Numerical Simulation of Geothermal Heat Exchanger Equipped with Turbulator Containing a Two-phased Hybrid Nanofluid

Abstract

This study simulated a geothermal heat exchanger numerically using computational fluid dynamics (CFD). The geothermal heat exchanger is equipped with a turbulator and a simultaneous combination of a turbulator and a vortex generator filled with a two-phased MWCNT-Cu/water hybrid nanofluid. Geothermal heat exchanger geometry is analyzed 3D using Ansys Fluent version 2022 software. In order to model viscosity and two phased flow, K-Epsilon Realizable turbulence model and mixture model are used respectively. This climate study was carried out assuming a warm semi-arid climate for Isfahan province at a depth of 1 m from the ground. The results obtained from this study showed that by increasing the input speed in the geothermal heat exchanger and the volume fraction of nanoparticles, the thermal performance and pressure drop increased in all stages of the numerical simulation. Also, the maximum thermal performance of the geothermal exchanger, when using the combination of turbulator and vortex generator, was 4% volume fraction and Re = 32000. In addition, the thermal-hydraulic evaluation index was greater than 1 in all cases. Therefore, using a turbulator, a vortex generator, and a combination of a vortex generator and a turbulator simultaneously in a geothermal converter is desirable in terms of the PEC index. In addition, increasing the Reynolds number at the entrance of the geothermal heat exchanger increases the exergy efficiency.