Two-phase Simulation of Nanofluid in a Heat Exchanger in Turbulent Flow Regime

Abstract

Turbulent forced convection of different nanofluids consisting of -Al₂O₃/water and CuO/water in a concentric double tube heat exchanger has been investigated numerically using two-phase approach. Nanofluids that are used as coolants flowing in the inner tube while hot pure water flows in outer tube. The study was conducted for Reynolds numbers ranging from 20,000 to 50,000 and nanoparticles volume fractions of 2, 3, 4 and 6 percent. The three-dimensional governing equations are discretized using the finite volume approach. Although, two different nanoparticles have almost the same thermal conductivity but using CuO/water nanofluid showing better enhancement in heat transfer that proves thermal conductivity is not the only reason of enhancing heat transfer. Also, CuO/water showing bigger shear stress in comparison of -Al₂O₃/water nanofluid. As a result, nanofluids show higher overall heat transfer coefficient in comparison of pure water.