Optimization of turbulent flow heat transfer in a 3D cubic shell heat exchanger using non-mixture multiphase nanofluids

The present work investigates the turbulent flow heat transfer in a three-dimensional cubic shell and tube heat exchanger employing non-mixture multiphase nanofluid, specifically SiO₂-H₂O. Computational Fluid Dynamics (CFD) simulations were carried out to study the variation of both shell and tube inlet velocities and optimize the thermal performance of the exchanger. The Reynolds-averaged Navier-Stokes (RANS) solver and the k-epsilon turbulent model were employed, and the results were validated against experimental data and numerical results from the available literature. Key results showed that reducing the tube’s Reynolds number to 75 % of the shell’s inlet velocity yields the highest total heat transfer rate of 26,692 Watt, marking an impressive 54 % improvement over the baseline conditions. Lowering the tube inlet velocity improved the fluid residence time leading to enhanced heat absorption and higher performance. However, reductions in either fluid Reynolds number below 75 % led to diminished heat transfer rates, attributed to reduced turbulent kinetic energy and less effective thermal mixing. These findings provide valuable insights into the role of nanofluids in boosting heat transfer efficiency, offering practical implications for industries seeking to enhance energy conservation and optimize thermal systems such as air conditioning and heating systems, thermal power plants, automotive and aerospace industries, as well as solar thermal power plants.