uniquely reliable and continuous power supply, independent of weather conditions, significantly reducing greenhouse gas emissions while utilizing the Earth’s immense internal heat. In this study, a W-shaped geothermal heat exchanger with an elliptical cross-section, equipped with perforated conical turbulators and filled with a Cu-SiO₂- MWCNT/water ternary hybrid nanofluid for the first time, is numerically simulated using CFD. The k-epsilon realizable turbulence model and mixture model are employed for turbulent and two-phase flow, respectively. This climate study was carried out assuming a warm arid climate at a depth of 1.5m from the ground. The results obtained from this study show that by increasing the input speed in the geothermal heat exchanger and the volume fraction of nanoparticles, the thermal performance and pressure drop increase in all stages of the numerical simulation. Also, the maximum thermal performance of the geothermal exchanger is when using the turbulator and 3% volume fraction and Reynolds number of 5000. In addition, the thermal–hydraulic evaluation index is greater than 1 in all cases. Therefore, using a turbulator in a geothermal converter is desirable in terms of the performance evaluation criteria index. In addition, increasing the Reynolds number and increasing nanofluid volume fraction at the entrance of the geothermal heat exchanger increases the exergy efficiency. Analysis 4E (Energy, exergy, economic and environmental) has been performed for the system. The highest exergy efficiency was 32.34%. The payback period was 6.23 years, levelized cost of energy (LCOE = 0.0856 $ kW−1h−1) and the carbon dioxide reduction rate was 0.956 tons/year.